Does anyone know what settings work well for a 15 inch Maxprop when the engine is a M25XP Universal with a 2:1 Hurth transmission on an E-34? I tried 22 degrees, but the engine would not go past 2400 rpm. A distributor said "the Book" says to set the prop at ten degrees! That seems too low. Any ideas?
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Geoff Johnson
Fellow Ericson Owner
I have a two bladed Maxprop on my 32-3 with an M25 engine. Don't know the setting, but I cruise at 2000 rpm (about 6 plus knots) and reach hull speed at 2200 rpm. My engine seems happy with this. Why do you want to go over 2400 rpm?
Geoff Johnson
Fellow Ericson Owner
PS While I don't know the precise setting, I recall that the blades certainly open far more than 10 degrees and possibly more than 22 degrees.
I'm weighing in on this with only partial facts. I don't have a max prop but recently repowerd. During repower, I went through a couple of different pitch settings on my fixed two blade.
My engine is a Beta marine BD722, 3 cylinder 20 hp, based on kubota industrial engine. Max rev's are 3600, best fuel is ~2700. I was advised to pitch the prop so the engine could turn max RPM. This was to prevent overloading the engine. Don't know all the technical points on this, but it's supposedly better for the engine.
hope this helps.
My engine is a Beta marine BD722, 3 cylinder 20 hp, based on kubota industrial engine. Max rev's are 3600, best fuel is ~2700. I was advised to pitch the prop so the engine could turn max RPM. This was to prevent overloading the engine. Don't know all the technical points on this, but it's supposedly better for the engine.
hope this helps.
Geoff Johnson
Fellow Ericson Owner
The "Cruising Range (Approx.)" for the Universal M25 and M25XP engines is listed on the www.marinedieseldirect.com site as 2100/2600 RPM. So I feel I am sufficiently in the ball park. It seems to me (and I am no expert) that running the engine at higher RPM will just cause more wear and tear - like driving your car around in lower gear. Also, with a two bladed Maxprop like mine, you get pronounced vibrations at higher RPM (something about the way the tips interact with the hull).
reply to Geoff Johnson
I'm new to large motors inside boats and diesels, but the answer to the question of why do I want a higher possible rpm are the following. 1) higher rpm results in higher torque (force) which means you can push through waves and tides better. The rip tides in the passes up here are dangerous. 2) higher rpm means less vibration, and that means less noise and wear on bearings. (I'll let you know about the vibration off the hull). 3)with higher rpm possible you have less chance of overloading your engine. If you overload you see black smoke (unburned gases) and you carbon up your cylinders. 4) with higher rpm possible your boatspeed at idle (1000 rpm) will be slower, that means more controlled close quarter maneuvering under power. Right now my slowest speed is 3.5 kts. Whole marinas tremble at the mention of my name. Thank you all so much for your input. The shipwright just phoned and I am going with 18 degrees (settings E and H). I'll let you know how it worked after this weekend.
I'm new to large motors inside boats and diesels, but the answer to the question of why do I want a higher possible rpm are the following. 1) higher rpm results in higher torque (force) which means you can push through waves and tides better. The rip tides in the passes up here are dangerous. 2) higher rpm means less vibration, and that means less noise and wear on bearings. (I'll let you know about the vibration off the hull). 3)with higher rpm possible you have less chance of overloading your engine. If you overload you see black smoke (unburned gases) and you carbon up your cylinders. 4) with higher rpm possible your boatspeed at idle (1000 rpm) will be slower, that means more controlled close quarter maneuvering under power. Right now my slowest speed is 3.5 kts. Whole marinas tremble at the mention of my name. Thank you all so much for your input. The shipwright just phoned and I am going with 18 degrees (settings E and H). I'll let you know how it worked after this weekend.
Geoff Johnson
Fellow Ericson Owner
Strange, because when I idle at 1200 RPM I creep along. As for the currents you mention, it brings to mind a recent Discovery Channel show on whirlpools which apparently appear only seven places on Earth, one of which is the Northwest. They filmed currents up to 30 knot (!) between the islands. They then threw a dummy into one of the whirlpools (not sure it was the Northwest) and it was sucked down 600 feet. Best we can do around here is 4.5 knots where Long Island Sound empties into the ocean. You're right; if I sailed in the Northwest I'd want all the torque I could get.
Geoff Johnson
Fellow Ericson Owner
For the sake of completeness, I am posting a recent message from the Ericson newsgroup:
I've had a Max-Prop on our 1988 E-32 for 12 seasons, and with the Universal
XP-25 the setting which works best is 24 degrees. At 22 I cannot achieve
hull speed, and at 26 degrees there is a bit of blackness in the exhaust
which I view as a 'laboring' condition on the engine.
Just my experience.
Leon & Barbara Sheean
"Therapy" Cleveland, OH
1988 E-32-200 #805
I've had a Max-Prop on our 1988 E-32 for 12 seasons, and with the Universal
XP-25 the setting which works best is 24 degrees. At 22 I cannot achieve
hull speed, and at 26 degrees there is a bit of blackness in the exhaust
which I view as a 'laboring' condition on the engine.
Just my experience.
Leon & Barbara Sheean
"Therapy" Cleveland, OH
1988 E-32-200 #805
Success
Well, I was out on the hard a week longer than expected (what's new), but it was successful. The 18 degrees pitch on the three blade 15 inch Maxprop gives me 5.4 knots at 2000 rpm, 6.2 at 2500, and 6.5 at 3000. At 2500 the trailing edge of the transom just skims the surface of the water and the engine is not straining, at 2000 the engine sounds very relaxed. I also installed a flex coupling on the propeller shaft and a dripless stuffing box (from PYI), so the vibrations (and therefor noises) from the engine have been significantly reduced. My speed at 1000 rpm has dropped down to around 2.5 knots. Thank you everyone for your input.
I have had trouble with electrolysis eating up my Maxprop. It cost $800 USD for PYI to float new material into the blades. I have since installed a brush that rides on the prop shaft and is connect by a thick copper wire to a zinc that I hang over the side when I'm in a marina. I went through a $15 CDN zinc this past year but no electrolysis proplems.
Well, I was out on the hard a week longer than expected (what's new), but it was successful. The 18 degrees pitch on the three blade 15 inch Maxprop gives me 5.4 knots at 2000 rpm, 6.2 at 2500, and 6.5 at 3000. At 2500 the trailing edge of the transom just skims the surface of the water and the engine is not straining, at 2000 the engine sounds very relaxed. I also installed a flex coupling on the propeller shaft and a dripless stuffing box (from PYI), so the vibrations (and therefor noises) from the engine have been significantly reduced. My speed at 1000 rpm has dropped down to around 2.5 knots. Thank you everyone for your input.
I have had trouble with electrolysis eating up my Maxprop. It cost $800 USD for PYI to float new material into the blades. I have since installed a brush that rides on the prop shaft and is connect by a thick copper wire to a zinc that I hang over the side when I'm in a marina. I went through a $15 CDN zinc this past year but no electrolysis proplems.
Geoff Johnson
Fellow Ericson Owner
What does it mean to "float new material into the blades" and why isn't a shaft zinc effective? My PO apparently neglected shaft zincs at some point and there is some pitting on the blade surfaces.
"floating" and zincs
When I took my badly pitted prop into PYI they said that they would heat up the blades and "float" new alloy onto them. That way, where the prop had cavities inside, the alloy would run in and fill them. If the cavities were right through the blades I would be out of luck and have to purchase new blades. I was lucky and they could fill them. They now look like brand new blades. The main trunk of the prop is badly pitted but it is so thick and strong that it is fine. PYI said that normally the inside of the trunk is not pitted because the grease protects it, and that was the case for me.
When the electrolysis began for me I went through two shaft zincs and the zinc on the end of the maxprop in about eight months. When I hauled they were all gone. I now have three large squarish shaft zincs plus the zinc on the prop and the one I hang over the side. Also, I put a little anti-fouling on the zincs in between where the bolts hold them together in the case of the shaft zincs and between where the three bolts hold it on in the case of the prop zinc. I like zincs.
Your response about the tides was interesting. There are some serious whorlpools here, but on a basic level many passes are just not navigable for a sailboat except at slack, and even then it can be a wild ride (more so if a tug with a tow is coming the other way). A friend last week came down Haro Strait (about 5 miles wide and maybe 15 miles long) with the tide motoring at 6.5 knots, over the ground (GPS) he was doing 12.9 knots. Yesterday I came down with a thirty knot headwind at 6 to 7 knots with my GPS reading 8.5 knots. Tides, and hence your engine (and your boat's ability to point high and sail in light winds), are critical here. Check out the recent Swiftsure race: 60% of the boats dropped out after they were about 10 miles behind the starting line when the wind died just before they could it across. The average sailboat motors 75 percent of the time in the summer if it doesn't sail well in light air. A trip up to Alaska will mean 80 percent motoring according to those who have done it. You are always in a trough with a headwind, tailwind or no wind -- but it's beautiful.
Cheers, Duncan.
When I took my badly pitted prop into PYI they said that they would heat up the blades and "float" new alloy onto them. That way, where the prop had cavities inside, the alloy would run in and fill them. If the cavities were right through the blades I would be out of luck and have to purchase new blades. I was lucky and they could fill them. They now look like brand new blades. The main trunk of the prop is badly pitted but it is so thick and strong that it is fine. PYI said that normally the inside of the trunk is not pitted because the grease protects it, and that was the case for me.
When the electrolysis began for me I went through two shaft zincs and the zinc on the end of the maxprop in about eight months. When I hauled they were all gone. I now have three large squarish shaft zincs plus the zinc on the prop and the one I hang over the side. Also, I put a little anti-fouling on the zincs in between where the bolts hold them together in the case of the shaft zincs and between where the three bolts hold it on in the case of the prop zinc. I like zincs.
Your response about the tides was interesting. There are some serious whorlpools here, but on a basic level many passes are just not navigable for a sailboat except at slack, and even then it can be a wild ride (more so if a tug with a tow is coming the other way). A friend last week came down Haro Strait (about 5 miles wide and maybe 15 miles long) with the tide motoring at 6.5 knots, over the ground (GPS) he was doing 12.9 knots. Yesterday I came down with a thirty knot headwind at 6 to 7 knots with my GPS reading 8.5 knots. Tides, and hence your engine (and your boat's ability to point high and sail in light winds), are critical here. Check out the recent Swiftsure race: 60% of the boats dropped out after they were about 10 miles behind the starting line when the wind died just before they could it across. The average sailboat motors 75 percent of the time in the summer if it doesn't sail well in light air. A trip up to Alaska will mean 80 percent motoring according to those who have done it. You are always in a trough with a headwind, tailwind or no wind -- but it's beautiful.
Cheers, Duncan.