Pitch vs. Diameter?

[champion221elite]

I have a 29" Sprint Cat powered with a 1600 KV Leopard 4082. This is a dedicated 6s boat running a Seaking 180 v2 ESC with 5.5 mm bullet connectors.

I've run a number of different props starting with an M545, Y547, X448 and now a cupped S215. The S215 is by far the slowest prop in my collection, but for sport running it's plenty fast and things come back nice and cool. The speed calculations I've done say the S215 should be running about 64 mph with this setup as described. I hooked up my truth meter (GPS) and found the best the S215 would do is 51-53 depending on batteries. What I formerly thought was "good enough" now has me wanting to get more speed by bumping up the pitch just a bit.

For those with experience, is it better to increase pitch or diameter for 29" class cat hulls? I have two props in the 2.64" overall pitch range. Both are S/B, one is an M545, the other is an X642. Overall pitch is roughly the same, the difference being one has more blade pitch while the other has greater diameter.

I plan on doing some testing within the next week, but figured this might be a good place to start.

As always, thanks for any insight.

[Fluid]

Actually the S215 with that motor should be turning mid-50s max. You need to push more water faster to go faster. "Blade pitch"? Pitch is pitch, and a larger diameter prop moves more water for more thrust. Eventually increasing the diameter requires too much power, overheats things and leads to handling problems.

The S215 is just 40mm in diameter so it moves a smaller quantity of water - less amps and lower temps and less thrust and speed. IMO it is too small for the boat and setup you run. I would stick with props in the 45-47mm range and increase pitch to go faster. That motor could swing a larger diameter prop but that might hurt handling on a 29" cat and draw too many amps.



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[champion221elite]

I will try my M545 next time I'm able to hit the water.

[champion221elite]

Update: I was able to run my 29" Sprint Cat this morning with the M545 prop. Conditions were not the greatest with some strange variable winds and boat wakes. I was able to make some passes when things were relatively calm which resulted in 59-60 mph as opposed to 51-53 with the S215 prop. Besides the additional speed, the biggest thing I noticed was the motor seemed quieter with the M545. Guessing the motor was loaded a bit more with the added pitch. There is probably some additional speed to be found with this prop by messing with the strut height. CG is pretty much set because the batteries are way up in the bow due to the hull layout. A better day with less wind will also yield some better speed. I was right on the edge of blowing over a few times because of wind gusts.

[Erroneous]

Can always try some ABC 16 to 19 range. The 17* rake ABCs have less transom lift than the props you listed. The thrust cone is tighter (more forward thrust)...A 1815 or 1816-17 would be a world of difference but you would stay in your diameter range. Wont help with blowovers though.

[champion221elite]

I am not familiar with ABC props at all. Does Octura make anything that compares with the ABC props you listed?

[oscarel]

I am not familiar with ABC props at all. Does Octura make anything that compares with the ABC props you listed?

No, completely different props.

[champion221elite]

Ok, maybe I'm an idiot... but can someone provide an exact link or part number for the ABC prop that would be correct for my Sprint Cat. I've read through ABC's alphabet soup trying to figure out their designation system but it's not making much sense. Right or wrong, I have a much easier time figuring out Octura's system of naming props.

[oscarel]

Ok, maybe I'm an idiot... but can someone provide an exact link or part number for the ABC prop that would be correct for my Sprint Cat. I've read through ABC's alphabet soup trying to figure out their designation system but it's not making much sense. Right or wrong, I have a much easier time figuring out Octura's system of naming props.

Man, wish it were that easy. What works for one probably isn't going to work for the next. There's way too many variables involved. There's already a few possibles provided in earlier posts. I have one I raced with but on 4s 2200kv leopard and I used a cupped Octura 447, never tried an ABC.

[Erroneous]

http://www.offshoreelectrics.com/pro...7-45%282%29CLL Looks like hes out of the higher pitch 15/16s. I switched from Octura and Prather to the ABCs and got cooler temps and better speeds on more than one boat. They are touchy while tuning though. I only called out the ABCs because you will be able to run higher pitches with lower temps. If you are already light in the bow steer clear and detounge some Octuras.

[fweasel]

The abc props are diameter/pitch and come in series that are rated rake/blade_area. The first two numbers I understand, the second two, I sort of understand, but fortunately have not had to venture outside of the 17*45 series for my needs. Contact someone like Dasboata about a specific abc prop for your needs.

[champion221elite]

The abc props are diameter/pitch and come in series that are rated rake/blade_area. The first two numbers I understand, the second two, I sort of understand, but fortunately have not had to venture outside of the 17*45 series for my needs. Contact someone like Dasboata about a specific abc prop for your needs.

I think getting in touch with Chris (Dasboata) is exactly what I'm going to do. I have several of his worked props in my collection, and it only makes sense to have an ABC done by him.

[Erroneous]

He will definitely be able to help. He has prepped alot of mine.

[fweasel]

I think getting in touch with Chris (Dasboata) is exactly what I'm going to do. I have several of his worked props in my collection, and it only makes sense to have an ABC done by him.

He's sending me an abc 1914 hopefully early next week.

[champion221elite]

I ran the M545 again this am, and raised the strut just a bit. Speed increased to 61.5 on gps, but handling got worse. The Sprint Cat ran with a very nose high attitude and was right on the edge of blowing over.

[Erroneous]

Try putting a lil negative angle on the strut (prop pointing down slightly) a couple degrees. Only has one strut bolt right?

[champion221elite]

2 strut bolts. Its slides in a channel that prevents neg or pos abgle. Up and down only

[Erroneous]

Lil chainsaw file action will take care of that.