Zen and the art of sailboat maintenance

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Comment by PCarrico on May 23, 2009 at 9:36am

Lola,
When the diver puts the prop back on, have the diver measure the distance between the prop hub and the prop strut. Then, on the engine, measure the distance of the movement of the engine mounts by measuring something on the front or rear of the engine, with something in front or aft of the engine that is stationary. Another way to do that is to make the measurements between the coupling at the aft end of the gearbox to the shaft log. Do whatever's easier.

Make one measurement with the engine off, then the next measurement with the engine at WOT in forward gear and compare the difference between the two measurements, and compare those measurements with the gap between the prop and the strut. There should be at least 3/16th's of an inch of a gap between the prop and the strut so the cutlass bearing keeps cool with seawater flow through the bearing, and especially that the prop does not rub on the strut. There would also be some noise at the strut if there was rubbing contact.

Comment by LOLA on May 21, 2009 at 6:34am

Thanks Veranda...so much to learn in my exciting to say the least new venture.,
I want to be a knowledgeable sailor....

Comment by Veranda on May 20, 2009 at 9:15pm

Hi Lola,

I had the opportunity to sit in on that Mac Boring class a few years ago. It'll give you a good understanding of whats going when your engine is running. It was given by a guy with a great chunk of knowledge and he shared it in simple terms without making anyone feel stupid.

It will remove a lot of the mystery for you.

Bill

Comment by LOLA on May 20, 2009 at 8:06pm

Thank you Art and h,

It's just that I have so much invested, with little knowledge...but I am learning.

I feel better with the comments i am receiving.

Max Boring offers diesel Yanmar classes, 45 min from me. $400, but worth it...so when i get funds, I'll take the course..

Comment by h on May 20, 2009 at 7:48pm

Lola,

When engine is starting well, running well, can achieve full RPM when under load, not smoking, not overheating, then leave it alone.

They are crude devices, that do not have to be abolutely perfect to perform reasonably well.

You should see my engine. It needed a lot of work, like painting and injector recalibration. But I have not done it yet. I leave it alone, because it is running well enough. The fixes it needed are only cosmetic.

h

Comment by Art Dufresne on May 20, 2009 at 5:03pm

I assume you have a diesel. The statement is a bit garbled but essentially correct.

Since a diesel starts and runs solely on compression, poor compression would make it hard to start when cold. So if it starts right up when cold the compression is fine. Low compression when running would translate to low power under load (in gear).

You can still have lots of smoke when you start it, but when warm it should not smoke excessively. It should also be able to power the boat at a reasonable rate of speed (whatever is typical for that boat) without either the engine overheating or excessive smoke after running for some time.

Exhaust color is also an indicator. Black exhaust means you're spitting unburned fuel out. That means the injectors may need cleaning, adjustment or replacement. White exhaust can mean water is getting into the engine and can be an indicator of serious issues.

A good surveyor checks all this, plus more, during sea trial. (I'm not a surveyor)

Comment by LOLA on May 20, 2009 at 6:16am

Am I ok with this answer, when asked what were the results of the Compression test?
Remember I need your support...Thank you all.

We did not do a compression test, as the problems lead to other areas. The leak down test, the replacement of the valves (reconditioning the head includes testing for leaks and faults), etc. would show a fault that would cause low compression. If the compression was now low, you would expect the engine to be hard to start, smoke, esp. when cold, show pressure in the base or valve cover. In as much as the engine has no problem, even when run in an over prop condition, I would see no reason to be concerned.

Comment by LOLA on May 14, 2009 at 10:48am

. This has been done..his reading at max = 3160 mine 3300..( my meter is off by 124 higher, upon testing)

at Neutral his was 3793

I had the first diver go down and no zincs and he put on 2zincs...he said bottom was not too dirty.

2nd diver to go down and get the 3 blade propeller off and it will be re pitched...and then another rpm check

I will keep all posted here.

@nd

Comment by Randy on May 13, 2009 at 10:52pm

LOLA. What you need to do is to see what you motor will run up to in the slip not in gear. Record that, then take it out and run it at wto (wide open throttle) and record that. They should be very close, if rpm is lower, you have to much prop pitch. I have an adjustable pitch prop and pitch it just about 100 rpm under wto. That is then about the correct pitch.

Comment by h on May 13, 2009 at 8:17pm

Lola,

What RPM can you get with the current Prop?

What is the mechanics target RPM, before he say that all is OK?

h

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