Slowly over the last few years my hull speed under power has dropped from around 5.7 knots to around 4.5 - 5.0. Also the boat doesn't seem to be able to make headway against heavy weather conditions as well. I have a Westerbeke 21, the engine runs fine, no smoke to speak off. The engine RPM maintains a steady 2800 rpm. I was thinking the transmission was slipping but was told that the engine rpm would increase if this was the problem. Has anyone else experienced this problem??
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The hull is clean
The hull is in very good shape. The boat is hauled every winter, scraped, power washed and painted. I'm sure that is not the problem. I spoke with a transmission guy and he seems to think it might be my prop. The prop also looks fine. Is it possible the pitch of the prop has changed over time????
The hull is in very good shape. The boat is hauled every winter, scraped, power washed and painted. I'm sure that is not the problem. I spoke with a transmission guy and he seems to think it might be my prop. The prop also looks fine. Is it possible the pitch of the prop has changed over time????
Transmission
Check the transmission. I had the same problem the year after I purchased my boat. Its easy to check with 2 people. Go out for a cruise and have one person watch the shaft with a flashlight while the other steers and revs the engine. there should be a direct effect on the shaft when the engine is rev'ed.
Check the transmission. I had the same problem the year after I purchased my boat. Its easy to check with 2 people. Go out for a cruise and have one person watch the shaft with a flashlight while the other steers and revs the engine. there should be a direct effect on the shaft when the engine is rev'ed.
Richard, transmission reply?????
Richard, You say you had the same problem, what was the problem and solution? You mention watching the prop underwater, was this underway or tied to the dock. There is no way I can imagine seeing the prop underway unless I was in a wet suit under water. I suspected the transmission but a trany guy told me the engine would race as the transmission slipped. I haven't seen this at all. The last time I used the boat last season I got caught in a squal that had me down to 1 knot with the wind and waves right on the nose. The engine held a rock steady 2800 rpm. So what was your problem and how did you fix it?
Richard, You say you had the same problem, what was the problem and solution? You mention watching the prop underwater, was this underway or tied to the dock. There is no way I can imagine seeing the prop underway unless I was in a wet suit under water. I suspected the transmission but a trany guy told me the engine would race as the transmission slipped. I haven't seen this at all. The last time I used the boat last season I got caught in a squal that had me down to 1 knot with the wind and waves right on the nose. The engine held a rock steady 2800 rpm. So what was your problem and how did you fix it?
Try again...
"Go out for a cruise and have one person watch the shaft with a flashlight while the other steers and revs the engine. there should be a direct effect on the shaft when the engine is rev'ed." Open the aft engine cover(inside the cabin)and watch the shaft as the engine is rev'ed and you'll notice that the shaft won't spin or react as quickly as the engine does. If this is the case consider having a mechanic look at it. You may be able to adjust the tranny but if it has been doing it over a long period of time your presssure plate is most likely glazed over and you'll wind up pulling the tranny and getting a rebuild. And if you haven't replaced the cutlass bearing that would be the time to do that also. This little adventure, tranny,shaft and bearing, cost about $850 on this side of the sound..
"Go out for a cruise and have one person watch the shaft with a flashlight while the other steers and revs the engine. there should be a direct effect on the shaft when the engine is rev'ed." Open the aft engine cover(inside the cabin)and watch the shaft as the engine is rev'ed and you'll notice that the shaft won't spin or react as quickly as the engine does. If this is the case consider having a mechanic look at it. You may be able to adjust the tranny but if it has been doing it over a long period of time your presssure plate is most likely glazed over and you'll wind up pulling the tranny and getting a rebuild. And if you haven't replaced the cutlass bearing that would be the time to do that also. This little adventure, tranny,shaft and bearing, cost about $850 on this side of the sound..
Thanks Richard.
Interesting, since the boat is hauled for the winter I won't be able to try this until the spring when I launch. That's right about the time I'm totally burnt out physically and financially on the boat. Is there anyway I could confirm it's the tranny now while the boats hauled? You say you had the same symptom. Let me ask again, did you engine's rpm race as it would in a classic tranny slippage situation or did it just appear to maintain rpm but seem to have a loss of power and over all loss of hull speed (which is what I'm experiencing)?
Interesting, since the boat is hauled for the winter I won't be able to try this until the spring when I launch. That's right about the time I'm totally burnt out physically and financially on the boat. Is there anyway I could confirm it's the tranny now while the boats hauled? You say you had the same symptom. Let me ask again, did you engine's rpm race as it would in a classic tranny slippage situation or did it just appear to maintain rpm but seem to have a loss of power and over all loss of hull speed (which is what I'm experiencing)?
2800 is governor rpm
It would appear that your mechanic is a “gas” guy. The M25 XP has a governor that limits the engine to 2800 rpm. If you run the engine in neutral at wide open throttle it will turn 2800 rpm. When everything in the drive train is just right you will only be able to get about 2700 rpm max in gear.
It would appear that your mechanic is a “gas” guy. The M25 XP has a governor that limits the engine to 2800 rpm. If you run the engine in neutral at wide open throttle it will turn 2800 rpm. When everything in the drive train is just right you will only be able to get about 2700 rpm max in gear.
M25XP??
Not sure what you mean M25XP? I have a Westerbeke 21. Open throttle I'll get about 3300 rpms. It seems with this engine around 2700 - 2800 is the sweet spot. The eingine sounds smooth, little vibration.
Not sure what you mean M25XP? I have a Westerbeke 21. Open throttle I'll get about 3300 rpms. It seems with this engine around 2700 - 2800 is the sweet spot. The eingine sounds smooth, little vibration.
Engine did not race..
same symptom as yours. It was really noticable into a headwind or chop. I believe my mechanic also took a sniff of the tranny fluid and confirmed by the smell that it was burnt. Ask your mechanic at the yard about it, maybe he can tell by the smell.
same symptom as yours. It was really noticable into a headwind or chop. I believe my mechanic also took a sniff of the tranny fluid and confirmed by the smell that it was burnt. Ask your mechanic at the yard about it, maybe he can tell by the smell.
Trans fluid
G Assume you've also changed the transmission fluid. Re hull (again) - do you have a diver do it during the season? I go three months between them and notcie a definite change for the better after it's cleaned by hand after that period of time. Stu
G Assume you've also changed the transmission fluid. Re hull (again) - do you have a diver do it during the season? I go three months between them and notcie a definite change for the better after it's cleaned by hand after that period of time. Stu
Guilty about not changing fluid
I a bid ashamed to admit I haven't changed the transmission fluid in over 10 years. I have checked it every season and the level was fine, smelled ok. I'm wondering if permiment damage has resulted or if I can get lucky and just change the fluid and my problems go away. As for the bottom, I noticed straight off last year at spring launch the boat was going slower under power. Under sail everything is fine, even up to the fall hual out, she still rips along at 7 knots + with a good wind. I've been to the Hurth website and I see they sell a rebuild kit and manual for under $200. I'm thinking about buying them and either doing the re-build myself or having a frined who is a mechanic do it for another $100 or so. Either way I can save a ton of momey doing it this way. It looks like sending it out for a re-build will cost between $600 - $800.
I a bid ashamed to admit I haven't changed the transmission fluid in over 10 years. I have checked it every season and the level was fine, smelled ok. I'm wondering if permiment damage has resulted or if I can get lucky and just change the fluid and my problems go away. As for the bottom, I noticed straight off last year at spring launch the boat was going slower under power. Under sail everything is fine, even up to the fall hual out, she still rips along at 7 knots + with a good wind. I've been to the Hurth website and I see they sell a rebuild kit and manual for under $200. I'm thinking about buying them and either doing the re-build myself or having a frined who is a mechanic do it for another $100 or so. Either way I can save a ton of momey doing it this way. It looks like sending it out for a re-build will cost between $600 - $800.
Transmission fluid on M25 engines, lotsa resources
G Why not just change the fluid first before you start ripping things apart. I left mine go for a lot less time than you did (3 years) but it gets thinner and darker. Give it a try first. Then....... Try these links to the C34 website Transmission change explanation: http://c34.org/faq-pages/faq-transmission-oil.html Transmission search on C34 website: http://www.picosearch.com/cgi-bin/ts.pl Transmission fluid Find on C34 Message Board: http://c34.infopop.cc/6/ubb.x?a=srch&s=329609511&result_detail=3&x_as=&findw=transmission+fluid&f=&sis=&dt=&author_name=&sort_order=2&action=simplesearch&search=Search Happy reading on this one. Same engines, same stories. Good luck. Stu
G Why not just change the fluid first before you start ripping things apart. I left mine go for a lot less time than you did (3 years) but it gets thinner and darker. Give it a try first. Then....... Try these links to the C34 website Transmission change explanation: http://c34.org/faq-pages/faq-transmission-oil.html Transmission search on C34 website: http://www.picosearch.com/cgi-bin/ts.pl Transmission fluid Find on C34 Message Board: http://c34.infopop.cc/6/ubb.x?a=srch&s=329609511&result_detail=3&x_as=&findw=transmission+fluid&f=&sis=&dt=&author_name=&sort_order=2&action=simplesearch&search=Search Happy reading on this one. Same engines, same stories. Good luck. Stu
keven, rebuild kit
Keven, this company MER Equipment sells the kit. http://merequipment.com/Transmissions/marine_trans.htm
Keven, this company MER Equipment sells the kit. http://merequipment.com/Transmissions/marine_trans.htm
PROBLEM MAY BE WITH MY PROP
I've spoken with 2 tranny mechanic's and both of then do not believe my problem is a slipping tranny. They explained that if the tranny was slipping I would first be experiencing difficulty shifting into gear at low RPM. I do not have any trouble shifting. Although they would like me to spend hundreds of dollars with them, they both stated honestly that they didn't believe it's my problem. One guy asked if I had a lot of bottom paint on my prop which I do. He said it's possible the prop could be cavitating. I any case I'm going to clean and polish the prop and possibly have it re-conditioned and the pitch checked. In any case, the type of dialogistic testing I need to do must be preformed with the boat in the water. So it will have to wait till May.
I've spoken with 2 tranny mechanic's and both of then do not believe my problem is a slipping tranny. They explained that if the tranny was slipping I would first be experiencing difficulty shifting into gear at low RPM. I do not have any trouble shifting. Although they would like me to spend hundreds of dollars with them, they both stated honestly that they didn't believe it's my problem. One guy asked if I had a lot of bottom paint on my prop which I do. He said it's possible the prop could be cavitating. I any case I'm going to clean and polish the prop and possibly have it re-conditioned and the pitch checked. In any case, the type of dialogistic testing I need to do must be preformed with the boat in the water. So it will have to wait till May.
Got Slower After Engine Transplant
I replaced the YSE-12 Yanmar single cylinder in our 1977 Cat 30 last summer with a 13 H.P 2GM Yanmar. We went from just over five knots under power down to just over 3 and no power to speak of when fighting the weather. The two engines had different trans ratios and the new one produces its power at a higher RPM. I recently located a used 3 blade Campbell Sailor Prop and had then cut it down to 13 inch with a 9 inch pitch. I will be hauling the boat in early March to change the prop from the 2 blade 12 inch that is now on it. I have been reading the replies to your problem and started to think that maybe my trans was slipping which it should not be as the engine and trans were totally rebuilt by a marine engine dealer when I purchased it. I also spoke to the Yanmar people at the recent Vancouver boat show and they agreed that the prop was probably the cause. I will let you know after I change it. Cliff Carter PlusOne Cat30 #598 cliffc@city.victoria.bc.ca
I replaced the YSE-12 Yanmar single cylinder in our 1977 Cat 30 last summer with a 13 H.P 2GM Yanmar. We went from just over five knots under power down to just over 3 and no power to speak of when fighting the weather. The two engines had different trans ratios and the new one produces its power at a higher RPM. I recently located a used 3 blade Campbell Sailor Prop and had then cut it down to 13 inch with a 9 inch pitch. I will be hauling the boat in early March to change the prop from the 2 blade 12 inch that is now on it. I have been reading the replies to your problem and started to think that maybe my trans was slipping which it should not be as the engine and trans were totally rebuilt by a marine engine dealer when I purchased it. I also spoke to the Yanmar people at the recent Vancouver boat show and they agreed that the prop was probably the cause. I will let you know after I change it. Cliff Carter PlusOne Cat30 #598 cliffc@city.victoria.bc.ca
Interesting read on prop theory
Cliff, Keep us updated. I found this link on the web. Pretty good paper on prop theory in laymens terms.
Cliff, Keep us updated. I found this link on the web. Pretty good paper on prop theory in laymens terms.
RECONDITION
Definetly start with a cleaning and reconditioning of the prop. If you have a heavy paint coat and have been adding to it, I would think that you could be losing the proper foil shape.
Definetly start with a cleaning and reconditioning of the prop. If you have a heavy paint coat and have been adding to it, I would think that you could be losing the proper foil shape.
Engine stuff
G Don't know if you are an Association member. If you are you should get and read (cover to cover) Mainsheet magazine. There was a long story in the C34 tech section (Feb 2004 issue) about engine problems. Could be hull (nixed), shaft, tarnsmission, prop or engine. Pick your poison. Read the article. May help. Stu
G Don't know if you are an Association member. If you are you should get and read (cover to cover) Mainsheet magazine. There was a long story in the C34 tech section (Feb 2004 issue) about engine problems. Could be hull (nixed), shaft, tarnsmission, prop or engine. Pick your poison. Read the article. May help. Stu
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