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Bertram 31 power options

Posted: Nov 5th, '07, 10:58
by J Graham
Has ayone heard of a 31 being powered with a large single screw diesel?
Realizing it will be a lot of work, does a single QSB 540 or 600 make any sense. The boat will be stripped to the bare bones to start with. It is a Bahia Mar with twin Chryslers now.
Thanks,
JG

Posted: Nov 5th, '07, 11:22
by CaptPatrick
JG,

First, to get any performance, you'd have to power with at least a 500 hp engine which would probably swing around a 30" diameter wheel. With the deep v of the 31, that would entail a very large prop pocket, or more like a tunnel. The engine would have, of course, to set on the center line of the boat. Now you're redesigning fuel tank space. There's at least a dozen other engineering problems beyond those mentioned.

The long & short of it is that the answer is pretty much the same as it was for configuring a B31 with outdrives. No sense at all...

Br,

Patrick

Single screw?

Posted: Nov 5th, '07, 20:44
by Capt. Mike Holmes
While it isn't a good idea, and would be a whole lot of work, the split system marketed by Mastry that runs two marine transmissions shafted to a single engine, turning twin shafts and twin screws. You can use the engines fro manuevering, as the transmissions work separately, but with only one engine, rpms will be constant on both sides.

Still not a good isea.

Posted: Nov 5th, '07, 21:05
by Harry Babb
A buddy of mine had an Sportcraft "Offshore 30" with a single inboard 454.........now that would be a good candidate for a single inboard diesel 400 HP or so........a day boat with plenty of room for fishing

I'm waiting for someone to consider a mast and sail..............

Harry

Sail 31

Posted: Nov 5th, '07, 21:37
by Capt. Mike Holmes
Harry, I did a humor column on rising fuel prices a few years ago in which I sarcastically imagined both sails and galley-style oars on my 31 - if the customers wanted to go further than I was willing to spend fuel for, they could provide their own power.

Posted: Nov 6th, '07, 09:49
by Craig Mac
I am pretty sure that Bob Lewis (Fishing Kites) used to run a single screw 31---

Posted: Nov 6th, '07, 11:14
by CaptPatrick
Craig,

Think that was Bob's son's, B31 powered with a single DD671 natural. Set up as a center console, open fisherman... I saw the boat at the Glass Tech's yard during the re-build in '95, but never saw the finished product or heard performance results.

Br,

Patrick

Posted: Nov 6th, '07, 13:03
by John Swick
Check out the job James did on his B25, www.sbmar.com (under repower articles).
If anybody can do it (right), he can.

Posted: Nov 6th, '07, 13:27
by randall
would encourage everyone to check this out....outstanding job!!!

Posted: Nov 6th, '07, 14:01
by John F.
That B25 is fantastic. What a great job.