T-Pain Is On A Boat: [Electric Boats] Power Consumption for Minn Kota Riptide 50 & MotorGuide 54

Friday, September 25, 2009

[Electric Boats] Power Consumption for Minn Kota Riptide 50 & MotorGuide 54

Hello to All,

I have a MotorGuide 54 that has these specifications:

12 Volts 0.34 Kwatts

I also have a Minn Kota Riptide 30 with these recommendations & specification:

12 Volts
105 Ampere/Hour Battery
"... your 12 volt motor with draw 1.0 ampere/hour ... for each pound of thrust produced when the motor is running on high."

By my calculations these work out to:

MotorGuide 54: (0.34 * 1000) / 12 = 28.33 ampere / hour

Minn Kota 50: 1.0 * 50 = 50.0 ampere / hour

Do those numbers look correct to all of you? The units and the pounds of thrust they produce are pretty similar, which makes me suspect the somewhat significant difference in the ampere/hour ratings.

All enlightening efforts are greatly appreciated. I plan to use these two units to move a Cal29 sailboat about six to ten miles across (or down) Boca Ciega Bay to downtown St. Petersburg Florida early next week, and need to calculate what size batteries I should get. The boat is not refitted yet, so I need to jury-rig all of this, including battery locations, cabling, breakers, and so on.

I have found a local firm that has what appear to be 85 amp/hr (they "rate" them thus: 205 minutes at 25 Amps each) 12 Volt deep cycle marine batteries currently on sale for about $60.00 each. Again, according to my calculations, three of those should give me either 2.5 hours (using the Minn Kota) to 4.5 hours (with the MotorGuide) of full speed motor use with about 50% battery consumption. Does that look correct?

Thanks much in advance,

Brad Bates
Play Mate
St. Petersburg, FL
(I am dangerous with a calculator)