At that point the BS rule is in effect. You are allowed to exagerate by 20% when consuming beverages and talking with friends. If you are trying to impress the dock babe, you are allowed to exagerate by a full 400% before your buddy is allowed to holler Bull$%it.

That estimator came frightnening close to my actual so I deleted it from my bookmarks!!!

you guys are right, this thing was right on the money!

are you guys able to use the fast V constant? I match well with the heavy V in a 272 baja.

My PRogression matches up well with the fast V setup. Of course I'm estimating weight and assuming that factory HP is reasonably correct.

I think those slip numbers are a little off. I am running a 26' cat with a dry weight of about 3850# and I am seeing about 13% slip at 104 on gps, but I was a little heavy on fuel. I think being light on fuel I might see 10%. A V bottom running less than 10% slip with a pleasure set up would not be very probable. My .02

I can't vouch for the slip numbers but plug these in and see what you get for the constant.

Weight 3900 (3100 dry plus 300lbs of gas, 325 lbs of passengers plus 175lbs gear)
HP 415
Speed (GPS) 82.3

I used the "fast V bottom" and got 82mph. You did not say what type boat you are running. That sounds a little fast for me in a V with that hp. I know a Mach 26' (cat) with an hp 500 (470 hp at the prop, not shaft) will only run low to mid 80's. Just my opinion but I don't think you will see to many V bottoms running less than 10%. If you are getting those kinds of speed with 415 pshp in a V that is damn good.

Actually I agree that you probably not see many V hull achieve these numbers. My boat is a Progression 24' V and experience tells me that few V hulls with equal power will run with this hull. Bottom is a notched transom, pad bottom deep Vee with a fair amount of rocker and all edges are sharp. Bottom is string straight for the last 6 feet. I don't know the X but it is higher than average.

Now I get sceptical when I run those numbers with the Whipple installed. Add 200 HP and about 100 lbs. I'm gonna need a lot of witnesses if that works out right.