Yes, another prop pitch question

1) Performance issue you are trying to correct.
I can sometimes find if difficult to hold the boat at a constant speed when trying to go slower. I just need a prop that would be good for general wakeboarding. Maybe a 4 blade?

2) Current prop manufacturer, model, aluminum or stainless and as a minimum.
Current prop is aluminum. Other than that I do not know. It is the stock prop that came on my Larson. Volvo Penta Model #3850301

3) Current prop diameter and pitch (required).
14.5", 19* Pitch

4) Wide open throttle RPM and speed with an average load (very helpful)
I do not currently know. I am going today (weather pending) and I will figure that out.

5) Engine/drive make, model, year, and HP
2000 4.3 Volvo Penta 190hp

6) Boat make model, year, length and weight
2000 Larson 186 Lxi
18'
I do not know the weight but NADA lists net weight at 2235.

Re: Yes, another prop pitch question

Eric, you can definitely use a 4 blade prop to minimize the problem you are having holding the boat at a constant speed when you are going slow. The 4th blade will help you plane at a lower speed as well as give you a much better hole shot and acceleration. You may lose 1 or 2 MPH at top speed, but you may not depending on your prop slip, if it is high now you may not lose anything.
When you give us the WOT RPM and speed we can tell you what prop will do much better than what you have now, for your needs.


H

Re: Yes, another prop pitch question

Ok, I went out today. Conditions were optimal. Perfect glass. I hit ~50mph @ ~5k rpms. That was after I played with the trim just slightly.

Re: Yes, another prop pitch question

Where you lightly loaded? Rpm's are a bit high, but that's ok if it was just you in the boat, once you load it with people and gear you will be good. Four blades are good for water sports, I use one and prefer it for my typical boating, tubing, wakeboarding, skiing. The ultimate question is which one, if you want stainless there are a bunch of good ones, I use an 14X20 Apollo and it works great for me, Solas Amita Aluminum props have a lot of cupping and act a lot like SS. Cheap Al props's like Mich. Wheel Vortex work, but I tried a 14X20 four blade and I was able way overev it. I think a Stilletto BayProII 14X18 would perfect, an Apollo is not quite as agressive with the cupping so you may be able to rev an 18 too high, maybe a 20 would work better. There is a big differance sometimes just in MFG, even when changing pitch for pitch, blade for blade. Typically drop one inch of pitch when going from a three blade to a four blade, 19 to an 18 in your case, but not alway's, you may find that your boat can spin a 19 four blade just fine. Time to expirement, which for me is the fun part, I've tried a bunch of props, and my rev's varied as much as 400 rpm's never changing pitch more than 1 inch.

Re: Yes, another prop pitch question

Eric, Ramster is right in many of the things he told you about the different props and there characteristics. I would recommend the Solas Amita 4 blade in a 19" pitch specifically or the BayPro II if you don't mind spending more money, because you are talking about wakeboarding and not being able to stay on plane easily at slow speeds. The Amita will help hold the stern up so your boat will be at a better attitude for slower planing, and the 4th blade will add surface area to better hold the boat at a constant speed while going slow. At this point you have a prop slip of 8%, if your gear ratio is 1.66:1, please verify this. It doesn't get much better than that, but it doesn't have the right blade geometry at slow speeds to hold the boat up without it wanting to fall off plane, that is why you are having to adjust the throttle every once in awhile. I am recommending the 19" pitch because you are currently above the recommended operating range by about 200 RPM and with the change to the Amita you will drop down to right below maximum RPM at the top of your recommended operating range.

Prop Slip




H

Re: Yes, another prop pitch question

Thanks for all the information guys, there is a lot to take in. The boat was lightly loaded with 3 (including me) adults, I myself weigh around 125 and my son who weighs about 75