Feathering or Folding Props - Increase Performance?

[fastcat435]

What a difference it makes to cruise 10 % faster , did you also notice that it also helps in pointing higher ?
I noticed in low wind speeds the difference is almost 15 % in gained speed

[Yotboss]

Fastcat,

I didn't really make any attempt to measure how our new props may have helped pointing, but, in general, one points better when one is going faster, so I suppose it did help. We used to race a bit and really noticed the improvement over our regular competition immediately. Now that we're cruising, arriving at our destination hours earlier than we would have is pretty sweet.

Tom

[gramos]

hi , i fitted folding two blades to my sunstar and removed the standard volvo saildrive two blade fixed , i lock the drives in reverse to stop the gearbox from turning ,why have your gearbox running without the engine ?? . the props are from CJR in southampton uk called Vari - Prop and have been in service 7 years and are perfect . they gave me .5 of a knot straight away . not quite so much grip in astern , but i dont go backwards that often ! recommended .

[Jeannius]

Originally Posted by gramos

... the standard volvo saildrive two blade fixed , i lock the drives in reverse to stop the gearbox from turning ,why have your gearbox running without the engine ?? . .

My Volvo saildrive manual warns not to lock in gear when sailing as it will damage the gearbox. Don't know how or why but that's what it says.

[gramos]

i cant see how it could be damaged in any way if its not turning? if i leave them in forward gear the gearboxes run and issue a slight whine , . does your manual explain the damage potential ?

[Yotboss]

If one were to hit something with a fixed prop locked in position, I suppose you just might screw it up. Sounds like a factory CYA move to me...

[fastcat435]

I suppose the reason for not locking the prop in reverse might be that if a boat sails fast that the prop might actually turn the engine in opposite direction and so damage the engine , the waterpump will also work in reverse and might take in water if the outlet is below water line. I guess this could only happen with very high speeds and a type of prop with big surface blade area

[2Hulls]

Hi, this is my first "offering" on this forum.

I have three blade folding Volvo props and am very happy with them. Prior to acquiring these (they were attached to the boat I bought) I was a folding prop skeptic and always planned to have feathering props on whatever boat I bought.

Well.

During the sea trial I backed down from powering full ahead and I was instantly "converted." They work very, very, very well and if I ever have to replace them I will have to be really convinced to go with anything else. That said, they do go through zincs rather quickly, but at least I can replace them in the water in 30 second increments.

Dave

[Jeannius]

Originally Posted by gramos

i cant see how it could be damaged in any way if its not turning? if i leave them in forward gear the gearboxes run and issue a slight whine , . does your manual explain the damage potential ?

Can't remember, sorry. Boat and manual are in the BVI and I'm in the UK so can't check right now.

However, I have tried it a couple of times and it was almost impossible to get the box back into neutral while sailing so there is certainly a lot of pressure acting on the system.

[fastcat435]

Hallo 2hulls you present use the volvo / radice props that still have a considerable resistance if you ever want to change props and gain another 5 % in speed go for the Gori 3 blade folding props or another folding prop . the revers on the gori 3 blades is excellent and the speed gain remarkeble I switched from the same to these 3 blade folders with my st francis 48 and sail faster .
greetings and welcome to the forum

[2Hulls]

Originally Posted by fastcat435

I switched from the same to these 3 blade folders with my st francis 48 and sail faster .
greetings and welcome to the forum

Hi fastcat - can you please elaborate on this? Do you mean you switched from Volvo folders to Gori and sail faster? - or do you mean you can motor faster?

I'll bet that any sailing speed differences between all the folders and feathering props are very small or undetectable. Motoring performance is where the differences will be - or so it seems to me.

Thanks,
Dave

[Steve Rust]

To lock a saildrive in gear or not. I think the manual recommending that it be locked in reverse is ment if you have a folding prop as it helps it to fold up. I put a fixed 3 blade on for one specific trip and we let it spin in neutral. I was afraid that my small diesel (17hp) would turn over if we locked it in gear at the speeds my tri can sail. Lower speeds and larger engines may stop that from happening. I can't see how letting it spin can cause any damage as it is just a shaft and gears sitting in an oil bath. I suppose there would be more wear on seals and bearings if you did this constantly year after year. It does whine a bit as speed increases and there was some loss of performance even with it spinning. It was a one time thing and now the folding prop is back on.

[fastcat435]

Originally Posted by 2Hulls

Hi fastcat - can you please elaborate on this? Do you mean you switched from Volvo folders to Gori and sail faster? - or do you mean you can motor faster?

I'll bet that any sailing speed differences between all the folders and feathering props are very small or undetectable. Motoring performance is where the differences will be - or so it seems to me.

Thanks,
Dave

Hallo Dave

Just picked this one up a bit late but OK
When I changed from the Radice props to my present Gori 3 blad folding props we gained 5 % in speed and even more in low wind conditions
With less than 10 knots of wind actual sailing speed has increased with 8 %
and on a long voyage it makes a difference
The Volvo radice props have the disadvantage that the hydrodynamic resistance is still very high.

It does depend on the type used on your cat , they have 2 , 3 and 4 blade folding props 2 has the least and 4 the most resistance

greetings and happy sailing

[Joli]

We've used Martec folders locked in reverse and Maxprop feathering porps locked in forward. No problems with any of the props over ~25 years. Good forward and good reverse.