Pitch to high for 115 Ficht

[ChrisAG]

I have a 115 Intruder, and the specifications say the ideal operationg range is 5500-6000 rpm (I believe). The guy that sold me the boat says it has a 14x 21" aluminum prop - I will verify this once I have it off. At WOT my speedometer indicated speed is 51mph at 5200 rpm.

Assuming it is 21", I'm guessing going with a 19" prop would get me to 5700 rpm at the cost of top speed. Would going with a stainless steel prop (say, a Viper), at 21" also increase my rpms, or would I also need to go down in pitch with SS to get the rpms up?

Best case scenario would be to maintain (or increase) my 51mph top speed while getting close to 6000 rpm.

 

[steelespike]

Re: Pitch to high for 115 Ficht

I'm sure you can maintain speed or maybe even improve on it.If you give us all the info you can. (check the stickies at the top of the page)Boat size,type and weight.
Height of plate just above prop in relation to the bottom of boat."above,below even?"a straight edge along the keel will help you measure pictures would help.

 

[ChrisAG]

Re: Pitch to high for 115 Ficht

Thanks, forgot to include that info:

Boat: Silverline 1700 LS bowrider, 17', approx 1100 lbs.

Engine height: mounted 2nd hole from the top, I believe the cavitation plate is 5/8ths of an inch above the keel. I raised it from the first hole upon taking posession of the boat, before putting it into the water. The cavitation plate was originally even with the keel.

Even after raising, I can't see the top of the cavitation plate when on a plane. I might raise it to the 3rd hole.

 

[steelespike]

Re: Pitch to high for 115 Ficht

Yes if you don't have any venting (cavitation) problems raise it to a point just before venting becomes a problem.Would be nice to have a gps speed as well.
Whats the weight as tested?