Take a guess!
 

02 38 Lightning, semi stagger, full cabin, 575SCi's w/704HP, -1 IMCO's 1.5:1, Hering 6bl 15.8"X35P w/22 degree rake.Finally got approved for drives and props (by you know who).The drives are on and props should be here in a week. As soon after the props arrive as I can we'll find out. It's a weather thing here in Seattle.How fast?Will it get on plane?Can I turn these props to 5350RPM?Boat did 96MPH on limiters hard (more than 1/4 throttle to go) with stock XR lowers and 32P5X's or lab 32 Maximus'

109- 111 say round 5000-5200. i dont think you'll get to the limiter with 35's with your ratio and -1's. unless you have a high x-dimension from the factory.

5350 rpm with 35 pitch props, if it did run 111 that would only be around 6% slip. I say 105, if it can turn 5350 without over trimming the boat. I hope that you do run 109-111 and I am way off. I have screwed up before. Monstaa has set up many boats, so he is probably right. Either way show us some pics of the speedo, be safe, and good luck.

I'm hoping for 106 and happy at 103. The boat's run at 12-13% slip with several different setups in the past which would put me about 103 with the new stuff. Can't wait til the props arrive.
Stock X was 19.5". I don't have ITS either.

So are you saying that effectively with the 1 shorty that you have a 20.5 x deminsion?
Allen

Thats still great.....its funny how we casually talk about V bottom boats running 103, 106, not too many years ago, that speed in a cat was unheard of. Fountains feel so safe at those speeds but it can be decieving, things can go wrong in a big hurry, so be careful, wear a lanyard and a lifeline, and I still wants some pictures of the speedo:boat:

03' 38 half stagger, its, 1:50 ratio, -2 imco's, 575's with a pulley, intercooler, brain re-map. 111.3 one way. 109.1 the other. half tank fuel. tachs said 5400. 34 x 15 3/8 hydro p5 with extended hub and polished/ satin finish.
you should be close. no its may drop 3 . steps are a lil diff.
you'll probably be in the 32-34 range with herrings.

good luck

19.5" X -1" = 19.5" X still but propshaft is 2.5" below bottom of hull instead of 3.5". Sorta like a 20.5 X just that the leverage of the drive on the boat based on a 23" propshaft to inputshaft dimension has been lowered. The plus is keeping the engine CG lower.

I would use a -2 !!!!!:party-smiley-004:


U know u can always space down ,,but u can't cut them off !!

monstaaa,

What's your experience with the Hydro P5's on a 35 T/S? Mine is an '06 with 34" centers and a 19" X. Tom at Hydromotive was not real sure if the P5 or the P5X would be the pick, he was saying that the P5 would be better for a higher X set up.

-1 or -2, now that is the question. Was the question. I'm only looking for 100.5MPH or better (today) and didn't want to lose the rudder and planing ability. If I had ITS or extentions I would've gone -2.

also did an 01 with 750 single 4's. 1:50 ratio, -2's, side by side standard transom. spining a tricked out set of 32 4 blds . ran 104@6000 +/-.
these hulls react to prop cup and diameter very well. i wouldnt hesitate due to hieght as stated above you can allways space down. water pressure is an issue. as for handling and plamning, a 19.5 start with -2's has no issues to really be concerned with just a lil more tab and 3 seconds or so slower planing.

The hull has really good working steps and a big notch ,,,that is your extension box !!!!!!!!!!!

Go -2 !!!!!!!!!!!!!!!!!!

In race configuration the run it 1-2 inches above the HULL !!!

Just thought i let u know !:ernaehrung004:

Props aren't here yet. I'm not ready yet anyways, too busy at work. I did have a vivid dream last night that it went 135MPH!!! 101 might not cut it now.

its ok to dream,,,,,, and it may as well be big.

5 guys, 200 gallons of fuel, 5400RPM, 100MPH
5 guys, 60 gallons of fuel, 5400RPM, 99MPH
5 guys, 100 gallons of fuel, 3800RPM, 70MPH
I've noticed before that the boat slows when lower on fuel.
I didnt notice any speed change when trimming from 4-6, or tabbing from 2-4.
Slip's way up from before. Way longer planing time. Porpoises in the midrange at times.
But...100MPH

I set the drives straight/parallel.
I wonder about my innercooler PU tubes being too long.
They are mounted perpendicular to the running surface on either side of the drain plug, chopped at 45degrees, with the scoop side about 3/4" below the running surface. Innercooler pressure is 8# at speed.

Engine water pressure dropped with the new lowers from 20-25# to 10-15#. I watched for dropouts when turning and overtrimming and didn't notice any.

What do you think?
Thanks, Rob

BTW- the props I got ended up as 15.5"X35P with a 20 degree rake

12-13% slip - Unless this is a race baot with no interior and light on fuel I have a really hard time believing your slip is that low, especially with bravo drives and a short stagger. Are you data logging the speed / RPM's? My boat was dialed in at the factory, has #6 drives and 6 blade Herings and the report has shows 107mph at 5350 = 16% slip. The best I ever saw was 104mph = 18%, however that is with a typical summer day, e.g., coolers, 3/4 full tanks, supplies, tools, etc.

Wasn't that also a somewhat stripped down F2 boat?

Boat did 93MPH at 5350RPM from factory with stock 575's and 32 Bravos. About 11% slip based on 31pitch.
I added HP and got 96MPH at 5350RPM with labbed 32 Maximus'. About 11% slip based on 32pitch.
96MPH w/32P5x's and 96MPH w/34 Bravo's stopped by limiter.
100MPH w/35 Herings just shy of limiter.
Full cabin, no A/C, no crapper!

Smartcraft tach readings or analog? My friends '09 38 Lighning with a full stagger, 700's, #6 drive and 6-blade Herrings is at 13% from the factory (115 mpy @5350), but that is a top of the line combo. I think the best he has seen is 110 - 111 mph (16% slip). However, we do run out of lake pretty quick at 100+ mph and can't stay in the throttle long enogh to really stretch it out. Would kill for 12-13% slip.

I believe those numbers. 2001-42', 95 MPH, 31 P5Xs, 5450 RPMs. 575 SCIs, tuned by Precision Marine and I have full cabin, AC, and Crapper.