indysupra

iTrader: (3)

Procharged 540's. I'd say somewhere slightly north of 900's.

Thewhitemongoose

Carburated, MPI, EFI, engine weight per side.

MILD THUNDER

iTrader: (3)

My fountain is a totally different hull than your 42 Eric, but, from what I have seen, Fountains, don't need stern lift. The Pad helps keep the azz end of the boat up on top of the water. However, it is a 42FT long boat. They need to be able to carry the bow. I think its a fine line of keeping the drives deep enough to have bow carrying leverage, but not too deep, to where its killing speed from drag from the lowers and prop.

My propshafts are 1.5 to 2" below the bottom. I honestly forget, its been a while since I measured. Anyhow, its a side by side 38 with #4's. I can trim the drives out to 3, then 4, then 5, and the more trim I give it, the faster it goes. I've trimmed all the way to 6 on the fountain indicator panel, and still no signs of blowing the props out at top speed, with 17" four blades.

I'd say if you are unable to run with any positive trim before blowing the props out, your drives are just too high. If it was a poker run 42 with no cabin and super light layup, maybe that wouldn't be the case. But with a pleasure version, heavy cabin, I think you'll find the boat might be more efficient and simply run better by spacing it down a bit.

Just my theory, and it may be way off.

MILD THUNDER

iTrader: (3)

https://www.youtube.com/watch?v=h3_jJR_TydA That rooster might be a bit excessive for a #4 drive full pleasure 42 lol

Were you trimmed out here? Or nuetral trim, or what?

Tinkerer

Is this a stager set up? IF not why do I only see one roost. I always had two distinct roosts. Are you blowing out both drives or just one.
Sounds to me like you need to go down a little.

indysupra

iTrader: (3)

19.5" stagger so they are fairly close. Joe that is only trimmed up slightly. I have not tried to trim up that far because the slip is already high and it has been running good numbers. I was pretty thin on prop testing time since the season was over so didn't really get to experiment much.
Motors are Holley efi. Not sure on weight.

MILD THUNDER

iTrader: (3)

How does she carry at high speed? Does it seem like its running wet ?

Wonder where the 900sc #6 stagger 42s were for PS height?

ICDEDPPL

iTrader: (1)

like I said huge roost cause the drive are too high and/or prop is too small (for that height.)
A rooster is just wasted energy.

Thewhitemongoose

Mild Thunder has it right 2 inches under the hull is where the shaft should be especially on staggered motors, that's standard, 80% prop below the hull thrust and 20% prop above the hull lift, even to the hull, is actually -2, 67% prop below the hull thrust and 33% prop above the hull lift, with a 17 inch prop, that's a 65% increase in stern lift that the 42 lightning does need with the staggered motors and 5-blade props. For mine at 67/33 a 4-blade slips 23.39 and a 5-blade slips 36.64, because the 5-blade has 25% more lift than the 4-blade, at 80/20 the 4-blade slips at 18.71% and the 5-blade slips at 11.45%, currently I run at 86/14, a 4-blade will blow out and not stay on plane and the 5-blade slips at 8.97%, that is what I look for when fitting a prop when one less prop won't stay on plane and blows out.

indysupra

iTrader: (3)

Well joes is a straight bottom side by side so I'm certain he and I would require different xdim. Even when there were no 5 blades avail my boat would have never been rigged that low.