bertram31.com

Hello Brain Trust,

1983 38’ Convertable III
Cat 3208T 300hp

Engines coming out, and new bilge painting and update starting.

Wife says…. “Lets look at putting new engines in it”, especially after redo of the interior etc.

Yanamr, FPT, Cummins, Scania, Cat…….?

Port motor just came out, and sitting on trailer in driveway.
It just got real.
Both Cats are running and need to be Needle Gunned and repainted, but they are a 50 yr old design, and Extremely heavy.

So what are the thoughts on which power package to seriously consider?

Going over to Boat Diesel, to see what others have done.

Thanks for any thoughts.

Do whatever the wife says. QSB 550s?

I have been very pleased with my QSB's. The have no detectable smoke or smell and relatively quite. They fire right up and were easy to install.

I would suggest upping the Horse power but you'll likely need new shafts and struts.

As the saying goes….
In for a Penny, in for a Pound

1 3/4 shafts on it now.

I've seen the QSB's done with relative ease. Was watching a boat in the Mediterranean with John Deer 315's that looked like a solid package.

What do you have that you can get support for locally?

1 3/4” shafts are plenty for any power you could squeeze into a Bertram 31

Amberjack wrote: ↑Aug 25th, '24, 17:55 1 3/4” shafts are plenty for any power you could squeeze into a Bertram 31

Not for a 31, but a-

1983 38’ Convertable III
Cat 3208T 300hp

Support for CAT’s, Cummins, John Deere, and FPT that are local to me.

my attention to detail sucks - but yes if you have a 38 - then I would definitely up the HP - Cummins QSB 550's would probably put a smile on your face.

Carl, you are correct of course. I have 1 3/4 shafts on Amberjack and think I may be over sized but that’s what started this train of thought.

Kevin I look forward to hearing what power plant you decide on and what shaft diameter the power people call out. My repower happened the same way yours did. My wife got tired of watching me fret over our worn out big block Crusaders and said it was time to replace them with diesel power. Our wives are smarter than we are.

Think about the cost of parts. The nice thing about Cummins you can get a lot of everyday parts at the local Cummins Truck dealer. I usually buy my engine antifreeze, oil and all filters from the one near me. The price of Valvoline Blue from them is actually a little cheaper than every other place near me.

Just makes life a little easier.

Thanks Gentlemen.
Will keep you appraised with the choice of motors.
BTW, my wife likes this boat more than I do!!

Kevind767 wrote: ↑Aug 27th, '24, 14:12 BTW, my wife likes this boat more than I do!!

That my friend is a good thing!

I'd answer on motors, but aside from what Tony said about parts and Jeremy about service I do not know much about one motor over another. I love the 6BT Cummins, but they only go up to 370 or so hp. On those I have to say if I have to work on them they are designed to be user friendly. No special tools and very accessible. Engineered to be worked on makes routine maintenance easy.
Things like oil filters are mounted out and open with the opening facing up. Sounds stupid, but dads Steyer has the filter horizontal...makes for fun changing the HOT oil. Need to replace waterpump...lots of fun trying to reach in and around, then small screws so the heads round off. Volvo with rubber o-ring seals on the aluminum piping...expensive to replace if the part can be found and with aluminum and salt water its only an amount of time before they pit. Cat...great motors but as you said heavy and they need specialized expensive tooling. Replace a .02 seal in the fuel (injection ?) pump requires removing several huge items to gain access.

If the larger hp Cummins are designed like the 6BT's I'd be looking at those.

Good luck, let us know the way you go and why.

I have to agree with Carl, I am partial to Cummins.

QSB 550 is a true contender..
My only worry( issue), is that is that is the max HP package out of that block presently.

Is that such a smart idea, ie. longevity and stress on the engines?

You’re coming from heavy 300hp cats to 550hp Cummins. You can move a bit quicker without taxing motors much at all and they should last a good long while. Or you can run em hard and all bets r off.

Could also step down in hp, run em like you ran the Cats with a longer motor expectancy, less coin involved.

It really all depends on what your going after… longevity or do you have a new need for speed. Speed costs more on all levels. Or a compromise…only you can answer that.

I’m past the “Need for Speed”

Yes I don’t mind going fast, but that is not my main want with this Repower.

If I’m going to spend the money, I would like the best package for the next 10 years.

Looks like the QSB6.7 425hp is going to be the choice.
Not yet finalized, but Damn close.