360 express 1980 diesel low speed HELP!!

[contarctor]

I've got a 360 express with 3208t caterpillar engines ar# says they are 300 hp,, boat will do no more than 19-20knots tops.it weighs 20000lbs
my friend has a 390 sundancer wich is practically the same boat 22000lbs he has 3208ta:s 375hp,but that bastard runs 32knots
what it the problem with the 360:s 150hp cant make that diffrence!!besides he has an add 2k lbs,, i know that i should have 4 blade propps
but anyway???? please someone must have the experiance in this matter..

Thanx Anders

 

[abalmuth]

Besides the props, which can make a big diffrence, hull shape and trans gear ratio also make a very big change in speed

 

[contarctor]

So i also figured ,, but i have messured the hull angle and the overall shape with muy boat neighbour, and to me they seems like perfect match,, he also have twin disc gears with 1:51 in ratio.teh only thing looks diffrent is some small shapes in the tunnels.. and the fact that he's got four böade screws with larger AR

 

[abalmuth]

on my boat different wheels can mean 3-6 knots change depending on RPM

 

[contarctor]

I thank you for that,, well i sort of figured that the propps,, is involved in the issue, but
whan compareing the boats it sort of feels that
the 390 flyes away,, and the 360 is towing a Barge..I have a sense that some small but significant changes are plesent ,, just cant figure out what..

Thanx