New prop makes boat faster, but scarier...

[Mark42]

Replaced the 12.5 x 13 OMC prop with a 12.25 x 15 Turning Point Hustler (cupped) and the boat is faster. The weather was windy so the lake was choppy this past Sunday, but I found a calm area to speed up in.<br /><br />The old prop would push the boat about 24 mph at 5700/5800 rpm. The new prop pushes the boat 27mph at 4500 rpm at part throttle. I could have gone faster, but I ran out of space. Bet I could have reached 30mph easily.<br /><br />It also felt like the hole-shot was faster than before, even though everything I read said it would be slower. Go figure.<br /><br />But I have to say, 27mph is fast in a 14.5 foot runabout. I hit some waves that made me wish I had a seatbelt on!!!<br /><br />This boat has a max rating of 50hp, and I think that is pure trouble.<br /><br />Most of the time I was doing aprox 20mph at around 3000 rpm. Wondering if a 17 pitch prop will give me better fuel economy. Most of the time, this boat will just be cruising 15 to 20 mph.

 

[quantumleap]

Re: New prop makes boat faster, but scarier...

Choose the prop that allows you to run near the upper end of your motor's recommended RPM range at WOT. This will usually provide the best mpg's at crusing speed also.

 

[JB]

Re: New prop makes boat faster, but scarier...

Didn't notice where you told us what engine you are using, Mark.<br /><br />Prop selection should be based on rpm at WOT. NOTHING else. <br /><br />You can destroy your engine by over revving it if you use too short a prop and lugging it if you use too long. <br /><br />Fancy designs make props with the same "pitch" perform differently, but you should still select the one that gives you max operating rpm at WOT and lightest load.<br /><br />Good luck.

 

[TwoBallScrewBall]

Re: New prop makes boat faster, but scarier...

JB, it's in the sig. <br /><br />Agree with everyone else, find what your engine WOT is supposed to be and then find the prop that lets the engine get exactly there.

 

[Mark42]

Re: New prop makes boat faster, but scarier...

I just haven't had the opportunity to run WOT for long enough to see if it will still over rev or if it will hang in the 5000/5500 range. Next week I'll be out by Shelter Island, NY and should be able to run it hard on the water on a calm day.<br /><br />Strange thing these lakes. Lake Hopatcong NJ has been rougher than the Sag Harbor NY area bay every time I've been there. Much prefer boating on the bay. <br /><br />Depending on how high the RPMs run, may have to go up again to a 17" pitch.