bertram31.com

On the Boatdiesel.com site, in the vessel performance calculators...would the 31 & 25 Ray Hunt hulls be:

1) Slow Planning
2) Average Planning
3) Fast Planning

Seems to make a BIG difference in estimated speeds, etc. So which one to use for these hulls when designing a re-power.

Also, based on the design of these hulls what would you guy's consider a "safe or stable" WOT knots to design toward during a re-power?

Thanks,
Scot

scot....my 25 with twin inboards will do 40 and is very stable on flat water at that speed.................hardly ever do it for long however as its kinda like pouring the gas down the drain......i think 32-34 would be tops for a 31.....in todays world is this "average" planning speeds?

Thanks Randall,

The calculators on the boatdiesel.com site are using the hull category to determine a theoretical speed, they are asking "what type hull is it?"

I believe this relates to the basic design and performance of the hull in question and not the desired performance of various re-power options.

The results of the calculations differ with the same HP / RPM inputs, leads me to believe that I need to determine which of these categories the hulls "best" fit into?

I have been using "average planning" for various calculations, I don't think these hulls would be considered "fast planning". I would think fast planning would be more like an ocean racing hull?...dun-no?

Maybe someone out there has used the software and back checked it with actual performance numbers??

Thanks,
Scot

When I was messing around with the calculators for my gas powered 33, I started with what I had (2 300hp gas motors, 2:1 trans, 18 knot cruise, prop size, etc...). I just kept making changes (weight, and hull type) until it matched what I was already doing and went from there.

I wound up having to use a fast planing hull to get the calculator to give me an approximate match to what I'm currently getting.

Hope this helps.

Thanks...I love hearing that, the results obtained with the calculator in the "fast planning hull" mode are much better.

Scot

I have a 25B with 3.7LX Merc's 190hp. I am up on plan around 15/16 knots, its one the easiest planning boat Ive ever run and being in the boat buis I have run my share. I would say this falls in the fast/easy planning section.

Keep Smilin

Ron,

I'm disappointed that I won 't be able to get to Fla for the show. I wanted to get a chance to meet everyone from the sand box. I read that you will be down with some clients in tow. You guy's enjoy the show.

Maybe next time around,

Scot (Old School)