Thursday, December 10, 2009

[Electric Boats] Re: Electric Catamaran

 

Jason,

To my eye, your estimates are off. I've got a few questions and comments.

Thundersky LiFePO4 batteries should be calculated at 3.1v - 3.2v nominal. Typically, they are linked serially in groups of 4 to replace a 12v lead acid battery. Which leads to "why 13"? 12 cells will drive a 36v system, I've purchased 16 cells for my 48v system. 16 200ah cells would have a total rated capacity of 10Kwh (200ah x 50v) or 8Kwh usable.

What kind of catamaran do you own? 1500w @ 5kts is an extremely low estimate for any 30' boat. I would only believe it with a ultra-lightweight beachcat type of racing boat and probably not then. For a heavier cruising cat with a bridgedeck cabin, 3kw @ 5kts may be difficult to attain, especially using converted outboard drive legs due to efficiency losses in the gearing.

Although more expensive, Torqeedo Cruise 4.0 motors seem to be the most efficient outboard replacements readily available today. They are also extremely light at only 18kg per unit. With a maximum draw of 8kw, a pair of these should have enough power to overcome windage while docking. Even with these motors, 3kw will still probably not deliver 5kts.

I only bring these numbers up to make sure that you don't invest a lot of money and end up with a system that doesn't fulfill your requirements.

Fair winds,
Eric
Marina del Rey, CA

--- In electricboats@yahoogroups.com, "jason_d_s_uk" <jason_d_s_uk@...> wrote:
>
> Hi, i've been watching this group as I'm hoping to do a conversion in the future on my 30ft cat.
>
> I'm realistically upbeat that this can be done and have the following as my concept.
>
> 13*200ah Thundersky Lithium Batteries
> 94.9 KG, 9.75 KW ( 200ah * 3.75v)
> 2 motors attached to twin outboards as replacement for the engines.
> 2 Controllers, BMS etc.
>
> Based on a previous post, using 1.5kw /h @ 5Kts, this would give me:
> 9.75/1.5 = 6.5 hours continous use. Limit it to 80% DOD = 5 1/4 hours.
>
> As reserve, I would have a small generator (honda 2kw) which is about 25kg and a couple of gallons fuel. This would provide me with at least 12 hours running in an emergency situation.
>
> This also excludes the 1 x 200W solar panel and 400w Wind Generator which main use would be recharging for free.
> My requirements at the moment are for sailing a couple of days, then stopping at a harbour overnight. Having done this recently, the most time I used the engine for was 2.5 hours in a day and more likely 1.5h which would easily be recouperated by the wind/solar gen.
>
> The two motors this setup would replace would match weight wise (50kg x 2).
>
> Any comments?
>
> Regards, Jason.
>

__._,_.___
.

__,_._,___
Posted by at No comments:

Wednesday, December 9, 2009

[Electric Boats] Solidnav on ebay

http://cgi.ebay.com/ebaymotors/Inboard-Electric-Sailboat-or-Power-Boat_W0QQitemZ290379104058QQcmdZViewItemQQptZBoat_Parts_Accessories_Gear?hash=item439bf17f3a

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Posted by at No comments:

[Electric Boats] Re: Electric Catamaran

 

Hi, i've been watching this group as I'm hoping to do a conversion in the future on my 30ft cat.

I'm realistically upbeat that this can be done and have the following as my concept.

13*200ah Thundersky Lithium Batteries
94.9 KG, 9.75 KW ( 200ah * 3.75v)
2 motors attached to twin outboards as replacement for the engines.
2 Controllers, BMS etc.

Based on a previous post, using 1.5kw /h @ 5Kts, this would give me:
9.75/1.5 = 6.5 hours continous use. Limit it to 80% DOD = 5 1/4 hours.

As reserve, I would have a small generator (honda 2kw) which is about 25kg and a couple of gallons fuel. This would provide me with at least 12 hours running in an emergency situation.

This also excludes the 1 x 200W solar panel and 400w Wind Generator which main use would be recharging for free.
My requirements at the moment are for sailing a couple of days, then stopping at a harbour overnight. Having done this recently, the most time I used the engine for was 2.5 hours in a day and more likely 1.5h which would easily be recouperated by the wind/solar gen.

The two motors this setup would replace would match weight wise (50kg x 2).

Any comments?

Regards, Jason.

__._,_.___
.

__,_._,___
Posted by at No comments:

Tuesday, December 8, 2009

Re: [Electric Boats] Re: Electric Catamaran

 

You're designing a conventional boat and asking if you can use electric propulsion...wrong design approach.
If you want an electric boat, then don't sub-optimize with a conventional boat design -- design the electric boat.
For starters, why do you need a 60' mast with sails, when you could design a boat that uses wind turbines and solar panels to harvest the wind (which is really just a form of solar) and solar power?
I'd rather "point and shoot" with wind turbines and solar panels driving electric props than have to deal with cumbersome sails -- I can sail directly into a head wind with wind turbines and solar panels for power.

ScottO

From: john_casperson <john_casperson@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Tue, December 8, 2009 10:43:17 PM
Subject: [Electric Boats] Re: Electric Catamaran

 

Hi Bill--

I don't think you can obtain the speed you want for long periods.

I didn't see mention of weight in your initial post.

Using the speed calculator at

http://www.psychosn ail.com/BoatSpee dCalculator. aspx

and assuming a 34 foot waterline, one ton per hull, I come up with

5 mph requiring one HP per hull, or about 1.5 KW in aggregate.

For running off lead acid batteries, you'll need about 150 lb of batteries for each hour of 5 mph running time.

Unless you can figure out a way to make your collectors track or receive concentrated sunlight, you'll probably need about 2.5 KW of panels to meet the power requirement for a 5 mph cruise for several hours a day.

John Casperson

--- In electricboats@ yahoogroups. com, "Bill Gow" <billgow@... > wrote:
>
> Hello Group!
>
>
>
> I just joined today. The reason for my interest is finding help in planning
> out an electric alternative to conventional internal combustion engines on a
> catamaran I'm beginning to conceptualize.
>
>
>
> The dimensions will be ~ LOA 36', Beam 22', Mast Height 60'. It will be a
> light, fast, demountable sailboat that will fit on a trailer ~ 8' wide for
> towing anywhere. I may consider going into production if this works as I
> plan. The first one will be used to do a lot of fishing in the Pacific Ocean
> from Mexico to Panama. Weight is critical! Reliable power is critical. The
> boat will have all the necessary systems to sustain 4 adults for extended
> voyages, maybe even an ocean crossing some day. 3 or 4 knots in calm waters
> is of no use to me. I have to be able to control my boat in high winds and
> surging ocean currents and troll or motor at above 6 knots for extended
> periods. I have a couple things most sailboats do not, twin hulls = less
> weight for a much larger usable space and a huge hard bimini top for solar
> (~13'X14'). I'd like to cover this bimini with something like the Uni-Solar
> (http://www.uni-solar.com) PVL-68 laminates. I figure I can get 8 of the
> them up there and they'll weigh less than 100 Lbs.
>
>
>
> It looks like my bogey is battery weight. There is no way I'm adding a ton
> of lead to this boat! I can get great performance from a couple 20HP
> outboards that weigh less than 120 Lbs each. Is there any hope of electric
> propulsion or am I dreaming?
>


__._,_.___
.

__,_._,___
Posted by at No comments:

[Electric Boats] Re: Electric Catamaran

 

Bill--

You won't have conventional outboard steerage with the motors mounted near admidships. You will have skid steerage with the motors and aft steerage with the rudders. If you lose a motor, you will need an aft rudder, (or some other means to steer) since there is no skid steerage with a single motor.

John Casperson

--- In electricboats@yahoogroups.com, "Bill Gow" <billgow@...> wrote:
>
>
> From: Jason Taylor
>
> At least with an inboard solution, the additional weight is not all
> located on the transom.
> You can place your batteries and even your generator where they have the
> most desirable (or lest undesirable) affect on trim.
> Trade-offs. It's all about the trade-offs.
>
> - Actually, the outboards weigh about what the electric motors, shafts,
> props, etc. weigh so those two comparisons are equal. The net weight gain
> would come from adding a generator. I'm already adding in the "house"
> batteries and solar (which just gained 200 Lbs). In a pinch, I can start the
> outboards with a pull start too. Redundancy is important and the outboards
> add a little more on that score too. My intention is to not have the
> outboards on the transom but in pockets forward of the rudders. I want to be
> able to pull them up when not in use. If this doesn't work out, they'll be
> mounted on the bridgedeck and tucked into boxes that will double as seats
> and storage.
>

__._,_.___
.

__,_._,___
Posted by at No comments:

[Electric Boats] Re: Electric Catamaran

 

Hi Bill--

I don't think you can obtain the speed you want for long periods.

I didn't see mention of weight in your initial post.

Using the speed calculator at

http://www.psychosnail.com/BoatSpeedCalculator.aspx

and assuming a 34 foot waterline, one ton per hull, I come up with

5 mph requiring one HP per hull, or about 1.5 KW in aggregate.

For running off lead acid batteries, you'll need about 150 lb of batteries for each hour of 5 mph running time.

Unless you can figure out a way to make your collectors track or receive concentrated sunlight, you'll probably need about 2.5 KW of panels to meet the power requirement for a 5 mph cruise for several hours a day.

John Casperson

--- In electricboats@yahoogroups.com, "Bill Gow" <billgow@...> wrote:
>
> Hello Group!
>
>
>
> I just joined today. The reason for my interest is finding help in planning
> out an electric alternative to conventional internal combustion engines on a
> catamaran I'm beginning to conceptualize.
>
>
>
> The dimensions will be ~ LOA 36', Beam 22', Mast Height 60'. It will be a
> light, fast, demountable sailboat that will fit on a trailer ~ 8' wide for
> towing anywhere. I may consider going into production if this works as I
> plan. The first one will be used to do a lot of fishing in the Pacific Ocean
> from Mexico to Panama. Weight is critical! Reliable power is critical. The
> boat will have all the necessary systems to sustain 4 adults for extended
> voyages, maybe even an ocean crossing some day. 3 or 4 knots in calm waters
> is of no use to me. I have to be able to control my boat in high winds and
> surging ocean currents and troll or motor at above 6 knots for extended
> periods. I have a couple things most sailboats do not, twin hulls = less
> weight for a much larger usable space and a huge hard bimini top for solar
> (~13'X14'). I'd like to cover this bimini with something like the Uni-Solar
> (http://www.uni-solar.com) PVL-68 laminates. I figure I can get 8 of the
> them up there and they'll weigh less than 100 Lbs.
>
>
>
> It looks like my bogey is battery weight. There is no way I'm adding a ton
> of lead to this boat! I can get great performance from a couple 20HP
> outboards that weigh less than 120 Lbs each. Is there any hope of electric
> propulsion or am I dreaming?
>

__._,_.___
.

__,_._,___
Posted by at No comments:

RE: [Electric Boats] Re: Electric Catamaran

 


From: Jason Taylor

At least with an inboard solution, the additional weight is not all
located on the transom.
You can place your batteries and even your generator where they have the
most desirable (or lest undesirable) affect on trim.
Trade-offs. It's all about the trade-offs.

- Actually, the outboards weigh about what the electric motors, shafts,
props, etc. weigh so those two comparisons are equal. The net weight gain
would come from adding a generator. I'm already adding in the "house"
batteries and solar (which just gained 200 Lbs). In a pinch, I can start the
outboards with a pull start too. Redundancy is important and the outboards
add a little more on that score too. My intention is to not have the
outboards on the transom but in pockets forward of the rudders. I want to be
able to pull them up when not in use. If this doesn't work out, they'll be
mounted on the bridgedeck and tucked into boxes that will double as seats
and storage.

__._,_.___
.

__,_._,___
Posted by at No comments:
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