Bertram 37 with 2 x DDC 6V92TA engines

"Hi

I am not that familiar

"Hi

I am not that familiar with the Bertram 37 and am looking for some advice.

I have a Bertram 37 and the max power I get from it is 2100 rpm, is this correct? and if so what is the cruise speed, I don't want to overload the engines. I did notice the manual states 2300 rpm max but I am not convinced, mainly because both engines are giving me the same rpm, give or take 30 rpm.

Thanks"

"Hello,
I'm going to assu

"Hello,
I'm going to assume that these are mechanically governed engines. Is the 2100rpm attained while powering the boat or no load in neutral? That 2300 rpm max.specification is for no load, neutral and the rpm on those engines will "droop" to around 2100 loaded and that would be "normal".

These engines are in their optimum power band/torque curve at the 2150 rpm setting and to turn them any faster (or slower for that matter)only increases fuel consumption and wear. Turning them up does you no good at all and engine damage will begin to occur around 2500 and beyond.

It sounds to me as if you have a couple of sweet running turbocharged, aftercooled 92's and they were born to run at full throttle all day and night as long as the hull will hold up. Trim the vessel the way you intend to use it and GPS your maximum speed now so that you have a baseline to go by in the future.
Gday Mate."

Hi Jimmy

The 2100 rpm is at

Hi Jimmy

The 2100 rpm is at full throttle powering through the red sea. The reason I ask is that the manual shows a graph with 2300 rpm max and looking across it gives a specific speed.

"All I can tell you is what I

"All I can tell you is what I know of the V-92. You could have a mechanic turn up the wick and run them on the ragged edge but I'll wager you won't gain a whole lot. I think that whomever put that tune on those engines knew EXACTLY what he was doing to get the best out of them and they will live a much longer and healthier life because of it. Offshore, I value dependability and reliability a great deal more that an extra 1-2 knots of speed. Everything in this world does come down to comprimise and, if you are willing to comprimise the longevity of the engines to satisfy what is probably an over-optomistic speed quotient used to sell boats in the first place, you're the boss and you can certainly do just that. If you are missing a great deal of speed off of that "chart" that they gave you then you might want to look at some of the other factors involved like props, transmissions, the boat's bottom etc...

I made a living for years turning up 400 horsepower engines to 600 horsepower engines and always marveled at the owner that would bring it back and complain that it used too much fuel or that the his last engine (400hp) lasted much longer before giving him trouble."

"The background to the boat is

"The background to the boat is that it is approx 25 years old and was not used for the past 10 years, in september last year it was removed from the water and the hull, etc was completely cleaned and the engines serviced.

There is a problem with the stbd transmission in that when you throttle to go forward it does nothing for about 30-45 seconds and then kicks in and is fine for the rest of the day, the next day it will do the same.The port transmission responds immediatly

Also there is a bit of black smoke when the engine is accelerating and at cruise speed. I may have the turbo's stripped and rebuilt.

Apart from that it goes fine"

"I'm an engine guy, not a

"I'm an engine guy, not a transmission repairman. I know enough about transmissions to just be dangerous. To diagnose your stbd unit, it would be necessary to hook up a pressure gauge manifold to look at main pressure and drive circuit pressure through the control valve assembly. Sounds like a sticky accumulator valve or a slightly damaged seal, part of the problem with machinery sitting around for ten years.

As far as rebuilding the turbos, I'm not sure why you would want/need to do that unless they were leaking or not making enough boost. Although, I would agree that the seals would probably be iffy after having set up so long. Do you have boost gauges and documentation on the requisit boost pressures?

Those engines will smoke on acceleration and that would be normal because of turbo lag and those probably don't have any smoke control devices or they've been disabled. If black smoke is rolling at cruise, that is not normal but could be something as simple as restricted intake (air filters?), dirty aftercoolers, or sticky blower bypass valves. If the engine sat up that long it's hard to tell what had condensation sitting in it. The only way to address any of this is at the boat with some specific knoledge and some fairly simple test instruments such as fuel pressure gauge, boost gauge and a manometer. I'm afraid I'm not going to be of much help 4,000 miles away."