Re: [electricboats] Anyone with ME1616 experience? planning to run one at 48VDC, what is the actual kW available? 6kW continuous?

That's the first I've heard of props being most efficient around 1000RPM.  Are there references for that?

On my trawler, I have a 1.25 : 1  gear ratio in the transmission.   My engine guru tells me I *should* be running the engines at least 1600 RPM to keep them hot enough to not accumulate soot.   With the 1.5 ratio, that's already over 1000 RPM.

People like to run gas boats at a LOT higher RPM ("pointy end forward, FULL speed ahead!!!").  They have higher gear ratios, but seems like even with a 3:1 transmission, they'd still be over 1000 RPM at the shaft.

Maybe that's just as close as they can reasonably compromise on?

John

On Wednesday, August 14, 2024 at 12:49:59 AM CDT, Paul J. Thompson <bathroomdirectit@gmail.com> wrote:

While running the motor in its efficient band is important, possibly even more important is to keep the shaft (prop) speed  below about 1000 RPM as that is where props are most efficient and it's the prime reason for reduction gears.

--
Regards,

Paul J. Thompson
IT Manager - Bathroom Direct
(W)09 913 3110 (Mob)021 260 8249 (txt only please)

On Wed, Aug 14, 2024 at 5:40 PM Charlie via groups.io <cp3sail=gmail.com@groups.io> wrote:

Dan do you know what speed your motor is spinning at for the 3kW at 5.5kts?

 

I saw your gear reduction unit and I am trying to decide if i need to build that as well. To get the rotor rpms up where the motor is happier to run at.

- (Also is that true for this ME1616? are motors happier at higher RPMs? I thought DC motors were happy to put out torque at low rpms?.. but everyting i have read recently says keep the RPMs in an efficient band which is elusive to ascertain.

 

So i am trying to find out where the motors are running at RPM wise and if I should direct couple or gear down the motor. Then if I gear down (which seems logical now) to which RPM range am I calculating towards?

 

Thanks guys!

 

- This boat is a catamaran, has very interesting hydraulic drives at the moment. Has standard saildrives mated to the hydraulic gearmotors like on a piece of farm equip. Very compact and tidy but not very efficient.