underpsi68

Aren't those rpm vs mph slip numbers very high? I run a stock 26 bravo with a 1.5 rato and cruise about 48mph at 3500rpm. You have a 30 with a 1.36 running 55mph at 4000rpm.

mod58

Thats what I'm thinking,works out to be like 40% @4000 rpm 55mph and 22% @5000rpm and 82mph.

Griff

I think you need some seat time and with trials of various trim and tab positions.

A 30 Eagle with twin 620's is going to be a handful. Its a light stepped hull boat for that much HP.
I've seen a single 30 Eagle spin out and eject everybody at 40mph.

mod58

You're absolutely right Griff,Yes,seat time is key! Just trying to get it somewhat efficient at cruising speed. Right now 4000 RPM at 60 miles an hour I feel was a little high.

bbladesprops

That's 19%. Not that bad for 4000 rpm. Use 29.3 for pitch. 82 at 5500 is only 11.33%.
These boats do run some higher than normal slip #'s as the "X" dimension is critical. Usually the "X" is little high?

Brett

mod58

Brett,prop shaft is 4-5/8 bellow the bottom,thats with a 1" spacer that actually measures 7/8.Called you around noon and left a message with Mindy.Maybe if you have what I need I can have it for this weekend!Thanks Steve B.

underpsi68

Using the prop slip calculator on your website I get 26.4% slip at 60mph and 26.9% slip at 82mph (1.36 gears).

bbladesprops

Thank you, yes, 1.36g.r. I saw that earlier but didn't use it in my calc.
mod58, I'll call you shortly.

Brett

mod58

Well after getting some seat time and kinda getting this boat some what figured out,then scratching my head for a bit as to how I was able to spin the 30's @ 5400.I pulled a drive and checked the ratio and sure enough the previous owner change them to 1.50's.Anyway with the 30's it would chine walk and bow hop quit a bit.So I set the tabs even with the bottom and that took most of the walk away but not the hop.I could run it up to about 88-89 and back out b 4 it would get to violent.tryed more tab,it would com it down a bit but mostly just scrubbed off speed. Tryed a set of 28's,got rid of the hop,gained 400+rpm but lost 6-7 mph across the board. Put a set of 32's on,turned 5200 and picked up 3-4 mph across and some walk came back but the bow hop was not so violent and got out at 91.Next Im gona try taking the 1" drive spacers out and see how that affects it.