# Moving chainplates outboard (from "through deck" configuration), I have a question..



## chrisncate (Jan 29, 2010)

*Moving chainplates outboard (from "through deck" configuration), I have a question..*

...


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## sailingdog (Mar 19, 2006)

Chris—

Without the support of the toerail, the chainplates are far more likely to flex and if they do, it will cause the chainplates to fatigue. I think you do need to incorporate the chainplates into or with the toerail.

Don't forget, the angle of the mast tangs needs to be modified to match the angle from the new chainplates, which are now further outboard.


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## SlowButSteady (Feb 17, 2010)

I've seen some older boats with outboard chainplates that have a sort of "rub-rail" (for lack of a better term) below the toe-rail, with the chainplate bolted below that. The chainplates bend over the top of this rub-rail, and are thus held just outboard of the toe-rail.


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## mitiempo (Sep 19, 2008)

Like this:


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## gtod25 (Aug 5, 2000)

*I too like the idea of moving the chainplates outboard...*

but eventually compromised on this;










Full saga here

Boat is a Whitby 42, big daddy to your Alberg 30.


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## mitiempo (Sep 19, 2008)

You will sacrifice a few degrees of pointing ability with the chainplates mounted outboard. Not a disaster but something to be aware of.

I think chainplates can be seaaled properly through the deck. gtod's link is one example. The other issue is that most leaky chainplates have been ignored for 20 to 30 years. Properly done, which requires the most work, will take the longest time. Pulling them for inspection in 10 years and rebedding them won't take as long.


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## SlowButSteady (Feb 17, 2010)

mitiempo said:


> Like this:


Bingo!

I've also seen set-ups with wood blocks under the chainplates to avoid the extra bend over the "rub-rail" (is there a better word for that?).


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## mitiempo (Sep 19, 2008)

There is but it escapes me right now.


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## jrd22 (Nov 14, 2000)

I usually stop and think real hard whenever I'm contemplating changing something the guy that designed the boat thought was important. Just sayin.


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## chrisncate (Jan 29, 2010)

jrd22 said:


> I usually stop and think real hard whenever I'm contemplating changing something the guy that designed the boat thought was important. Just sayin.


Na, this ones easy jrd... there is no reason that I cannot get the tangs to be within an inch of where they currently are, so no geometry changes will happen, just structural strengthening of the "known to be weak" Alberg 30 chainplates.

No one questions the reinforcing of the cabin top from the inside where the mast step is on Alberg 30's (the famous aluminum beam retro fit), nor should it be a problem to move the CP's outboard. I just have to make sure the rigging alignment stays the same, which like I said ..._should_ be easy...


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## Bilgewater (Jul 17, 2008)

gtod25 said:


> but eventually compromised on this;
> 
> 
> 
> ...


Nice job on this...good idea and I like your blog.


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## SlowButSteady (Feb 17, 2010)

SlowButSteady said:


> Bingo!
> 
> I've also seen set-ups with wood blocks under the chainplates to avoid the extra bend over the "rub-rail" (is there a better word for that?).


Chain-wale, or channel!!!!


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## gtod25 (Aug 5, 2000)

Thanks seayalatermoonglow, I like your videos too. Regards Gerry


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## Ajax_MD (Nov 24, 2009)

gtod25 said:


> but eventually compromised on this;
> 
> 
> 
> ...


+1, Great blog, great photos.

I have spare chainplates coming in the mail, and my mast is down so I'll be pulling mine for inspection.


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## Jeff_H (Feb 26, 2000)

I am surprised that people have not been more strongly negative about doing this. It really offers less than zero advantage in any real way and has a number of disadvantages such as: 

The boat will not be able to point as high since the limit on pointing on an Alberg 30 is that the foot of the genoa is hard up against the shrouds that is all it can be flattened.
You will need to get your genoas recut or make new genoas which have a more open foot.
You probably will need to reinforce the inside of the hull since the prior installation used the bulkheads to distribute the loads around a larger portion of the hull.
If possible I would suggest that you try to avoid the various bends in the chainplate as these will flex and unevenly load the bolts and increase the likelihood of fatique over time.
You would be way ahead of the game re-engineering your inboard chainplates to minimize potential leak and live with them for the forty years of lifespan that the existing chainplates had lasted.

Jeff


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## smackdaddy (Aug 13, 2008)

Let me ask a question on a somewhat related note...

I need to essentially "de-tension" my center port shroud to do some work on my chainplate and bulkhead. I've heard you can do this with a halyard going to the toerail - but I don't want to mess up the mast-top sheave by applying lateral force (it's plastic).

Is there another way to use maybe a prussic knot with small line on the wire shroud and anchor that down to the to rail? Other recommendations?

Or do I need to not worry about the sheave?


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## Beersmith (Nov 5, 2008)

I am highly considering moving the chainplates to the outside on my 1975 Downeaster 38. Somewhere around 1981 Downeaster decided to use external chainplates on all of their boats, I guess they concluded it was the better option to minimize leaks. The chainplates are bolted through the hull as is and come up out of the caprail, no new holes would need to be cut (NOT bolted through a bulkhead).

The difference between having them on the caprail and on the outside of the hull is only about 2", maybe less. I highly doubt the pointing ability would be drastically compromised especially considering my main headsail is a small yankee. It is a heavy displacement cutter, and upwind performance isn't the best to begin with. 

I know of quite a few Downeaster owners who have moved the chainplates to the outside with no complaints.


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## Ajax_MD (Nov 24, 2009)

smackdaddy said:


> Let me ask a question on a somewhat related note...
> 
> I need to essentially "de-tension" my center port shroud to do some work on my chainplate and bulkhead. I've heard you can do this with a halyard going to the toerail - but I don't want to mess up the mast-top sheave by applying lateral force (it's plastic).
> 
> ...


"Plastic" doesn't necessarily translate to "fragile". It depends. Have you seen it? Is it UV damaged? Brittle? Delrin sheaves are quite durable. Acetol sheaves seem durable as well, but they feel more brittle to me. I've just replaced my old wire sheaves, so I spent quite a bit of time shopping for new ones.

Sure, you could detach your shroud and run a piece of low-stretch line from the top of the turnbuckle to the toe rail temporarily. Unless your sheaves are badly worn and UV damaged, I don't see why either solution wouldn't be ok.


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## smackdaddy (Aug 13, 2008)

BubbleheadMd said:


> "Plastic" doesn't necessarily translate to "fragile". It depends. Have you seen it? Is it UV damaged? Brittle? Delrin sheaves are quite durable. Acetol sheaves seem durable as well, but they feel more brittle to me. I've just replaced my old wire sheaves, so I spent quite a bit of time shopping for new ones.
> 
> Sure, you could detach your shroud and run a piece of low-stretch line from the top of the turnbuckle to the toe rail temporarily. Unless your sheaves are badly worn and UV damaged, I don't see why either solution wouldn't be ok.


Cool - thanks bubble. The sheaves are new. I just replaced them last summer - so they should be fine.


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## tdw (Oct 2, 2006)

Have to say I don't like it. All that rig tension is trying as hard as it can to straighten out all those bends in the new chain plates, particularly if you are trying to get the rigging screw attachment point near to where it is now. 

Chris, I ain't no physicist I readily admit, but it just feels wrong to me.

(Then again Boat B won that bloody race )

It may well be that over the years it has been successfuly accomplished but I'd still rather repair/rebuild existing than going for the outside alternative.


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## mitiempo (Sep 19, 2008)

chrisncate

You will note the chainplates in your second picture (the one under the pic of the cardboard mock-up in your first post) are attached just before they bend in. I believe they are in the pic I posted as well. And they are in the pics below. They have to be to eliminate movement.


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## GeorgeB (Dec 30, 2004)

If you have a water intrusion problem on deck, why won’t you have a worse problem with the bolt holes drilled in the hull where at least the lower ones would be constantly under water while going to weather?

If you are going to the hull mounted solution then you will want to install a dead-eye wale on the hull (see the previous photos). The Al extrusion looks like a trim strip to cover the deck hull joint and won’t be strong enough to carry the compressive loads alone. Plus you will want access to it so you can re-seal the inevitable leaks when the compressive loads flex and “break” the old water-tight seal from the old caulk/adhesive.

Do you have any photos from the inside of the boat? I’m not getting a visual of your current problem. If you have wet core, you’re going to have to do the same repairs anyway? Are you getting a marine architect to recalculate your new rigging loads? You may be looking at longer spreaders in order to keep the same geometry or at least changing their angle to the mast. Keep the photos coming as this looks like a fascinating project no matter which way you go.


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## LandLocked66c (Dec 5, 2009)

What would "Yves Gelinas" do? Was this done to Jean-du-Sud?

I don't see any here, or....


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## LakeSuperiorGeezer (Oct 8, 2010)

Get a copy of this book and do some real design calculations: The Elements of Boat Strength: For Builders, Designers, and Owners by Dave Gerr. Amazon has it for $23.07


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## LakeSuperiorGeezer (Oct 8, 2010)

*Correction*



LakeSuperiorGeezer said:


> Get a copy of this book and do some real design calculations: The Elements of Boat Strength: For Builders, Designers, and Owners by Dave Gerr. Amazon has it for $23.07


I just had a look at The Elements of Boat Strength and did not see much on chainplates. There was some mention of increased thickness of the fiberglass where a chainplate attaches. I also found it interesting on how secure bulkheads have to be in their attachment to the hull and can see that the bulkhead could make a good attachment point.


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## mitiempo (Sep 19, 2008)

Butyl can be used on thru deck chainplates.

Masonite does absorb water if not totally sealed in epoxy. It is a pressed paper product.


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## tdw (Oct 2, 2006)

Chris,
My comments was based on there being bends past the last fastening which may or may not be into the toe rail. 

Now if that fastening is into your toe rail then there will surely have to be some movement in the rail which worries me somewhat and if you then have further bends in order to get the rigging screw attachment point back to the same plane as before then I am seriously worried.

If you run the rigging straight up from the toe rail as would seem logical then you do have the sheeting issues that Jeff mentioned.

Mate, it just doesn't feel right to me and I'd definitely be giving it all some serious thought. Just because you want it to work does not mean it will.

Cheers

Andrew


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## LakeSuperiorGeezer (Oct 8, 2010)

The Elements of Boat Strength does state the bulkheads are an important part of the load bearing structure of the sailboat. When you move the chainplates outboard, be sure you maintain the structural integrity of the bulkheads as something has to transmit the forces from “the famous aluminum beam retro fit” to the hull and ultimately to the outside chainplates.


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## sailingdog (Mar 19, 2006)

mitiempo said:


> Butyl can be used on thru deck chainplates.
> 
> Masonite does absorb water if not totally sealed in epoxy. It is a pressed paper product.


It also rots, and is a PITA to replace once rotted away.


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## sailingdog (Mar 19, 2006)

LakeSuperiorGeezer said:


> I just had a look at The Elements of Boat Strength and did not see much on chainplates. There was some mention of increased thickness of the fiberglass where a chainplate attaches. I also found it interesting on how secure bulkheads have to be in their attachment to the hull and can see that the bulkhead could make a good attachment point.


If you're moving the chainplates outboard, you do want to make sure that you're using a decent backing plate, and that it is well glassed to the hull and adjacent bulkhead to spread the loads to the hull properly.


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## gtod25 (Aug 5, 2000)

*The great thing about sailors is.....*

that if you ask six of them their opinion on a subject you will get seven answers, because at least one of them will be a schizophrenic (yes I am, no I'm not).

You are obviously at stage Two of the seven stages of a project. Go for it!!!!!
Most of us here have been around the circuit numerous times and have finally realized that KISS is the way to go.

Seven stages of a project;

Phase 1: Uncritical Acceptance
Phase 2: Wild enthusiasm
Phase 3: Dejected disillusionment
Phase 4: Total confusion
Phase 5: Search for the guilty
Phase 6: Punishment of the innocent
Phase 7: Promotion of nonparticipants

And ALWAYS ALWAYS remember that free advice is worth exactly what you pay for it.

Gerry


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## Maine Sail (Jan 6, 2003)

chrisncate said:


> Since I have the attention of the forum heavies in this thread, and on another note, let me ask you guys..
> 
> ...what do you think I should expect to pay for a cutlass bearing replacement, a stuffing box replacement or rehab, and a Yanmar 2GMF maintenance overhaul (engine pulled by yard I'm at - I can get her loose and ready to be pulled out, they would just need to crane her out and rehab/paint the motor)?
> 
> This stuff here is also on the "short" to do list...


I am perplexed that you feel you have the engineering skills to re-design the chain plates but are then asking about having a yard do a cutlass & stuffing box and engine paint/overhaul. The latter items are kids play compared to chain plates.

You might also talk to Carl Hayn or Navtec about those bends and how they would treat the chain plates and inspect them before installing them. From my understanding you don't just bend them and slap them on. They then need to be treated to relieve stresses, passivated and highly polished to minimize the chances of crevice corrosion.

Personally I know of many Albergs sailing around with intact chain plates, my friend Paul owns one that has probably 100k nm on it, he's cruised everywhere, and the plates are in the original location.

I would seriously ask you to consider talking with, and perhaps paying for an hour or so of consultation by an NA. You can try *Roger Long NA* he's good and reasonable. Jeff H. I believe is an NA as well and has already given his .02..

Here's one of his designs to fix an inherent design flaw on an Endevour 32.

Images courtesy *Roger Long Naval Architecture Inc.*









And the original problem:


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## LakeSuperiorGeezer (Oct 8, 2010)

*What Type of Bronze*



chrisncate said:


> ...my silicon bronze flat bar stock in hand...will be hand forged...


Everdur Silicon Bronze is used for propellers and is the usual bronze for saltwater. Is this what you have: Everdur Silicon Bronze Other bronze alloys will also work, but need to be careful on what you use. When you say hand forged, I am thinking you mean just bending the bronze flat bar stock. To forge metal is to heat it to help form it, but ususally refers to iron and steel products. Some hand crafted knife makers have tried forging of silicon bronze. Forging Naval Bronzes Maybe you mean to cast. At any rate this bronze can be welded as you can see from the link. The tensile strength of 316 stainless is 74,700 pounds per square inch so if you size your bronze to the approximate demensions of stainless you should be OK. The tensile strength of 304 stainless is somewhat higher than 316.

About the various bends in the diagrams on this thread, bronze is flexible, it has spring to it. You do not want any give when you tension your shrouds so look for straight lines from wherever the bronze is attached to the boat. Wherever there is a bend, also think about pulling forces that could pull out a bolt such as where the bronze is bent where it attaches to the hull at the top most point before being bent outward.


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## LandLocked66c (Dec 5, 2009)

Good stuff! This thread reminds me to keep my repairs simple.

Good luck Chris!


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## mitiempo (Sep 19, 2008)

Working on the engine is pretty straight forward. When you are done it will work or not. You should know the results immediately.

But changing rig geometry will not result in an immediate win or lose. The flaws of a change may take a while to be evident. Whitby did take shortcuts with the Alberg 30, modifying the ballast without consulting with Carl Alberg, but I don't think they would have changed the rig without his blessing.


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## chrisncate (Jan 29, 2010)

I guess I'll ask it this way: _Would_ I be changing the rig geometry if the new CP's lined up within an inch of where they currently connect to the shrouds? To me it seems no, I wouldn't, but maybe I'm wrong?


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## Faster (Sep 13, 2005)

Chris, I've stayed out of this one til now, but I'm in the 'don't do it' camp.. Not so much for reasons of geometry, though I do believe that's a factor. The biggest issue for me, as touched on by others too, is the long term stability of what you propose... The only way to even get close to the original position of the shroud termination is to have an off-angle unsupported section of chain plate. I can't believe that over time, with the tension and the shock loads of regular use that the chain plate wouldn't stretch/straighten/move until your rig tension is soft, eventually leading to other problems.

There are hundreds of designs with in-deck chainplates that can be properly sealed and are properly anchored with fair leads and stable attachment points - such as you have now.

Why mess with that?


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## chrisncate (Jan 29, 2010)

Well, the "against" arguments make sense in many ways. How the heck do I make the final decision though? I am thoroughly confused as to what to believe. On one hand, the arguments make sense. On the other, I know how forums can be, where people (not any of _you_ of course..:laugher  ) look for reason to take the counter point, simply for arguments sake.

I want my boat to be safe and right, but I also had a vision of how she could be (the outboard CP thing to begin with) stronger. I'll throw it out here in naked honesty: Do you guys against HONESTLY believe it would be wrong to move them outboard, not for the sake of taking a counterpoint, but for the best interest of the OP's honest plea for help and advice?

I get one shot at this, since the rest of our budget is mostly spoken for and screwing this project up would have an effect. This will be our traveling home, I need her to be right.


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## mitiempo (Sep 19, 2008)

Not a major change, but the ability of the new chainplates to be flexed inboard could be a problem. If the spreaders are left the same, the lower part of the upper shroud will be less vertical and will try to pull them inboard. If you look again at your second picture or any of the pictures I posted you will see that the lead upwards is fair after the upper attachment of the chainplate to the part of the hull that has been built outwards. This part (its name still escapes me) is not small and weak as it takes a large amount of compressive force, but it is beefy and extends a fair ways along the hull, and is reinforced internally. The chainplates in the pictures are not able to be straightened by this force. Instead it is transferred to the hull very effectively. 

If I were doing this, and not rebuilding the chainplates in their original location, I would beef up the inside of the hull with additional layers of biaxial roving, over as large an area as possible to spread the load far and wide. Probably something like 1' to 1 1/2' wide and 2' to 3' down the hull. I would build the thickness up to 3/8" to 1/2" where the chainplate is attached and taper the thickness down and fore and aft smoothly. The hull is not designed to have a chainplate attached to it as built. And I would keep the chainplate tight to the hull, bending it slightly inboard to match the angle of the upper shroud. This would require the toerail to be notched to allow for the angle, and the aluminum rubrail is in the way as well. This would be a stronger method than the one you have suggested. 

But I would rebuild them in their original location as it is much easier than doing this properly and not hard to keep leakproof.


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## CalebD (Jan 11, 2008)

I'd work more on that nice teak toe rail for now and keep conjuring up new ideas and researching same.
It is easy enough to to do bright work and gives you plenty of time to read between coats drying.
Outboard mounted chain plates are susceptible to docks and other boats whereas inboard chain plates offer some protection by the hull/deck joint and might last longer in a catastrophic situation. 
Don't get me wrong. I have thought about this for my old boat too but I am far too lazy to embark down the path you have suggested and I do think that our already limited upwind pointing ability would be further reduced. The first navigation buoy you plow into at night could take off your chain plates if mounted outboard. 
If you have the energy and time just make the boat look great by working on the wood, learn the engine and improve things simply and gradually. So no, I vote no, don't bother with moving the chain plates but fix them where they were originally designed to be. 
Simple.
And no. I am not trying to be a contrarian.


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## tdw (Oct 2, 2006)

chrisncate said:


> I guess I'll ask it this way: _Would_ I be changing the rig geometry if the new CP's lined up within an inch of where they currently connect to the shrouds? To me it seems no, I wouldn't, but maybe I'm wrong?


Listen to the Fast man, Listen to the Fast man, Listen to the Fast man....


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## jackdale (Dec 1, 2008)

tdw said:


> Listen to the Fast man, Listen to the Fast man, Listen to the Fast man....


Yep - There are structural reasons why the chainplates are where they are.


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## LandLocked66c (Dec 5, 2009)

chrisncate said:


> I have had the outboard CP idea beaten out of me handily, I am replacing them as designed..


And let that be a lesson to you!


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## bljones (Oct 13, 2008)

A lot of work for no gain. Drill out the bulkhead mounting points for the chainplates and pot with thickened epoxy, use larger hardware, build deck islands out of thickened epoxy to deter water intrusion through the chainplate ports, and call it done. Bigger, stronger, better, faster, cheaper with no change in geometry.


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## gtod25 (Aug 5, 2000)

*Well done Chris...*


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## bljones (Oct 13, 2008)

Urine is salty. Potato chips are salty. Which would you rather ingest?

Sometimes, salty is a bad thing.


oooooh, sig line!


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## LakeSuperiorGeezer (Oct 8, 2010)

*Outrun Storms*



chrisncate said:


> Gotta at least admit, outboard chainplates certainly are salty on any vessel though...
> 
> Hey, you guys got any thoughts on my retro fit plans of a small block chevy 350 in place of my Yanmar? NO ONE could possibly poo poo _that_ idea, right?
> 
> ...


To outrun storms, how about a top fuel dragster engine, Chrysler Hemi 426, with racing alcohol, 85% nitromethane and about 15% methanol, instead of gasoline. Top fuel dragster Worlds Fastest Cars


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## chrisncate (Jan 29, 2010)

LakeSuperiorGeezer said:


> To outrun storms, how about a top fuel dragster engine, Chrysler Hemi 426, with racing alcohol, 85% nitromethane and about 15% methanol, instead of gasoline. Top fuel dragster Worlds Fastest Cars


That's just silly LSG.. 

I need _practical_...


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## mdbee (May 2, 2007)

*I will take your word for that*

"Urine is salty" 



bljones said:


> Urine is salty. Potato chips are salty. Which would you rather ingest?
> 
> Sometimes, salty is a bad thing.
> 
> oooooh, sig line!


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## LakeSuperiorGeezer (Oct 8, 2010)

chrisncate said:


> That's just silly LSG..
> 
> I need _practical_...


Quite true, so about the 2GM20, does it have fresh water cooling (heat exchanger) or has salt water been eating at its insides.


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## SlowButSteady (Feb 17, 2010)

bljones said:


> A lot of work for no gain. Drill out the bulkhead mounting points for the chainplates and pot with thickened epoxy, use larger hardware, build deck islands out of thickened epoxy to deter water intrusion through the chainplate ports, and call it done. Bigger, stronger, better, faster, cheaper with no change in geometry.


I'm not so sure that the change in geometry would be all that big a deal. Moving the shroud outboard 4 inches would only increase the angle by about one degree. I seriously doubt that the original tangs, etc., were made with a tolerance of less than one degree.


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## procrastonator (Feb 24, 2011)

Hi , I am in the same situation with my Utzon 30 spidsgatter, with a want to negate as much potential water ingress through deck as possible, The plates I have seen are recessed behind rub rails etc with nice flat sections,I photographed a liberty 30 setup the other day I will try to post same, I will follow your thread with much interest. cheers chris


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## Faster (Sep 13, 2005)

Guys and Gals.. Since this thread drifted into an engine discussion that I thought had some pretty valuable info hidden behind the 'chainplate' title, I've culled the relevant posts to its own thread.

You'll find it here:

http://www.sailnet.com/forums/diesel-engine-forum/72380-older-yanmar-rebuild-replace.html

Carry on!


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## sailingdog (Mar 19, 2006)

Wow, that's pretty good for a 52nd stater...  :laugher:laugher Thanks Faster.



Faster said:


> Guys and Gals.. Since this thread drifted into an engine discussion that I thought had some pretty valuable info hidden behind the 'chainplate' title, I've culled the relevant posts to its own thread.
> 
> You'll find it here:
> 
> ...


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## Barastiboy (Oct 28, 2011)

I have had my boat a 48 ft frers 1980 out of the water for 4 months and noticed the
Teak deck cracked across the grain adjacent to the single in line chain plate. I figure this could be due to temporary hogging of the boat, plus drying of the teak plus or either slight movement of the chain plate/s either way, listening to you guys I think I will take a closer look. Ps It's been it's very hot here in Dubai.


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## Barastiboy (Oct 28, 2011)

*moving chain plates outboard*

I've got the same decisions to make.
Barastiboy


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## Capt Len (Oct 9, 2011)

Gotta love those channels. Great for standing on when preparing to board a passing pirate ship.Hope the big fenders are out when needed. I've seen outboard chainplates in cast bronze with a T cross section at the top to prevent any flex.Could this be the best of both worlds? Neat and salty.


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