Due to Hurricane Irene last fall, I need to replace my prop. I had a two blade 13" x 12 rh prop. I am considering a three blade for additional power and control. I know there is a drag factor, but I don't race. Any suggestions? What would be best replacement size if I'm trying to replace the 13x12 above. Thanks, Fogg
Two or Three blade prop
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Prop Choices
I have some personal experience, over 15 years, with a two blade fixed, a two blade feathering, and currently a three blade "sailor" fixed.
Sidebar: please do not imagine that "racing" is relevant. Whether you enter a race or not has nothing to do with your problem. Efficiency under sail and under power is the issue.
By far, and I mean a knot of speed gain in all wind speeds, the feathering prop is the best answer for sailing. It's a mechanical device, though, and has its own maint. requirements, beyond the high initial cost.
Fixed props are a the same or maybe a little better for motoring, and I now find that the three blade fixed is way better than the two blade I used to use.
Even though we went with the narrower (sailor model) blade version, the increase in power delivered to the water is very noticeable. If you are in a steep chop in a channel where sailing is not practical, the added power is wonderful.
I have a bit more waterline than you, but about the same displ. We might even have the same diesel, an M25XP Universal.
So be prepared to love the motoring performance and realize that there's a price to pay when under sail. Everything's a compromise, as someone once said...
We now motor, with a clean bottom, at 7.5 kts, and can maintain an easy cruising 7.0.
Advice worth about what you pay...
Best
LB
I have some personal experience, over 15 years, with a two blade fixed, a two blade feathering, and currently a three blade "sailor" fixed.
Sidebar: please do not imagine that "racing" is relevant. Whether you enter a race or not has nothing to do with your problem. Efficiency under sail and under power is the issue.
By far, and I mean a knot of speed gain in all wind speeds, the feathering prop is the best answer for sailing. It's a mechanical device, though, and has its own maint. requirements, beyond the high initial cost.
Fixed props are a the same or maybe a little better for motoring, and I now find that the three blade fixed is way better than the two blade I used to use.
Even though we went with the narrower (sailor model) blade version, the increase in power delivered to the water is very noticeable. If you are in a steep chop in a channel where sailing is not practical, the added power is wonderful.
I have a bit more waterline than you, but about the same displ. We might even have the same diesel, an M25XP Universal.
So be prepared to love the motoring performance and realize that there's a price to pay when under sail. Everything's a compromise, as someone once said...
We now motor, with a clean bottom, at 7.5 kts, and can maintain an easy cruising 7.0.
Advice worth about what you pay...
Best
LB
LB, Thanks for the quick reply. I'm not ready to spring for the feathering or folding prop. I just want to max the juice I can get from my M25 Universal. We do quite a bit of distance cruising and the iron jennicker often plays a big part. Have a great summer! Fogg
One little caveat, if I may...
If you go with a Michigan Sailor three blade, make the seller provide a Written Guarantee that the pitch is actually accurate for all blades.
QC from Michigan Propeller seems to be hit n miss. Cost me about $150. to get it repitched to what it was supposed to be when purchased. And that was causing some vibrations. One blade was off pitch by about a full half inch.
Then there was the cost to haul it out and block it again, too.
(mutter mutter...)
"Trust, but verify!"
L
If you go with a Michigan Sailor three blade, make the seller provide a Written Guarantee that the pitch is actually accurate for all blades.
QC from Michigan Propeller seems to be hit n miss. Cost me about $150. to get it repitched to what it was supposed to be when purchased. And that was causing some vibrations. One blade was off pitch by about a full half inch.
Then there was the cost to haul it out and block it again, too.
(mutter mutter...)
"Trust, but verify!"
L
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Catalina Direct has the three blade prop for sale. I have the three blade prop.
I do a lot of cruising but I also have time limitations. This means that I do my fair share of motoring. It is nice to have that three blade prop.
When the wind speed gets up you won't notice the prop. Seriously, hull speed is hull speed. It drags in less than 10 knots of wind but it is worth the price you pay when you have to motor into current or chop.
If you go to a three blade, make sure you put your transmission in reverse to lock the prop. It saves your transmission.
I do a lot of cruising but I also have time limitations. This means that I do my fair share of motoring. It is nice to have that three blade prop.
When the wind speed gets up you won't notice the prop. Seriously, hull speed is hull speed. It drags in less than 10 knots of wind but it is worth the price you pay when you have to motor into current or chop.
If you go to a three blade, make sure you put your transmission in reverse to lock the prop. It saves your transmission.
I was facing the same choice when we were considering taking the Mark II to the ICW for an extended cruise. You see I have the two cylinder Universal M-18 and with a two blade prop this combo would make us suffer in a strong head-on tidal current (say the Carolina's or Georgia). With a whopping 14-15 horsepower a change over to a three blade might provide enough torque to get me out of trouble. You three cylinder engine guys are far luckier on reserve power needs.
I used to sail my Helsen 22 with a Volvo 5 hp outboard out of Jekyll Island, Georgia back in the late 70's. When we went against the incoming tide heading to the inlet I recall very crazy moments of being close hauled, heeling like crazy with the engine blasting watching the same guy fish from the bank without making any headway!!!! Kind of a twilight zone sort of experience!! Pretty crazy sensation that seemed to last for hours.
Additionally, these days I get a bit fed up with the two blade prop walk that I deal with when in reverse in close quarters in the marina. The three blade I understand will eliminate that problem.
For me when the time comes, three blades are my choice strictly because of the prop walk and limited engine power. I always thought a three bladed prop was more fitting anyways.
Bob
'88 Mark II
Georgia
I used to sail my Helsen 22 with a Volvo 5 hp outboard out of Jekyll Island, Georgia back in the late 70's. When we went against the incoming tide heading to the inlet I recall very crazy moments of being close hauled, heeling like crazy with the engine blasting watching the same guy fish from the bank without making any headway!!!! Kind of a twilight zone sort of experience!! Pretty crazy sensation that seemed to last for hours.
Additionally, these days I get a bit fed up with the two blade prop walk that I deal with when in reverse in close quarters in the marina. The three blade I understand will eliminate that problem.
For me when the time comes, three blades are my choice strictly because of the prop walk and limited engine power. I always thought a three bladed prop was more fitting anyways.
Bob
'88 Mark II
Georgia
Better yet if going with a Michigan Wheel order your prop from Accutech Marine in NH and it will be set up with either Hale MRI or the Prop Scan machine. It will be the best balanced prop you've ever used. They come with full documentation as to how smooth. Larry is a great guy and a true miracle worker..
Thanks to all for your advice. I'm going to go with the local Hale Propeller guy in Clinton. Have a great summer!
Fogg
Fogg
Sailer prop vs. MP 3 blade
Quick afterthought: Are those of you with the narrower Michigan 3 blade prop happier than those with the broader MP prop?
Quick afterthought: Are those of you with the narrower Michigan 3 blade prop happier than those with the broader MP prop?
Well, I'm happy enough i guess....
but then I have not tried the conventional wide blade.........
L
Jimm is right....you still get prop walk with a three blade prop. The key to prop walk is learning how to use it in your favor. It is usually consistent and you can predict it. Learn to adjust for it/use it and you will be fine.
My limited experience has lead me to expect more propwalk from a 3 blade. In backing 2 C270's one with a 2 blade and the other a 3 blade, I found that the 2 blade would back to starboard (slightly) while backing out of a slip in gear at idle. The 3 blade would not back to starboard while at idle in gear.
Extendo Prop?
Friends, I'm still pondering the best approach to a new prop for my destroyed 13x12rh prop. I've thought seriously about 3 blades and then came upon an Extendo Prop put out by Performance Propellers in NY. It's hard plastic and the cone extends the shaft by several inches allowing the installation of a 15 x 10. Without the extension I could only put in a 13" diameter prop. Has anyone come upon this product?
Thanks,
Fogg
Friends, I'm still pondering the best approach to a new prop for my destroyed 13x12rh prop. I've thought seriously about 3 blades and then came upon an Extendo Prop put out by Performance Propellers in NY. It's hard plastic and the cone extends the shaft by several inches allowing the installation of a 15 x 10. Without the extension I could only put in a 13" diameter prop. Has anyone come upon this product?
Thanks,
Fogg
I am interested to hear more on this prop....but I am not sure if this will effect the engine and transmission combo.
A friend of mine has and loves a Kiwi Prop. It is a plastic folding prop.
A friend of mine has and loves a Kiwi Prop. It is a plastic folding prop.
I have the Extendo. Put it on two years ago when I replaced the engine. I am quite happy with it. Gives great top end speed. I joke with my friends to put on their seatbelts when I throttle up! But since I replaced the engine and the prop at the same time I have no idea what a regular prop would have been like with this engine. Overall, no regrets and I'd buy this prop again.Fogg said:
Rob,
Thanks for the reponse on the Extendo. The logic explained to me by the plant manager made beautiful sense. The Cat 30 was desigend for the Atomic 4. When they switched to diesel no accomodation was made for those preferring two blade props.
I think I've finally found that last piece to my puzzle.
Have a great summer!
Fogg
Thanks for the reponse on the Extendo. The logic explained to me by the plant manager made beautiful sense. The Cat 30 was desigend for the Atomic 4. When they switched to diesel no accomodation was made for those preferring two blade props.
I think I've finally found that last piece to my puzzle.
Have a great summer!
Fogg
The yard is doing most of the insurance repair work and has not yet gotten to the prop. When the boat splashes with new Extendo prop, new Idasailor high density polyethylene rudder, new strut, new SS shaft and PSS dripless shaft seal, I'll post my thoughts on all of it. Why am I not doing the work myself? The boat was a constructive total from Irene, and I want the yard receipts to show the insurance company and the surveyor that the job was done right and proper. BoatUS handled the "recovery" and have agreed to reinsure the boat. Another month, I hope, and we'll be in the water. I had some surgery and have been useless until now. Slow rehab for a geezer like me.
Be well.
Fogg
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