Need a good midrange cruising prop for SX22

[Fishwater2002]

I have a 2018 SX22 with elliptical toons & a Yamaha 115 Vmax SHO, with 2 passengers & about half a tank it’s at 29-30mph @ 6200 RPM. That part is fine but when I load the boat down with 8-10 people I’m lucky if I can hit 20mph, the boat is typically loaded for the day with 6-8 people so I’m looking for a prop that’s better when the boat is loaded with people, coolers, etc. I also noticed that there seems to be a a small window where the motor goes from perfectly trimmed to cavitating if you go a tiny bit past perfect trim or if the boat is turning.

I tried to identify the current prop but the only thing I can see is where it was stamped with BB1970 so I have no idea what the current specs are but it’s obviously pretty close. A lot of folks seem to like the Turning Point 4 blades so maybe that’s a good choice but not sure if I should go with the standard 13.5x15 or something else or a different prop all together. Any suggestions are appreciated.

 

[fitz73222]

The BB1970 may be the code for a prop shop that did some work to the propeller, it does not look like a manufacturers stamp. Take the propeller off and look for numbers in the hub behind the washers. Honestly, it sounds like you're pretty dialed in. Is this a pontoon or a tritoon?

 

[DVW]

Your lightly loaded straight line top speed is outstanding. If you are willing to trade off a top speed that you can brag about for a higher speed during your common operating conditions then there is a couple of things that you can do. First drop the motor one hole at a time. There might not be a speed trade off if you like to fiddle with trim at top speed. Reducing prop pitch will make the motor lug less with heavy loads. Under thus conditions the motor will be free to rev up to a speed range where it makes more power. The result can be more speed under those conditions.

 

[Fishwater2002]

The BB1970 may be the code for a prop shop that did some work to the propeller, it does not look like a manufacturers stamp. Take the propeller off and look for numbers in the hub behind the washers. Honestly, it sounds like you're pretty dialed in. Is this a pontoon or a tritoon?

It’s a pontoon with elliptical tunes

 

[mtudb24]

It’s a pontoon with elliptical tunes

The twin Elips are the fastest straight line configuration that Bennington makes with the same HP per boat model. The problem is they don't turn well and slide into turns like a typical twin tube boat, unlike a tri toon which cuts and carves into turns. ESP, SPS+, and SPS are the best for turning but given the same HP, will be slower top end.

As DVW said, if your typical load is gonna be 6-8 people and not your 2 person with 1/2 tank of fuel, I'd prop the boat to your normal load. Typically you prop a boat on the light side that way when you load the boat up, you still fall in the WOT RPM range. But if are always running with a heavy load, prop it for that load and if you find yourself running light on occasion, you just don't peg the throttle to the max or you may over rev.

This means either dropping pitch by a couple inches and or lowering the motor if you can to stop blow out in turns. You can also goto a 4 blade prop which will help with the cavitation.

What's your RPM with your load of 6-8 people? This number will tell you how far you need to reduce your pitch. You might be finding your load is dropping your WOT range out of where its supposed to be. 115 VMAX SHO is 5300 to 6300 rpm.

Most if not all props, when you reduce pitch, you also increase diameter which will give you more surface area which will help with the cavitation in turns etc.