Forums > Sailing General

Electric motors

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Created by theselkie > 9 months ago, 7 Jun 2018
theselkie
QLD, 555 posts
7 Jun 2018 11:36AM
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Thought?
Experiences?

Looking at this boat which has an electric engine instead of a diesel.

Thanks

yachthub.com/list/yachts-for-sale/used/sail-monohulls/vagabond-31-cruising-yacht/218650

zilla
144 posts
7 Jun 2018 11:32AM
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No experience but thoughts yes.
If it is for local day cruising maybe it would be okay. My primary concern would be safety in a worst case scenario. In other words let's say you are out cruising and for whatever reason you need to use the engine to get out of trouble. How long will it work at full power? If you have to anchor for a couple of days in poor (no sun) weather then how do you ensure the motor batteries remain fully charged? How easy is it to repair at sea? And so on.
The equivalent "battery" for a diesel is a full tank of fuel and that may last several days at full power - no sun required.

samsturdy
NSW, 1659 posts
7 Jun 2018 2:47PM
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I like the concept of it....smooth and quiet. If there's a take off point on the shaft that will
drive an alternator of suitably large charge rate, wouldn't that dramatically increase longevity
of battery power under load.

BlueMoon
866 posts
7 Jun 2018 3:10PM
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One of my concerns would be how contemporary is the motor and battery technology onboard??...
Battery technology is getting better every year, who still owns a Ni-Cad battery drill for example, they were superseded by Ni-MH, then they were superseded by Li-ion

Ramona
NSW, 7740 posts
7 Jun 2018 6:10PM
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Select to expand quote
samsturdy said..
I like the concept of it....smooth and quiet. If there's a take off point on the shaft that will
drive an alternator of suitably large charge rate, wouldn't that dramatically increase longevity
of battery power under load.


There is no such thing as a free lunch! The race cars do generate power braking but that does not work in this case. I like the idea of straight electric propulsion. Even with straight wet acid batteries.

fishmonkey
NSW, 494 posts
7 Jun 2018 6:24PM
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Select to expand quote
samsturdy said..
If there's a take off point on the shaft that will
drive an alternator of suitably large charge rate, wouldn't that dramatically increase longevity
of battery power under load.


good thought, but that would be like a perpetual motion machine! there are unavoidable losses converting the stored electrical energy to mechanical energy and back again, so you would essentially be wasting power...

southace
SA, 4794 posts
7 Jun 2018 6:49PM
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It's a lovely looking yacht. Seems the bow sprint and bobstay is a addition? Only much good for flying a scretcher and putting additional strains on anchoring. As for electric motor getting in and out of a Marina no problems but for long passages without wind may cause some problems and frustration.

Trek
NSW, 1194 posts
8 Jun 2018 6:41AM
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Nice boat. Interesting to see it has a tiller not wheel. In the same way yachts usually have their drinking water and diesel tank capacity listed it would be handy if boats with electric motors had their battery capacity listed.

In one of the pics there are 5 big blue batteries visible that might be 12V 200AH each. That being the case I think the motoring might be limited to getting on and off the mooring. (Guesstimate based on 20hp motor running at half power is 10hp means its generating 7.5kW of force. Assuming its 50% efficient it needs 15kW per hour to run doing that. Battery capacity is 12kW so thats 1 hour of motoring).

If the boat has stacks of diesel though they could presumably run a genset on board to charge the batteries giving it a bit more range, like a diesel electric loco.

boty
QLD, 685 posts
8 Jun 2018 8:15AM
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i have fitted a few electric motors to boats and quite like them but for delivery style passages where you need to stick to a schedule less than ideal having said that a nice boat in excellent condition at a cheap price

DAMA
QLD, 239 posts
8 Jun 2018 10:19AM
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Found this while ordering battery pack,
40hp, re-generative
www.ev-power.com.au

theselkie
QLD, 555 posts
8 Jun 2018 1:12PM
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Thanks for your thoughts on this.
Going to give it a miss and so, the search continues (ah, see next thread ).



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"Electric motors" started by theselkie