Just Another Prop Question

[cptbraine40]

IBoats Experts,

I am just looking for some advice on prop selection for the following:

-17.7" bowrider boat with Mercruiser 3.0LX (135hp) and Alpha One Gen II (2.0 Gear Ratio)
-Weight Approx with people, gear, beer, etc: 2300lb
-I do have the SX trim tabs in place.
-No dolphin fin on outdrive!!!
-Current Prop: 4 Blade Aluminum Solas Rubex, diameter: 14 1/3 Pitch: 19
-WOT: I am hitting about 4700 to 4800 with this prop with a speed of 38 mph (GPS Verified)

Questions:

1. Does this speed sound about normal with this set up?
2. I understand what pitch does but what about the diameter size?
3. Should I look for a smaller diameter but same pitch?
4. I am really just looking for an overall good prop. Something good for basic tubing, skiing, and cruising (if this is all possible).
5. Will stainless steel really make big difference? ( I go to a DEEP lake and run little to no risk for hitting anything).
6. Should I stick with a 4 blade or take it down to 3 for this size boat and engine?

Any advice would be greatly appreciated.

Thanks,
Brian

 

[Starcraft5834]

Re: Just Another Prop Question

Those numbers sound like a winner Brian. you might pick up a few mph with 3 blade but will lose hole shot.. keep the 4 blade and be happy..

Ive got a 19.6 cuddy, the boat weighs 2500 empty,, i had a 3 blade and felt like I was trying to pull a fridge out of the water and get it on plane.. I put a Solas 4 blade 14.75 15P on and now jump up on plane in less than 5 seconds, get 33mph GPS. Im thrilled with it and would not go back. Most people will probably agree that a 4 blade offers more benefits overall.

 

[cptbraine40]

Re: Just Another Prop Question

Should I move to a stainless steel prop though? Will it really be worth the $300.00 or is it too heavy for this boat's engine?

Thanks,
Brian

 

[SkiDad]

Re: Just Another Prop Question

I'm no expert. you can run SS but i wouldn't expect miracles - i tried one on my boat and it does accelerate faster but I like my aluminum prop better for my setup. So i keep it for a spare. Now i think it's a different story when you get into the high performance boats, which neither of us have - ha ha. I don't think you have any issues with propeller weight. Smaller diameter will give your more rpm but it will not push as much water.

I say when you find a prop you like just keep it - 38 is fast enough if you are doing water sports.- that's about what I run with my setup - i can hit the low 40's with another prop but it's not good for skiing. You probably could hit 45 with a 21p 3 blade but you would have the kind of hole shot you have now.

 

[steelespike]

Re: Just Another Prop Question

Your present numbers are very good At 4700 and 38 your slip is about 10% While aluminum to stainless is a little hard to predict.
I don't see the stainless adding more than a couple of mph.It might make slightly better low to mid range performance.
The prop weight has no affect on performance.The added weight could add the slightest bit more wear on the clutch dogs.
But the correct idle and crisp shifting will minimize that. I don't think the improvement worth $300.
Prop diameter is a secondary consideration.In the extreme it may add or subtract 100 rpm.For heavy boats a larger diameter
will usually do better.If you look up props for your boat you may notice that generally as pitch goes up diameter goers down and vise versa.

 

[cptbraine40]

Re: Just Another Prop Question

That sounds great, thank you so much everyone for your input, I greatly appreciate it. I am just going to ask Santa Clause for a stainless steel prop since boating season will be ending in about a month or so here in Tennessee.........................and what Mitzyman, the Mercruiser 3.0 is not a high performance engine?????? I have the LX which gives me more HP.............hehehehehe