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15kW electric motor for Sailing Catamaran

12195 Views 16 Replies 11 Participants Last post by  popobowa

Looking for advice on a 15kW 48V electric motor to fit to a Yanmar SD25 sail drive (new model of the SD20).

Application is an under construction 52' sailing catamaran.

Some broad boat parameters:

Ocean going world cruising catamaran – composite epoxy structure.
L 52’, Draft 2’ Weight approx. 8500kg / 19,000lb
Full electric propulsion, galley and other services including hot water.
Motors retractable: 2 x 15kw 48v + regen
Battery bank: circa 16kw 48v
House loads: 24V DC – Estimated peak approx. 3kw
Solar: circa 3kW.
16kW 48v DC gen set.

The plan is to fit motor to a Yanmar sail drive SD25 and complete unit be retractable. This involves a wet lower tube and a watertight inner tube with hull closure plate below the prop – motor and sail drive leg fitted to this at their join. We should be able to couple motor shaft to SD25 upper gear box shaft with a coupler and bolt units together without too many modifications. Be great to hear of others experience with this.

We are trying to limit motor voltage to 48V – makes batteries & solar easier plus ability to share bank via DC:DC converters & battery for house loads at 24V.

The boat will be light and shallow draft = easily driven. A similar 62’ catamaran was fitted with 2 x OV SD15s and achieved over 9 knots in flat water so we believe 12 to 15kW motors will be adequate.

According to Vic Prop boat specs, twin 12kW (16hp) motors with RPM max of 2200 (2:1 gear reduction on SD25 so prop speed 1100 max.) & 3 blade 15" x 13" prop will yield a top speed of 8.92 kts which is fine.

We have looked at turn-key offerings from Bell marine, Oceanvolt & Electric yachts but none tick all our boxes so would like to have a crack at customizing our own solution.

Some motor options Ive stumbled across include:
1. Motenergy ME1302 or ME1616 Liquid cooled
2. Parker GVM210-100-DPW
3. Go cart or Elec motorcycle motors: Revolt, Zero, ???

Bearing in mind 48V supply and max RPM of around 2400, be grateful to get your thoughts on best motor and associated controller and any tips or constructive suggestions for our project.

Thanks RC
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How much do you want to spend?

Are you a thrifty person who likes making stuff work, or are you more of a "I want to spend the money and get it done" kind of person?
Usually the cheap option is to grab a used forklift motor. You can usually get them for $200. They're bulletproof and functionally last forever.

In your case, since you're dead set on a low voltage battery solution, it might still be the best option since forklift motors are low voltage and slow.

For low power requirements, you might be able to get away with just reusing the forklift speed controller too.

You'll need to fabricate a coupler, but, this is no big deal.

Alternatively, you could buy something like a Gen2 or Gen3 Prius inverter, which has an onboard boost converter, and then use it to crank your 48v to 400v or whatever you want to use to drive the motor. Then you could use an AC motor which has nearly zero consumables (DC motors have brushes that will have to be replaced once every other decade or so, depending on use). I imagine that AC motors are better in marine environments, what with there being physical contact and corrosion potential for a DC commutator.
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