Hey Bondo

[MooseHootie]

About the prop question you answered. My boat is a 21 foot sportcraft. 4500 pounds. Would switching to a 16 inch from a 15 inch help push that big boat any better. The engine is only putting out 175 hp. It runs 32 mph with a 15 x 17 prop . It seems to take for ever to plane out.

 

[f_inscreenname]

Re: Hey Bondo

Not to step on Bondo’s toes but I think you need a set of trim tabs. 4500rpm’s WOT is about where you should be. IMO any larger the prop the slower to get on a plain, more WOT speed. Smaller prop, hole shot, higher rpm (slower speed) WOT.

 

[Bondo]

Re: Hey Bondo

Hi Moose,<br /> I can't remember what your Boat is,+ I Agree with f_inscreenname about finding the proper WOT.....<br />I also Agree that a set of Smart Tabs might be the Answer to your Problem..........<br />But, I Don't see changing the Diameter of the prop a viable choice....<br />As I've stated before,<br />You Only get to choose the Pitch, <br />Material,(SSteel, Alum, Plastic)<br />And Style(Round Ear, Chopper, Cleaver, 4 blade, 5 blade, Shifting, Etc.)<br /><br />Diameter is Built into the Design by the Artist who Designed it in the 1st Place.......

 

[Jdeagro]

Re: Hey Bondo

Moosehooty;<br /><br />I am assuming that the engine is an I/O, which would indicate that the WOT RPMs should be about 4500 to 4800. If your current pro puts you in this range then you should be OK. The rest of the performance needs to come from the hull efficiency. Trim tabs are an extension of the hull which is variable. They allow the hull to compensate for the ever changing conditions, such as fuel load, weight balance, speed, current etc.<br /><br />The problem with changing the prop is that this is a fixed change that will allow you to improve one situation ( ie: hole shot with a lower pitch ) but degrade other situations (ie: fuel economy, top speed, etc.)<br /><br />Smart Tabs will give you better low end performance as well as more top speed, without a change in props. Why, because they are constantly active. Once the hull is dialed in, then you can concider a prop change, depending on the RPMs at WOT.