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what RPM's do you M-25xp guys cruise at?

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Feb 20, 2011
7,773
Island Packet 35 Tucson, AZ/San Carlos, MX
edit- Sorry, I thought M25xp meant Experimental Macgregor 25. Now I know it's an engine. :redface:
Please ignore.
 
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gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
I'm usually around 2000RPM when motoring through the inlet if I'm not sailing it. If the current and wind are against me going out or coming in, sometimes I'm around 2400. My pedestal guard acts as a governor so I can't get above 2400 right now but I get 6-7kt out of the boat at that RPM when conditions are right. Universal recommends crusing RPM at 2000-2500.
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
Same here. Usually around 2000 but will go up to 2500 for brief shots in high current. Usually get 5.5 without current influence at 2000.
 

paulj

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Mar 16, 2007
1,361
Catalina 310 Anacortes,Wa
I run the engine at 2450 rpm for cruising....seems to be best .5 gal/hour.







At 2500 rpm I get acoustic resonance.



paulj :troll:
 
Feb 26, 2004
21,904
Catalina 34 224 Maple Bay, BC, Canada
2450-2650 M25 w/ 3 inch HX and new alternator bracket :)

Why do you ask?
 
Oct 17, 2011
221
Catalina 310 USA
thanks for the info.

I am new to this engine and noticed different vibrations at different RPMS. Was not sure if I was being paranoid or if this was normal for this motor.

I was worried that my engine does not seem to run "smooth" at times but from what I am reading this motor seems to have more vibrations at different RPM levels.
 

gpd955

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Feb 22, 2006
1,164
Catalina 310 Cape May, NJ
Check the wood cover over the water lift muffler.

I had a loud vibration when the engine ran from about 1400-1800RPM. While attempting to figure out what the problem was, I got frustrated and sat down in the quarter berth and the vibration stopped. It seems that the wood covering the bilge where the muffler and prop shaft enters the boat just slightly touchéd the top of the muffler and at that RPM it was enough to cause the wood to vibrate. A little sanding and the noise is gone.

Not saying that it is the same problem but these forums have taught me (and still teach me) to go simple first!!
 
Feb 26, 2004
21,904
Catalina 34 224 Maple Bay, BC, Canada
thanks for the info.

I am new to this engine and noticed different vibrations at different RPMS. Was not sure if I was being paranoid or if this was normal for this motor.

I was worried that my engine does not seem to run "smooth" at times but from what I am reading this motor seems to have more vibrations at different RPM levels.
That's correct, they do just that.
 
Apr 8, 2010
1,605
Ericson Yachts Olson 34 28400 Portland OR
Stu is right....

As other experienced owners tell you, 2400 to 2600 rpm for sustrained cruising. That's in your engine manual, too. We have owned a Universal M25XP for almost 20 years, and nowadays have a bit over 2000 hrs on it.

As to vibration, ALL diesels have some rpm ranges where they put more -- or less -- vibration into a boat. Often this is only a very limited range of a couple hundred rpm.

There is a lot of rotational mass, connected up and suspended in several ways, between the tranmission output and the the water being moved by your prop. And, going forward, between the block and the hull.

Starting with prop being checked for true-ness of each blade to its stated pitch, and balance, look to the shaft to be true, running through a good cutlass bearing. Center that shaft in the alley. Finally allign the coupling with the transmission.
On the other end of the situation, replace the mounts at (round numbers...) 1500 hours and 15 or 20 years. Both time and useage will degrade that "rubber" compound that is engineered to dampen vibration and support XX number of pounds.

Sounds more complicated than it is.... Just some preventative maintenance that goes with an inboard engine.

(Oh yeah... and don't go envying the guys with sail drives. You don't even want to know the yard time that goes into the scheduled replacement of the rubber membrane/boot that seals out the water.

"No free lunch" as the old saying goes.

:)
 
Mar 22, 2009
355
Catalina 310 Gulfport Small Craft Harbor, MS
Just to throw another wrinkle into the discussion...

I got some advice that it is better for the engine to vary your cruising RPM. Maybe just do 2200 RPM one day then the next do 2400...then 2100...then 2500...

That is what I have been doing. Of course I haven't been doing "long distance" cruising. Just in/out of the harbor and around my local sailing grounds.

Anybody heard this before? Does it offer any benefits?

Thanks,
Jim
 
Feb 26, 2004
21,904
Catalina 34 224 Maple Bay, BC, Canada
Nope.

The best things you can and should do:

1. Don't lug the engine, run it at cruising speed.
2. Always get up to temperature, don't just motor out of your slip and turn it off.
3. Adjust your revs if cruising long distances as you suggest, not on a daily basis (engines don't have memories :)), but when running for long hours.
4. Run at WOT every once in a while.
5. Change your oil regularly.
 

pk104

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Jun 30, 2009
205
Catalina 310 Atwood Lake
I'm 6'5 and we sleep head to bow. I feel like I have enough length and room to sleep. Like some one else said, head first makes it easy to get to the head at night. Only complaint is the wood under the mattress that covers the water tank squeaks sometimes when I roll over. Haven't found the cure for it yet.
 
Dec 25, 2008
1,577
catalina 310 Elk River
Nope.


3. Adjust your revs if cruising long distances as you suggest, not on a daily basis (engines don't have memories :)), but when running for long hours.
So your saying engines don't have long term memories, but they do have short term memories?
 
May 3, 2008
189
Catalina 310 Catawba Island
Interesting about vibration points

Check the wood cover over the water lift muffler.

I had a loud vibration when the engine ran from about 1400-1800RPM. While attempting to figure out what the problem was, I got frustrated and sat down in the quarter berth and the vibration stopped. It seems that the wood covering the bilge where the muffler and prop shaft enters the boat just slightly touchéd the top of the muffler and at that RPM it was enough to cause the wood to vibrate. A little sanding and the noise is gone.

Not saying that it is the same problem but these forums have taught me (and still teach me) to go simple first!!
Are you talking about the panels that cover the storage under the aft berth? That might explain why the resonance points seem different when there is more or less junk or people in the aft cabin.
 
Feb 26, 2004
21,904
Catalina 34 224 Maple Bay, BC, Canada
So your saying engines don't have long term memories, but they do have short term memories?
I have NO memory left! :)

Just quoting the instruction manual.

RTFM - oops, I;m a guy! :D
 
Jun 4, 2004
65
Catalina 310 LaSalle, MI
Hi Gang! I'm back after (over) 2 years!

Our boat is now 7 years old (how time flies).

I usually run the engine at full throttle...she seems to respond nicely (and this is what the dealer recommended so many years ago). My issue is at idle...the engine shakes something awful (and I've actually had wiring come loose)... now I throttle up to about 1100 right after the engine turns over (and she smooths out nicely)...this works fine except when I'm trying to recal the auto pilot and the boat needs to be going 2 knots...at 1100 rpms she is usually going 3-4 knots...so I have to keep putting her in and out of gear (which does wonders for the trans I'm sure)...
 
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