hp / torque and trimming for speed
 

what does it tell you when you must trim excessively for max speed?
I just did a prop slip cal and it was between 15-17% About right for a 28 Pantera (from what I know)
I feel like I need heavy trim to turn the prop to 5700-5800rpm. My speed seems ok. I'm just suprised it needs so much trim. Any thoughts?

Its not uncommon on a single engine boat,my 272 baja is the same way. The high slip numbers don't mean much either,I have tried to lower the slip numbers before,I only went slower. My hull loosens up when you start to trim it up and gets up on the pad and the drive,thats where I get my last 5-8 mph,Smitty

How high are you trimming on the mech indicator???? I would trim to about 7 on my Pantera for max speed. Your slip is about the same as mine was.

my indicator won't show much movement if any. I put on a diferent indicator set up to have all my directions the same on the tabs and the drive. I may try to move the atachment point on the lever to show more movement ,but it might cause problems with the range of movement.

I'm just supprised that I could add 125+ hp to my same set up
and not spin the same prop faster w/o trimming alot.
I definately have more speed than before. The very odd to me part is, the same prop and maybe 2-300 rpm more producing 5-6 mph more speed. now top speed is 79-80gps @ 5700ish . I do need to trim to get the rpm out of it but it runs faster???
Last mtr would spin around 5500-5600 and run 74 gps. If I kept trimming, it would gain rpm and not speed.

Are you running a stock Bravo 1 prop?
If yes, send it to BBlades and have them alter it to get you more bow lift.
With more bow lift at less trim, you will gain speed.
Our old school straight deep V hulls like bow lift.
I gained about 2mph from having BBlades alter my B1 prop.

the prop is bone stk b1 26 .
Thanks Pat. I'll call him tomorrow.

Question: If all things were the same on a set up and you add torque to the pwr plant, would it have a tendency to lift the transom more or would it have zero effect.

I believe the faster you spin the prop and the faster the boat is pushed, more boat will rise out of the water.