Quote:
Originally Posted by flyingfrizzle
I have a question for the knowledgeable up here, I have some questions about setting up twins on the 25' . . . Bushwacker, and any of you other engineers or experienced guys in performance twin set up help!
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Friz,
If closely spaced motors see much air from that inner step on the VDH, they may be just as likely to blow out or might have to be trimmed down lower than if they were mounted further outboard! However I only know enough theory to be dangerous, and have absolutely no experience with twins and so I respectfully defer to bilgerat, and especially Fr. Frank, who has lots of experience rigging and running twins on very deep narrow hulls. Forum member Flying Time is a naval architect who also owns a race boat hull that's similar to your 25 and may also have some good advice.
I'd also suggest you send a PM to Carla (65Bowrider) to see if she can ask her dad what he'd recommend for a 25 Seafari with a bracket. I know he recommended the wide spacing for their Moesly 21 project boat which originally raced with the twin Homelites, both for "clean water" and minimum draft considerations. He also commented that the twin 250's on the bracketed 27' Seamaster "Sea Mistress" he bought were mounted too close together. Both of those boats have less transom deadrise than the 25 however, which may be a totally different animal. At the transom, GFS's race boat hull looks a lot like the 25 Seafari without the outer panels, so whatever worked best on the narrow race boat hulls might also apply to the 25. You probably have the motors mounted close together on your race boat, so that gives you a test vehicle that you could use to experiment with toe-in/out, etc. I'm sure that the Merc folks probably did lots of testing at Lake X on the race boats to determine what combinations gave the highest WOT speed. On a family cruising boat however, other factors like draft, handling characteristics, fuel efficiency, and low speed planing ability are more important than a couple of mph in WOT speed, and that might be why Carl recommended the wide spacing!