how fast/go

Westdevil

Seaman Apprentice
Joined
Jul 30, 2003
Messages
48
i have a 1978 17ft bayliner tri-hull<br />470/170hp mercuiser<br />it runs 35mp top speed with two person<br />it plains out real easy<br />but i think it should run faster <br />am i wrong <br />just wanted some out put<br />thanks
 

JasonB

Lieutenant
Joined
Feb 10, 2003
Messages
1,455
Re: how fast/go

If it is in good shape, I would think it would run faster. What is your RPM at WOT and what size prop?<br /><br />For comparison, I run a 16' tri-hull and get 38mph with an 85hp outboard at 5000rpm and a 19' deep V hull with a 225hp V8 and get 48 @ 4300 or so.
 

JasonJ

Rear Admiral
Joined
Aug 20, 2001
Messages
4,163
Re: how fast/go

There could be many variables. You could have the wrong prop, too much weight in the boat from too much gear, waterlogged floatation foam, etc. I fixed an old 17 ft Tahiti ski boat for my friend that has the 470 in it and that little boat was pretty darn fast. Trihulls tend to be heavier and not as fast as comparable length V hulls.<br /><br />Rpms for that motor should be around 4600 or so, don't go too much higher, it'll blow. Also, the heat exchanger was too small that year and the possibily of overheating is higher. It is an interesting motor, it has a Ford 460 big block cast iron head, Ford pistons/rods, Merc crank, Merc aluminum block. It can be fun to get parts for, as a lot of parts are no longer available. Good luck...
 
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