20' center console and 90hp evinrude. What will cruising speed be?

[Fr. Frank]

Originally Posted by Bushwacker

there’s a great story about a competition conducted in the early 60’s on Biscayne Bay between the Moesly 21 and a couple of other boats with successful racing histories (I’m guessing maybe Bertram and Magnum or Formula) by a “secretive government agency”.

Carl did reveal the name of the agency a few years back, but I think it was inadvertent, so I won't repeat it here. He also named both Formula and Donzi as among the 5 or 6 early competitors for that contract back in '64.

He said Donzi made a prototype 22' patterned after their race 28' that "just wouldn't go", and Formula, (which had just been bought out by AMF) submitted the early 233, which needed a lot more power to get on plane.

That contract as awarded to Seacraft eventually was modified to included both 23' & 27' hulls along with the original 21'.

The 23' and 27' hulls later built for the unnamed agency were both called "SeaVette". Only the 23' SeaVette was later introduced to the public.

Carl was not specific, but did say there were 3 prototype 27' SeaVette boats built in '67, each different, and of the later government 'production' 27' SeaVette he said, "of course, we never built very many of them, just a very few..."

More rare than the 15' Scampi...


As for the thread, I rigged lots of early 20' Seacraft hulls with 85-115hp V4 motors, and even with a single 70 hp. Johnson once. It, too, ran and planed just fine.

[Bushwacker]

Fr. Frank,

Thanks for providing additional details/date on the participants in the government's "Biscayne Bay Shootout"! Steve D's article indicated there were only 2 other participants, but there were so many competitors on Miami's "Thunderboat Row" back in those days, I figured there were probably more than two! Do you know what I/O setup they used? I heard they used a big block Ford? Denny

[Fr. Frank]

All Carl said was that they were BB Fords with the TRS drive behind a BW tranny.

The larger TRS drive was still pretty new, having been just introduced in '62. It was called the "Mercruiser II" when it was introduced.

I imagine that in 1964 the motors probably were actually medium block motors. i.e., the FE series engines, (332/352/360/361/390/406/410/427/428) which many called "big blocks", made from 1958–1976. The later 370/429/Boss 429/460/514 motors are also medium block motors, being developments from the FE series.

Fords true big blocks in that day were the MEL series (383/410/430/462) block, and the "SuperDuty" series (401/477/534) big blocks. Ford actually made a 601 c.i. version of the MEL block for one year only, in 1963, for use as a passenger bus motor.

[FishStretcher]

Ditto on Bushwacker and Fr. Frank. They talked me though my setup. A 100 HP 4 stroke with lots of attention paid to prop type and motor height. Even with a 4 stroke kicker and 4 stroke main on the transom, (410-410 lb total?) I can about touch 34MPH, and with a special foil, plane below 14 MPH, 12 MPH on a good day. You won't need the foil if you have a light 2 stroke back there.

I moved batteries and fuel tank forward for better trim, too.

[Beaver]

When I was looking for a SeaCraft I ran across a 20' that had a 90 Johnson on it and I remember thinking "That boat must be way under powered". I ended up buying an 18' with a 90 Tohatsu and was thinking that it too must be under powered and that I would probably end up switching to a 115. Now that I have had the boat for over a year I can tell you that I am shocked at how well a 90 hp pushes this boat. I have no desire to put a 115 on it. The amazing thing about SeaCrafts is their ability to plane quickly despite having a significant amount of vee in the hull. I am sure the 20' you're looking at will move just great with the 90 HP. Good luck.