Recomended RPM range explained

[Crash]

so we all have read it here at OSE a few times if you ever bought a motor.

OSE Suggests 20,000-35,000 total rpm for boats. We suggest most Fast Electric Boaters should run in the 25,000RPM range for Sport Boating or 30,000RPM Range for racing. These are only guidelines, we suggest if you do not have the knowledge to pick the correct motor, please consult us first or other members of the rc fast electric boating community. Either at a local club or on our OSE Forums.

My question is what is the science in the eqaution?
A uniformed consumer may assume higher rpm means faster top speed.
What's the danger of going beyond these recommended rpm ranges?

[Fluid]

Higher rpm usually means the potential for very high amp draw especially if even a slightly too large of a prop is fitted for “higher speeds”. Racers are more likely to be aware of high amps, plus they usually don't run for more that two minutes, reducing the risk of excess temperatures. Sport boaters are more focused on long run times which means higher temps and a higher risk of damage. It is the high temperatures which damage ESCs and motors, not amps. This is why racers often get away with setups which cause a burn down in a sport boat. Sport boaters who copy winning race setups are often victims of severe damage.

An aware boater can exceed the rpm/amp draw limits with safety, but many years of experience has shown that the average sport boater runs a large risk of burning down. This is the reason for a more conservative approach to motor selection recommendations. If a new boater burns down on his first attempt, he/she is less likely to remain in the hobby.


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[Prodrvr]

There's no real danger if you follow some rules. The best thing to do is see what others with the same boat are running in the speed range that you're looking for. Then you can copy it, or go for a faster setup. Temp everything on a hot setup every 30 seconds. If anything is stressing, it'll get hot. There are people that think 6s on a 2200Kv motor is a recipe for fire...no, it's not. Do a lot of reading on the subject...you'll figure things out quickly.

[T.S.Davis]

There are people that think 6s on a 2200Kv motor is a recipe for fire...no, it's not.

Yes it is. Especially if you don't have the experience Jay mentioned.

[Alfa Spirit]

Here is a Tenshock Electra twin setup 2 x 2200kV and 2 x 6S

https://www.youtube.com/watch?v=RxnB2u26-qc

[Prodrvr]

Yes it is. Especially if you don't have the experience Jay mentioned.

Typical racer answer lol...j/k. You don't need that much experience, just a brain that works.

[Prodrvr]

Here is a Tenshock Electra twin setup 2 x 2200kV and 2 x 6S

https://www.youtube.com/watch?v=RxnB2u26-qc

That's cool!

[properchopper]

I'll try to keep this simple and civil () This "controversy" can (like the Elephant that's always been in this room) be seen from two different sides :

A] : The actual racer who needs a boat rigged to do a mill + six + one extra laps on the 1/6 mile oval, come in and survive to repeat 3 or four times an afternoon and

B] the sport boater who sees pretty much only the need to go max-banzai for two to three seconds to get his ya-ya's.

The "Type A" situation will mostly stick to the tried and true lower KV guidelines for obvious reasons - reliability and predictable handling on the course

"Type B" rigs can overpower/overvolt for that momentary thrill of the (psuedo) saw pass if that's what satisfies their aspirations

Whatever gets yer toes to tappin and your wallet to pop open

[Prodrvr]

Yeah, I'm Type B for sure. Overpowered for saw passes...nothing better.

[Peter A]

Here is a Tenshock Electra twin setup 2 x 2200kV and 2 x 6S

https://www.youtube.com/watch?v=RxnB2u26-qc

To be fair these guys are unlikely to got too hot running in ice cold water.

[Crash]

Great discussion guys.
Thanks for the great responses.

[properchopper]

To be fair these guys are unlikely to got too hot running in ice cold water.

Plus they stay WFO less than 3 seconds at a shot. They are very nicely trimmed, run sweet, and I'd bet their pilots were having a ball

That's What it's All About (except for the Hokey Pokey)

[T.S.Davis]

Typical racer answer lol...j/k. You don't need that much experience, just a brain that works.

I was gonna go with "typical world record holder" but my record was beaten.

[Prodrvr]

Ok ok, but I like fast boats lol

[Speed3]

If you are doing saw passes you may get away with the 2200kv on 6s.

If you try that 2200kv in the oval racing on 6s for 6 laps you will learn quickly why you need to avoid those high rpm setups.

I think offshore recommendation is spot on. 25000rpm for sport boating and 30000rpm range for racing.

This recommendation should keep the amps with in a safe limit for the longer runtime of sport boating. And for the length of an oval race.