Auto Prop

[Amaranth]

I am thinking of putting some type of more efficent props on my Fontaine Pajot Salina 48 Cat, to replace the current fixed three blades.
After some pokeing around I am getting close to selecting the Autoprop.
Does anybody have any experience in fitting the Autoprop to similar cat or any veiws on my choice?

[fstbttms]

My mother always told me, "If you can't say something nice, don't say anything at all."

So I won't.

[Dockhead]

Originally Posted by fstbttms

My mother always told me, "If you can't say something nice, don't say anything at all."

So I won't.

So you finally remembered after 40 or however many years? We will expect a radical change I'm sure the whole forum will be jubilant.


To the OP:

There is a thread on here on Autoprops which ran to thousands of posts. It would be worth reading. You can find a lot of useful information, including strong opinions from Fstbttms, oops, maybe not intersecting sets


A thumbnail summary:

1. You will be very happy you got rid of your fixed props no matter what folding or feathering prop you choose.

2. The Autoprop is one of the most popular of these, and you can read about the practical experience of a lot of people on here, including that of yours truly, who has been using them for about 20 years on two different boats.

3. There was a run of early Autoprops which had defective locking washers which resulted in a rash of thrown blades. That was more than 10 years ago. Nevertheless, that has given them a bad reputation with some people. Since the recall which solved that particular problem, there is no evidence that Autoprops are less reliable than any other variable geometry prop.

4. There are a lot of reports of poor factory support. I can't vouch for that -- I've had only one contact in 20 years, just this year, and it was pleasant and efficient. Nevertheless, there are a lot of reports.

5. The Autoprop has a supreme advantage in that the pitch varies automatically, which is a feature you can't get in any other prop for sailboats of modest size other than the new MaxProp Ecowind. This is supreme for motorsailing, and is also very good for situations like punching into strong winds or seas. It transforms motorsailing.

6. The Autoprop is the worst variable prop you can buy in terms of drag. It droops one blade when feathered due to the nature of its design (no gears or springs). This means it might not actually be the best choice for a catamaran, where you have two of them. Of course it's still one-tenth or less the drag of a fixed prop Still, most cat owners don't choose feathering props at all -- they go for folding ones, which have less drag.

7. The newer type of Autoprop with greased bearings requires more maintenance than the older ones with water lubricated bearings. I grease mine every time I lift out (every 3 - 4 months).

8. The Autoprop has a particularly carpy anode which is proprietary, expensive, and quickly falls off because the zinc around the screws is thin. It's important to put some antifoul or prop wax on the thin parts to keep them from being eaten away.

Good luck.

[fstbttms]

Originally Posted by Dockhead

We will expect a radical change

You know, that dawned on me after I wrote it.

[Amaranth]

FSTBTTMS and Dockhead.

Thank you both for your rapid reply, clearly expressing both sides of the argument.

Dockhead , your precis of the previous tread is of great value. Thanks

[carstenb]

I looked closely at the Autoprop and finally installed a Maxprop. Mainly because everyone I talked to said that when sailing with an Autoprop you end up with a minimum speed of something like 4 knots, because it automatically changes the pitch. So very slow sailing for longer periods of time requires moving the gear shift in and out of gear.

I do like my Maxprop.

[SVI]

Originally Posted by Amaranth

I am thinking of putting some type of more efficent props on my Fontaine Pajot Salina 48 Cat, to replace the current fixed three blades.
After some pokeing around I am getting close to selecting the Autoprop.
Does anybody have any experience in fitting the Autoprop to similar cat or any veiws on my choice?

Check the quote from Italian manufacturer Radice elicheradice.it - they supply OEM folding props for Volvo Penta. I have heard they have very reasonable prices, and the models are tested on FPs (your Salina would have them from the factory if you choose the folding option)

But those Italians need the propeller specs to give a quote.
What engines your Salina has, and what prop specs?

[Dockhead]

Originally Posted by carstenb

I looked closely at the Autoprop and finally installed a Maxprop. Mainly because everyone I talked to said that when sailing with an Autoprop you end up with a minimum speed of something like 4 knots, because it automatically changes the pitch. So very slow sailing for longer periods of time requires moving the gear shift in and out of gear.

I do like my Maxprop.

You mean motoring, not sailing, right?

Indeed this is another disadvantage of the Autoprop -- at idle and in gear, the Autprop pitches up and you can't motor slowly. I get about 3 - 4 knots in smooth water and at idle. It's an illustration of the efficiency of the prop, but can be PITA in some docking situations.

[carstenb]

Originally Posted by Dockhead

You mean motoring, not sailing, right?

Indeed this is another disadvantage of the Autoprop -- at idle and in gear, the Autprop pitches up and you can't motor slowly. I get about 3 - 4 knots in smooth water and at idle. It's an illustration of the efficiency of the prop, but can be PITA in some docking situations.

yes, motoring of course. I dislike this. Many harbours in the baltic are quite small and 3-4 knts is way too fast. On the other hand, lots of wind in the baltic so you generally want to have engine control.

My Maxprop doesn't seem to have these issues. I move quite happily at 1,5 to 2 knots at idle. This is enough to make the keel and rudder "bite" so I retain control.

But props react differently on different boats. I replaced a 3 bladed Volvo folding prop because it didn't brake (and I mean did not brake) nor did it go in reverse very well. Probably because my boat is a fin keel with a very flat bottom.

But the Max does well. Now all I need to do i find someone who wants to buy a 3 blade fold that is in new condition

[Dockhead]

Originally Posted by carstenb

yes, motoring of course. I dislike this. Many harbours in the baltic are quite small and 3-4 knts is way too fast. On the other hand, lots of wind in the baltic so you generally want to have engine control.

My Maxprop doesn't seem to have these issues. I move quite happily at 1,5 to 2 knots at idle. This is enough to make the keel and rudder "bite" so I retain control.

But props react differently on different boats. I replaced a 3 bladed Volvo folding prop because it didn't brake (and I mean did not brake) nor did it go in reverse very well. Probably because my boat is a fin keel with a very flat bottom.

But the Max does well. Now all I need to do i find someone who wants to buy a 3 blade fold that is in new condition

I understand. It's also an issue for me sometimes.

The MaxProp is a great prop; standard fitment to Oysters for decades. If you don't need self-pitching I don't think you can do much better than a MaxProp.

The ability to go well in reverse is an extremely important quality in a prop, in my opinion. Here the AutoProp does extremely well because in reverse, the blades turn all the away around to face the correct hydrodynamic direction. The MaxProp is also very good. Many folding props are not good in reverse; the OP would do well to check the ratings. There are different good prop tests available on the 'net. I would not want, myself, to have any prop that didn't stop the boat well -- dangerous.

[jeremiason]

You are definitely right to replace your fixed prop. Feathering or folding props will add sailing speed to your boat. On my boat, I went from a 21" three blade fixed prop to a Max Prop VP. It added 1 knot of sailing speed, which for cruising boat is a considerable gain.

The Max Prop itself performs almost identical to the original fixed prop, including the prop walk, which is great for close quarter maneuvering and overall boat speed while motoring is the same in both RPMs and overall speed.

The down side is it requires a special zinc, which like the AutoProp tend to wear out around the bolt holes and throw the zinc. To counter this, I drill a 1/2" hole through the zinc, which seems to extend the life of the zinc by almost twice as much.

By the way here is another discussion on Auto Prop:

http://www.cruisersforum.com/forums/...prop-4299.html

[carstenb]

Originally Posted by jeremiason

The down side is it requires a special zinc, which like the AutoProp tend to wear out around the bolt holes and throw the zinc. To counter this, I drill a 1/2" hole through the zinc, which seems to extend the life of the zinc by almost twice as much.

By the way here is another discussion on Auto Prop:

http://www.cruisersforum.com/forums/...prop-4299.html

I take a small brush and paint the screw holes with bottom paint. That effectively stops the wear. Still need to replace every year, but all zincs should be replaced at least once per year

[Cotemar]

The AutoStream may be a better option for you.

Seahawk AutoStream Stainless Steel Feathering Saildrive Propellers