T-Pain Is On A Boat: Re: [Electric Boats] Boat Hull Animation

Wednesday, July 13, 2011

Re: [Electric Boats] Boat Hull Animation

Hi Tim,

Your boat will take the same amount of power to go a given speed, whether it comes from ICE, electric, steam engine, sails, etc.

So 40hp (about 30kW) will drive the boat the same speed, electric or not. Just like with an ICE, you can change the prop to allow the motor or engine to operate at its most efficient or powerful speed.

The problem with a quote of 40hp to drive your 2000lb boat at 17kts is how much an electric drive will weigh. I've got an $1800 Warp9 electric motor that can operate at 30kW continuous, the bare motor weighs 146 lbs. Now lets talk about batteries.

A flooded battery pack rated for 240Ah at 144V will drive your boat at 17kts for 20 minutes to a 60% depth of discharge. The down side is the batteries will cost $3600 and weigh 1500lbs. Not much left for the rest of the boat. If you went with AGM, you can use 145Ah at 144V to get the same 20 minutes of 17kts to a 70% depth of discharge. These batteries will cost $5200 and weigh 1050 pounds, things are better but still not good. Going with Lithium batteries you need 100Ah at 144V to drive the boat at 17kts for 20 minutes to an 80% depth of discharge. These batteries weigh 375lbs and cost about $6500.

Spend all of this money and do all this work, and you can drive your boat for 20 minutes on a single charge, at a top speed that is 10mph slower than today. Building it to go 28mph makes the calculations get much worse.

Are you sure that you want to head this direction?

Fair winds,
Eric
Marina del Rey, CA

--- In electricboats@yahoogroups.com, Tim Williams <tajw@...> wrote:
>
>
> Thank you Ryan,
> and I wonder do you or anyone know if the Bayliner "sequential lift" hull would have approx. the same performance as the semi-planing hull?
> It seems from your calculator that my 2,000 lb., 19' boat would do about 17knts with 40 hp at the shaft (of course many, many other variables and my calcs are rough) In reality my 125hp ice (running so_so) can only get upto about 28mph. Any idea what hp of electric and prop changes would equal that?
> Thanks,Tim
>