articfriends

iTrader: (1)

I recently bought a 99 33 ft Scarab AVS with HP 500's, it has low water pick up, standard length bravos, no boxes. . I am told that using low water pickup bravos is pretty much a neccesity with stepped hulls? The drives arent especially high or anything on this boat, left over from my 272 Baja however I own 2 complete Bravos drives with every Max machine worx upgrade part with exception of the upper and lower housings, they are in pieces right now until I re-assemble them but both lowers have side water pickup water pickups and well blended nose cones. When I repower this boat to reach my speed goal of approx 100 mph I would want to use these drives. Aside from assembling both drives, switching gimbal bearings to xr bearings and running them to see what happens with water flow and water pressure is there alot of truth to stepped hulls needing low water pickup bravos? IF this is really true I would install my billet shafts, xr prop carriers, treated lower gears etc in my existing low water pickup housings and not waste my time pizzing around, thanks, Smitty

BUP

iTrader: (9)

I can not say this 100 % but in OEM schools it was always said duel water pick ups or just low water pickups are installed because of these main REASONS

Higher X dimensions by many of the boat manu's and part of the higher X become more so popular was because of current props to market and hull designs. Of course the boat manu's wanted the higher X for speed gains and less drag overall.

Next was because of stepped bottom hulls across the board from the boat manus.

and next was with these combos mentioned they needed improved cooling. the deeper the water intake inlets the less water aeration entering the cooling system if the water inlets was outdrive specific only.

Griff

When you repower, I would use your drives with the side pickups and nose cones and then install thru hull water pick ups to cool the engines.
Dump the water that goes through the drive back on top of it.

articfriends

iTrader: (1)

Thats great advice, thanks. There has been some talk of thru hull pickups hurting speed, causing issues, was it ever determined the perfect positioning and depth for them to work right?

smiklos@sunprint

iTrader: (1)

What is x dimension? If they are not to high you can use pipe plugs to block the top 2 holes in the side water inlets.
Steve

BenPerfected

This is pretty simple to do. You can adjust the exact water pressure with a slight trough using a small barrel type sanding disc. We started with a trough and then ended up filling it in. You can just use gelcoat and cabasil. Super easy to set your water pressure anywhere from 10-40 psi.

articfriends

iTrader: (1)

My used labbed 30s showed up friday, boat went from 76/77 to solid 82 w full tank of gas and 4 passengers, saw 83 later w 3/4 tank and 3 passengers. Not going to take 1000hp blower motors to hit 100, might just buy another set of matching afr heads to mattch the ones off my Bajas blower motor and put cams/port hp 500 intakes for next year,then go NA 540 down the road and see if I can get close to 100 mph! rethinking how much hp im going to need to hit 100, starting to really like this stepped hull!

scarabman

iTrader: (1)

At the speeds you are looking to obtain, things might be different, but with my 502 and 500HP powered 33s, both had standard side pick up Bravos and I never had any cooling/water pressure related issues. At one point, I had installed dual water pickup lowers, and actually lost about 1 mph up top.

Griff

My Pantera and my AT both have thru hull water pickups. Both had them already when I purchased the boats, so I can't tell you the difference.
The pickups on both were only about an 1/8 inch below the bottom.

ezstriper

anything sticking down will slow it down...just how much ????