9.9 sailmaster - prop. problem?

[chill2772]

I'm running a 1997 Johnson Sailmaster with the standard 10 x 7 prop. (I think) on a full keel sailboat that displaces 6400 LBS. on 18'1" LWL. I've calculated that my max. hull speed should be 5.7 knots & that theoretically 9.3 HP would be all I would need to push the boat to hull speed. However on my boat I rev the heck out of the engine & can only get 3 knots max. The motor is properly submerged in the water so ventilation should not be the problem. So I'm thinking it could be the prop that needs replacing. <br /><br />The engine does sit in a lazarette locker & so the lower unit (w/prop) never tilts up when the boat is in the water (but antifouling is used). <br /><br />What is the largest diameter prop./pitch combo that can fit on this model motor & will that get me up to hull speed? <br /><br />Any help or first hand experience would be appreciated!<br /><br />Thanks, <br />Chris

 

[rickdb1boat]

Re: 9.9 sailmaster - prop. problem?

Propeller Type: Outboard<br /> Manufacturer : EVINRUDE, JOHNSON<br /> HP / Model : 9.9-15 HP (Thru Hub Exhaust)<br /> Year : 1974-PRESENT<br /> Boat Size : HEAVY BOATS - SAILBOATS<br /> Material : ALUMINUM<br /><br />A 10" X 5" is the recommended Prop and I believe that 10" is the largest you can go!<br /><br />Blades Diameter & Pitch Rotation Part number Style Comments <br />3 10 X 5 RH 012113 MICHIGAN MATCH

 

[sloopy]

Re: 9.9 sailmaster - prop. problem?

I would go for a prop with a larger pitch for more speed

 

[Reel Appeal]

Re: 9.9 sailmaster - prop. problem?

Frisco,<br /> Before you start changing props.What condition is the bottom of the boat in?If the boat bottom looks like a barnacle farm or there is other growth,that would slow you down considerably.This is especially true on moored boats.Take a look below the waterline first.A good scrubbing/scraping may be all you need.