01scarab29

Used Imco plates. My shafts were 7 3/8 deep. Hard to get on plane. Couldn't find the right props at the time, the ones we had and thought would work didn't. I still want to check more into it.

endeavour32

iTrader: (4)

No, Ive been busy with other boat projects. I am going to dig into this over the weekend and hopefully get the cavitation plate designed, built, and mounted. I'll post pics, as progress happens.

endeavour32

iTrader: (4)

I'm finally getting close to getting the drives done. I've got the -3 lowers and am building them now. I have the modifications almost done to the upper to run the new lowers. Here are some pictures of the first plate. There are a few things I'm going to change on the next one, but over-all it turned out well. I'm going cut around 1.5" off it, as its currently to long. I'm going to have it stick 1" past the prop, currently it's almost 3".

Tinkerer

I would leave it as long and wide as you can stand. The bigger it is the better it will keep the prop from pulling air down and cavitating the prop. The bigger it is the easier the boat will get on plane. those plastic "whale tails" worked by keeping the prop from sucking air and then they acted like a K plane to push the boat stern up.

endeavour32

iTrader: (4)

I already trimmed it an 1.25 inches, if I have time I may make a few sizes. Swapping them out would be pretty easy.

bigblockbill

That came out very clean... I like it!

endeavour32

iTrader: (4)

I'll post some more pictures when I get them all done, which should be tomorrow. I'm really hoping that by next Monday I can be on the water and do some testing.

bigblockbill

You ever get this thing running and have any results to share?

endeavour32

iTrader: (4)

I did, I ran it twice, then tore it all apart and sold everything, to move onto a new project. So the results were great! I gained close to 8 mph. Some of that was due to the in fuel system, AN-8 lines tank to carb, new carbs, Dominators, new intakes, Brodix HV 2002's, Eickert Headers, and last but probably most important, the -3's I experimented with cavitation plate lengths. The best length was the standard length. I had one standard and one short. The short one would cavitate and was a real pain to get the boat to plain off. Once I lengthened it, problem solved. It would pop on plane. So in the end I gained roughly 400 rpms and 8 mph (88 mph) and prop slip stayed the same. It was a success all the way around. Anyone with a Formula I would suggest going to -3's. It was well worth the work.

Now I'm restoring a 38 Scarab with notched transom. It's getting 1000 hp ea. blower motors, #5 drives on boxes and I'll be running the drives 1" above the transom. According to Dan at Archer this is were I need to start. I'm hoping to break the 100 MPH barrier with this combo. While not really fast in todays standards, I'll be happy.

Tinkerer

I can't wait to see the end results.