Cat 3208 Question

Get a mechanical surveyor on board. He should be able to answer real quick if your tacs are correct and if it's the governor holding the rpms back.

You need 200 more rpm.

See what it turns up in neutral. That will tell you if it's governed. I'm not familiar with the boat but if it's a planing hull you need to run it in deep water with a full load of fuel to see where you are with the props. If the tachs are accurate it sounds like you need to take an inch of pitch out to pick up approx. 200 rpm. What size props were on the boat when it was new?

Some owners (like me) take 2-250 rpm of the top in order to preserve wear on the mains and prefer to run at that top rpm, however if the boat is not performing and needs the extra rpm, then yes, fix it.worth checking first before changing props etc.

get a mechanical survey, it will be money well spent.

you will want the boat to reach max RMP at WOT under load....
a no load test will confirm that your gov's are properly set.

if not getting max rmp at wot under load you can substantially shorten the life of a diesel.

You may have just have to take some pitch out of the props. It could be that simple. A clean bottom and fresh scanned props will help you get an accurate

An engine survey by a qualified CAT tech shouldnt cost more than a few hundred dollars for a pair of 3208s.

Also, oil analysis can be a helpful look into the life and condition of an engine, but sometimes hours on oil is not accurate. Oil analysis is best if you have a documented history of the samples and hours on oil along with fuel through the engines.

The full spa treatment from a CAT certified tech for a pair of 3208's including sea trial and oil analysis, you're looking at more like $800 - $1,000 or more.

Still, money well spent though.

RER,

i agree you are correct in your cost estimate.

worth every penny....

RT46


I also recommend that the buyer be present for the hull and system survey.

I like to observe and ask questions along the way.
Some surveyors might not like this, but if i am paying them, I want to be there to gain knowledge and awareness and ask questions....

Plus the spoken word is often more descriptive than a written report.

...and the seller says "Well I don't know what to tell you, I never run the boat that hard" ...it's a common problem with older boats. Original prop specs are calculated for a bare boat with fresh motors. Manufacturers want to demonstrate peak performance. Those calculations change over time with added weight and as motors get older. You need to determine if the boat is propped correctly. Don't guess. And you need a mechanic shooting the rpms in the engine room. Don't buy a boat without a mechanical inspection from a qualified tech - in addition to the vessel survey.

RER,

you on right on point.

RT46

Be careful

I have 3208 TA's 375 HP in a 38' Ocean Yacht. In neutral they should spin up to 3000 RPM. FULLY loaded [fuel water gear and people ] you should go a little over 2800 RPM with a clean bottom and no opposing wind or current. If necessary do an average of a two way run.

When you say Glycol inn the port engine you mean "real " glycol ? wow....there goes a set of bearings.....

A little more info

My transmissions have a 1.5 to 1 gear ratio. I have been running 22x21x4 blades with a light cup, that now after 10 years only make 2700 RPM.
The diamater is in part a factor of the tip clearence to the hull. You may also have a higher gear ratio than I.
I also have a set of 22x24x3 blades that were the original spec from Ocean Yacht but now they only spin to 2650 RPM. Both sets are in the shop at this time.
Call your local Cat dealer with the engine S/N's like the previous poster suggested to make sure what they should spin up to.
Over propping will shorten the life of your engines and does not save on fuel like some people think. It raises the combustion temps which is detremental to engine life.

depending on how long the head gasket has been leaking...the bearings may be still ok.....any other metals high in the oil?

If the owner makes repairs on the head gasket, then I would want full receipts and documents from a qualified CAT guy. ask for tranferrable warranty.

Sometimes you are better getting allowances and having the repairs done yourself.

also, you really need to know exactly which 3208 you have in there, i suspect WOT will be different for the N/As vs the Ts, vs the TAs and whatever other variation was available for the 3208s

Fresh Water

You brought up a point a few back and nobody picked up on it. Your moving the boat to fresh water?
Is that way up river or on a lake your going to do most of it's use on? I know nothing about your part of the world on how fresh the fresh water is.

In fresh water (lower density water), your boat will sit lower, have more drag and run slower. This ads more issues to your rpm questions.
Look well at your boot stripe now, you may need to raise it an inch or two during your next bottom job.

On the blown head gasket main;
With out all of the hot exhaust gasses it needs, the turbo, then whole engine, Can not make full horsepower or rpm. If it can not make full hp, the second main engine is now under a larger load and may not be able to make up the missing horsepower and make it's rpm (domino effect).
Get that engine fixed and oil changed, and run-em-again. Make sure engine syncs are off.

More thoughts;
Is there a lot of extra gear on board since factory? BBQ grills, extra anchor, all chain, tower, all curtains, Tools and spares? Bow comes up or a monster of a bow wave?

You make a good point.

I would recomend you do not change the props until the engine repair is compleated and the boat sea trialed again to see what they spin up to.