Autoprop ?

[Silver Cloud]

I have an Autoprop. AB Marine had rebuilt the prop in 2007. In May of 2009 and 225 hours later a blade came off. I sent it to AB Marine who sent it Buntons Marine in England. Buntons Marine replaced the blade for $1500. I had the prop lubricated every six months. I am always in deep water. It never touched anything but saltwater. I only go to Catalina and back. Other than the lost blade there was not any evidence of damage or distress.

At the time Steve Armitage of AB Marine told me that losing a blade was a “rare occurrence” and that he did not have an explanation for why the blade fell off. David Sheppard of Brunton's Propellers Ltd, told me losing a blade is an “an exceptional case”. Contrary to their comments the prop has been subject to a recall for lost blades. If you search other support groups and blogs you will find many others that have lost Autoprop blades. It demeans their credibility to say otherwise.

Although I enjoy the performance of my Autoprop my experience with AB Marine and Brunton's Propellers has been extremely disappointing. They are unwilling to stand behind their expensive product. In all their replies I feel like I am hearing from a politician trying to avoid giving a straight answer. I would stay away from anything that might need to be serviced by AB Marine or Buntons Marine (Varifold, Autoprop, Gori).

[Yachts66]

WOW very glad you shared that. I've heard the same thing from others which is largely why I've begun to lead towards VariProp.

Thanks,

Thomas

[fstbttms]

I have personally seen at least two Autoprops that have thrown blades. Guess how many feathering props (and there are orders of magnitude more of them in the water) I can say that about. That's right- zero.

There is plenty of anecdotal evidence supporting the problems with Autoprop and the service AB/Brunton's provides. I don't know why anybody would buy one.

[Dockhead]

Originally Posted by fstbttms

I don't know why anybody would buy one.

Because there is nothing like them for efficient motor-sailing, or motoring in general. For most cruisers, they are the ideal prop in terms of their performance. They produce more drag than other feathering or folding props, so they are not good for racers, but still a fraction what a fixed prop produces.

The only other variable pitch prop on the market is the one which Maxprop just came out with. Maybe that's better than the Autoprop -- certainly Maxprop has a great reputation. I have not met anyone yet who has tried one, however.

It is very disappointing to hear of such experiences with Brunton's, who are a serious company which have been making propellers for ships for decades. They should get their act together and take responsibility for such incidents. A blade flying off -- that's extremely bad. They should make whatever engineering changes are needed to prevent it ever happening, and provide modified parts free of charge to owners who are affected.

Still, it seems that relatively few Autoprop owners have had such problems. My father has thousands of hours on an old water-lubricated Autoprop which has performed flawlessly over more than a decade. My boat has a newer sealed grease-lubricated Autoprop which has performed without problems. I grease it, clean it, antifoul it, change its anodes, and generally pamper it every three or four months when the boat is out of the water for a scrub. I hope a blade won't fly off.


By the way -- Autoprops are not the only props to lose blades. I was in the Windward Islands a few years ago on a chartered Norseman catamaran, when a blade flew off of one of the folding props -- I believe it was a Flexofold. Good thing we had an entire spare propulsion system -- an advantage of cats.

[fstbttms]

Originally Posted by Dockhead

By the way -- Autoprops are not the only props to lose blades.

Yes, and fixed-blade props lose blades as well. My point is that feathering props do not. At least none of the many hundreds that I have come across haven't. If you were to calculate the number of Autoprops in use and the number of those that have lost blades versus the number of feathering props in use and the number of those that have lost blades; the Autoprop ratio would be very high.

[Dockhead]

Originally Posted by fstbttms

Yes, and fixed-blade props lose blades as well. My point is that feathering props do not. At least none of the many hundreds that I have come across haven't. If you were to calculate the number of Autoprops in use and the number of those that have lost blades versus the number of feathering props in use and the number of those that have lost blades; the Autoprop ratio would be very high.

Well, if you're basing it on your own personal experience, it will be a fairly small statistical sample -- valuable information but maybe not a complete picture.

There was a problem with retaining rings or screws (or something) which was the subject of a recall. I have not heard that Autoprops without this known problem have any tendency to lose blades.

If the OP had a recalled prop which had not been sent in for the modification, and lost a blade, the distributer should have jumped through his a** to make it right. Actually, he should have done that in any case. Does not sound like good service.

[msponer]

Funny, a friend of mine's MaxProp threw a blade. So I thought MaxProp's were unreliable.

I loved my Autoprop. I had it for several years with absolutely no problems. In calm seas we went very fast with the engine just above idle. And we could punch into bigger seas like a large trawler, it really was night and day -- say, a 3' chop with a short period, we could make 4.5 knots, where as our fixed blade prop couldn't even hold 1 knot as it would cavitate and whistle whenever a wave stopped us.

I'm disappointed to read here that they do throw blades and the customer support is bad -- I may then not get one for my next boat. It's such an enormously expensive luxury, but was one of my favorite improvements to my last boat. When coastal sometimes you have to punch into seas for 10 or 20 miles to get around a headland, or just want to get into an anchorage, and going 4-5 knots instead of 1 knot is the difference between getting there in 4 hours or nearly a whole day of pitching and being wet.

[Dockhead]

Originally Posted by msponer

I loved my Autoprop. I had it for several years with absolutely no problems. In calm seas we went very fast with the engine just above idle.

Indeed. Last summer, I did an English Channel crossing the long way over -- from Salcombe to North Brittany, about 100 miles. In a dead calm and dead flat sea. You would think that 100 miles under motor would be torture, but actually we had a wonderful time -- in a flat sea, with the Autoprop, we were maintaining 7.5 - 8 knots with engine just loping along at 1500 RPM and almost inaudible, and using just 3 liters an hour or so. It was fantastic.

That's what self-pitching does. Probably not worth it for the fuel savings alone, but definitely worth it for the way the engine sounds and feels.

Similar thing with motor-sailing. You save some fuel from the fact that you can throttle down to 1500 rpm (say), taking into account the drive from yoru sails, instead of maintaining 2500 turns. But that's not the real point -- the real point is that at 1500 rpm the engine is not spoiling the feeling of sailing.

[sogin]

We installed an Auto Prop on a Beneteau 411 in 2001 and thought it was a great upgrade over the Michigan fixed prop. We haul every winter and noticed the blades lose and sent off to Steve Armitage for repair. He provided great service but this turned into bi-annual ritual stimulated by increased engine vibration. Three or four years ago I gave up and purchased a Maxprop. We have not looked back. We instantly experienced a much quieter engine in terms of vibrations and so far there have been no maintenance issues. We sold the Beneteau last month and the new owner will now have his/her choice of three different props but I'm sure they will stick with the Maxprop

[seasilk]

Let's talk Autoprop blades falling off.
I have a H5 on my Hylas. It came with the boat. First blade fell off in 2003 a day north of Cabo. It was repaired in England under the recall noted earlier. Second blade fell off in 2010 just before I went down on the Baja Ha Ha. it was repaired at a cost of $1600+. LAST blade failure happened less than 9 months later, just a couple of weeks after my diver had inspected the prop and replaced the cap zinc. Lucky for me, this failure waited until I had completed the Baja Bash back from Cabo. The prop had been cleaned and inspected no less than 6 times in the 9 month period. I say LAST because I have asked Bruntons to send me a new prop and they have just repaired the same hub again. Although I like the way Autoprop performs on my boat, I don't see how I can properly trust this particular unit with my life. Perhaps it isn't the manufacturer who is to blame, but I know this LAST failure was not maintenance related, so I can only think that either I got a "lemon" or Autoprop's are prone to loosing blades.

[fstbttms]

Originally Posted by seasilk

...I can only think that either I got a "lemon" or Autoprop's are prone to loosing blades.

My money's on the latter.

[Yachts66]

With so many people essentially saying the same thing, you'd think the manufacturer would be taking some action to seriously address the issues sited. More than anything, their silence speaks volumes to me.

Regards,

Thomas

[GALAWA]

Originally Posted by dkall

I'm currently dealing w/ Autoprop in a new install. I followed the manufacture - distributers rep suggestions and have the following.

Hull speed is reached at 1300 rpms when the engine max is 2600. At 1400 rpms I receive a HUGE vibration with bending of the shaft.

The prop stops the boat very quickly. Almost on a dime if one can say that about stopping boats.

I have an enclosed area for the prop (full keel boat) and rudder.

I checked w/ Autoprop the diagrams they sent and sized the prop accordingly. The diagrams they sent with the correct prop showed that it fit the opening.

I know of two sisterships boats with Autoprops that don't have this issue so I'm hoping to get this resolved soon.

I liked the Autoprop because at the time I couldn't find any negative comments about them. I like them because there is no mechanical stop. I like them because the auto pitch to current conditions. I like them because I didn't have to modify the end of the prop for any nuts and can in an emergency put a fixed prop back on.

I don't like the vibration issue but hope to get that resolved soon.

I do feel they overproped me. I have an 1/14" shaft and the prop they said was best was 21". I believe that is above the ABYC recommended standard.

I believe the issue will be resolved soon and I'll be entirely satisfied with the setup.

It occurs to me that several interesting feature of the autoprop are overlooked:
Autoprops auto ajust their pitch according to the motion of the boat:
When powering astern to stop the boat in an emergency, it reduces it pitch enabling maximum RPM are reached . I have tried it aboard and AMEL 54' : the boat stops on a dime !
Same when punching against sea and wind, maneuvering at low speed against strong wind, pulling out from a grounded position forward or backward: the autoprop reduces its pitch, sort of putting itself in low gear. You get 20 % or 30% more thrust than you would with a set pitch prop.
When motor sailing , it encreases its pitch and delivers thrust at lower RPM than a fixed pitch prop would.
All this makes fitting an autoprop an interesting alternative to replacing an engine with a more powerfull one.
Another feature is often overlookek : Contrary to a folding or feathering prop, if you do not brake the shaft or engage the reverse gear, the autoprop does not feather. It spins and can be used to drive a shaft alternator very effectively.

[Pete the Cat]

I wonder what the diesel mechanics say about obtaining cruising speed at just above idle. My thought is that this is nice for noise and fuel economy and a disaster for the life of your engine. Or am I missing something?

[GALAWA]

You do not reach cruise speed at idle revs.
Suppose you are sailing at 4 knots and start your engine
With a set pitch prop, 2000 RPM yields some thrust and some load on the shaft and an extra knot.
With an autoprop you get same thrust and load at 1500 RPM.
So you can run your alternator, your water maker, ... and gain an extra knot at nicely silent 1500 RPM with a proper total load on the engine.
Better than running the engine with the insuficient load of your alternator or water maker only