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Originally Posted by 79 excalibur 24
I have been on alot of the superboat forums reading up on their setups and i have a good idea of where to start but i have no idea if my 79 excalibur is an exact hull as the old supers or not. How much dose my hull weigh and how fast should it go with the right rigging?
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Hey 79 Ex, nice rig. Those hulls can be fast. That four inch pad works well above 70-75.
(I'm putting almost the same motor in my 64 vette during accident rebuild - AFR's, but 355ci. See pic.)
Here's my Excalibur experience if it helps:
Owned a 1976 from '95-2000. Hull was light and fast, but the lay up was like a damn jet boat - small stringers and no cross bulheads or braces - cockpit tub sat right on chine so that as hull sections for and aft of it flexed, it created a hinge point in the bottom and cracked through - whole boat twisted like an empty shoebox. Deck WAS glassed to hull though!! Seem to remember a 79 Ex I looked at seemed to have a better layup and maybe larger stringers.
Custom dash boxes added before I got it.
14 gallons of epoxy later it was as tight as I had patience to get it -- full bulkhead in front of and rear of cockpit - enlarged stringers slightly, and added another small set right on top of strakes from transom to front of cockpit. Bonded and tabbed sides of tub to hull bottom at the chine area before putting floor back in. Did bildge area before motor went in the first winter, under cokpit the next winter, and the bow area the 3rd winter, using the boat each summer as I went.
Standard 1st gen '89 Bravo with nose cone - x dimension at 17 or 17.5" not sure which - supposedly was 2.5" higher than "stock". straight edge placed on bottom of hull pad would hit about center of water intake on drive at neutral trim - cavitation plate parallel to bottom. Shot small rooster tail at top speed at optimum trim - had to trim all the way in on sharp turns or 3-blade would spin - I thought it was about perfect.
468 BB at 470+hp with 25 mirage at 5,400 rpm and 78-80 mph. Your SB is probably at 450 ft lbs of torque, little more?? My BB was around 550+ ft lbs, so it will be interesting to see the difference. I seem to remember prop slip was in the 12% range??
Boat liked lots of trim for last few mph - let it porpoise - the speed still comes, and you might have to saw the wheel a little to balance any chine walk, but the speed would still climb. Tried a 4-blade Hydromotive, which gave too much "transom lift" and it chine walked violently - with no increase in speed.
My drive had maybe two seasons on it before I got it, and I put almost 500 hours on it in four seasons before the boats demise. The drive then sat in my shed till this summer, and is now pushing a friends 22 donzi with 454/wieind 174, 5 lbs, to 82 GPS so far.....Drive has held up fine.
Bennet twin piston 16" tabs are all you need - worked fantastic, and held up fine in the big stuff, including hitting the beach at 50-60mph..............
Let us know how yours turns out.
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