Another Prop Question

[thunder219]

I have a 94 GW Invader with a 4.3, merc. outdrive with a 21 (prop # 48-78122-21). The boat is 18 foot and usualy has 6-7 people in it. The water tube I have is a 3 person Super Mable. Now my question is when I pull the tube I have a hard time getting the boat to plane out (people that are left on the boat have to go to very front to get it to plane.) Then when I turn it just feels like the prop blows out. I was wanting to know what would be a good place to start on prop selection.
The engine rpm is supposed to be around 4400-4800 and if I remember correctly it runs around 4650-4700 at wot. I am not concerned with top speed as much as pulling power for tubing. My cousin is trying to get me to buy a (high 5?). He said he had one and it was the best prop he ever had for tubing. That is way to much money to just go buy and have no idea rather it will work or not.Any help would be great

 

[kp913]

Re: Another Prop Question

I would buy a 3 blade prop with 2" less pitch for tubing. 48-78120-19 14 x 19. This should help you with planing, and pulling power. Your RPM will raise by about 400, but if you watch and keep an eye on it while you are running it should be OK.

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[propper_advice]

Re: Another Prop Question

A three blade prop with a lower pitch will deffinetly help because when you go down in pitch your rpms go up. so dropping your pitch from 21 to 19 will help with your planning proplem by giving you more power, but if your taking out 6 to 7 people at a time and pulling three of them on a tube then i would reccomend switching to a four blade prop. switching from a three blade to a four blade prop will give you more surface area creating more power and should also get rid of that sliping problem your having when you make turns. check out both style props at www.piraha.com we have a pretty interesting type of propeller i think you might find interesting.

-nick

 

[kp913]

Re: Another Prop Question

4 blade would help a lot too, just make sure you go down an inch in pitch to make up for the additional blade. Mercury Quicksilver makes an aluminum 4 blade that is a 14 x 20, that might work well for you.

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