Autoprop ?

[dkall]

Honestly, I don't think the Autoprop has changed much in the last 6 years. I do believe; hope there isn't any more blades coming off. I have one. As for prop walk on the Autoprop there is very little and loads of power in reverse. Also you won't go 6 kts unless they only take into account the engine and not the boat. They first outfitted me with a prop for the engine not really taking into account the boat and the aperature. Once they made it right I've been quite happy with it. All that said if you get the autoprop and you have a hydraulic tranny you will need to get a prop lock. So figure that in your cost calculation.

And. .... the I think I'll need to own the boat for about 20 years and circumnavigate the globe twice to save in fuel what I paid for the prop.

Ciao

[hoolie]

We fitted an Autoprop for the same reason and it's made the boat much more controllable going astern. Because the prop pitch adapts to revs AND speed when going slowly the pitch is fine and doesn't accelerate much at low revs. If speed builds up just select neutral ... ...

[cfarrar]

I've used / owned both Autoprop and Maxprop. Both will improve your reverse performance significantly. You can idle slow ahead with both props; no worries there. The Autoprop is better at motorsailing and motoring in big waves, because the blades auto adjust their angle with load. The Maxprop is slightly less drag when sailing. At the end of the day, I would choose based on reliability, availability of parts and service, and price. I don't know which is more reliable - many opinions in this thread.

[carstenb]

Thank you

Anyone else had both?

[fstbttms]

Max Prop is as reliable as the day is long. Can't say that about Autoprop.

[athene]

We're now laying up Athene of Lymington and total engine hours with our new Autoprop are 67 for the season (effectively just three months this year). Fuel usage is 148 litres, which gives an average for the season of 2.2 litres per hour.

That compares, as I reported in my earlier posting (see below), with 3.3 litres per hour with our former Maxprop - effectively a 33 per cent reduction in fuel consumption. I've also noticed our stern is clean, whereas it used to get sooty after several hours motoring with the Maxprop (set at 21 degrees pitch). It seems that, for our boat at least (Oyster 435 cutter-rigged ketch), the Autoprop is a more efficient combination, especially when motorsailing.

Otherwise, nothing has happened to change my earlier observations on the motoring or sailing qualities.

[fstbttms]

Originally Posted by athene

...effectively a 33 per cent reduction in fuel consumption. I've also noticed our stern is clean, whereas it used to get sooty after several hours motoring with the Maxprop (set at 21 degrees pitch).

What this says to me is that you had your Max Prop pitched incorrectly.

[Blinky]

Originally Posted by fstbttms

What this says to me is that you had your Max Prop pitched incorrectly.

Crikey! Would you like to borrow my grinder for that axe? Having used and owned the Auto prop I have to say it does exactly what it claims to do. Having read through several threads on props of all types, and makes, it would appear that if they are not fitted or maintained correctly there is a risk that they will either loose a blade or fall off, and some so called boat yard engineers would struggle with Mecano. I would certainly not let them near my boat net alone fit a prop!
Latest sealed bearing auto prop is well made and solidly constructed. I can’t comment on the older models because I have neither seen one or used one. However, everyone I have spoken to who has this type of prop says how good it is and has not complained of loosing a blade. There is a down side, they do eat annodes.
Blinky

[fstbttms]

Originally Posted by Blinky

Crikey! Would you like to borrow my grinder for that axe?

What does my remark about your Max Prop have to do with my opinion of Autoprop? If you are making smoke with one prop but not another, that says your prop is pitched incorrectly, not that Autoprop is better than Max Prop.

Regarding Autoprops losing blades; I have personally seen this on several different boats and if you search this forum, you will find many other reports of owners losing blades and that a whole range of model years were recalled to address this problem. I don't doubt that the Autoprop performs as advertised, but having installed and maintained a bunch of them, I don't see the advantage of having bearing races open to the sea (and therefore fouling organisms), easily breakable nylon screws for anode attachment and the absence of any fail-safe mechanism to secure the prop to the shaft. Not great design features, IMHO. Not to mention their propensity (in the past, at least) for thowing blades.

[Blinky]

Originally Posted by fstbttms

What does my remark about your Max Prop have to do with my opinion of Autoprop? If you are making smoke with one prop but not another, that says your prop is pitched incorrectly, not that Autoprop is better than Max Prop.

Regarding Autoprops losing blades; I have personally seen this on several different boats and if you search this forum, you will find many other reports of owners losing blades and that a whole range of model years were recalled to address this problem. I don't doubt that the Autoprop performs as advertised, but having installed and maintained a bunch of them, I don't see the advantage of having bearing races open to the sea (and therefore fouling organisms), easily breakable nylon screws for anode attachment and the absence of any fail-safe mechanism to secure the prop to the shaft. Not great design features, IMHO. Not to mention their propensity (in the past, at least) for thowing blades.

I have an H20 it has sealed bearings and 2 no M6 316 ss screws securing the anode. Even if these were nylon and there were 3 of them the bolts are in shear not in tension, any load on them is due to the rotational force exerted buy the mass of the anode (Newton’s 3rd law), this is extremely low, and you should also consider the friction between the two surfaces. My prop has an M14 securing nut locked by an M8 socket head bolt (which Brunton supply a marine grade thread lock for) this bolt has a keyway into which an M6 socket head machine screw locks both the nut and M8 bolt.
I agree that an open bearing is not a good solution in a marine environment, especially in a silty estuarine environment, as the bearing surface could become fouled with particulates harder than the bearing surface. However, having taken a look at technical details and done the maths the even if the bearing failed and locked it would not cause the blade to fail, IE fall off. There must be another contributory factor such as a prop strike or poor fitting.

Simply condemning all Brunton auto-props, is not an objective or informed view, is it?
There are also accounts of many other props shedding blades, such as the Kiwi prop and worst of all the Volvo folding prop! The Kiwi has plastic blades which disintegrate if they strike a solid object at speed. The Volvo has to be fitted by someone who knows what they are doing or they miss of the tabs not included in the fitting kit.

You are entitled to your opinion but condemning all Bruntons is harsh.

When I have got of this horse you can borrow my ladder, yours look hi too.


Blinky

[fstbttms]

Originally Posted by Blinky

ISimply condemning all Brunton auto-props, is not an objective or informed view, is it?

It's very nice that Brunton's have corrected some of the design flaws the original Autoprop suffered from. But a well-thought out design wouldn't have had those flaws to begin with. Further, most of those old, poorly designed Autoprops are still out there, giving people like me headaches. So yes, my opinion of Autoprop is harsh. Fortunately for me, Autoprops are relatively rare.

[Blinky]

Anode now down to 30% the Sikaflex on the bolts has helped but is not a good solution. So I decided to come up with my own. @ £42 inc tax and shipping the Brunton one is not economical. Hope this is of use to someone? Zink can be melted in a bean can with a gas torch. Warm the mould first! Walking round the yard picking up those discarded anodes to melt down is a cheaper solution!

Best regards.

http://www.cruisersforum.com/attachm...2f04284b89.jpg

[hellosailor]

Blinky, I have been told that not all anodes are the same alloy, not all are 100% pure zinc, and that the ones you see tossed have already had some change in the content, not just reduced size. I don't know how true that is.

But when you are melting down zinc, be very careful about the fumes. Apparently those who work with it (like welders on galvanized piping) get lung damage from inhaling the fumes. Stay upwind.

[Dockhead]

Originally Posted by fstbttms

It's very nice that Brunton's have corrected some of the design flaws the original Autoprop suffered from. But a well-thought out design wouldn't have had those flaws to begin with. Further, most of those old, poorly designed Autoprops are still out there, giving people like me headaches. So yes, my opinion of Autoprop is harsh. Fortunately for me, Autoprops are relatively rare.

Maybe Autoprops are rare in San Francisco Bay, but they are not in other parts of the world. They are the predominant type of non-fixed prop in the UK by far.

My father and I put about 10,000 hours on one of the water-lubricated bearing type Autoprops without any issues, and it's still going strong. My present boat has the newer type with sealed, greased bearings, that you have to lubricate with a special nipple at every haulout. I am not sure that there is anything inherently wrong with water-lubricated bearings in this application, and I am not sure that the sample of thrown blades is statistically significant. Do we know that the old Autoprops did that any more than any other folding/feathering prop? I had a Flexofold prop throw a blade on me in the Windward Islands; a certain risk of that goes with the territory of every folding or feathering prop. I keep a spare fixed prop on board at all times; as I would do with any folding/feathering prop.

MaxProps are great props and are original fitment to Oysters. If you don't need variable pitch, they're a great choice. But variable pitch is tremendously valuable. I would not, personally, want to be without it on a sailboat, having experienced it.

I do agree with comments above about the carp anode design, to my mind the biggest weakness of this prop.

[hellosailor]

Dockhead-
Perhaps part of the answer lies in the same issue that bedevils bottom paint? That is, the nature of the surrounding water. A water-lubricated bearing will also be abraded by whatever is in the water. If the somewhat cold clear waters around the UK contain less abrasive matter, the bearings will hold up just fine, as compared to warmer waters with more life, perhaps full of gritty little diatoms and more particulate matter?
I'm sure someone, somewhere, knows how "local" waters compare that way but I suspect that information would be hard to come by. It would be interesting to find out though.