"thrust" is confusing and is really a sales gimmick. Lets start by stating for quick math sake we use 745 watts per HP, its not exactly true but lets use that just to start with. Lets assume for the moment we get overall efficiency of 70%, which is highly unlikely. Lead acid batteries don't even get that much. The average is 63%, new of course Lets take a typical Minn Kota. ad, The ad will state that a certain motor has: MAX Thrust of 40 and will MAX draw 42 amps at 12 volts. (at above %), But none of this information is reliable to use, what you will end up with once it is on the boat is in question. here's partly why, 42 amps by 12 volts is 504 watts the motor at full on, you are getting 0.47 of a HP, not a chance, probably about 1/3. There is no industry standard used to determine thrust, its a company digression, based on several different possible engineering answers. There is for example an industry standard when it come to word "torque" ----- Original Message ----- From: "Harvey G Wilson" <harveywilson@juno.com> To: <montgomery_boats@mailman.xmission.com> Cc: <montgomery_boats@mailman.xmission.com> Sent: Sunday, November 28, 2004 8:12 PM Subject: Re: M_Boats: dc vs ac drive
Hi Richard..
However you could use an inverter to produce ac from 12v dc, they have about 92% conversion efficienct.<<
That you could. IIRC, 1hp is about 750 watts. Dunno how this would translate into thrust..guess it would depend on the propeller<GG> Inverter cost would be high if it'll take 2hp to drive the boat at a reasonable speed..say at least as well as a 55 pound thrust trolling motor.
Then, what would the motor size be?? bigger then the 55 pound trolling motor, I'll betcha<GG>
Interesting thought, but I'll stick to my noisy Seagull.
Harvey/ Ga
M-17 Stargazer #294
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