Any of you ever messed around with the bam speed calculator???
 

It's pretty cool and was wondering if anybody had real world numbers compared to the computer numbers???? It seems pretty accurate...

http://go-fast.com/boat_speed_predictions.htm

I tried the calculator, According to their numbers my 330 HP Pachanga22 should be running 76 mph, I'm only seeing 60 to 62 on a good day so I must need a bigger engine, at least thats what Im telling myself to justify it !! LOL

Mine comes out pretty close! Cool

You can play with it, the small flats boats I used to build it was right on,the Open fishing center console cats it was close (a lot of drag) Top side,on the race stuff,fudge the constant up and it worked.

It's cool for some stuff, but you have to remember that the constant has to be right. 225, 250, 275, 300 are not enough, you'll need to figure out exactly what number you need. The new OL SV43 needs a constant of 300+ in some cases. mecapndave probabley need a constant of 205-210 for the Pachanga and make sure the weight is correct. It works very well for figuring out, which kind speed increase you can expect for an hp upgrade.

only about a million times, the slip calculator is actually more useful once you have some real numbers

AO is right. You are "calibrating" the model with your own specific hull constant based on known HP and speed. Then you can input new HP and get a prediction for your hull. You could also gain speed without increasing HP by bottom blueprinting, drive blueprinting, drive height changes, CG changes etc. all of which are lumped together in the hull constant.

Figures don't lie, but liars figure..... That calculator is a blow-up of Crouch's Theorum, from 1929. With correct (NOT from the brochure) figures,
it can be spot on.

TC, is right it is adjustable and can be tweaked, I used to build a couple lines of composite Flats boats ,the old computer analysis said 48 MPH with a 90 ,the second line I did was a foot longer and ran 54 MPH This time with a 70 ,I put those numbers in the RAM program and got the same exact speed ,a decent NON POD Cat will be well above 300 on the efficiency.

How do I determine slip on a Ocean Express 25' cat with 2x 250 Yamahas. 15x30 pitch 3blade merc cleavers?????? I only can spin to 5700-6000 redline. Thx

http://go-fast.com/prop_slip.htm

this is easier haha http://go-fast.com/Prop_Slip_Calculator.htm

Hey Brownie, thanks for reminding us that there is nothing new under the sun. All of these equations also need to be adjusted according for local conditions, like whether or not you are in a bar. And don't forget Smoky Yunick's theorem (I think it was him)

OA + T > Y + E

i think whats crazy, even with all the new bottom tech, the major factor in speed is still weight. Also the fact that a non-step hull starts running out of bottom at certain speeds, but I would like to see a 42 cigarette straight bottom vs a 42 twin step with optimal props and drive heights using todays tech. Both boats with 700's......This would give an accurate idea of how much better the bottom is. I remember speaking to somebody that worked at Cig back when the first stepped boats started coming out and he told me that the step really only gained a couple if any mph, and it wasnt until they started raising the drives and lightening up the boats that the speeds came up.

And this even more so:lolhit:

http://www.heringpropellers.com/prop-slip