# Brunton Autoprop



## TSOJOURNER (Dec 16, 1999)

I am considering an Autoprop for my Bayfield 25. Anyone have real world experience of these? 
I have the 1GM Yanmar and need to know the gear ratio. Where would I find this? On the gearbox? Or will I have to measure it at haul out?


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## jrd22 (Nov 14, 2000)

We installed an Autoprop on our last boat. It had a fixed three blade and there was a big improvement in light wind sailing speed. The biggest difference was in motoring speed, we gained a full knot at the same RPM. My brother still has the boat and the Autoprop has been on for at least 8 years with no problems. Very well built. I have heard some discussion about people losing a blade, but I have no details.

You should be able to find the gear ration either in your manual or from any Yanmar dealer.

John


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## Fstbttms (Feb 25, 2003)

Of all the props in the world- fixed, feathering, folding or otherwise- the Autoprop is the only one I would recommend you do not buy. Among other issues, they have this nasty habit of throwing blades. Check this thread from cruisersforum.com:

Autoprop?? - Cruisers & Sailing Forums


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## TSOJOURNER (Dec 16, 1999)

Thanks for the replies. I read the other forum and have decided against the Autoprop. It makes interesting points and as I have an angled shaft and the prop is in an aperture both of which cause vibration problems with the autoprop it is apparently unsuitable for the Bayfield. I'll probably stick with my fixed propeller. I was inspired to investigate variable pitch though. That would be idea as forward and reverse could be regulated infinitely by a cockpit control and the prop could be manual feathered for sailing. Anyone know of a manufacturer of small variable pitch props? I do recall seeing one on a small powerboat in Small Boat Journal several years ago.


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## christyleigh (Dec 17, 2001)

Fstbttms said:


> Of all the props in the world- fixed, feathering, folding or otherwise- the Autoprop is the only one I would recommend you do not buy. Among other issues, they have this nasty habit of throwing blades. Check this thread from cruisersforum.com:
> Autoprop?? - Cruisers & Sailing Forums


I went through over a hundred of the postings there and the only mention of "thrown blades" was Yours speaking about Max Props - Not AutoProps ??? Your posting -
Originally Posted by *smm* 
_Also, I've heard too many lost prop stories regarding Maxprop (Profligate here in SF twice) to be sanguine about them._
They have been known to throw the ocassional blade as well. I have personally seen this on several different boats.
So..... do you happen to remember if there are any AutoProp blade losses in the next hundred postings, or were you actually speaking of Maxprops ?


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## Fstbttms (Feb 25, 2003)

christyleigh said:


> I went through over a hundred of the postings there and the only mention of "thrown blades" was Yours speaking about Max Props - Not AutoProps ??? Your posting -
> Originally Posted by *smm*
> _Also, I've heard too many lost prop stories regarding Maxprop (Profligate here in SF twice) to be sanguine about them._
> They have been known to throw the ocassional blade as well. I have personally seen this on several different boats.
> So..... do you happen to remember if there are any AutoProp blade losses in the next hundred postings, or were you actually speaking of Maxprops ?


Yes, I posted in that thread several times about Autoprops throwing blades, as did others. I think I must have misread, two and a half years ago, the particular post that I replied to (and you quoted here.) I did not mean to infer that Max Props throw blades. In actuality, I have never come across a Max Prop that has done that. But as you read, I have firsthand knowledge of several Autoprops that have lost blades and have heard anecdotally of many others. In fact, Autoprop issued a recall because of the problem. There is further discussion of the Autoprop issue in that thread (and others) on Cruisers Forum.


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## jrd22 (Nov 14, 2000)

Fast- do you know if this problem with the Autoprop has been resolved by Brunton? With the 10+ years experience I had with our Autoprop on the last boat I would really like to install one on the new boat. The ability to motor at lower RPM"s, amazing stopping power and no walking in reverse make it a very desirable prop. But reliability outweighs the other advantages, I don't want to be in a remote location and need to send the prop back for an expensive repair.

Thanks for any info. you may have, John


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## tommays (Sep 9, 2008)

If you treat any prop with moving parts like a fixed prop it will fail at some point









If you look at the parts drawing it clearly requires matiance far beyond a fixed prop


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## Fstbttms (Feb 25, 2003)

jrd22 said:


> Fast- do you know if this problem with the Autoprop has been resolved by Brunton?


I have zero information regarding any resolution.


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## Fstbttms (Feb 25, 2003)

bluerover said:


> I was inspired to investigate variable pitch though. That would be idea as forward and reverse could be regulated infinitely by a cockpit control and the prop could be manual feathered for sailing. Anyone know of a manufacturer of small variable pitch props?


I have never seen or heard of such a prop for small boats. My guess is that there is no market for it due the ineveitable installation, maintenance and cost issues.


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## Fabiosail (Feb 25, 2011)

*Autoprop may have some issue*

I was looking for information on Autoprop problems because I just run in to one and I registered because I have firsthand experience with this type of propeller.

I am not trying to promote Autoprop, I found an H20 on the boat at the time of purchase (second hand 37 ft + Volvo penta MD30).
The performances of this propeller are out of discussion. Automatic variable pitch, identical forward and reverse blade profile, low prop wash, good top speed, amazing performance while motor sailing and optimized thrust depending on boat speed, load and sea condition.

All good things but:
It costs a lot of money to buy and you would expect it to last what you pay for instead it is demanding on maintenance and regular checks.
Bruntos recommends greasing every two years and that should be enough.
The reality is that every year the propeller wants to be greased and inspected for seals conditions and bearing condition, the seals are supposed to be good for 1000 hr.
The risks? Unfortunately (and I say this because my boat has this propeller) the risk is losing one blade and I am not saying this by guessing, this is Bruntos writing to me that once the seal starts wearing the water gets in and the grease leaks out. The clearance between the blades and the prop body increases and the bearing balls starts damaging the housing.

The spare parts and repair are astronomically expensive (they easily hit 50% of the cost of a new propeller) and the repair (new machining of the housing) must be done by Bruntos.
You also need special tools to open the hubs, they are not fancy tools but if you don't have them or you cannot build them yourself they sure don't come cheap.

I am glad my boat already had this propeller but if today I had the opportunity to change I would go for a Volvo three blades folding, I would lose a bit in performance but would have almost zero maintenance to do beside cleaning the blades.

Once seals and bearings deteriorate the risk of losing a blade is there and there is not much vibration to warn you that it is about to happen.

Ciao


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## harryws (Sep 4, 2001)

Brunton Autoprop
Has any vessel you know of lost a blade from a Brunton Autoprop propeller.
I have one fitted to my 42 ft Adams cruising yacht and three years ago one of the three blade dropped off. It was because the securing nut came loose and disappeared along with the blade. I returned the prop to Bruntons to have them install a new blade and balance the propeller. They did this at some cost.
Recently another blade has dropped off. I have again returned the Autoprop to Bruntons UK. What should I do? Has anyone had a similar experience?


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