prop advise /sugestions

[Limodan66]

hi there im kinda new here but fig id post to see what kind of response or previous learning was achieved ....


i just upgraded from a 9.9hp evenrude 73 to a 20hp Johnson 87 wasn't too impressed with the difference in speed gain ...... on a 1963 starcraft 14 .4 foot boat

its sits on a 1963 star-craft 14.4 ft boat three seats not a lot of extras small trolling motor , two 6 gal fuel tanks and the rest of the saftey equipment but that's about it so i grues it weighs less then the original set up but not sure
any who


the 20 hp came with a prop with a size and pitch of 10 . 13 like i said earlier i wasn't impressed with the speed /power difference in the two motors .. i spent $500 on the motor bu it did come with a steering wheel package to upgrade from pulley steering to i grues conventional rack and pinion style steering that was a plus ..

oh k so i just a purchased a 11 9 prop and im going out tomorrow to see what it can do i hope i get a combined result of both power and speed but i guess we will see tomorrow any opinions on thi9s would be a great help as i know i will be checking this post out to see if anyone else has had issues smiler Thanks in advance Danny

 

[usskydvr]

Re: prop advise /sugestions

I would think a 10 1/8 x 13 or a 10 1/2 x 11 would be about right.

 

[steelespike]

Re: prop advise /sugestions

Your description isn't much help.We really need your present max rpm and speed.A tinytach and a gps would be perfect. The 9.9 should approach about 20 mph lightly loaded. the 20 about 27 mph.Hole shot should be brisk on both.
At least more performance detail on the 9.9 and 20.I don't think a prop change is needed.I think 2 tanks is overkill. the 20 will run about 3 hours at wot(wide open throttle) on 6 gallons.