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Propeller replacement

J

jmcentyre

Jim McEntyre
I'm about to replacethe cutlas bearing in my 20 year old vessle.
While doing this task I thought it would be a good idea to
replace the present 2 baled propeller with a 3 bladed unit.
The one I have on now is the original unit provided when I bought
the boat new in '78. It's a 2 bladed 18rh 13pitch.I think that by
puting a 3 bladed unit on it would smooth out some of the
vibration along with the new bearing. The Yanmar engine manual
suggests a 3 baded 18X13 standard prop.
I know this might slow the boats sailing speed a little but as I
find that I'm powerong more often now that is not a real concern.
Are there any suggestions from the group as the this and are
there any good deals on a new prop around?

 
The three bladed prop will be smoother but it will cost you 10 to 15 percent in speed. To put that in prospective, If you were sailing a day with a group of your fellow 38's with two bladed props which were lined up with the keel, your friends would get into port one hour before you. I took off my three blade 18 years ago in favor of the sailing speed. Recently I added a MAX PROP but this was at great cost. Maybe fixing the cutlass will cut the vibration to a tolerable level. Good luck.
 
<div>Chris,I have the 3QM30 also and am currently useing a 16 x 12 three blade. It allows the engine to turn all the way up to max RPM and will cruise at about 6.3knots at 2200 RPM (78% of max.RPM).Vic C.
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I had a Yanmar 3QM-30 in our 1979 M-382 until I replaced it with a new engine this summer. The 3QM-30 turned a three blade 17 x 12 prop. The performance was fine but if anything the engine was slightly over-propped with the 17 x12. A 17 x11 would probably have been better. I suspect an 18 x 13 would be way too much. When I got my new engine, I was warned that running it with too big a prop, even at lower rpm's, could seriously damage the engine in a relatively short time.
 
<div>One other problem with a three-bladed prop on Brewer-M-38s is that the prop's position so close to the rudder means that a lot of turbulance crosses the rudder under sail, compromising its effectiveness. I think this would be more of a problem on M-382s, which have a smaller rudder than M-383/4s.The Max Prop is expensive but probably worth it. I'm saving up my $$ to get one in couple of years. I believe the prop itself costs about $2300, installation extra. (Installation involves cutting the shaft -- see Ron Hoogewerf's article in the Spring '98 Newsletter.)
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<div>MAX PROPS - Try $2730 for the regular 3 blade with internal adjustment and $3215 for the fancy VP model with the adjustor outside.(as of 28-10-98)OUCH!
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I just ordered the Prowell Sailprop. German engineering.
See the web www.IMTACORP.com or ProwellGMBH.com.
Purchase - $2166 plus spare kit for $50. Still ouch! but not quite as bad.
 
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