Folding vs Fixed Prop STW?

[Davidasailor26]

There is an assumption above that is not my case, "If you're a cruiser...doesn't care if you're going 6.1 or 6. kts". I'm a cruiser, and cruising is not as simple as this implies. Of course, I'm talking passage making, not costal cruising. So perhaps that's a difference. In passage making, getting there as quickly as possible minimizes risk by spending less time in the open ocean. Getting enough speed also allows one to watch for and possibly avoid the worst of a storm by changing tack. So I don't think this should be dismissed quite so quickly. In fact I am quite concerned with speed. Now the whole PHRF system is of no concern to me, but the discussion of what is realistic in terms of speed gained by moving away from a fixed blade to a folding or feathering prop is of great interest to me.

If as you suggest it's only a matter of 0.1 kts, then it may not be worth the cost. But if truly it's more like 0.5 kts, or more, then the cost/benefit may well be worth it.

dj

Good point about the difference between cruising and racing considerations. I’ll add one more aspect to that consideration. A racer might need the bigger speed difference that the folding prop provides at a lower wind range, but a cruiser might not care as much about that. If the wind is blowing 4 knots the racer will want to travel 3.25 knots instead of 2.5, but the cruiser is probably motoring at that point. The cruiser tries to pick weather windows, as much as possible, to sail when the wind is in that 8-12 knot range where my plot shows not much difference from the folding prop.

 

[dLj]

Good point about the difference between cruising and racing considerations. I’ll add one more aspect to that consideration. A racer might need the bigger speed difference that the folding prop provides at a lower wind range, but a cruiser might not care as much about that. If the wind is blowing 4 knots the racer will want to travel 3.25 knots instead of 2.5, but the cruiser is probably motoring at that point. The cruiser tries to pick weather windows, as much as possible, to sail when the wind is in that 8-12 knot range where my plot shows not much difference from the folding prop.

Yes, this is an excellent point and while applies to me, if this were a cruiser (passage maker?) running an all electric boat that may not be the case as currently with electric, they really are limited to in and out of ports. Crossing the ITCZ for example, I would likely just run the motor and cross as time efficiently as possible, for many reasons. But the all electric boat may not have the range and be forced to rely on sails so the motoring part may not be so applicable. Of course in both cases, reliability and maneuverability in forward and reverse are very important.

Someone commented if going to a feathering prop, to go to a 4 blade instead of a 3 blade for all the added power in forward and reverse while still minimizing the drag. Now that to me sounds like superb cruising (passage making) advice!

dj

 

[dlochner]

Yes, this is an excellent point and while applies to me, if this were a cruiser (passage maker?) running an all electric boat that may not be the case as currently with electric, they really are limited to in and out of ports. Crossing the ITCZ for example, I would likely just run the motor and cross as time efficiently as possible, for many reasons. But the all electric boat may not have the range and be forced to rely on sails so the motoring part may not be so applicable. Of course in both cases, reliability and maneuverability in forward and reverse are very important.

Someone commented if going to a feathering prop, to go to a 4 blade instead of a 3 blade for all the added power in forward and reverse while still minimizing the drag. Now that to me sounds like superb cruising (passage making) advice!

dj

If you are considering a zero emissions all electric boat, read about Jimmy Cornell's experience on Aventura.

Cornell Sailing Publications

Long distance cruising books by Jimmy Cornell, accomplished sailor and successful best-selling author, and his family.

cornellsailing.com

 

[dLj]

If you are considering a zero emissions all electric boat, read about Jimmy Cornell's experience on Aventura.

Not me - I'm running a 57 hp Yanmar diesel with onboard fuel above 120 gallons. That should give me approximately 200 hours of motoring capability.

dj

 

[dlochner]

Not me - I'm running a 57 hp Yanmar diesel with onboard fuel above 120 gallons. That should give me approximately 200 hours of motoring capability.

dj

On a Hunter 30?

 

[dLj]

On a Hunter 30?

Oh I have to update my profile. No for sure not. On a Belliure 41.

dj

 

[dlochner]

Oh I have to update my profile. No for sure not. On a Belliure 41.

dj

that is a bit of an upgrade from a Hunter 30.

 

[dLj]

that is a bit of an upgrade from a Hunter 30.

I've been looking for a blue water boat for about 2 years. Just found her early this year.

The Hunter was always just a lake boat. It's a super boat for lake Champlain, but was never being considered for ocean traveling. I guess one could cross oceans in it, but I wouldn't....

dj

 

[Mikem]

Yes, this is an excellent point and while applies to me, if this were a cruiser (passage maker?) running an all electric boat that may not be the case as currently with electric, they really are limited to in and out of ports. Crossing the ITCZ for example, I would likely just run the motor and cross as time efficiently as possible, for many reasons. But the all electric boat may not have the range and be forced to rely on sails so the motoring part may not be so applicable. Of course in both cases, reliability and maneuverability in forward and reverse are very important.

Someone commented if going to a feathering prop, to go to a 4 blade instead of a 3 blade for all the added power in forward and reverse while still minimizing the drag. Now that to me sounds like superb cruising (passage making) advice!

dj

I looked at a four blade flexofold to replace my three blade flexofold but flexofold said my 76hp diesel was not strong enough.