Boat with shorties question
 

Are boats with shortie drives generally slow to plane (whats the trick) v bottom 96 scarab 31'

Depends mainly on final drive height. If it was real high with a std length drive prob will be tough to plane. If it was very conservative and deep then no it will prob walk right up.

As you know, the higher the prop shaft height generally the more speed. It sounds to me that you have the prop shaft height at a good spot. When getting on plane with the tabs down, try move the sticks slowly in unison and when the tach shows that one side is blowing out, leave the throttle position on the this engine as is and then easy the throttle forward on the other engine until you get on plane.

Ben, so I should allow the props to cavitate (Blow out) and it will eventually bite (alto `thats what ive been doing, just dont want to wreck anything)? Props are 32P 4 blade Bravo's....when the boat is on plane she runs great


one thing that Ive noticed the 3 times I have had it out so far is that if it is rough out its even harder to get it to plane, but when its up it runs and rides fine

Clarify

One thing you could try - I guaranty it will work is to increase the negative trim by shortening the trim rams 3/4 inch. ( take them apart and take them to a machine shop that has a lathe with a 3 inch head. They can cut them off and duplicate the end. Then do a LITTLE grinding on the helmet and gimbal ring. ( all of the grinding is in non structural areas and will not weaken the parts.) This will allow the drive to tuck under a lot more and the boat will hop on plane. You could just shorten the rams without doing any grinding and that may be enough all by itself. I have done this on two boats and it works perfect. My 26 Daytona would just laugh at me trying to get on plane with the Bravo 4 blade. I did this mod and it got right up. ( my prop shaft is 1 inch above the lowest point on the bottom)

My 34 SCARAB had -2 IMCO shorty's with Bravo 4 blade 28 pitch and getting on plane consisted of taking off and when you got to a point the props would start to slip and I would just hold it at 5000 RPM and it would just go up on plane. Less than 5 seconds.
With stock length drives and 25 Mirage props if you tried to get on plane too fast it would just blow out. There is a video on here somewhere.

you could just make a cavitation plate and it will work fine.

there is an IMCO cavitation plate on it currently

take the trim cylinders off of the end of the drive..if the hole is oval where the pin goes through then their should be a wedge in the hole..i think the wedge on the inside drings the drive closer to the boat..some had it and the old bravos did not... put the tabs on 5..roll throttles to 3k and let the boat go..when it starts to nose over raise tabs ..when flat trim up..5 blades make a huge differance..but you loose mph..of you domt mind loosing 3-5 go 5 blades..