Another prop pitch question

[billb1981]

Hi guys-

I've been looking through the forums and found a couple of great videos through here that explained all of the pitch stuff for props, I think I understand it now. I had a 2013 Mercury Optimax 4 stroke 60hp bigfoot as they called it back then, with a 14x10 Black Diamond Prop when we bought the boat new from Cableas. (2015 Lowe SF214 with lifting strakes). We keep the boat in the water during the summer so it has a small amount of algae build up, but I take it out and blast it with a power washer or give everyone a sponge and a beer and tell em to get to work, so we keep them pretty clean overall. I think with the 60 I hit 21-22 with just me, but now we're at about 5200 RPM and 18mph with 3 people and average fishing gear, and I never had a problem with thrust, at least I didn't think so.

I just upgraded to a new Mercury 115 CT and my dealer is going to start looking into props. Was the 10" kind of low as far as pitch? I would have expected more along the lines of 15", but again I'm just learning this so maybe I'm not all there yet. Just wondering what your guys' experience has been with average pitch on props. This new motor will swing the bigger props, so I'm excited about that, just trying to make sure when my dealer says a 15, that it makes sense.

[Liquid Asset]

Your dealer might be able to let you try a prop. It's hard to say exactly where you'll be. I'm currently turning a 15.3x14 enertia on my 22' tritoon with a 175. With adding the outer lifting strakes ( 6 in total) I'm now at 63/6400rpms with my family and a half tank of gas. New prop is in the very near future lol.

If you can try a 15" I'd say it's a good starting point. Every boat acts different especially a pontoon. The lifting strakes will actually help you quite a bit with the added HP. You need to establish a starting point with one prop and go from there. Congrats on the new power plant , keep us posted!

[billb1981]

Thanks for the thoughts!

[Marc K]

My old 25' has a 115 hp Yamaha made in 2000. It spins a 13.5" x 15 pitch 3-blade aluminum prop at 5700-5900 RPM for 25-26 MPH wide open with 6 adults. I do not have enough HP to raise the front of the tubes up to reduce drag, so I plow.

With a bunch of people up front where everyone wants to sit, my top speed is about 21 MPH at 4800 RPM and 22-23 MPH at 5800 RPM Did I mention that I plow?

[billb1981]

Hah....sorry for the plowing...thanks for the info though!

Picked up the boat this evening, he fitted me with a 15 pitch to test out for a bit. They told me the sweet spot is around 5800, so we'll start the break in process tomorrow. So far happy with the physical size of the motor.

[steve1313]

My old 25' has a 115 hp Yamaha made in 2000. It spins a 13.5" x 15 pitch 3-blade aluminum prop at 5700-5900 RPM for 25-26 MPH wide open with 6 adults. I do not have enough HP to raise the front of the tubes up to reduce drag, so I plow.

With a bunch of people up front where everyone wants to sit, my top speed is about 21 MPH at 4800 RPM and 22-23 MPH at 5800 RPM Did I mention that I plow?

Mark-
I'm sure you know this, but for others with less experience that might be reading this at some point trying to learn, let me offer a thought or two.

All pontoon boats "plow". The design of a pontoon makes it a displacement hull and not a planing hull. Even with lifting strakes to try to help at least get the front of the toons out of the water to reduce drag, these boats are still plowing. That's why you see video of boats burying the nose into a wake. Even tritoons are displacement hulls, but they sort of "cheat" by having much more buoyancy spread over a wider area, which does make it easier to get the front half of the pontoons out of the water especially with lifting strakes. This increases speed, and greatly reduces the chance of stuffing the bow in rougher waters. The extra buoyancy also allows them to have a larger engine which helps them "plane" even more.

[Marc K]

Good point. I should have simply explained that my boat throws a sizable bow wake at all speeds as the nosecones push through and spread the water in lieu of riding above it. The difference is so dramatic that I tend to call that plowing vs. planing, even though it really isn't.

Last week a tritoon with twin 250's blew past me with even less of his tubes in the water. I am used to seeing how my neighbors' pontoon boats with 250 and 300 HP run, but this was very different - and certainly faster. Less plowing too

Marc

[gerard143]

my 07 evinrude etec 115 was not turning enough rpms with a 15 pitch. just installed a 13.

[Marc K]

my 07 evinrude etec 115 was not turning enough rpms with a 15 pitch. just installed a 13.

What is the diameter?