calculate the crouch factor for your grady

[suzukidave]

i came across this interesting calculator that tries to quantify the effect of hull shape on performance for a given horspower. supposedly very accurate with whalers. it would be interesting to see how consistent it is with gradys, especially on different cv hulls. if members could please plug in your stats and report back we would have a little database that may be helpful for others to estimate the impact of hp changes.

http://continuouswave.com/cgi-bin/crouchcalc.pl

 

[suzukidave]

1986 tournament 190, 120hp, 38mph wot, estimated weight 3000lbs

hull factor 190

 

[cgmiller]

1990 230 Gulfstream with 2004 F150's...estimated weight = 7500 pounds. Max speed 40 mph, Hull factor 200.

 

[wahoo33417]

Low confidence that I did this correctly. But for a 258 weighing 5,000 lbs. (I'm guessing this is wet weight?) with and F300 and a hull form of 180, it predicts a top end of 44 mph. That's pretty close, as on a good day I can hit 46 mph.

So I did it again, this time entering a speed of 46 mph and solving for hull factor and it returned a hull factor of 187.

 

[GulfSea]

The numbers are about 4-5 mph slow for mine. Is there a hull factor for Grady's listed anywhere?

 

[suzukidave]

for some reason there is a default crouch factor of 180 in there. if you erase it and fill in everything else then it will calculate the crouch factor for your boat.

it won't be the same for every boat of the same hull. prop, individual engine performance, twins vs single, hard tops, bottom paint and engine height will affect the number. however with a few comparatives it should tell us roughly what the number is or can be for each hull.

i am curious to see how the cv2 and old hulls compare, and also whether all the different cv2 hulls have a similar factor.

if you know your weight it is also supposedly very accurate in estimating the speed change you will get from a horsepower change.

 

[CKJR]

Estimating my hull weight fully loaded at 9000 lbs, factor at 192 with a top speed of 43 mph

 

[GulfSea]

If you look at the hull factor section, they mention most Whalers are in the 180-200 factor range; the 180 default appears to me to be something just entered for a starting point. When I put a hull factor of 200 on mine, the number is very close.