We are in Oz and installing two mars brushless motors in our 45' cat homebuilt, only two banks of 120amp agms @ 48v. later we will install a diesel genny 6kva aircooled ac, we have two pro charges ps4 putting out 60amps each and using a petrol genset at the moment, will be back on the water in six weeks, thanks to to the group for all the info over the years, Ian
--- In electricboats@yahoogroups.com, Chris Baker <chris@...> wrote:
>
> Hi Adam,
>
> Welcome to the group. I'm also downunder, but on the 'west island'.
>
> I can offer some observations about the use of Torqeedo electric outboards for use on multihulls - I have installed one on my trimaran, and know of four catamarans at various stages of implementation of installing these motors.
>
> To begin with, you mention being on a budget and do not wish to spend more than you have to. And its fair to point out that you'd probably find a much more economical solution than the setups that I'm about to describe. And I'm sure others from the group will offer advice on "rolling your own" electric drive, and that would certainly better meet your budget objectives. On the other hand there can be time advantages in buying off the shelf items.
>
> My boat is a 43 ft trimaran displacing around 3 tonnes. You may even know the boat, she was raced extensively in these waters in the past as Bullfrog and Verbatim, and she's now called Current Sunshine because her energy comes almost entirely from the sun. The energy is stored in Lithium-ion batteries set up as a 48v bank of 200ah, and that gives me a range of about two hours at full throttle (about 6.5 knots) and about 8 hours at four knots (in calm conditions). The motor is a Cruise 4, which is a 4kw outboard - its thrust is claimed by Torqeedo to be equivalent to a 10hp petrol outboard, and in my experience that feels about right.
>
> Of the catamarans, Schools Out has been cruising on and off for about 6 months, and the other three are still being prepared for launch. Schools Out has two Cruise 4's and its energy comes mainly from a Polar-Power genset producing 48 volts. It also has solar panels and a wind generator. The batteries are lead-acid and its set up so that the genset starts automatically when the voltage drops to a set point. I know this boat has been caught in a squally afternoon thunderstorm blowing at 30 to 40 knots. She was at anchor at the time and sudden wind change dislodged the anchor and to avoid the possibility of dragging onto other boats she got under way. The two Cruise 4's were able to hold her on station while retrieving the anchor tackle and then make slow headway, about 1 or 2 knots against the wind - around 30 knots and gusting to 40, to re-anchor in better location. The boat is a 45 ft Oram design displacing about 6 tonnes. The initial installation included long cable runs and this caused cooking of the controller and motor, apparently due to voltage spikes. So its important to limit cable length to avoid induced voltages.
>
> Room With A View will be launched soon and it has three Cruise 4's, energy storage in Lithium Ion batteries, and a genset cobbled together using the boat's original engine with large alternators added. (three I recall). Its a larger boat - I think about 50 overall, but very light as she is from racing stock as well.
>
> There's another Oram 45 being setup similar to Schools Out, but with a genset from local manufacturer Watts2C, and fairly small Lithium-Ion battery pack. (I recall its about 45 ah) It will rely much more on generator power rather than stored energy.
>
> I'm helping out with the electrical installation on the fourth cat, Monkee Me, a Wharram 38. This one will be set up similar to my boat - that is primarily relying on power from the sun to charge the batteries. It has a bank of 400 ah at 48 volts for the motors. It too is a few months away from launch.
>
> On both Monkee Me, and my boat our emergency backup is simply a small Honda genset (1kva) and a 10 amp charger. It takes the genset 20 hours to charge the pack from empty, and if I wish to run on its power alone, that is, no draw from the batteries, the boat will move along at 2 to 3 knots.
>
> The cost for my setup was (In Australian dollars) $6300 for the Cruise 4, $10,000 for the Lithium-Ion batteries and battery management system, $1500 for generator and charger, $1500 for extra solar panels, and another $2 or $3k for miscellaneous electrical bits such as amphour meter, contactors, charge control, circuitbreakers, cables, voltage converters and so on.
>
> Since I bought my batteries the cost has reduced by about 30% and is still falling. The batteries have also increased in energy storage for the same weight and size of cell. If you do decide to use Lithium-Ion cells, hold off purchasing them until the last minute - you'll be bound to get a better price.
>
> The cost of these batteries may seem daunting, and you might be tempted to use lead-acid. But the cost saving is illusory - Lithium-Ion cells have many advantages, especially if the energy source is limited. If you compare the nominal ah capacity of a lead-acid battery, as it is labelled, with that of a Lithium-Ion battery, the Lithiums look expensive. But when you properly consider the useful energy that is stored in the cells, their cost is comparable to AGM batteries. I won't clutter this message with the details just now, but I'd strongly recommend Lithium Ion batteries for use on boats that are weight sensitive, such as multihulls.
>
> Both the Polar Power and the Watts2c diesel gensets are similarly priced at around $16000 AUD. So there is a substantial cost for off-the-shelf marine generators of 48v and around 4kw capacity. The mass of these is around 120kg.
>
> I'd guess your design would typical be powered by twin 9.9 HP high thrust outboards, and in this respect the Cruise 4's are a similarly powered replacement. But much lighter and more compact. So if your budget could handle it they'd be a good choice without having to make modifications to the design plans.
>
> I hope this helps. I'd be happy to expand on the details if you're inclined to explore these options further.
>
> Cheers
>
> Chris
>
> On 25/05/2010, at 6:25 AM, nzsilvia wrote:
>
> > hi everyone, im new to the forum.
> >
> > i live in new zealand and i am about to start building a 35' sailing catamaran.
> >
> > http://www.wallerdesign.com.au/cs35.html
> >
> > simple deep v hulls 3600kg(8000lbs) displacement.
> >
> > the boat is designed for petrol outboards but i am really not keen on this idea. have been in contact with the designer who says due to the deep v hulls twin diesel installation would not be ideal. he reccomended somehow using a single centrally mounted diesel powering 2 smaller drives. this led me to consider diesel-electric propulsion. (or hydraulic but from what ive read so far it is inferior to electric)
> > knowing little on the subject i have spend many hours reading many webpages but alot of things still dont make sense to me! i would have 10-12hp on each side if using diesels, would i need similar sized electric motors? i was at first thinking of modifying 2 outboards to run with electric motors in the designated positions but it sounds as if just having the electric motors inboard mounted in the hulls would be more efficient?
> >
> > where i get most confused is it the many possible ways of doing things.. i am on a budget and do not want to spend more $ than i have to. the main reason for having electric drives is just to use a single engine.. i am not worried about having a long battery range or anything just decent efficiency and reliability. i would quite happily just run the motors straight off a generator and start it whenever i want to move.. what would i require for such a setup? is ac or dc the way to go? to be honest i still cant get my head around the difference!! what would be the best speed controller to use? props? as you can probably tell im pretty lost..
> >
> > any help would be greatly appreciated! im keen to learn alot about it
> > thanks
> > adam.
> >
> >
>
No comments:
Post a Comment