Engine Repower Advise

[Schweinsberg]

We recently purchased a 34' Creekmore cutter (just under 8 gross tons). It currently has a 36hp Volvo MD3-B inboard diesel with a direct drive to the prop (not a sail-drive). We are planning to repower and were looking for suggestions on engine models. We will be doing some extensive cruising, so availability of parts (world-wide) is key. We are considering the Yanmar 3GM30 or 3YM30, and are wondering if 27-29hp is adequate. This of course yields about 3.5 hp/ ton. Size should not be of concern for new engines are smaller. Price is of course a concern, but safety in strong current comes first. All models/ makes of suggestion are appreciated.

Thanks,
Sue & Graham

[never monday]

The 3GM30F is no longer an option. A 3YM30 is, also the 3JH, Unversal 35, Volvo D2-40

[GordMay]

Two to three Horsepower per Ton, is a common rule of thumb for powering a Sailing Auxiliary.

[Whimsical]

Originally Posted by GordMay

Two to three Horsepower per Ton, is a common rule of thumb for powering a Sailing Auxiliary.

Many seem to have a lot more these days especially lightweight cats.
I am pondering this issue at the moment for my 4.5 ton, 6.5 t loaded, 40 foot cat. Has a fairly high shear line but well streamlined. Designer recommends 2X 10 hp outboards or 2x 29 hp diesels. Most strange I think.
What can I glean from all the experience here?

Mike

[GordMay]

I suspect that the 2-3HP/Ton guidance may be a little old fashioned - developed when designers expected their boats to power at about 1.0 x Root LWL.
As discussed elsewhere on CF, most of us currently expect about 1.33 x Root LWL - which would require (about 75%) more Horsepower.