Too much prop for my boat? 14 1/2 x 22 ss prop

[dtescher]

Here's the info that might help.

1) Why do I ask? I would like more top end speed
2) Current prop manufacturer, QL Marine E series, Mod#41102328
3) Current prop diameter and pitch, 14 1/2 X 19 Aluminum, 3 Blade
4) Wide open throttle RPM and speed with an average load, WOT 4800RPM at 45MPH
5) Engine/drive make, model, year, and HP, 4.3GL with SX-C1 Drive, 1997, 190HP
6) Boat make model, year, length and weight, Reinell 180, 1997, 18', 1960LBS Dry Weight

Hope this helps. Also, I found a local SS Prop(like new) 14 1/2 X 22 for $100

 

[Maclin]

Re: Too much prop for my boat? 14 1/2 x 22 ss prop

Too much prop for my boat? 14 1/2 x 22 ss prop ?


Probably.

1.) That is a 3 inch jump in pitch, and
2.) Going from aluminum to SS can actually put more load on the engine as rpm's increase, even within the same pitch, because the blades will hold firmer.

But mainly #1. Too much difference in pitch in my opinion.

 

[steelespike]

Re: Too much prop for my boat? 14 1/2 x 22 ss prop

According to my info your gear ratio is 1.66 and you're present rpm and speed has about 13% slip a little high but acceptable.
How ever I think a 19" pitch should produce more rpm and speed.
Typically a 4.3 would produce speeds over 50 with a 23" pitch at 4800.
23 wouldn't be expected to handle heavy loads or water sports that well.but have good speed.
I wonder if your rpm is accurate? would seem should be higher. with a 19.
The way it stands a 22 would be too much prop lowering rpm by 300 to 600 rpm.
Need to confirm the rpm and is the speed by gps?

 

[dtescher]

Re: Too much prop for my boat? 14 1/2 x 22 ss prop

Thanks for you're replies. I've been out of town(Boating of course). Speed is by Tach, I'll check it with my GPS(great tip). My gear ratio is 1.85(not sure if that changes anything). I was thinking it was too much prop. But it was such a good deal. I did check the prop chart for my motor/drive and it looked like it was barely within the limits.

 

[steelespike]

Re: Too much prop for my boat? 14 1/2 x 22 ss prop

1.85 Does change the results of the numbers you gave makes slip a low 3%, unlikely.
But the rub us the rpm should be even higher probably way over revving.Perhaps you can borrow a shop tach to check rpm
when you check gps speed.If it remains 45 with gps then rpm may be accurate.

 

[dtescher]

Re: Too much prop for my boat? 14 1/2 x 22 ss prop

Thx Steelespike. I'll check and let you know what I find.