need prop and don't know where to start

[suzukisam]

1979 seasprite 16" tri-hull
140 merc pre-alpha
3.0 GM 4-banger I/O

Ok I've read a few posts but don't see anything to help me. I need to buy a prop for my boat, the current prop is un-useable, I understand I need to see what will make my boat run at the right rpm's @WOT, but I have never had this thing on the water. it had a bad drive shaft(another post) and bad prop. The prop explains the driveshaft!!! I will be skiing and cruising mainly.. so I need a pitch that will pull a skier out with realitive ease, but not burn the motor up @WOT I would like to buy a couple different props, but I just need a starting point, if I would be better off to buy two props than I will. what would be my range of props for this boat, if someone has a similiar boat I would like to hear some personal experience. I would like to get a good prop to get me going and then when I know I have a hard day of skiing I could put a stronger prop on but I don't want to have them so specialized than I'm playing musical props everytime I go to the lake!

 

[mthieme]

Re: need prop and don't know where to start

Here's what Mercury's prop selector suggested for good overall performance....

Black Max Aluminum 13.375 x 25.0 48-78126A45
High 5 Stainless Steel 13.250 x 25.0 48-816374A46
Laser II Stainless Steel 13.750 x 25.0 48-16550A46

Personally, sounds a little too pitchy.

 

[suzukisam]

Re: need prop and don't know where to start

yeah.. I expected like a 20 or something.. but hey I guess I don't know or I wouldn't be asking right!! where did you find this "prop selector", I'd like to check it out

 

[mthieme]

Re: need prop and don't know where to start

http://www.mercurymarine.com

Can you read any numbers on the prop you have?

 

[Tail_Gunner]

Re: need prop and don't know where to start

One go to I/O forums and find the wot rpm for that motor...slap the cheapest 18p 3 bl alum on and post your results

 

[Bondo]

Re: need prop and don't know where to start

the current prop is un-useable,

Ayuh,... So what are the #s on it,..??

That's probably the Best place to Start......

 

[steelespike]

Re: need prop and don't know where to start

I think TG hit it right at 18.If I was guessing I would lean toward the light side
If its too light you can back out a little to keep the revs down if its too heavy and she can't make her recomended rpm you plain shouldn't use it.

 

[suzukisam]

Re: need prop and don't know where to start

well I haven't read the numbers, but the idiot that had the boat started chaanging stuff and I don't even know if it's the prop that should be on it, so before sending the money on one and finding out it's the wrong thing, I thought I should check with you guys and see if anyone just knew spot-on what the sweet spot on this one would be