Electric powered yachts.

[Allan]

I have wondered for a long time if it would be possible to have yacht driven by an electic motor. I would envisage a system with motor, batteries, generator, wind and/or solar power. Most of these parts are more efficiant now than in previous times. Most of the time I only use the motor to get out of or into a mooring etc. I think the power for this could come from batteries charged by wind/solar or shore power. If the motor is needed for an extended period, a diesel generator could be used. Ideally the batteries could be placed low down in the hull. I would be interested to know where I could find somewhere with figures on power/current requirement.
Allan

 

[VicS]

Although battery technology is creeping forwards all the time I suspect you will find that the size, and weight until we get away from lead acid, of the batteries rules it out.

 

[oughtoc]

See this month's Classic Boat. Electric motor installed to replace previous diesel

 

[dombuckley]

Try the Electric Boat Association www.electric-boat-association.org.uk

 

[Kilter]

Already being fitted to some boats and why not?

 

[Bajansailor]

Nigel Calder is having a new Malo built with all sorts of cutting edge technology on board, and I think he has an electric propulsion motor - more about his new Nada at http://www.maloyachts.se/Blog/tabid/195/EntryID/5/Default.aspx

 

[William_H]

From physics 650 watts equals one horsepower. 650 watts at 12 volts is 54 amps. Which is about all you could hope to get out of a 100Amp Hour battery in an hour. For efficiency of wiring and motor you need a higher voltage motor around 100volts is common for electric cars.

So imagine 8 x 100AH 12v batteries in the keel of your sailing boat. Where the lead will have an advantage for stability. At 100% efficiency you could get then 8hours of 1 horsepower or 1 hour of 8 horsepower. However you probably should divide this in half to allow for inefficiencies.

So as you can see from the figures it is do able but would require a very large solar panel array or wind generators to provide a recharge over a week between discharge.

Electric power for a boat then is for the dedicated greenies and those willing to accept the limitations. It is not practical if boating is your primary required outcome. ie most of us yachties want the flexibility in our engine to go anywhere anytime. It might be quite good for a ferry. olewill

 

[Bajansailor]

Here is a copy of Nikki's article re their new electric motor :

Lots of other excellent articles (as always!) as well in this current issue.

 

[roly_voya]

Diesel electric technology is well established in the commercial sector and powers everything from cruis liners to trains but is still 'emerging' technology at the smaller scale. Ther are an increasing number of hybred car systems and a very small number or reletively experimental boat systems. Potentially it has so good advantages, particularly much better slow speed control and wher power is needed quickly for short periods. The cost and wight of all forms of battery storage are probably always going to limit endurence so for the forseeable future you are probably looking at short term battery, long tem internal combustion withe the elecric motor effictively used as a 'gear box' Its an area we are likely to see change in the next few years as the technology becomes more competative. The 'green' argument is a bit of a myth though, you already have the ultimate green energy drive - its caled a sail!!

 

[Achillesheel]

We hired an electric powered yacht, a Pegasus I think, some years ago on the Norfolk Broads. Trouble was it was the windiest week I have ever seen on the Broads; the engine didn't have the guts to drive the boat into wind, and we ended up having to be towed back to base.

But it was a great pleasure to flick a switch to instantly start the engine, and silently glide into a berth.

 

[reeac]

Don't be misled by the existence of hybrid cars. Their only efficiency gain is due to their having regenerative braking and this gain is somewhat offset by the additional weight of their batteries. I can't envisage regenerative braking in a boat. I agree that the diesel electric route gives easy control especially when maneuvering.

 

[Allan]

I have never really seen the too much point in hybrid cars. The fuel figures seem no different from ordinary equivelent cars.
It does however bring up the possibly of using the prop as a fourth method of charging.
Allan

 

[whipper_snapper]

They exist


Look here http://www.africancats.com/

 

[tobble]

I couldn't disaggree more (with the regenerative braking bit nyway!) The point being that on a saling boat, you have a built in hydro generator, whihc you can disengage if you want, but under sail you can recharge the batteries very effectively at little cost to speed. You never really 'brake' a yacht anyway, that burst of astern as you come alongside envolves the engine, of whatever description, doing work, rather than simply imparting a load of friction as in a conventional car, therfore the concept doesn't apply to boats at all. Maybe I'm being an engineering geek, but there is a definite difference between these two...

I must say, assoon as I read the bit about using the system 'backwards' to re-charge I was sold on the concept, however, being based in the Bristol chanel now I'd be nervous of missing a tide and not having the juice to get home (on time - if you're not in a hurry there's no real problem...).

The other major advance that will make the concept more viable is fuel cells and hydrogen storage, whereby you can achive a much better energy stored:weight ratio. There was a sailing cat in PBO last year that was electric motored, and used fuel cells.

Just re read someof that and maybe I'm being a pedantic a-hole... /forums/images/graemlins/tongue.gif

edit: Must type faster! Allan, My guess would be that if you had the option, charging of the prop undersail would be first choice, as you can easily get much higher charging current out of water generators than most other devices. You're probably right about the cars, although that Mini top gear drove to scotland and back on a tank, I think, was a hybrid. The technology is still in its infancy tho.

 

[ctelfer38]

or wind powered yachts!! /forums/images/graemlins/cool.gif

 

[Allan]

I met a number of sailors, when I lived in France, who had no motor in their boats. That was one of the things that made me start thinking of electric power.
Allan

 

[pampas]

Must have more powerful Watts down under, Here in the UK we have to use 746 watts for 1Hp. /forums/images/graemlins/laugh.gif

 

[Allan]

I didn't see the Mini trip but they also did a similar thing with a conventional diesel Audi. I would not think such trip would show a hybid in best light.
I too sail in the Bristol channel, so I understand your feelings. That is one reason I think a generator would be required.
Diesel electric has been used for trains etc for many years, so there must be some figures out there. Running an engine at optimum speed could go someway to offset the inefficiatcy of converting mechanical motion into electricity and back. I think the keys would be the control system and type/voltage of the other parts of the system.
My 22ft one ton boat could easily be powered by a 4hp outboard, so I feel that some of the figures given for the power requirements are sometimes a little high.
Allan

 

[MacMan]

They not only exist the have been sold by major manufacturers

Lagoon and hybrid electric

I think Moorings/Leopard also do a version.

All the stuff I have seen so far has been Cat focussed - not seen anything production wise on a monohull.

 

[Adaero]

Gideon the owner of African Cats has also designed a retractable motor system for monohulls that drops down using hydraulics from an internal box (I believe a couple of manufacturers are waiting for the results of sea trials later this year). The next Fastcat to be built will be fully electric but with a generator for back up as well as for running thirsty toys such as AirCon. Power for the Li batteries are supplied by 8off 210W solar panels and a 300W wind generator plus whatever you can get from re-generation whilst under sail. When you want to sail fast the motors are retracted, his 46ft epoxy built Cat only weighs 5000kg so when I say fast I mean very fast.
It's worth reading his posts on the Cruisers forum under the tag of FastCat435, a very clever guy who will share his knowledge with anyone.
Adaero