HI I'M CUURENTLY IN THE PROCESS OF RESTORING MY 1968 FORMULA 233 WHICJH IS A STRAIGHT INBOARD SET UP WITH BORG WARNER 72C DRIVE AND I'M DROPPING IN AN OLDS 455 THAT I JUST BUILT. I'VE NEVER SEEN THIS HULL BEFORE WITH AN INBOARD SETUP. LOOKING FOR ANTY ADVICE AND MY FIRST PROJECT IS SOURCING OUT THE MOUNTS FOR THE VELVET DRIVE, ALSO CAM SELECTION FOR THIS ENGINE. THE MOTOR I'VE BUILT SHOULD HAVE ABOUT 400 HORSE SO I'M SHOOTING FOR 60MPH. DAVE IN FT. LAUDERDALE
1968 233
- Thread starter DOGGYDOO
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HI DAVE! Sorry can't really help much, I've never seen an inboard in one either. It must draft a ton! I think 60 with an inboard may be optomistic. I don't really know. Got any pics?
DOGGYDOO461
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OK I HAVE 450 HORSE , TORQUE ABOUT 525, RPMS GOOD TO 6000, WHY CANT I DO 60? I HAVE A 1 TO 1 BORG WARNER 72C AND A 16 INCH PROP. WHAT DO I NEED TO DO TO REACH 60 BECAUSE I HAVE HEARD OTHERWISE,,,,, DAVE IN FT. LAUDERDALE. 1968 233
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I think depending on the location of the prop, it may prevent the boat from getting up on the 4' of flat hull ahead of the transom, therefore it would be running on the rocker. Just too much drag for that amount of HP, When I ran mine with the twin baffed 350's and 19" four blades all I could get was 50 on GPS, it would run 43 until I started trimming, then you could really start to feel it get free of the water. I really don't know , this is just a theory. Most inboards I have seen are ski boats, centre of gravity is way foreward and they have some rocker built in. They come out of the hole like an NFL lineman but run out before 50MPH. Fast inboards/V-drives are usually flat chips of resin with a blown bigblock. Just my 2 cents 
Have you run this boat in stock configuration?
Have you run this boat in stock configuration?
NO WHEN I BOUGHT THE BOAT IT HAD ALREADY BEEN CONVERTED TO INBOARD, I SEE YOUR POINT ABOUT THE LIFT AND DRAG THOUGH. THE ENGINE IS WAY FORWARD AND THE FUEL TANK IS WHERE THE ENGINE WOULD BE ORIGINALLY ALL THE WAY AFT IN THE COMPARTMENT JUST FORWARD OF THE TRANSOM. THIS BOAT DOES NOT CURRENTLY HAVE TRIM TABS BUT I WILL PROBABLY BE ADDING THEM. THE PROP IS ABOUT 10 INCHES FORWARD OF THE TRANSOM. IT ALSO HAS A HUGE RUDDER MORE SUITED TO A 46 BERTRAM !! HOPE THIS MEANS SHE WILL TURN ON A DIME BUT NO I HAVE NEVER HAD THE BOAT IN THE WATER, I AM HOPING TO HAVE HER DONE BY JUNE BUT IT'S JUST ONE THING AFTER ANOTHER. I AM WONDERING IF SHE WILL BE MORE APT TO RIDE LOWER IN THE BOW BECAUSE OF THE CENTER OF GRAVITY BEING THIS FAR FORWARD. DAVE IN FT. LAUDERDALE
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New name, same boat! It would make a cool wakeboard/ski boat! What does it have for a prop!
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With an inboard it certainly make a great fishing boat! With 1:1 final, mathematically it will have no trouble going fast! How did it run for the previous owner? What kind of RPM range are you building the Olds for?
WHEN I BOUGHT IT THE ENGINE WAS A SINGLE CHEVY 292 INKINE SIX COUPLED TO A B/W 1.52 RATIO 71C, IT RAN AVOUT 30MPH ACCORDING TO THE PREVIOUS OWNER. I BOUGHT THE VESSEL ON THE TRAILER SO I NEVER ACTUALLY RAN IT. I AM BUILDING THE OLDS 461 WITH ALL THEB USUAL TRICKS TO RUN AROUND 4400 AND AM INITIALLY GOING WITH A COMPPCAMS GRIND AND A BG CARB, MSD IGNITION, ETC. DAVE
A big factor of running past 50mph, and more so, the 60mph threshold, is the larger propellors.
Large diameter props are great for lower speed efficiency, but the just have too much surface area, and create drag as you push it through the water.
Faster turning, smaller props with more pitch are better at speed, vs cruising speeds in 30-40mph area.
It's similar to the jet boat issue. Eventually the speed that you are accelerating too, gets closer to the thrusted jet, and gets less efficient.
Where a good prop, essentially screws itself though the water, with about 10% slip.
Old thread, yes...but I think It's worth mentioning.
Resurrected mentions the twin Inboard with 2 350s, and 19" props. I suspect theb19s are of the limiting facfors for getting past 50.
Large diameter props are great for lower speed efficiency, but the just have too much surface area, and create drag as you push it through the water.
Faster turning, smaller props with more pitch are better at speed, vs cruising speeds in 30-40mph area.
It's similar to the jet boat issue. Eventually the speed that you are accelerating too, gets closer to the thrusted jet, and gets less efficient.
Where a good prop, essentially screws itself though the water, with about 10% slip.
Old thread, yes...but I think It's worth mentioning.
Resurrected mentions the twin Inboard with 2 350s, and 19" props. I suspect theb19s are of the limiting facfors for getting past 50.