Electric Motor as Wooden Boat Option

[sshhss]

I am building a 15 foot cracker box wooden boat, what kind and size of an electric motor would work for this application. Top speeds would be around 25 to 30 MPH.

 

[bajansailor]

Welcome to the Forum Sshhss.
Are you planning on using an inboard engine or an outboard engine?
Which ever, your top speed sounds rather ambitious for an electric engine - you will need to have a large battery bank, and I doubt that you will be able to run at 25 knots for too long.
Changing tack slightly, as you have started this thread about your Cracker Box, would you like to post some photos and stories about her construction so far please?
We are all very keen on posts like these.

 

[Rumars]

Boats don't care what turns the prop, you need the same size electric as the gas engine, electric horses are not bigger. As to what kind, there are inboards and outboards, it's up to you.

 

[BlueBell]

what kind and size of an electric motor would work for this application.

Size: 30kw should make 30 MPH depending how big you make your lightweight lithium battery.
Type: Brushless motors are good but don't forget you need a charger and a speed controller too.

 

[wet feet]

There are a few high performance boats with electric propulsion; the downside is that they won't go very far at high speed before the charge is used up. If you were heading for the far side of a great lake it might not get there. Unlike an IC boat the weight doesn't decrease as the energy reserve is consumed. I expect a bit of googling will bring up examples of boats with a similar level of performance.

 

[duluthboats]

EP-30 Electric Outboard - Elco Motor Yachts

Deep Blue - Outboards with 25 to 50 kW - Torqeedo

Here are 2 manufactures that have plug and play systems big enough to push a cracker box to the speed you want. The weight and capacity of the batteries will be the limiting factor. Both sites have lots of useful information.

Welcome aboard

 

[Will Gilmore]

Welcome to the forum.

I'm interested in the subject of electric propulsion, so I'll follow along. Sorry, I wish I had more to contribute.

Changing tack slightly, as you have started this thread about your Cracker Box, would you like to post some photos and stories about her construction so far please?
We are all very keen on posts like these.

+1

 

[gonzo]

An ELCO 30HP sells for about $7,000. The 8 battery pack is about $4,000 and 7,000 lbs. The controller, charger, etc. about $3,000. It won't get the boat at the speed you want, unless you only install a small Li Ion battery to run for a few minutes.

 

[bajansailor]

An ELCO 30HP sells for about $7,000. The 8 battery pack is about $4,000 and 7,000 lbs. The controller, charger, etc. about $3,000. It won't get the boat at the speed you want, unless you only install a small Li Ion battery to run for a few minutes.

@sshhss Gonzo's post above is suggesting that regarding propulsion, you would be much better off (especially financially) by simply installing an outboard engine on your Crackerbox.

 

[fallguy]

An ELCO 30HP sells for about $7,000. The 8 battery pack is about $4,000 and 7,000 lbs. The controller, charger, etc. about $3,000. It won't get the boat at the speed you want, unless you only install a small Li Ion battery to run for a few minutes.

And herein lies the problem. The costs are exhorbitant; the outcomes less than ideal. If you buy a wrecked Tesla battery; you might be able to make it more affordable, but still 15 grand for 30hp is $500/hp.. And 15 is low..

 

[Will Gilmore]

An ELCO 30HP sells for about $7,000. The 8 battery pack is about $4,000 and 7,000 lbs. The controller, charger, etc. about $3,000. It won't get the boat at the speed you want, unless you only install a small Li Ion battery to run for a few minutes.

From the Elco Website:
EP-30 Electric Outboard - Elco Motor Yachts https://www.elcomotoryachts.com/product/ep-30-electric-outboard/
EP-30 Electric Outboard
$6,999.00
Voltage: 96 Volts
Suggested Battery (Ah): 130 amps DC
Comparable HP: 30HP
Required Accessories:
Battery Connection Kit $295.00
(You need this kit to connect your outboard to your batteries).

Battery Monitor | Victron BMV 700H $728.00
(This monitor is used to see how much charge you have left in your batteries).

Panther Electric Trim & Tilt $650.00
(This is a remote-controlled tilt to lower and raise your outboard from the water).

Deep Cycle Battery Charger (Elcon UHF3300) $895.00
* Deep Cycle chargers are only compatible with Deep Cycle Batteries.

Recommended battery pack:
Deep Cycle AGM Batteries (8x)$3,936.00
96 Volt Power Supply
8 Batteries - 12V/165Ah | L-19.1" x W-6.8" x H-9.4" | 103lbs. ea. X 8 = 824lbs

Their biggest battery offered:
Victron 12v AGM – 220Ah
$585.00x8=$4680.
Weight: 65kg = 143.3lbs (x8) = 1146.4lbs.

I don't know where Gonzo got his number for the weight, but it's still pretty excessive.

-Will

 

[fallguy]

Forget Gonzo's typo. What is more important is run time.

Am I correct in understanding one hour at Wot for option one or a bit under two for option two?

 

[wet feet]

A couple of things should be evident from the numbers presented.First the weight of the installation will immerse the hull quite a bit and an existing design might not work well with the burden.Second,the modest power mentioned may struggle to get all that weight moving quickly,or if it does it won't be doing it for very long.There may also be a need to arrange to keep the battery pack cool if the maximum output is being drawn.

 

[Will Gilmore]

Forget Gonzo's typo. What is more important is run time.

Am I correct in understanding one hour at Wot for option one or a bit under two for option two?

Maybe, but I don't see the amps rating for the motor, so you can't tell from those numbers.

[ Edit: maximum current is 130 amps. ]

 

[fallguy]

130 amps