Prop change

dLj

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Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
I think we need to verify that the OP's engine can hit max RPM's in neutral before replacing the prop
Good point. But the OP said he wanted to do the prop change and as an aside see if it can cure the current problem of not reaching RPM's. But answering if the motor will achieve max RPMs in neutral should be an easy answer...

Perhaps answering why the prop change in the first place if it's not for the RPM issue. What other things are being desired...

dj
 

Tom K

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Dec 20, 2025
6
Beneteau 36cc Southport
Does the max prop reduce prop walk over a three blade? Is it enough to justify a 3K investment?

@Tom K Does your engine reach max RPM's in neutral?
Yes. I can easily achieve max rpm in neutral. But even with tanks empty and freshly cleaned I can’t cruising even with a following tide. But the twist is it can hold the 800rpm lower cruising speed in all conditions.
 

Tom K

.
Dec 20, 2025
6
Beneteau 36cc Southport
Good point. But the OP said he wanted to do the prop change and as an aside see if it can cure the current problem of not reaching RPM's. But answering if the motor will achieve max RPMs in neutral should be an easy answer...

Perhaps answering why the prop change in the first place if it's not for the RPM issue. What other things are being desired...

dj
The main thing desired is the RPM issue. The main reason I tied it to the other things is the expected increase in motoring. It’s a sailboat and has spent most of its life as such. I’m just planning to help it transition to wind assisted trawler.
 

dLj

.
Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
Yes. I can easily achieve max rpm in neutral. But even with tanks empty and freshly cleaned I can’t cruising even with a following tide. But the twist is it can hold the 800rpm lower cruising speed in all conditions.
Ok so the question is - why change your prop? What do you wish to accomplish? What prop do you currently have?

dj
 

Tom K

.
Dec 20, 2025
6
Beneteau 36cc Southport
Ok so the question is - why change your prop? What do you wish to accomplish? What prop do you currently have?

dj
Yanmar recommends being able to achieve an RPM 600 rpm higher than I can achieve. The boat has the original 15x8 prop . It’s an Italian brand , the name escapes me.
 

dLj

.
Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
Well, trawlers don't use folding props. Just an observation. If you are going to do the great loop - you will be doing a lot of motoring.


I would talk to a prop shop and see what they think about modifying your current prop - sounds to me like it should be an easy fix.

dj

p.s. are you in Long Island?


Yanmar recommends being able to achieve an RPM 600 rpm higher than I can achieve. The boat has the original 15x8 prop . It’s an Italian brand , the name escapes me.
 

Tom K

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Dec 20, 2025
6
Beneteau 36cc Southport
No , NC. Just a little south. I consulted with a local prop shop and thought I would examine replacement of the prop , giver the cost of modification.
 

dLj

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Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
No , NC. Just a little south. I consulted with a local prop shop and thought I would examine replacement of the prop , giver the cost of modification.
Well, you can always keep the original as a replacement which isn't a bad idea.

For doing the loop, i'd be more inclined to run a fixed blade prop. Of course, after doing the loop, you are back to being a sail boat...

Talk to the folks that make the campbell sailor and at least see what they say. For doing the loop I really don't see any advantage to using a folding prop...

dj
 

dLj

.
Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
I'd triple check to see if that's the appropriate prop for your engine and boat
It's obviously not sized correctly for his engine and transmission. It's over propped...

This one does! It's a really neat setup. Hydraulically driven backup backup prop powered by the genset. See sailbits.com for more info on it
View attachment 235947
Talk about pulling oue out of your ... Or as they say, there's one in every crowd... (I'm joking - just in case you didn't get it hahahha)

That's a back up prop - it has nothing to do with the main drive prop. It's a feathering prop specifically because it's not a main drive prop... Show me a trawler with the main drive prop as a feathering prop - I've never seen one... but hey, I'm always open to learning...

dj
 

Tom K

.
Dec 20, 2025
6
Beneteau 36cc Southport
Thank you for the input. It was my plan to keep the old one for a spare. I filled out the prop calculator with the Campbell sailer folks. Haven’t heard back yet. If it’s less than $1000 it seems like a good investment.
 
Sep 24, 2018
4,004
Catalina 30 MKIII Chicago
Talk about pulling out out of your ... Or as they say, there's one in every crowd... (I'm joking - just in case you didn't get it hahahha)

That's a back up prop - it has nothing to do with the main drive prop. It's a feathering prop specifically because it's not a main drive prop... Show me a trawler with the main drive prop as a feathering prop - I've never seen one... but hey, I'm always open to learning...
I just happened to come across that boat the other day. Really nifty setup. The feathering prop for the backup is a really nice feature to reduce drag. Few expenses have been spared on this boat
 

dLj

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Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
Thank you for the input. It was my plan to keep the old one for a spare. I filled out the prop calculator with the Campbell sailer folks. Haven’t heard back yet. If it’s less than $1000 it seems like a good investment.
Keep us posted - I'll be very interested in hearing what they say.

dj
 

dLj

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Mar 23, 2017
4,780
Belliure 41 Back in the Chesapeake
I just happened to come across that boat the other day. Really nifty setup. The feathering prop for the backup is a really nice feature to reduce drag. Few expenses have been spared on this boat
That's a pretty cool boat!

Before buying my current boat, I considered a trawler thinking I was getting up there in age and maybe I should go that way. I spent quite a bit of time researching trawlers. What an amazing range of craft! In the end, I simply can't afford one, AND, I am still very much a sailor...

When I was in the Azores, there was a trawler that came in. It grounded in the harbor and sat in the middle of the harbor for a day waiting for the tide to rise. What a ship! But the fuel costs... There are trawlers made to be very efficient on fuel usage, but even those drink far more diesel then my sail boat...

There are a number of folks taking smaller sailboats and pulling the masts off and making them essentially trawlers. They are using them for the Great loop to keep the fuel costs way down compared to the more traditional trawlers. Kind of sounds like the OP in this thread, at least using a sailboat to do the loop...

I'm actually considering taking my boat up into the Great Lakes. I don't think I'll actually do the Great Loop, but spending a number of summers sailing in the Great Lakes might just be in my future. I'm really itching to sail the North Channel and complete my great lakes sailing by sailing Superior - I've sailed all the others.....

dj