While I await the insurance decisions on my seized engine, I've been looking into options for rebuild, long/short blocks and new engines.
I can get a rebuilt engine for nearly the exact same cost as a new yanmar, and the rebuilt engine only has a 6 month warranty. Yanmars are new, and have a 2-3 year warranty. Cheap long and short blocks don't seem to be avalible and so far the quotes to rebuild my engine are coming out as high, or higher than a new one...
So... lets shop for a new engine for me. First, what do I have and what is the boat designed to have.
The boat is a Nauticat 40
and it currently has a Ford Lehman 90HP naturally aspirated engine and a Borg Warner velvet drive turning a 22x16LH prop.
The boat displaces 31,000 lbs dry, and with my 420 gal of tankage, generator, stuff etc it likely weighs in at 35-36,000lbs. LWL is 32'8". The engine that's in the boat now is more of a production decision than a design one. You see, the Nauticat yard used to put the same 90HP ford in every one of their boats, from the 17,000lb 33footer to the 43 which weighs in at a ton more than my boat.
So, how many HP do I need? I've been told that 2HP per ton is what it takes to reach hull speed and my experience with my Formosa 41 and my other boats tells me that seems a little short. The formosa 41 weighed in at 28,000lbs dry and the engine put out 36HP or so at WOT....
Actually, since I ran her at about 80% of WOT and she wasn't cruised at "dry weight" the 2hp per ton might be pretty close. Things had to be absolutely perfect though for all this to work and the difference of one inch of prop pitch made all the difference in the world.
Going forward, I think I need 2HP per ton, with a bit of fudge factor built in so I can still go hull speed if the bottom isn't perfectly clean. I wouldn't mind a little more power to push a knot or 2 faster in a high current situation or when trying to make a slack current deadline.
I'd like it to be reliable.
I'd like it to be quiet.
I'd like parts to be cheap and available everywhere.
I'd like it to be fuel efficient.
I'd love to be able to re-use my VDO gauges instead of having to buy and figure out where to mount, expensive panels with wiring harnesses.
I really don't want a turbo, but I'm willing to listen to the arguments for one.
I'm probably going to need a new prop too, so we can talk about that as well.