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down_shift
Last seen: 3 weeks 5 days ago
Joined: 8/16/14
Posts: 65
M-25XP - loss of power (RPM down 440)

WOT I see ~ 2750 rpm (survey said indicated is 300 lower than actual) and 6.5 kts.  It has always been this way.  After 3 months of no use, WOT is 2350 rpm and 4.4 kts.  It continues to start and operate as normal, but just not seeing the power.  No smoke, easy start in 55F temps, smooth idle and transistion to WOT.  Being in mid Chesapeak, we don't see that much foweling, and after 4 hours of crusing, the ablative paint should have done its job, and WOT crusing speed did increase 0.3 kts.  Initially thinking partially cloged fuel filters, I changed them both.  No change to the performance.  Any thoughts on next items to check?  Thanks for the guideance.
Edit - just found this thread and will start with these suggestions:
https://www.catalina36.org/forum/technical-discussion/low-power-2100-rpm...

Russell Green
S/V "GoodwiII"  #759
1987 C36 MKI TR/WK M25XP
Moored: Deale, MD

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Russell Green
S/V "GoodwiII"  #759
1987 C36 MKI TR/WK M25XP
Moored: Deale, MD
William Miller
Last seen: 1 month 2 weeks ago
Joined: 10/4/08
Posts: 291

Sounds like you might need to clean your prop

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Bill Miller
S/V Lorraine
Pacific Northwest,Sound Sound
Grapeview,Wa
1990 Mk1

HCJ's picture
HCJ
Last seen: 2 months 2 weeks ago
Joined: 5/14/18
Posts: 17

Four weeks ago I hauled our boat and cleaned / repainted the bottom with antifouling paint. During the summer the hull seemed OK; just slime and some growth at the leading edge of the keel and very bottom of the rudder, nothing much. The prop had some barnacles.  After the haul-out the boat's a full knot faster and engine runs about 300 rpm faster.
Is there any growth on your propeller? I use a cheap waterproof camera at the end of a stick to inspect it close up. (waters here are very cold except during the height of summer) That prop will have a hard time turning if it has any growth on it.
Henk.

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Henk Hiensch
Mar Y Sol
1984 Catalina 36
Hull# 379 Universal M25
Ladysmith, BC
Catboat Willy's picture
Catboat Willy
Last seen: 22 hours 51 min ago
Joined: 12/22/14
Posts: 234

Russ;
 There is probably nothing wrong with your engine and I'm going to fall in line with others who are suggesting that you are seeing growth on either the prop shaft or the propeller. I'll share a brief story with you.
We were some 20 miles off shore, at night, motoring along at our normal 2400 RPM cruiuse speed when the boat developed a severe shake in the helm. This was after motoring for the previous 10 hours and we were sure we picked up a crab pot. We reduced the RPM to 1700 and limped the 20 miles in to port. Having no dive equipment on board, we contacted a diver to inspect the situation. His findings were interesting. He said there was no crab pot or barnaceles on the prop - but instead - a growth of barnacles that some how had attached itself to the prop shaft and caused the excentricity in the shaft causing the vibration.
I had someone clean the bottom the week before my departure but obviously he did not clean the prop shaft. But why that should show up after 10 hours of continious motoring was beyond me. I think the moral of the story is that it doesnt take much to slow you down and the prop and prop shaft would be the first place I'd look.
Bill
 

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Bill Dolan 1990 Catalina C-36 MKI - Hull #1041  'Williwaw'
Std. Rig, Walk Through, Wing Keel
M35, Oberdorfer Conversion,
Home Waters; Port Charlotte, FL
'You are never out of work if you own a boat'

 
breitz
Last seen: 1 month 1 week ago
Joined: 6/18/13
Posts: 79

Hi down shift,  I’m having the same problem with my m35.  A diver cleaned my prop and shaft.  Bled air from injectors.  Nothing.  Going to add diesel Kleen to clean injectors.  If all fails I’ll have my mechanic look at it.  Did you get your problem resolved.  If so how?

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Bill and Carla Reitz C-36 MK-2 1995 W/K Kind of Blue #1427 Sausalito Ca

down_shift
Last seen: 3 weeks 5 days ago
Joined: 8/16/14
Posts: 65

Sorry I haven't logged on to close the loop regarding my loss of power.  Sure enough, barnicals on the prop!  No ussues this season with lots of sailing.  This season has been a good one.

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Russell Green
S/V "GoodwiII"  #759
1987 C36 MKI TR/WK M25XP
Moored: Deale, MD
breitz
Last seen: 1 month 1 week ago
Joined: 6/18/13
Posts: 79

Russell,  thanks for the response.  Had the diver bottom clean along with prop.  Said all looked good.  Took the boat on the bay for a long motor.  Rpms increased to 2500 speed 4.7 knots .  An improvement but still not up to par.  Bottom paint next month.  I’ll have the yard take a closer look. I’ll report back when resolved as this seems to be a problem with others.   Bill

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Bill and Carla Reitz C-36 MK-2 1995 W/K Kind of Blue #1427 Sausalito Ca

breitz
Last seen: 1 month 1 week ago
Joined: 6/18/13
Posts: 79

Russell,  thanks for the response.  Had the diver bottom clean along with prop.  Said all looked good.  Took the boat on the bay for a long motor.  Rpms increased to 2500 speed 4.7 knots .  An improvement but still not up to par.  Bottom paint next month.  I’ll have the yard take a closer look. I’ll report back when resolved as this seems to be a problem with others.   Bill

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Bill and Carla Reitz C-36 MK-2 1995 W/K Kind of Blue #1427 Sausalito Ca

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