prop pitch

[drjayw]

1985 Ski Centurion Barefoot Warrior(19') with 1995 DT150 Suzuki 150 h.p. primarily used for barefooting and slolom skiing. Dealer I bought engine from didn't know what I used boat for, put a S.S. 28 pitch prop on. Boat does 60 mph plus and tachs out well within normal range according to marina. Hole shot is bad and top end when pulling a barefooter is only 41 and I need 42/43 mph. How low can I go with pitch to be optimal for what I use boat for and not risk blowing my engine? Also current prop is only 3 blade, should I go to a 4 or 5 blade prop? I can't get answer from Suzuki or my dealer--they're not familiar with these activities I guess. Thanks for your help. <br /><br />Also same boat--need rope guard--Centurion/Overtons/Malibu/MasterCraft all don't have. Know where else I can get one besides doing it myself?

 

[DJ]

Re: prop pitch

drjayw,<br /><br />A 28" prop has a HUGE bite.<br /><br />What is your top rpm with that prop.?<br /><br />You can figure that each inch in prop. pitch is good for about 200 rpm. The rule applies whether going up or down in pitch.<br /><br />A four or five blade will help in the hole shot.<br /><br />If you do pitch down, the operator is going to have to be responsible for not overevving the engine. However your Suzuki DOES have a rev. limiter. It won't blow itself up.

 

[ob]

Re: prop pitch

Sounds like a reduction of two inch pitch should put you where you want to be skiing.Just stay within the engines rpm limits when not towing skiers and if you can afford to , keep the 28 for pleasure boating.

 

[Forktail]

Re: prop pitch

"How low can I go with pitch to be optimal for what I use boat for and not risk blowing my engine?"<br /><br />It all depends on RPM like the others have said. If your DT150 has a 1.86:1 lower end gear ratio then max RPM should be 5500. If they are 2.08:1 gears, then 6000. Don't exceed max rpm.<br /><br />The prop pitch range for this outboard should be from 16 to 28, so you have a lot of options. I don't think you need to go to a 4-blade. It can drop your top speed even more. And going to a 4-blade propeller can drop your rpm unless the diameter is reduced. The 3-blade will be more efficient. Drop some pitch and try increasing diameter, cup, and rake angle. You've got lots of room to play.