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Old 02-03-2021, 11:30 AM   #24
DDW
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City: San Francisco
Join Date: Apr 2018
Posts: 3,094
Quote:
Originally Posted by cardude01 View Post
Yeah I would really like to do some experimenting before I haul off and spend $2000 on that epropulsion outboard. The battery on the Spirt plus is almost 1300 watts, so is it really only about 1.5 HP? If that’s all it is wide open it doesn’t sound like enough. I run this 3.5 hp gas engine at 1/3 to 1/2 throttle usually.
I think the Spirit Plus has the same motor as the Spirit (the battery is slightly higher capacity) The motor is 1000W so if 100% efficient 1.34 hp by definition. The prop is slower turning and larger than the gas, practically I'd expect it to be about the same as the gas at 1/3 or 1/2. Keep in mind that at displacement speeds, the resistance rises exponentially, so doubling the power may only get you a small increase in speed. For example I think with my Spirit and Bullfrog dinghy, 500 watts power gives about 3.6 knots and 1000 watts about 4.1 or so. The extra power is useful for punching through a chop or against wind. I got 4.6 knots wide open on a supposedly 5 hp gas outboard.
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