Re: 1998 johnson 3 cylinder 35 hp
I would opt for 15p stainless as best prop for top speed without engine being under too much work..
the stainless will give better holeshot and better top end due to not flexing like the cheap nasty ali props.
if your at the top of the range with a 15 ali then youl be around the same maybe a touch more with the stainless once she gets going.
the blades are thinner and will be more precise.
BUT if you plan on running in shallows or near logs where the prop might hit then get ali and stay with it.
the gearbox on your engine would probably get damaged if using stainless as the prop will not bend like an ali, and this needs to be considered unless using prop guards !!!!!
props are cheaper than gearbox casings !!!!!!!
regarding blades, a 15p prop is a 15 pitch prop never mind how many blades.
your not running a heavy ski boat so the 4 or 3 blade debate is not going to be making any noticeable difference.
if you only want flat out then get jack plate and run it high with a 19 pitch surface prop !!!!!!!
you need to work out what you want the boat to do, but try to stay as close to maximum revs as possible with your NORMAL load.
this will then tell you what is best size prop for your engine / boat set up.
you will lose at least 3mph with the engine 3 inches too low, get it up , the lowest it should ever be is level with bottom of the hull.
a normal prop will be ok with cav plate 1 inch above bottom, and that would give more speed top end.
3mph is a lot on a boat, especialy when the boat is around the 30 to 35mph rig.
just my opinions going on things ive done/found out myself
phill.
