Is my prop too small?

[imported_Captain Morgan]

I'm new to boating. I've got an 88 Wellcraft Classic 17' ski/fish boat with a 3.0L Mercruiser. It's got a 3 blade prop that measures 13.5 inches in diameter. I've read others that have 17", 19", and even 21" props. Is mine drastically too small or do I just have "prop envy"?

 

[Bob_VT]

Re: Is my prop too small?

I believe you are confusing pitch (the higher # 17, 19, 21) and diameter (13.5, 14, 15). I highly doubt your prop is only a 13.5 pitch unless you were performing as a tugboat.

If your current performance is in the mid 30's and higher your prop IS NOT a 13.5 pitch.

 

[kenmyfam]

Re: Is my prop too small?

Does seem that you are confusing the diameter with the pitch. You will need to supply at least the diameter, pitch, speed at WOT and the RPM to give the experts out here a chance at providing the best advice. They certainly helped me out with my prop decisions.

 

[imported_Captain Morgan]

Re: Is my prop too small?

Don't know the pitch. I do know that the diameter is 13.5". I suspect I was reading incorrectly when I read 17, 19, & 21. I haven't been able to take the boat out since I got it so I don't know the wot speed, or rpm's yet. I do know that the speedo only reads 27 mph with 3-200lb guys aboard. Seems low to me, but I'm still learning about proper trim settings and such. I'll post more info when I can obtain it. Thanks so far!

 

[kenmyfam]

Re: Is my prop too small?

Good Luck, get out there soon and let everyone know how you go on.

 

[roscoe]

Re: Is my prop too small?

Replace the other 2 200 pound guys, with one 130 pound girl.

 

[kenmyfam]

Re: Is my prop too small?

Replace the other 2 200 pound guys, with one 130 pound girl.

LOL...Now thats why tou are a fleet admiral !!!!

 

[imported_Captain Morgan]

Re: Is my prop too small?

Replace the other 2 200 pound guys, with one 130 pound girl.

I suppose doing just that would definitely increase it's performance. Don't know if the old anchor will go for that though.d

 

[Ron G]

Re: Is my prop too small?

Try to find some numbers on the prop and post them it should be on there.and 130 lb girl always helpsd

 

[imported_Captain Morgan]

Re: Is my prop too small?

Try to find some numbers on the prop and post them it should be on there.and 130 lb girl always helpsd

I prefer the 115lb girls myself, but an extra 15lbs in all the right places might be nice too.

I'll post any numbers found on my prop next time I can get to it(it's in a storage yard).

 

[imported_Captain Morgan]

Re: Is my prop too small?

Okay, I got some numbers off the prop. It reads "Michigan Wheel 031026 13.75 X 21. I'm assuming the 13.75 is the diameter and the 21 is the pitch? I believe a 21 pitch is more aggressive than a 17, right? Is this too much pitch for my little 3.0L 4 banger?

 

[dodge1971340]

Re: Is my prop too small?

Hi!! welcome to boating and to this forum its agreat place... your (WOT) for that motor will be 4200 to 4600 rpm. and a 21 pitch prop is maybe a little aggressive for that motor. when you decrease the pitch of your prop you will increase your rpm approx 200 to 300 rpm per 1" of pitch you decrease. On our boat with out the 4 friends just me and the wife it is about 7 mph faster so weight is a big factor. i Think with that boat you should get in the mid 30s at the least. but i would check your rps with that prop first an go from there.d Good luck !! Dodge

 

[Ron G]

Re: Is my prop too small?

we need to run hear some average runs with a normal load,whats the wot rpms,and speed?and what are we wanting to do with the boat cruising,water sports or fishing?without you rpm numbers were just shooting in the dark.

 

[Dhadley]

Re: Is my prop too small?

A 21 on that motor / drive may not be that far off. They can have a fairly low gear ratio.

 

[Jason Edwards]

Re: Is my prop too small?

Why would you want to replace the two 200 pound guys with only one 130 pound girl? You could actually replace them with three 130 pound girls and not sacrifice perfomance.

 

[Dhadley]

Re: Is my prop too small?

Jason -- that's the most common sense answer we've seen.

Mods -- please promote this man. He's truly not a cadet.

 

[walleyehed]

Re: Is my prop too small?

Us Kansans prefer 3 at a time....performance does suffer slightly, but over-all satisfaction is higher....simular to Bow-lift on a stern-heavy boat...

 

[Ron G]

Re: Is my prop too small?

ddddbut if ya got a hot motor you can only make 1 or 2 passes before something blowsd
I say jason needs to be promoted alsod

 

[walleyehed]

Re: Is my prop too small?

well said, Ron....I think we better stay on topic now....:%

 

[imported_Captain Morgan]

Re: Is my prop too small?

Why would you want to replace the two 200 pound guys with only one 130 pound girl? You could actually replace them with three 130 pound girls and not sacrifice perfomance.

You've got a good point there! I may have to try that just to prove if it's a weight thing or a load balancing thing. Anything for the sake of science.