# Locking your prop



## Cruisingdad (Jul 21, 2006)

Serious questions:

How many of you put your engine in reverse after you turn it off to lock the prop so it won't spin while you are sailing, of course.

- CD


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## brak (Jan 5, 2007)

Is that a "right thing to do"? 

I always wondered about prop/shaft self-spinning vs. impact on packing, especially "dripless" systems. But, at the same time, I never thought locking might be a good idea either - wouldn't this put a lot of strain on the transmission, which at that time is not being cooled or lubricated (I am not a specialist on transmissions, of course). 

And wouldn't this create more drag?


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## Cruisingdad (Jul 21, 2006)

Brak,

Before I answer your question, I would like to hear others and their comments.

Just tell me what you do, and why. By the way, there is no wrong answer on this... it is very debated.

- CD


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## brak (Jan 5, 2007)

Well, I do nothing - just let it freewheel, and occasionally (when I poke my head in the compartment) touch the packing and hope it isn't hot. On my previous boat (Beneteau 285) the entire packing system was basically a rubber cone over the shaft (Volvo invention), so heat would be pretty detrimental to that. 

If I had a 2 blade prop, I might have bothered with aligning it behind the keel and locking, but with 3 big blades - I don't know what the point would have been.


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## bestfriend (Sep 26, 2006)

Its not the packing gland, its the cutlass bearing that will wear more. How much more, who knows? I put it in reverse, but remember to go back to neutral before you start it up again.


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## Giulietta (Nov 14, 2006)

CD

I put in reverse to help fold the prop.

Even before I had folding props, I used to put in reverse.


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## Rickm505 (Sep 4, 2005)

I sail with my props freewheeling, as it's the lowest drag configuration. It's also allowable with my Yanmar transmissions as they have separate oil reservoirs.

It's my understanding that some transmissions share the engine's oil supply. In that case, if the engine isn't running, the oil pump isn't lubricating anything and you ought to lock your transmissions while sailing.

Rick in Florida


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## Cruisingdad (Jul 21, 2006)

By the way, regarding the forward, one of the folding props (is it Maxi's????) require it to be in forward. That was why it is there... this is not a trick survey.

- CD


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## Faster (Sep 13, 2005)

We've always locked in reverse while sailing - with folders to ensure that it folds, with fixed props to stop the spinning.

The drag issue has been hotly debated (ie whether there's more drag freewheeling vs locked) but aside from that, I find the noise of the free wheeling shaft annoying and can't imagine that it does any good for the cutlass bearing, the shaft packing/seal (of either type) nor the transmission internals that spin with the shaft.

And yes, do remember to put the gear to neutral before starting!!


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## jerryrlitton (Oct 14, 2002)

All I can say is from my flying experience, a prop turning in flight (no thrust, engine off) produces more drag then one that has stopped. (Both fixed pitch) I used to think water acted the same as air in those situations. Except for the density of course....am I wrong? 

Jerry


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## Rickm505 (Sep 4, 2005)

Faster

I had thought that the MIT paper on propeller drag ended that controvery years ago.

Rick in Florida


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## jerryrlitton (Oct 14, 2002)

What did the MIT paper say? I would like to know.

Jerry


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## Giulietta (Nov 14, 2006)

jerryrlitton said:


> All I can say is from my flying experience, a prop turning in flight (no thrust, engine off) produces more drag then one that has stopped. (Both fixed pitch) I used to think water acted the same as air in those situations. Except for the density of course....am I wrong?
> 
> Jerry


Jerry, you're right. The drag produced by a plane or marine prop walking is the same produced by the disk it prescribes.


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## MarkMiner (Oct 10, 2006)

The owners manual for my boat, which has a saildrive, says to leave it in neutral for a fixed prop, and in reverse for a folding prop. I have tried it both ways (I have a fixed prop for now), but have decided to do what the manual says to do, and leave it in neutral.


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## sailingdog (Mar 19, 2006)

I lift the OB out of the water and tilt it up...the prop and everything else is clear of the water.. no drag, no problem. 

A point I'd make is that some transmissions don't do well with a free-wheeling prop...others don't care.


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## jerryrlitton (Oct 14, 2002)

MarkMiner said:


> The owners manual for my boat, which has a saildrive, says to leave it in neutral for a fixed prop, and in reverse for a folding prop. I have tried it both ways (I have a fixed prop for now), but have decided to do what the manual says to do, and leave it in neutral.


By all means do what that manual say but I still would like to have a more of a difinative answer as to the drag issue. I think Giulietta hit it on the head ref the drag plate item.

Jerry


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## Rickm505 (Sep 4, 2005)

Now there's a 2nd post so I should be more thorough on this topic. 

In 1994 Beth Laurie and Todd Taylor of M.I.T. took this issue head on. Together they wrote a research paper profiling this very subject which is well known in the sailing community. They used 10 popular propellers in the comparison. 

The results were shown in a series of graphs. In short, freewheeling was lower drag than locking props, and the lowest drag available was from Maxiprop 2 blade feathering prop.

If anyone wants a copy of this paper, please email me and I send you a copy.

Rick in Florida


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## tagster (May 7, 2007)

I thought that the pertinent thing to do was to leave it in neutral...especially when having a big wheel on the prop belted to an alternator so you could get some power in exchange for your drag...

As far as damaging the stuffing housing or packing...why should that be a concern? Isn't the housing and packing designed so the shaft can spin inside of it? Isn't that what happens when you're under power?


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## Rickm505 (Sep 4, 2005)

It's the transmission you're concerned about not the packing or cutlass bearing. If your transmission doesn't have an independent oil supply your engine manual will require you to sail with the propeller locked, transmission in gear. 

Rick in Florida


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## bestfriend (Sep 26, 2006)

Rickm505 said:


> It's the transmission you're concerned about not the packing or cutlass bearing. If your transmission doesn't have an independent oil supply your engine manual will require you to sail with the propeller locked, transmission in gear.
> 
> Rick in Florida


With the tranny in neutral the drive is disconnected, so more specifically, you are talking about wearing the rear seal on the tranny?
If you are not racing or trying to go fast, you may as well put it in reverse.


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## Rickm505 (Sep 4, 2005)

Jerry

Check your email

Rick in florida


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## Rickm505 (Sep 4, 2005)

I guess the concern is wearing out whatever needs lubrication in the transmission

Rick in Florida


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## Giulietta (Nov 14, 2006)

OK...lets get a grip, ok???

we're discussing two things here, that somehow got all mixed up....

1) Drag caused by a prop when engine is off
2) Damage to drive due to prop moving.

The answer for 2 is easy...I don't care what Yanmar or Volvo says (Yanmar says in my manual its not necessary to reverse when stopped....*AND I DO*, because I can hear the damn thing rotating if I don't, as my prop will not close all the times. No matter what they say, the less that crap spins the better. By the way, one on my crew is the official Yanmar agent and he says...screw Yanmar...get it in reverse..they just want to sell you a new Saildrive). If a prop is rotating while engine is off its bad....I don't care what your arguments are.

Now for 1)....well.....

OK...if the drag caused by a stopped prop did not cause adverse effects;

a) I would have one that spun around already, and so would all the Transpac 52's, and I am sure someone in the ACC would have one already.
b) All racing boats would not have feathering props, but nice round free rotating props.
c) Airplanes would not need to feather their props when engine is off. I don't care what Prof. Kalamazoo did at MIT, when I did my multi-engine commercial (yes America I have one), and I had to spend many hours over the skies of Lubbok Texas in an old 310, and, until you feathered that right engine that the instructor cut off in the air...I had to keep both feet on the rudder pedal <dead engine -dead foot>), as hard as I could, then after it feathered, drag would reduce, then we could trim the rudder....

Do what you want....a prop spining gives me less speed I've seen it.


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## bestfriend (Sep 26, 2006)

On both terms, I agree. There are laboratory tests, and all kinds of formulas, but one thing you learn in basic physics is that some things defy the laws of physics. Sometimes common sense is mightier than the computer analysis.


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## MikeMoore (Jul 9, 2002)

*Drag and Trans Types*

back in the dawn of time i read a test where they dragged a prop with a tensionometer both spinning and locked the spinning prop dragged more. 
The bearing depends on a lubrication wedge which forms as the rpm goes up slow speeds tend to have contact rubbing and would wear the cutlass much faster.
Dripless seals were developed for submarines and we had backup packing seals on every dripless seal. once they fail it leaks a lot and usually you have to remove the shaft to replace very bad for a cruiser far away from boatyards. 
The older transmissions like Paragon lock in forward gear but had a brake band and planatary gears for reverse and don't lock. The newer Trans depend on a differential torque to lock the clutch so you have to go in reverse to cause the clutch to lock when sailing.
Of course any rotation will cause wear that is a given.


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## Rickm505 (Sep 4, 2005)

Such Passion!! 

But now I'm confused. How is it that you feather an aircraft prop and drag is reduced. But you argue that if you feather a 2 blade marine prop, drag is increased? Is it just in reducing the pitch?

Thanks

Rick in Florida


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## capttb (Dec 13, 2003)

Always, Hurth Transmission, says so in the book, also what Giu says.


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## Rickm505 (Sep 4, 2005)

*M.I.T. Is obviously wrong!!*

Well, M.I.T. must just be wrong!!



Offer still stands, anyone who wants a copy, shoot me an email and I'll email it, as it's worth the read.

Rick in Florida


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## Giulietta (Nov 14, 2006)

Rick..

I spent a few days at MIT once...does that make me right in everything? In fact I have a very good friend (he was my bowman in 470 in early 80's) that was a maths teacher there for 9 years, and he kept admiting errors in a lot of stuff he did!!

I am not discrediting your source at the MIT, I have not read it, you may send it to me, please, I'll gladly read...then think about it...just because its the MIT does not mean its a 100% sure thing. 

I did not test 10 different props with research funded by I don't know who....there's MIT, a fine School by the way...then..the school of life, I have been sailing since 1974. And allways allways put it in reverse, and will do, despite of what I will read in your paper.


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## trantor12020 (Mar 11, 2006)

I set mine to reverse whenever I sail. Not that the gear box will be screwed or cutlass/packing gland wears out, its that I can't stand the thumbing noise with the free rotating 2-blade prop. I've sensitive hearing & feel. Maybe when I get my re-pitched 3-blade in, the noise would stop, maybe.


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## Rickm505 (Sep 4, 2005)

I figured out a way for you guys to take a look at that MIT paper on their propeller drag test.

Click on this:

MIT Propeller Drag Test

Rick in Florida


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## Giulietta (Nov 14, 2006)

Thanks Rick Reading now...


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## Giulietta (Nov 14, 2006)

OK Rick

I read it
They clearly say that the reduction is -21 pounds, BUT assun«ming that the shaft etc. produce no drag, which they do.

However, bellow table 14, says CLEARLY, even thy don't recommend doing that.

I'll stay with reverse when engine off and sailing.

By the way...THANK YOU...that study just showed me I know how to choose a propeller. GORI rocks!!!


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## jerryrlitton (Oct 14, 2002)

I need to add something concerning the airplane thing since that is all I know. When a prop is feathered not only does it quit spinning (which reduces drag) BUT the blades are now knife edged to the wind which ALSO reduces drag. Now back to a single engine airplane with a fixed pitch prop. If the engine quit the engine would keep on rotating due to the air passing over the prop but if I were to raise the nose of the aircraft this reducing speed the prop would stop. I would then lower the nose to achieve either best glide speed or minimum rate of decent but the end result is the prop would be producing LESS drag since it is now stopped. What CG said about tension meter both spinning and locked the spinning prop dragged more bears this out. Time for a beer.
Rick, I am reading your paper now. Thanks for sending it...

Jerry


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## Valiente (Jun 16, 2006)

Giulietta said:


> OK Rick
> 
> I read it
> They clearly say that the reduction is -21 pounds, BUT assun«ming that the shaft etc. produce no drag, which they do.
> ...


I have a Gori 11 x 8 on my Viking 33, and it's a beautiful thing, especially in light airs. This fall, I am putting on my four-bladed VariProp, from which I expect great things. You have to get used to a slightly different way of shifting, but I've seen a similar boat to mine with a big AutoProp maneuvered like a minivan in a tight slip, and I was suitably impressed.


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## Rickm505 (Sep 4, 2005)

Giu,

You're welcome. 

Now as to Table 14....I pay particular attention to this table because I don't have one propeller in the water... I have two. So, I have to take these numbers and double them. 

In my case, I of course freewheel the props as it only makes sense, as my Yanmar transmission allows this. This was my point earlier in the thread. 

As for your Gori Prop?... It's a very good prop, and one of these days I'll buy a couple of them.

Peace

Rick in Florida


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## Rickm505 (Sep 4, 2005)

Valiente

Your Prop is a thing of Beauty. It's also the shiniest prop I've ever seen!!

Rick in Florida


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## sailingdog (Mar 19, 2006)

RickM505-

Might want to look at the Kiwi Feathering prop...it'll set you back fewer boat bucks...


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## brak (Jan 5, 2007)

Actually, if I read the paper correctly, they compare 3 situations:
- propeller spinning, moving forward (simulating boat in fwd movement under power)
- propeller spinning in reverse (simulating "backing down")
- propeller locked - simulating sailing with propeller locked

Nowhere in this paper did I see a comparison of "sailing with propeller freewheeling", i.e. water moving forward, propeller unlocked. So - I am not sure what to make of it. 

That said, it means a big 3 blade prop puts 80lbs of pull on the boat when fixed - thats a lot of drag. Feathering prop is definitely a good thing.


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## Giulietta (Nov 14, 2006)

brak said:


> Feathering prop is definitely a good thing.


But folding is even better. For me off course....


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## Giulietta (Nov 14, 2006)

Val....hey I know that prop!!!!   

Where did I see that before??


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## Rickm505 (Sep 4, 2005)

Brak

Page 19 "Drag under sail" which refers to table 14 that we've been talking about. It plots propeller drag vs forward speed in knots.

Rick in Florida


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## Giulietta (Nov 14, 2006)

Rick, if you have Yanmars...trust me. Put them in reverse.


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## T37Chef (Oct 9, 2006)

We're loving that Autoprop...thanks for the article Rick


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## blt2ski (May 5, 2005)

while waiting for the report to download and print........
Question to whomever, being as I have never been told, nor thought about having the motor in reverse per say, or ANY of the other comments here, be them good or bad or...... 

i ahve a max prop, while not in reverse, I typically sail with the button keeping the tranny enguaged. Is this teh same as in reverse? Or do I need to put the throttle in the back position, as I will leave up upright in nuetral.

I have an 85 yanmar motor. If I get a chance to sail this weekend, I may have to see what happens, as I will have a knot meter that works for the first time in two yrs of owning this boat.

marty


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## MikeMoore (Jul 9, 2002)

feathering props don't drag. if you have one even putting the newer trans in reverse wont lock it up since there is no differential torque nothing happens This apllies to fixed blade props


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## MikeMoore (Jul 9, 2002)

sorry I ment to say this discussion about locking the shaft applies to fixed blade props


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## TSOJOURNER (Dec 16, 1999)

Skip says he purchased an engine that would allow for free spin without harm. I think this was in case he wanted to harness extra power for something else. We have two pully wheels on the engine. Anyway, this past weekend when we came in from sailing and were in the downtown harbor I was at the helm and Skip was going to take the sails down. I was unable to get the geer shift to go from reverse to neutral so I could start the engine. It had locked up and would not be freed by me or Skip. Skip had to go into the engine room and tap it free. 
On monday, I happened to see our Yanmar guy at the dock and asked him about it. He says Skip should leave it in neutral and then go to engine room and devise something that would stop it from spinning. Do not put it in reverse any more. 
Kathleen
aboard
Schooner MISTRESS
PS I sure hope this is helpful


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## Giulietta (Nov 14, 2006)

SchoonerMISTRESS said:


> Skip says he purchased an engine that would allow for free spin without harm. I think this was in case he wanted to harness extra power for something else. We have two pully wheels on the engine. Anyway, this past weekend when we came in from sailing and were in the downtown harbor I was at the helm and Skip was going to take the sails down. I was unable to get the geer shift to go from reverse to neutral so I could start the engine. It had locked up and would not be freed by me or Skip. Skip had to go into the engine room and tap it free.
> On monday, I happened to see our Yanmar guy at the dock and asked him about it. He says Skip should leave it in neutral and then go to engine room and devise something that would stop it from spinning. Do not put it in reverse any more.
> Kathleen
> aboard
> ...


I don't want to sound rude or anything, but here is what I think...

*STAY AWAY FROM THAT YANMAR GUY!!!!!!!!!*

So your throtle gets stuck, and this guy, instead of repairing, or telling you guys how to repair, or give you an obvious reason or fix, gives you a *PERFECT SOLUTION...*

Well if your throtle sticks when in reverse, DON'T PUT THE ENGINE IN REVERSE???????????????????????????????????????????????

What the hell is wrong with that guy???? what kind of advise is that???

What happens next time you are reversing with the engine, and the throtle sticks again???? Or you don't reverse???

Really....I am completely (I don't know the word)...that guy is really at the top of the list for me....

I will use that as a joke amongst my freinds....

UNBELIEVABLE...and I guess you asked a real Marine Engine mechanic for a second opinion???

Darwinism at its best.....

That's like going to the Doc with a broken finger, and instead of fixing it he tell you...well stop touching your finger and don't use your hand....

OHHHH My!!!! Jaysus, Mary, and Joseph, the Saints and Our Lady Of Fatima!!!!!!!! (All together at least 4 times)........


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## sailortjk1 (Dec 20, 2005)

The past three weeks my transmission has been engaged with the motor running. NO wind.


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## TrueBlue (Oct 11, 2004)

Kathleen - Did you actually think *not *ever putting your boat's engine in reverse is a smart solution to a sticking throttle problem?

To reduce wear on seals, my engine stays in reverse when sailing - hydraulic trannies freewheel otherwise.


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## Rickm505 (Sep 4, 2005)

*Puzzled*

Forgive me for joining in again, but I'm puzzled by some of the info posted here. Transmissions are made to transmit power, that's their one and only job. In the course of doing their job, gears spin and seals , well, they seal. The transmissions don't break, they spin.

Why would anyone think that if they are spun by the engine, everything is OK, but.. if they are spun by water moving the prop when sailing in neutral they will break?

Actually, there is one scenario that will break a tranny if spun by the prop under sail. This scenario is behind everyone being told not to do it.

Many engines lubricate the transmissions out of the engine sump. If the engine is off, there isn't any lubrication to any of the parts within the transmission case. This will cause a failure. Other engine/transmission combinations have an independent source of transmission oil. These transmissions are as well lubricated being spun by the engine as they are being spun by the prop. It's what they were made to do.

The Yanmar mechanic was correct. This isn't a cause for failure on Yanmar transmissions, switching them in and out of gear wears the internal cones smooth and thus causes a failure.

However, this may not be true for other engine/transmission combos.

Best to check the manual

Rick in Florida


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## Anjin-San (May 15, 2006)

Well, wouldn't it depend on the transmission? Some are hydrolic, other mechanic. A saildrive and a shaft must have different behavior too, don't they?


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## Rickm505 (Sep 4, 2005)

You're right, it's best to check the manual. This contention arose when I posted that I sail in neutral with my Yanmar engines. I can't speak for any other engines other than my own.

Rick in Florida


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## kptmorgan04 (Apr 10, 2007)

glad this discussion came up because I was about to ask it after my first big sail from annapolis to cape may when we were making anything over 4-5 kts under sail the prop was definitly spinning a lot and as it is a new boat to me I didnt know what to make of it. we were in neutral the whole time, the thought to put it in reverese did come up, but i didnt know if this would be good for engine or transmission or whatever part it would be associated with the prop spinning.

I dont care about drag, I am cruising not racing. its a three bladed non-feathering prop. 
so basically I have gathered from reading this that it is somewhat normal practice to put gear in reverse to stop prop spin and this shouldnt do any damage to parts below? 
please correct if I am wrong. 
thanks for the help.


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## sailortjk1 (Dec 20, 2005)

SchoonerMISTRESS said:


> I was unable to get the geer shift to go from reverse to neutral so I could start the engine. It had locked up and would not be freed by me or Skip. Skip had to go into the engine room and tap it free.
> On monday, I happened to see our Yanmar guy at the dock and asked him about it.


Did you ask the Yanmar guy what to do when the gear shift is stuck in reverse and the engine is running? Not a good time to be trying to "Tap" it free.


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## Cruisingdad (Jul 21, 2006)

Ok,

Here comes CD's opinion, sure to raise the ire of may of you.

First, I hate to say it, it will ruin my reputation, but I agree with Giu. Reverse. If you are going out for a short hop or something, it probably would not even matter. But as a rule, reverse.

Now, as far as getting stuck in reverse, does Schooner Mistress have a Yanmar??

Common problem with many of them. I believe the 3E will do that, and my 4e will do it too sometimes. Here is what you do... ready: START IT IN REVERSE.

Now, here come all the coments about why to do and why not to... but the truth is that there is so much torque on a diesel already, I do not see that causing some catastrophic failure. In my very humble opinion, the reason Yanmar has a neutral switch (or others) is becuase of the idiot factor. 

What is the idiot factor??

THat is where you are coming into the dock (or some approach) and reach down to start your engine in gear and it is at full throttle. Goodbye dock, or whatever you were approaching. Thus, make sure you are throttled back. 

I don't agree with Giu on everything... especially his dodger which I think looks great. But put it in reverse, as a rule... or just don't worry about it. Truth is that you will need to put some pretty good miles under that keel for it to do damage either way.

The point of this entire poll, which I hope to continue, is to make people aware of the practive and to see who really does it and who does not care (or who do not know).


- CD

OK... let the hate replies about starting in reverse come forth!!


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## Valiente (Jun 16, 2006)

Rickm505 said:


> Valiente
> 
> Your Prop is a thing of Beauty. It's also the shiniest prop I've ever seen!!
> 
> Rick in Florida


Thank you. The small bar of gold it costs us was even shinier.


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## christyleigh (Dec 17, 2001)

Cruisingdad said:


> Common problem with many of them. I believe the 3E will do that, and my 4e will do it too sometimes. Here is what you do... ready: START IT IN REVERSE.


Yup.... it's that simple. Been doing it for years.


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## Cruisingdad (Jul 21, 2006)

DOn't ask me for the technical, in-depth, mechanical and physics of it, but basically prop puts so much torque on the tranny that it gets hung there. It is not uncommon, honestly. If you think spinning that little prop is tough on a starter, why don't you give turning that diesel over by hand a try. Let's see, what does a Westerbeke 42b put out... about 550 psi, cylinder???? You think the starter is really going to feel that free-spinning prop in water???

- CD

PS JUST MAKE SURE YOU DO NOT HAVE IT THROTTLED UP.


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## cardiacpaul (Jun 20, 2006)

Dad, 

First time I did that on a sea-trial, I thought the owner of the boat was going to have a heart attack... (not like THAT scared me LOL) 

He had no idea.


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## scolil (Mar 9, 2007)

sailingdog said:


> I lift the OB out of the water and tilt it up...the prop and everything else is clear of the water.. no drag, no problem.


I will stick with this one


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## TSOJOURNER (Dec 16, 1999)

Yes, I have a brand new 56 hp desil Yanmar which Skip installed.
No, the engine was not running at the time the gear shift got stuck. We were getting ready to take the sails down and wanted the engine running because we were in the downtown harbor.
Yes, we decided to unstick it before we attempted starting the engine.
Yes, our Yanmar guy is a good guy.
No, it is apparently not ok to have this one in reverse and that is why he suggested what Skip had already decided to do. Put a locking system on the shaft???? so it would not cause drag while in neutral.
Sorry if I caused a ruckus again. I think I should not be trying to operate this site without a Master Shipwright standing right next to me. I am trying, but ...... 
Kathleen
aboard
Schooner MISTRESS


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## tomaz_423 (Feb 5, 2006)

I have my boat in charter at certain company (no advertising) with many bases all over the world.
Their policy (and that is what they instruct their clients) is: 

1) Some transmissions tolerate free-wheeling and some not. To be on a safe side (not knowing the tranny type): ALWAYS put in reverse when sailing. 
2) No problem if you free-wheel for up to one hour after the engine was running (there is still enough lubrication in the gears no mater what type of transmission you have (they do not actually tell you this unless you ask) 
3) If stuck in reverse (what is very common on Yanmar) just simply start the engine with gear in reverse and shift then. No problem.

As they have hundreds and hundreds of boats to maintain they should know what is bad for the transmission/engine.
About drag: They do not care as they are not the ones sailing, they just have to fix problems. 

I tried to do some measurements with locked or free-wheeling prop (3 blade fix) and I "think" the free wheeling is less drag, but it is not really measurable on a speed log or GPS - a small puff or wind or wave change influences the measurements more. 
The noise of free spinning is a good argument to put it in reverse (specially if you want to sleep in aft cabins).


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## tomaz_423 (Feb 5, 2006)

Kathleen, 
I was told that Yanmar gets stuck in reverse (or in gear) only if the engine is not running. My experience confirms this.
It never happened when the engine was running.
The reason is lack of any rotation to allow the gears to realign. As soon there is some rotation (engine running) there should be no problem.

Locking system on the shaft is a good idea until the day you forget to unlock it. And that would be at 3am on a rainy, dark night... So make sure it is not too strong, or have weak link. You want the damage on your locking system and not on the shaft or engine.
Also I think it is a safety factor if you can unlock from the helm.
If you ever find yourself in an emergency where you need the engine fast the last think you want to do is going down below and mess around the engine. 
P.S. Good to see your refreshing posts. It brings some more live to the site.


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## poopdeckpappy (Jul 25, 2006)

I always put it in reverse


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## SimonV (Jul 6, 2006)

I have always locked it in reverse, what with the constant DEEP sound EEEEEE - OORRRRRRRRR of the Auto pilot, I do not need the constant rumble of the prop shaft.


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## mpraca (May 12, 2001)

SchoonerMISTRESS said:


> I was unable to get the geer shift to go from reverse to neutral so I could start the engine. It had locked up and would not be freed by me or Skip. Skip had to go into the engine room and tap it free.


I don't know why it would get stuck but one time I had a problem and you should check if it is not the same. 
At one point I started to have difficulty engaging forward. On one day finally, I could not get it into forward and Ihad to go down and readjust the lever, and of course this happend when it was blowing 30 knots. When I got to the slip and tried to set it in reverse it stayed in forward and I ramed the dock. That was an indication that something had gone wrong so I finally decided to investigate. 
I found that my transmission cable was rubbing on the steering chain and wore through at one point. When that happened the cable (actually it's a wire) was poping out of the worn jacket when it was pushed into forward. It poped back when moved into reverse. One day I was unable to engage forward. So I had to replace the cable. 
You may not have that problem, but it's a good idea to understand why it won't work properly before it gets worse.


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## TSOJOURNER (Dec 16, 1999)

Someone else here posted saying that when it was put in reverse, after the engine had been shut off, the teeth locked in a position which made it not want to free itself easily. Had we either started the engine or as Skip did push it a bit to align the teeth better, there was no longer a problem. Accoriding to our manual we should not be putting into reverse. Check you manual for your transimission. I understand that our engine can be put in neutral without harming the tranny, however, as has been stated by a few of us, the noise is a bit annoying. All we want to hear in the wind in our sails, therefore, designing some simply, easy to remove locking system will make sence for us while we cruise outside and up the coast, hopefully later this season, assuming the house (land anchor) does sell at the end of this month as scheduled. 
Kathleen 
aboard
Schooner MISTRESS


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## SailinJay (Dec 6, 2002)

CD--

Maybe it's a Catalina thing (g)<G>, but my dealer's primary commissioning/maintenance guy, on the day he did the shakedown with us back in March 2003 on our 350, told me to always put it in reverse when sailing, and I always have. However, the manual for my Universal M-35B states the following:

*When Under Sail or Being Towed*

Rotation of the propeller without load, such as when the boat is being sailed, being towed, or anchored in a river, as well as operation of the engine with the propeller stopped (for charging the battery), _will have no detrimental effects on the transmission _[italics added].


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## Rickm505 (Sep 4, 2005)

*DC generators*

I've been looking into the possibilty of adding DC generators to my twin shafts for battery charging while under sail. There do seem to be a couple of products out there in the marketplace, but I haven't read of anyone evaluating or commenting on the feasability. I'd be interested to learn if 3 or 4 charging amps could be generated at say 6 knots with a 2 blade prop.

Rick in Florida


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## ultrablitz (Oct 4, 2006)

*velvet drive hydraulic transmission*

Should I put a brake on the prop shaft or let it spin? I know in a car with a auto-tran it hurts the transmission.
Help! Don


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## TrueBlue (Oct 11, 2004)

I've got a Borg Warner, Velvet Drive transmission and the PO told me he always put the prop in reverse when sailing - so I followed suit.

However, I just did a quick online check with a certified marine mechanic's site and found conflicting information:



> 1-1. Every Velvet Drive marine transmission is self-contained, having its own sump and hydraulic pump separate from the engine. The Rear driven pump affords assurance of positive lubrication.





> 3-4. Freewheeling
> It has been determined by tests and practical experience that all Velvet Drive marine transmissions can be free-wheeled without risking damage in sailing or trolling applications. Caution should be taken to be sure that proper oil level is maintained prior to freewheeling as well as normal running. Freewheeling one propeller of a twin engine boat at trolling speeds will not cause damage to the transmission connected to the freewheeling propeller.


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## TSOJOURNER (Dec 16, 1999)

*Locking Shaft (or Not?) for a Max-Prop*

Here is the Max-Prop Owner's Manual instruction:

PROPELLER USE The Max Prop works automatically. By putting the engine in gear the blades will engage in either forward or reverse. The best way to feather the propeller is; 
•	Power at 2 to 3 knots in forward. 
•	Kill the engine while still engaged in forward. 
•	When the engine has stopped, if the shaft is still spinning engage the transmission in reverse to stop the freewheeling. 
You can check to see if the propeller is feathered or not by taking the engine out of gear. If the propeller is not feathered the shaft will freewheel like with a fixed blade propeller.
In that case start the engine again and repeat the three steps. If your propeller has been greased properly it will feather in a fraction of a second as soon as you stop the shaft from freewheeling. Once the prop is feathered, you can either leave the transmission in gear or out of gear, it does not matter. DO NOT kill the engine while in reverse. In this case the blades will be in the reverse position and will not feather. You can actually use this feature to drive a shaft alternator.
IMPORTANT: If the Max-Prop is installed on a vessel that can attain sailing speeds over 15 knots, it is MANDATORY to return the transmission to neutral while sailing. If the transmission remains engaged and the propeller were to open (from hitting an object or water flow) it may turn the engine, flooding it, resulting damage to the engine.


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## Zanshin (Aug 27, 2006)

Jerry - Fluid dynamics are quite different between compressible (air) and non-compressible (water).


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## Rockter (Sep 11, 2006)

On the olde Volvo, I just put the gearbox into reverse. If not, you have to listen to a scuff-scuff-scuff sound as the prop spins and it will drive you round the bend. It would be a very good way of generating power though... at moderate speeds, there is some serious torque there but I would worry about wear, long term.

I have marked the shaft so that on a very long haul, we can align the two blade prop with the long keel to minimise drag.


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## sailusvi (May 3, 2005)

You must determine weather your tranny is hydraulic or manual before deciding on the decision  
Hydraulic transmissions will more than likely need some type of brake to stop rotation.


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## Iflyka200s (Oct 3, 2007)

I can't add much about Marine props but I can shead some light on airplanes. I have an ATP and fly (have flown) a King Air 200 about 800 hours. I am a corporate pilot.

The King Air 200 has a Pratt & Whitney PT6-42 engine that DOES have a transmission (of sorts) I had a high pressure fuel pump fail in flight and I got a chip detector light which suggusted shutting down the left engine. Even fully feathered, the prop DID rotate (not a lot but it did spin) In the simulator we have to fly every year, the airplane will not fly unless the prop is feathered so there is some drag.

As far as the marine prop's go. in the 80's I used to crew a 39 Yankee and a 30 Tartan, both owners had painted a mark on the prop shaft indicating when the folder (remember 70-80s tech here) was in trail meaning both blades left and right to each other. Then we wrapped a rag around the shaft and put a pair of vice grips on the shaft to hold it.

In order to keep from making a vice grip size hole in the boat by starting it with the vice grips holding the shaft, we would put the ignition keys around the handle of the vice grips so you had to take the key OFF the vice grips to get the key back. I don't know if it made one bit of difference to our boat speed as the Tartan 30 was pretty slow (I did LOVE that boat though) The Yankee won a bunch of races but the guy sailing it was pretty sharp.

Great topic all!


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## jimmalkin (Jun 1, 2004)

OK, CD - since this is a poll and a fascinating thread. Yanmar 4JH-DTE; maxiprop. I put it in reverse while sailing and pull the throttle back. In an emergin-stroke, I start it in gear.

Have been thinking about a gori prop to reduce Maine Lobsterpot tangle around extended (but feathered) blades, but decided the bloody cold water untangling bath saves what Sailing Dog calls "boat dollars."


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## MidLandOne (Sep 9, 2007)

Volvo cone clutched gearbox with fixed pitch 3 blade prop -

We always sail with it locked in reverse if only to stop the noise (sailing is supposed to quiet else should get a power boat  ).

Manual states leave in neutral if a fixed pitch prop and lock in reverse if not - commissioning engineer said to disregard and lock, and if jambs just start the engine (we find that on the occasional time it does jamb that just a quick crank of the engine with no fuel so doesn't even start always frees the box).

Prop designer states that our prop has least drag when locked and I guess he knows - it is a high aspect ratio 3 bladed (long skinny blades) prop optimised for sailboats.

As an aside, the experiments conducted in the MIT lab did not test locked props at all even though there are continual claims that they did (a simple read of the paper confirms that ). The experimentors did make a couple of very shallow assumptions, probably unsound in my opinion, and from those stated that freewheeling props had least drag - at best it was an unsound generalisation.

But in the end the silence of a locked prop wins out for us and all else is irrelevant.

I would have thought that if drag was important enough for someone to fuss over whether locked or not is least drag, they wouldn't have a fixed pitch prop would they ?


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## Tartan34C (Nov 21, 2006)

How interesting. We now have two studies and each backs a different conclusion. If I remember the MIT study correctly they had a freewheeling propeller without shaft drag at the bearing and stuffing box and Nigel Warren wrote an article published by Cruising World Publication in October 1979 where he took care to add a reasonable amount of friction to the system. Warren also took care to point out that a friction free system changed the result. Both studies I think agree that free wheeling is good if there is no friction in the system. But Warren says having friction tilted the balance in favor of locked. I also think the MIT study was designed for testing propellers and the free wheeling question was just an after thought.

A few short snippets from that Nigel Warren article, 

“Propellers have been tested in cavitation tunnels to discover their characteristics when reversing and when trailing. From these results I have worked out the drag of a typical yacht propeller 12 inches diameter with 8 inch pitch allowed to trail at various shaft speeds (in 3 knots of water with boat speed at 3 ½ to 5 knots) See figure 1. Zero rpm indicates the locked condition. When the prop is absolutely free to revolve (the shaft bearings are friction free) the rpm climbs to 376. Between the two extremes there is a varying degree of resistance to turning due to friction in the bearings. The interesting thing to note is that it only takes a bearing friction of about *1 pound foot to slow the shaft to the point were the prop gives as much drag as the locked case. Now 1 pound foot is a very small torque when it comes to conventional boat shafts. 

*Unlike a foot pound, which is the straight line force needed to move one pound one foot, a pound foot (a rotational measurement) is the torque produced by a force of one pound acting one foot from the center of rotation. 

I measured several shafts on yachts to see how much torque is necessary to slowly turn the shaft. Those with conventional shafts and stern tubes required torque loadings of 0.6 to 1.3 pound foot. 

So on that basis and looking at Figure 1, the prop will create three times more drag when allowed to rotate than it will when locked.” 

Snip, “As the speed of the water inflow increases, the drag increases as the square. In other words, at 6 knots (which is double the water flow speed of figure 1) the drag is quadrupled. But the shaft friction remains the same. Even so, it is still better to lock the shaft if the shaft friction is 1 pound-foot as shown in Figure 2.Six knots implies a boat speed of 7 to 8 knots - some sailing! I would think that inflow speed on small yachts are no more that 5 knots.” 

Snip, “The next factor in the four points is the ratio of the pitch to the diameter. Inevitably, boats that only do 4 to 6 knots under power have fine pitched props like our 12 x 8 the pitch is only two-thirds of the diameter. The tips of the blades of such props are almost square on the flow. They do not "windmill" very well. Coarse - pitched props have blades that more angled to the flow and consequently will "windmill" better. Nevertheless, a 12 x 12 propeller at 3 knots, for instance, will still give more drag revolving against a shaft torque of 1 pound foot than if it were locked.”

This is enough for me and I sail with the prop shaft locked. 
All the best, 
Robert Gainer


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## Cruisingdad (Jul 21, 2006)

I think most of us do sail with it locked, as the poll seems to represent. As far as the drag it presents.... who knows. Since I am towing a dink behind me half the time I guess it is insignigicant compared to the dink. Also, it would seem the newer engines have accounted for free spinning and it probably (PROBABLY) does not hurt. On the older ones... better read your manual or just be safe and lock. I seriously doubt it would hurt any diesel to start in gear.

Nice participation on the thread all - even revived from its slumber.

- CD


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## thekeip (Aug 8, 2007)

What is it about 'reverse' that's sacred, anyway? In my Ericson I simply turn off the ignition when the Main goes up...it's already in FWD, so I leave it that way. I understand leaving it in gear to prevent the auto-rotation of the transmission, and all that, but why reverse?
Howard Keiper
Sea Quest
Berkeley


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## Freesail99 (Feb 13, 2006)

Many Volvo engines turn the opposite way. That is why many have it in reverse. That is why I do it.


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## drynoc (Jul 17, 2001)

There must be something wrong with me. I have a new Yanmar with a flexible coupling, and a Martec folding prop, and I let the whole thing free wheel. What's wrong with this picture?


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## soul searcher (Jun 28, 2006)

We have a yanmar 4jh3e and sail with the tranny in reverse. you can not put the trans in neutral with out starting the engine.
It all depends on the gear, if the engine input shaft drives the oil pump and you allow the prop to freewheel then the trans will eventually over heat. at six knots this may take a while. but for instance on my work boat at 10-12knts on one engine it doesn't take long at all. I carry a 3 foot pipe wrench to lock the shaft on it just in case I ever have to come home on one.
The amount of torque generated by a locked prop going through the water at 10 knots is pretty incredible. I tried to tie one down with 5\8 line once and when we reached 12 knots it simply parted the line. granted those wheels are 34x34 sitting on 3" shafts but it made me go 
so i wonder some times if you could free wheel the the prop with out overheating the tranny. would it be better on the gears and bearings to not apply that load to them. probably not issue on short sails but over several thousand miles of passage I wonder what the difference would be. that amount of pressure has to build heat also but the hulk of the trans can probably dissipate it. 
If drag under sail is the only issue here then it's no brainer and you need to go to a feathering or folding prop.
just a thought


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## jerryrlitton (Oct 14, 2002)

Thanks for the definitive answer T34C. A spinning disk will have more drag through the water (and air) then a non spinning disk with alll else being equal.

Jerry


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## Rockter (Sep 11, 2006)

It has always been a problem trying to take power off a spinning prop, but it must be able to generate some serious poke.
Perhaps we would not have to run it long.
I wonder how it's done?


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## Zanshin (Aug 27, 2006)

soul searcher said:


> We have a yanmar 4jh3e and sail with the tranny in reverse. you can not put the trans in neutral with out starting the engine.


I've got the same issue, so tend to put a couple of pounds of pressure on tmy single-control lever to get from full power-reverse to idle-neutral while I hit the starter button.


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## soul searcher (Jun 28, 2006)

Zan
I'll try that. The only time I worry about it is when we start with good forward speed on. which is rarely. usually we are in irons taking down sails,
or dead in the water for lack of wind so i doubt it hurts anything but with headway on that poor little starter motor has its work cut out for it.


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## L124C (Oct 4, 2007)

*Reverse*

I lock in reverse. In forward, my prop still spins. The only drawback to locking the shaft in my case, is that when I get up to 4 or 5 knots, a loud eerie hum fills the cabin. I assume this is a resonance coming from water running past the stationary prop and transmitted through the shaft. It's a strange high pitched electronic sound and you can't determine where it's coming from (aft, V berth, etc..) The only way I know it's prop/shaft related is that it stops when I put the transmission in neutral.


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## beej67 (Apr 2, 2008)

Not normally into Thread Necrophilia, but this thread was a good one, and I've got some comments/questions.

First off, I've been letting my Yanmar 3gm30f freewheel for years and never had a problem. If the noise bothered me that bad, I'd buy a feathering prop.



tagster said:


> I thought that the pertinent thing to do was to leave it in neutral...especially when having a big wheel on the prop belted to an alternator so you could get some power in exchange for your drag...


I've always thought about doing that. Not sure I have the room on my P323 though, because the prop shaft is a major PITA to get to, under the engine, behind a V drive. Anybody got any pics of a rig like that? How big of an alternator do you need to make it worth your while?

Now, on to the flamewar. I may not be as educated as many of you, but I do feel the need to post my credentials. I'm a licensed Civil Engineer and have a masters degree in environmental fluid mechanics from Georgia Tech. So I understand the concept that spinning disks create more drag than fixed disks - it has to do with vortex tubes in high reynolds number flows forming at the tips of the prop wings. But going to that level of detail and complication is obscuring the big picture, and neglects other factors that go into the real question, namely which thing slows you down more.

The big drag argument in this thread is really pretty easy to resolve with a free body diagram and some basic high school physics. No need for fluid mechs required at all. Just ask some simple questions. Does it take force to hold your fixed prop in place, compared to letting it freewheel? _Yes. _How much force? Exactly the same amount of force your boat loses due to the drag difference. That's basic conservation of momentum, no MIT study required. Is it a noticeable amount of force compared to the force generated by the sails? Probably not at all unless you're in very light wind, in which case your prop probably isn't spinning anyway.


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## sailingdog (Mar 19, 2006)

One other problem with letting the prop freewheel is that it can cause wear and damage to the transmission, since the transmission will be turning with it...and if the transmission requires lubrication that isn't being provided, that would be bad. I'm generally in favor of locking the prop when not motoring.


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## TrueBlue (Oct 11, 2004)

Depends upon the transmision SD. As I noted back in Post 73, the hydraulic tranny on my Nauticat is lubricated by a self-contained sump and oil pump, so is protected from wear when free-wheeling.


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## sailingdog (Mar 19, 2006)

TB-

That's why I said IF...


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## TSOJOURNER (Dec 16, 1999)

I put it in reverse.


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## artbyjody (Jan 4, 2008)

There should of been a poll selection of "Huh - was I supposed to?"

Nice to see this thread revived as I learned what to do with the max prop "Hello Gorgeous" has. I probably would of never known and thought it would just "automatically" feather!


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## negrini (Apr 2, 2008)

*It's interesting how such discussions are still hot even ...*

today. I really though this only happened on my sailing ground where technology is come years far away. Locking the propeller is a fact that ressembles the old time where stuffing box contained simple rope with grease, and transmissions needed cooling and lubricants provided by the engine. In fact, if you still have a packing/gland using old materials (even some high teck argila ones) you should avoid premature wear if that's a concern. Another important point comes from transmition lubrification that in certains old models (even Hurth) use to have the entire tranmission spinning with the main axis. But major constrain, and still today is a threat, is cooling. This doesn't happens at all with a saildrive immersed on water. So, locking is always a safe measure, with a hudge drag. But if you know your transmission, leave it spinning, for efficiency.


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## DoomDahDoomDoom (Mar 3, 2008)

You guys sail with your props in the water??

I always make sure the outboard is locked in the "full upright out-of-the-water" position. Much less drag that way


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## sailingdog (Mar 19, 2006)

Doom-

What kind of boat do you have. Most of the monohulls don't have much choice... being poorly designed and have a large chunk of heavy metal to drag around too.


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## petegingras (Mar 29, 2007)

Forward, Maxi Prop's recommendation.

Soooo much discussion regarding the stuffing box wear. You's guys do replace that packing gland after every sail, or just forgettdaboutit.


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## JiffyLube (Jan 25, 2008)

The manual for our Pathfinder/Hurth, said that it can be in the zero position (neutral), or B position (reverse) to lock the propeller under sail, and under no circumstances should the transmisson be left in forward gear (A position) under sail.


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## JiffyLube (Jan 25, 2008)

DoomDahDoomDoom said:


> You guys sail with your props in the water??
> 
> I always make sure the outboard is locked in the "full upright out-of-the-water" position. Much less drag that way


Kind of hard to do with a inboard.


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## TSOJOURNER (Dec 16, 1999)

The owner's manual for our engine says to lock it in reverse. Today, I forgot and the hubby was in the engine compartment while we were under sail. He commented, "The prop sure does spin a lot when the engine is not running!" I replied, "Oh crap. My bad. It is in reverse now." and all was right with the world.....


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## negrini (Apr 2, 2008)

*JiffyLube, your Hurth is from a newer design, where*

leaving in neutral really disengage the whole thing, while in fwd, you'll have your propeller spining the entire transmition box. But the original problem is still the same, don't co that for lube and cooling.


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