Another prop question

[Skiffing]

The motor is a Merc 40HP 4s on a 16' side console V. Gross weight w/ two people is about 1,375 lbs.

Compression is on the money 180 - 180 - 180.

It's turning around 5600 - 5700 rpm WOT at less than 30 mph.

The prop is a Quicksilver 14 X 13p. It's dinged and needs to be replaced. I'm undecided if I should stay with this or go to a 13 X 12p and also look for a cupped prop.

Does anyone have experience with cupped props and dropping down in pitch?

I'm not looking for speed - but I've read that over-propping the engine can cause problems.

 

[DaleH]

FWIW I have a Merc 4-cylinder 2-stroke version of that 40hp OB motor and used this calculator to pitch that motor to my exact hull and the exact load that I will carry:

www.tinboats.net/forum/viewtopic.php?f=4&t=37433

The stock aluminum one it came with was really dinged up, so I bought a SS prop for the load of typical gear and 3 guys fishing, then bought an aluminum heavy load prop for taking the kids tubing. I propped the 3 previous tin skiffs I've had using Turning Point props and they're awesome. Plus, if not satisfied you have the right one, they'll exchange it for a small fee. But they will also consult with you to ensure you get the right prop.

Keep yours as a spare! Do not file it, but get some crocus cloth or metal cutting paper and using a hardwood block as a backer, sand out the dings.

 

[Zum]

Your prop doesnt look that bad to me, you seem to be at a good rpm range. If your not looking for a specific thing, better holeshot, towing tubes,top end speed,etc...your pitch is fine. A 12 pitch should increase your rpms, probably better holeshot and be good for heavier loads but again not really necessary(IMO). Depends on how much you want to play and how easy it is to get different props. Weight changes as well as prop changes can make big differences on small light aluminum boats.

 

[Skiffing]

I'm over-thinking this.

I'm going to stick with a 14 x 13P

Thanks guys.

 

[lovedr79]

prop doesnt look bad at all.