RPM's Question

[pdnervo]

Just got the boat.....i have a Westerbeke 30 in my 361 Beneteau.
at full throttle it rev's up to 2200 RPM only..amd cruises only about 4.5 knots.. how can i check and see what the problem is... i think it should rev up to 3000 while cruising.. is there a mobile tachometer i can install temporary to monitor the RPM's. thanx ans.

[Tellie]

Things to check first, is the prop clean, is the bottom clean, is the fuel and fuel lines clean, is the exhaust elbow clogged.

[pdnervo]

well the prop is clean the bottom is clean it was out of the water a couple weeks ago....boat is at mechanics and he is cleaning the fuel filter and hopefully the line.... cause the filter was green... but my question is can i or he put on an other temp gauge to check against the fixed gauge... i dont think the prop is a problem cause it would still turn and register the rpms no mater what prop is there... no or yes...tks ans

[boasun]

One other minor detail; What is the govenor set at on your engine. It just might be 2200 RPM.
Going back to "Tellie"; What is the condition of the bottom of your boat?

[bill good]

the rpm can be checked with an optical tacho. what rpm do you get out of gear? the 2200 is that while under way?

[pdnervo]

yep thats 2200 rpm under way....

[SkiprJohn]

There are digital tachometers that are easy to use and will tell you whether your boat tach is accurate. If someone installed a larger or higher pitched propeller than should be there it will keep your rpms down and cause your boat to lose speed. You might check out the propeller size. Check out the engine speed while in neutral to see if you can get the rated engine speed for your engine (probably 3500 to 4000) then put it in forward with the dock lines tied to see if you can get to 90% of that speed. If you can still only get 2200 rpms in neutral the trouble is with the engine and speed control or fuel. If you can get much higher in neutral than when in forward there is a problem with your drivetrain. Could be anywhere but I'd check to see if someone has changed the prop to larger. If there is a lot of heat on your stuffing box then there might be a problem with that being over tightened.
Hope you can sort it out.
kind regards,

[hellosailor]

" can i or he put on an other temp gauge to check against the fixed gauge"
Go to Harbor Freight or something similar, $20 will buy you a non-contact infrared temperature sensor with a laser sight. You aim the dot on your engine and read the temperature display. You can also check the tire pressure in your car that way, if the temperature is the same on all 4, the pressure is the same. High temps = low pressure in that tire.
All sorts of uses once you own it.

If you call Beneteau, they're great at customer response, they'll tell you what speed that engine should be making at what rpm. Could be low compression, too.

[pdnervo]

Hello Sailer the problem is with the tach not the temp gadge (my spelling mistake) but thanx your help....SkiprJohns answer was very helpful....thanks again. pn

[hellosailor]

pn, no porblem. Similar answer: You can buy a "contact" tach, that you place in contact with a rotating part like your flywheel, or a non-contact 9optical) tach, that requires you to put a white dot on the rotating part. A good mechanic or engine shop should have one. If not, they aren't all that expensive if you can settle for a "consumer" grade one, which should be good enough for this use.

[wallandj]

Might want to check the specs on this engine. I googled "Westerbeke 30" and the specs I saw indicate that 2200-2500 RPM might be about what it should max out at (its not a high-revving Yanmar). In fact, the performance graph only went to 3000 RPM and the torque curve peaked around 1800. I didn't see a redline, but "rule of thumb" is that you should cruise at around 80% of this figure.

If the throttle linkage is bottomed out and it still only runs at 2200 in neutral, that might be where its supposed to max out. If that is the case, you may be underpropped (i.e. the prop pitch should be increased). Did the previous owner replace the original prop with a folding or feathering version? If so, it might be incorrectly pitched. Such was the case when I bought my boat - the MaxProp was off 2-3 settings.

[SkiprJohn]

Yes, by all means check the manual for the engine before adjusting things. If it is revving to 2200 and max is 2500 for your particular engine then you are in the ballpark for rpms. I didn't realize Westerbekes were a lower speed diesel. I guess I should have known because they are much like the Perkins.
Good luck and let us know how things work out.
kind regards,

[pdnervo]

thanx i will get back to you soon im gonna haul it out in a couple weeks and look at the prop also...
thanx again for all the good info.. pn