Hi Len,
The hard part is that if your boat needs 40hp to hit the speed that you want, then you'll need 40hp (30kW) of electric motor. Without discussing your motor choices, let's just talk about your energy storage requirements.
Let's guess that your power demand to cruise at 15mph will be 20hp (15kW). If you want your max range at 15mph to be 30 miles (2 hours), here's your battery options:
1) Flooded golf cart batteries - 67.5kWh total capacity to provide 15kW power for 2 hours to 60% depth of discharge. Weight is 3000 lbs and cost is about $7000.
2) AGM deep cycle batteries - 52kWh total capacity to provide 15kW for 2 hours to 70% depth of discharge. Weight is 2500 lbs and cost is about $12,000.
3) Lithium (LiFePO4) batteries - 40kW total capacity to provide 15kW for 2 hours to 80% depth of discharge. Weight is 1000 lbs and cost is $16,500.
You solar panels will develop about 1200W during peak conditions and you shouldn't expect more than about 6kW collected between sunrise and sundown. That's about 25 minutes of your 15mph cruise if you save it up all day. The panels will weigh about 200 lbs (close to the weight of the outboard listed below).
Alternatively, a new 50hp direct inject TLDI 2 stroke Tohatsu outboard weighs 210 lbs, costs about $6500 and and should burn about 2 gph at cruise. Your 30 mile trip will take about 25 lbs of fuel at a cost of about $15. A 20 gallon (120 lbs of gas) tank should give you a 150 mile range.
In my opinion, the brand new gas powered outboard is more powerful, cheaper, lighter, simpler, and has greater range. But it's your boat, you get to do whatever you like.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, captnlen <trikini2008@...> wrote:
>
>
> Been following (lurking ) on this group for awhile so going to propose a
> what if.
>
> I have pulled my 32 ft power trimaran and am reworking the deck and
> interior to provide a more physically accessible boat.
>
> initially I had a 40 HP on it and that was OK but had a chance to buy a
> new 100 HP Suzuki in 2000 and that has been on it. does about 20 mph
> at 5000 rpm. 6-7 GPH
>
> Anyway stripped and sold the engine.
>
> When done easiest is a 4 cycle 40-60 HP but looking at a conversion
> option too. Don't want to go inboard
>
> So thinking a 50 HP lower unit OB no Power Head . Available used
> cheap and easy mount.
>
> for a DC motor to the shaft. ( pull the water pump and not use the gear
> shift or maybe use the Gear shift and not reverse the motor rpm. Lots
> of Golf Carts motors available . Thinking of one of them
>
> Just need a spline coupler and modify mounts.
>
> Pull the twin fuel tanks and have a battery flat about 3 ft x 7 ft.
> What size type batteries open to suggestions
>
> Have 6 x 16 ft roof for solar cells. Suggestions on them too
>
> Would need a controller and charger unit.
>
> Plan on using once or twice a week. Most times maybe under 25 miles but
> an occasional near reef outing which is close to 100 miles round trip
>
> Would like 15 mph cruise.
>
> Is it possible practical or stick with a 4 cycle OB.
>
> TIA
>
> --
>
> -- Live Long and Prosper
> Capt. Len Susman, retired
> Email : trikini2008@...
> Creator of the TRIKINI Double Outriggers
> 13-17-6.47-23-D-Spider-F41
>
No comments:
Post a Comment