Looking for a heavy load prop

[500dollar744ti]

1) Performance issue you are trying to correct.
I want a second prop that I can switch with my current prop for when I will be heavily loaded and/or towing skiiers or tubers.

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Solas HR Titan 3-blade SS

3) Current prop diameter and pitch (required).
14.75 x 20p

4) Wide open throttle RPM and speed with an average load (very helpful)
4400rpm, 51mph GPS trimmed out, lightly loaded

5) Engine/drive make, model, year, and HP
MCM 350 Magnum, 1990, 270hp

6) Boat make model, year, length and weight
Cobia San Marino 225ECS, 22ft, 3800lbs

It came with a 14x19p turbo SS prop, I didn't like it, it vibrated and was kind of beat. I did my research on here and picked the Solas I have now. I believe I have the best overall prop for my setup, top end is important to me.

Since I can't have my cake and eat it too, I'd like to buy a second prop to use when I plan to be heavily loaded and towing skiiers or tubers.

Ideally I'd be willing to spend bucks if I could find something that will let me keep my top end and increase my hole shot, I hear about the vented props, is that something I should look into? If not, then I was thinking something 4-blade aluminum for my towing needs.

I don't mind having two props that I switch for different uses. It may also be that with the size and weight of my boat, hole-shot will always be sluggish and I'm beating a dead horse as it already tops out nice for its size and power.

I can't find anyone else with a similar enough boat to compare.

Thanks in advance.

 

[steelespike]

Re: Looking for a heavy load prop

It appears to me your at the ragged edge for speed. Your at the bottom of your rpm range and I would expect
poor hole shot and a sensitivity to added weight.
It does appear your present prop is producing good numbers. 4400 with a 1.50 ratio 51 mph indicates about 8% slip
to me a good number for the weight and rpm.
Not being a prop Guru it seems to me that the same prop in a 18 would be a simple change with luck it could produce
up to 4800 rpm the same or better slip and a speed about 50.
I would think it would improve your hole shot and weight ability because it will stay within its rated rpm range.
The real experts may be along with a more detailed suggestion.

 

[500dollar744ti]

Re: Looking for a heavy load prop

I don't think my engine is a roller motor, I believe WOT is recommended 4200-4600rpm

 

[steelespike]

Re: Looking for a heavy load prop

The Mercruiser chart I use every "basic" motor I checked 3.0 to 350 are 4400 to 4800.
The only motor I recall is the old 165 having a lower rpm range.
If your going to combat heavy loads there isn't much you can do and keep your top end.
If your worried about going over 4600 only use the 18 when you will be running a load and watch the rpm.
A 19" 4 blade will give you a boost and should run about the same rpm, 4400 But you will surely lose your top end.

 

[500dollar744ti]

Re: Looking for a heavy load prop

I don't mind the top end loss when I'm pushing weight, I was thinking 4-blade 18p or 19p.

I tested a quicksilver aluminum 3-blade 14.25x17p and it was terrible. Hole shot was the same as my 20p, top end was like 39mph and it provided very little lift making the ride too bouncy.

 

[steelespike]

Re: Looking for a heavy load prop

Going from ss to al creates unpredictable changes and it seems at 14 1/4 the diameter is undersized to a typical 17" for your motor.
If you want a somewhat predictable result you'll need to go ss to ss. When going to a 4 blade it is suggested to drop an inch to maintain
rpm.
If you have to go al a solas amita or rube x should do well Just not as predictable as ss to ss. If you have a choice pick a prop with the larger diameter. Rubex and Amita are the same prop but rubex has a removable hub.