Offshoreonly.com - '02 38' Lightning SCX-4 water test today=good

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'02 38' Lightning SCX-4 water test today=good

Ran the boat today.

Getting on plane was normal to easier.

Slip is up

Was 5350 RPM 102.5MPH wSC-1 and 15.5 X 35P Hering 6 blades 14%, tabs even with the hull, drives at 4.5 where 2 is even with the hull.

Now I have Hering 17 X 37P 16*
4000 RPM 74MPH 21%
4500 RPM 85MPH 19%
5300 RPM 102MPH 18%

Now the boat feels like it wants to bow steer. Just like when I used to go fast and trim back in too far and/or put the tabs down too far at a given speed. Definately a different ride. Nowhere near as stable as it used to be.

Trimming out past even with the hull how I used to helped a little with the "feel" but slip went up and speed dropped where before the boat would go faster

Also, with the H2O PU's adjusted fairly deep, engine PSI is 10 and innercooler PSI is 5 at 102MPH. Oil temp ran 160*-170*(normal) and water got to 180*(a little warmer than normal)but usually stayed at 165*

Is this because I have aerated water getting to the PU from too much bow in the water?

I had 16* rake. Should I go 20*+?

Semi-stagger 704HP 575SCi's
SCX-4 1.5:1 with 24 hours of sanding to clean up.
No extention box
Propshaft is even with running surface
Hering 5B 17" X 37P 16*

i might be wrong but aren,t the slip #a little high?

Thanks for the update. Good luck getting her all dialed in.

Did you try spinning the props both directions?

Sounds like you need some bow lift. Talk to Jeff, see what he says about it.. I would think the added rake may help??
At least you made it to the water!! Keep us posted on what you figure out..

Dick

I would think you would need to try a smaller diameter prop as well as a higher rake. Your trim will not leverage the the transom as much with the reduced prop shaft depth.

Many of the 700/SSM 38s run the 17"-17½" props, I'll bet you anything your rake is too low, 18 or 20 would be a way to get the bow up and settle the stern, slip should also come down a bit with more rake. In terms of slip, I remember Julie from TU giving me a really long explanation to why you want to run slip high on the newer Fountains. To boil it down somewhat, Throttle Up had found optimum slip to be in the 15%+ range, depending on the "normal" variables when going for top speed.

Quote:

Originally Posted by 1 MAIDEN AMERICA (Post 3633357)

Those drives are not surfacing with prop shaft even with the bottom.you need to go up 3 more inches to get the drives out of the water .your drives are pushing your bow down .either you get the bullet out of the water or get it back in. there is no in between .your drives are acting like boats. they are getting on plane and forcing your bow down and lifting your transom.

Your bullet is skiing so to speek .

Here's a vid, after and before

To me the after looks like it rides pretty good , like they mentioned before I believe more rake the better .