I think we need to verify that the OP's engine can hit max RPM's in neutral before replacing the prop
Prop change
- Thread starter Tom K
- Start date
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
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
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?
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?
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
I'd triple check to see if that's the appropriate prop for your engine and boat
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
It's obviously not sized correctly for his engine and transmission. It's over propped...
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
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.
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
Boat manufacturers will sometimes over pitch a prop purposely. It will allow lower cruising rpm and allow a lower burn rate at cruising speed. Most cruising sailboats never run WOT. My Morgan 383 had a 50hp Perkins 4-108. 50hp@4000rpm. Its real world max rpm was 3500. The stern would squat, little speed gain versus 2700 which was our "in a hurry " rpm. 3/4 gal/hr burn at 5kn. @ 2400.
Big 'ole 16" pitch fixed 3 blade bronze prop which would be what I would want for looping it. Mostly motor work. Hurth trans allowed free wheeling in neutral while sailing. +1/2 kn. Change it out when you get back.
Big 'ole 16" pitch fixed 3 blade bronze prop which would be what I would want for looping it. Mostly motor work. Hurth trans allowed free wheeling in neutral while sailing. +1/2 kn. Change it out when you get back.
Good discussions.
I have a campbell sailor prop. I do love it and have had it for about 13 years. I purchased it to replace my old 3 blade prop which did not allow engine to get to max RPMs.. The replacement from Campbell Sailor achieved that for my Yanmar 3GMD. It also helped reduce the excessive amount of prop walk from my original prop (it was extremely difficult to get it to ever back straight). For reference,I back into my slip and didn't want more prop walk when making my choice
I think replacing a three bladed prop with a Campbell Sailor or three bladed folding prop is a better comparison on performance.
Also my engine is supposed to be in neutral when sailing, and the prop free wheels.
I wonder for those with a Max Prop, and a yanmar engine, do you put it in gear when sailing or for just a moment to allow the blades to close?
FWIW: I seen photos of some boats (YouTube ) that have filmed their prop while sailed with a folding prop to find it didn't fold entirely in light winds and slower speeds.
I have a campbell sailor prop. I do love it and have had it for about 13 years. I purchased it to replace my old 3 blade prop which did not allow engine to get to max RPMs.. The replacement from Campbell Sailor achieved that for my Yanmar 3GMD. It also helped reduce the excessive amount of prop walk from my original prop (it was extremely difficult to get it to ever back straight). For reference,I back into my slip and didn't want more prop walk when making my choice
I think replacing a three bladed prop with a Campbell Sailor or three bladed folding prop is a better comparison on performance.
Also my engine is supposed to be in neutral when sailing, and the prop free wheels.
I wonder for those with a Max Prop, and a yanmar engine, do you put it in gear when sailing or for just a moment to allow the blades to close?
FWIW: I seen photos of some boats (YouTube ) that have filmed their prop while sailed with a folding prop to find it didn't fold entirely in light winds and slower speeds.
Stop the engine while the boat is in forward and the prop rotating slowly. The blades will feather and once feathered the transmission is placed in neutral.
If this doesn't work, then something is wrong. The prop could be damaged, not enough grease, or the wrong kind of grease.
