3 Bladed Folding Prop Spinning While Under Sail

[solecollector]

I have a 3 bladed folding prop that spins when I'm under sail. I've checked it and the prop is very clean and seems to fold easily by hand. So why in the... is it spinning? It is 6 years old. Thanks!

[Jim Cate]

Often if you are motoring along at a few knots or more, shift to neutral and switch off the engine, the folder will continue to spin. If you then pop the transmission into reverse momentarily the shaft will stop, the prop will fold and you can, if desired, shift back to neutral and it will remain folded.

This has been true with all of the three folding props we have used over the years.

Cheers,

Jim

[delmarrey]

Unless it's geared (3 blade not likely), one of the blades may drop due to gravity. Once it starts moving it will continue. What is your trany type? Most you can put the trany in reverse and that'll stop it. But with a folding prop it shouldn't really matter. There would be so little stress that it couldn't do any harm. If it is locked in position then the dropped blade will just rise with speed.

[solecollector]

Jim - thanks for the insight. Makes total sense.

delmarrey - I have SD50s which I've heard that you shouldn't leave in gear while sailing.

[Jim Cate]

Originally Posted by solecollector

Jim - thanks for the insight. Makes total sense.

delmarrey - I have SD50s which I've heard that you shouldn't leave in gear while sailing.

That is true with fixed props, but once the folder is folded it does not stress the tranny at all. Should be no problem.

Jim

[sparrowhawk1]

I'm not a mechanic. But I understand that some transmissions will be harmed if a prop turns them when the engine is off. I have a max prop and when I'm motor sailing and want change to just sailing I put it in reverse rev it up a little bit and kill the engine. the prop then folds and having it in gear keeps the shaft from spinning.

[colemj]

Originally Posted by delmarrey

Unless it's geared (3 blade not likely), one of the blades may drop due to gravity.

All of the 3-blade folders I have seen are geared. Volvo, Flex-o-Fold, Brunton and Gori 3-blade models certainly are geared.

Mark

[delmarrey]

Originally Posted by colemj

All of the 3-blade folders I have seen are geared. Volvo, Flex-o-Fold, Brunton and Gori 3-blade models certainly are geared.

Mark

Thanks! I've never owned or dealt with a "3 blade" folder only 2 blade. I prefer feathering props.

[sparrowhawk1]

I said my prop folds I should have said it feathers. But the same procedure should be used regardless

[nhschneider]

We have well over 20,000 miles on our Gori 3-blade folding prop and we're delighted with it, however, getting the prop to stop spinning when we shut the engine down has taken a while to figure out. By the way, we have a hydraulic transmission so putting the transmission in gear when the engine isn't running is useless - the shaft spins anyway. We have tried putting the transmission in reverse prior to shutting the engine down but it doesn't stop the prop from spinning. The manual that came with our transmission clearly states that no damage will occur to the transmission if the prop shaft spins while we are sailing. The problem, though, is that we have a center cockpit boat with an aft cabin - the noise of a spinning prop while sailing is very annoying.

We have learned this: If we've been motoring and the wind begins to freshen, we'll normally hoist/unfurl sails while the engine is still running. After letting the engine idle for a few minutes in neutral, we luff up into the wind until our boat speed drops to about 2 knots, then shift the transmission into forward and shut down the engine immediately. This works for us very consistently although sometimes I get impatient and try to do the procedure while the boat speed is too high and then I have to restart the engine and go through the whole thing again.

Fair winds and calm seas.

[Jim Cate]

Originally Posted by nhschneider

We have well over 20,000 miles on our Gori 3-blade folding prop and we're delighted with it, however, getting the prop to stop spinning when we shut the engine down has taken a while to figure out. By the way, we have a hydraulic transmission so putting the transmission in gear when the engine isn't running is useless - the shaft spins anyway. We have tried putting the transmission in reverse prior to shutting the engine down but it doesn't stop the prop from spinning. The manual that came with our transmission clearly states that no damage will occur to the transmission if the prop shaft spins while we are sailing. The problem, though, is that we have a center cockpit boat with an aft cabin - the noise of a spinning prop while sailing is very annoying.

We have learned this: If we've been motoring and the wind begins to freshen, we'll normally hoist/unfurl sails while the engine is still running. After letting the engine idle for a few minutes in neutral, we luff up into the wind until our boat speed drops to about 2 knots, then shift the transmission into forward and shut down the engine immediately. This works for us very consistently although sometimes I get impatient and try to do the procedure while the boat speed is too high and then I have to restart the engine and go through the whole thing again.

Fair winds and calm seas.

That's interesting! Is your Gori one of the ones with the "overdrive" feature? That magical arrangement may influence how it reacts to the shut down procedure.

Jim

[sailorboy1]

I've had both a MaxProp 3-blade feathering prop and 3-blade Flex-O-Fold folder, they both have sometimes stayed open and we knew it by the noise of the shaft spinning. For both the answer was to shift the engine into reverse and then feathered/folded.

[nhschneider]

Originally Posted by Jim Cate

That's interesting! Is your Gori one of the ones with the "overdrive" feature? That magical arrangement may influence how it reacts to the shut down procedure.

Jim

JC-
I think all Gori props have the 'overdrive' feature, which is nothing more that putting the blades in the reverse attitude yet putting the transmission in forward. We rarely use it while cruising (at least we don't intend to use it while motoring any distance but sometimes we'll say to each other, "Wow, we must have a really strong current in our favor!" since we'll be doing 7.5 knots at 1,400 RPM. It often takes a minute or two before the light bulb clicks on over our head and a little voice from somewhere says, "You dummy! You're in overdrive!").

However, it is a very useful feature when it comes to maneuvering in a marina. Often as I'm approaching a slip, I'll put the prop in the overdrive mode and the boat will stop straight when I back down. Without it in overdrive, we pull badly to starboard (left-hand prop). I think its a grossly under-rated feature.

Fair winds and calm seas.