airplane propellers.

[urbs00007]

has anyone run an airplane propeller on one of our boat motors to get idea of the power that they are putting out? If so, what tachs work well and any instructions will be greatly appreciated. I have a great planes collet type adapter that clamps on my T.P. 8mm shaft. I tried my Hanger 9 mini digital tach, but it gets readings all over the place. help!

[trigger]

Yes

Start at post 537 lots of data.

https://forums.offshoreelectrics.com/showthread.php?52649-P-Limited-Motors-Im-going-to-jump-on-the-hot-seat/page18&highlight=jump+on+the+hot+seat

[MarkF]

You need natural sun light or a regular flashlight to get a good reading. Fluorescence garage lights don't work well with tachs.

Mark

[urbs00007]

You need natural sun light or a regular flashlight to get a good reading. Fluorescence garage lights don't work well with tachs.

Mark

thanks mark. i think airplane props are a great way to check power output on our electric motors. do you have any idea how to get approximate horsepower numbers after rpm readings on a particular prop? thanks, john

[785boats]

I use a simple power analyser meter like this.
They give peak amps, voltages, realtime running amps & voltages. Plus watts, which can easily be converted to horse power if you want.
http://www.ebay.com.au/itm/G-T-Power-130A-RC-Watt-Meter-Power-Analyzer-Digital-LCD-Tester-12v-24v-36v-/272052430789?_trksid=p2385738.m2548.l4275

[urbs00007]

I use a simple power analyser meter like this.
They give peak amps, voltages, realtime running amps & voltages. Plus watts, which can easily be converted to horse power if you want.
http://www.ebay.com.au/itm/G-T-Power-130A-RC-Watt-Meter-Power-Analyzer-Digital-LCD-Tester-12v-24v-36v-/272052430789?_trksid=p2385738.m2548.l4275

so you use an airplane prop? real time..... does that mean you have to read the screen while obtaining data? or will it show highest readings of a run in the boat?

[MarkF]

The best way to get data from a boat motor is to use a data logging esc. Your airplane propeller isn't giving you the same info a boat propeller is. It doesn't really matter what your setup is pulling. Either it's too much, to little or just right. You get this info from running the boat and seeing how hot your equipment is, or if you want to look at data you can do that too but it's not like you're going to go buy 10 motors to see which one performs the best. There's plenty of info already available on what motors work in what boats. 750 watts = 1 HP and that device 785boats shows is just another tool that would give you data. But the best tool is a Castle or other esc with data logging. I don't think your going to get much better than that.

Mark

[Prodrvr]

I use a simple power analyser meter like this.
They give peak amps, voltages, realtime running amps & voltages. Plus watts, which can easily be converted to horse power if you want.
http://www.ebay.com.au/itm/G-T-Power-130A-RC-Watt-Meter-Power-Analyzer-Digital-LCD-Tester-12v-24v-36v-/272052430789?_trksid=p2385738.m2548.l4275

Agreed. I run one of these in the boat to get readings while testing.

[785boats]

so you use an airplane prop? real time..... does that mean you have to read the screen while obtaining data? or will it show highest readings of a run in the boat?

Yes. It saves the data and scrolls through all the readings at the end of the run as long as you keep the battery connected.

[urbs00007]

Yes. It saves the data and scrolls through all the readings at the end of the run as long as you keep the battery connected.

great, going to get one.

[785boats]

They work well enough for me in both bench testing with air props, & in the boat. But as Mark stated, the best way to collect data is with an ESC that has data logging.
I've never used one myself mainly because I'm a technophobe & not any good with computers.:smile:

[dasboata]

We have gotten 12.4 hp from a tp4070 cm running 8 s with around 50000 rpm at around 335 amps with the xlx I have seen up to 14 hp the data logers are excellent


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[urbs00007]

We have gotten 12.4 hp from a tp4070 cm running 8 s with around 50000 rpm at around 335 amps with the xlx I have seen up to 14 hp the data logers are excellent


Sent from my iPhone using Tapatalk

I guess what really bothers me about electric is the hp figures. I know they can push a lot of water but are they really pushing 14 hp ?? I still like them though.

[NativePaul]

There are plenty of readily available and reasonably priced methods of measuring an electrics wattage and there is 746W to a HP so electrics power is very easily confirmed or refuted.

I would be more dubious of IC engines HP claims, there aren't many easily available or reasonably priced dynos, someone tested a bunch in the UK in the early '00s and found most HP rating to be pure BS, so now you cant advertise a HP rating unless you have dyno proof an very few have that so the HP ratings have disappeared.