G'day Matt,
I converted a few months with Electric Yachts, I have a 10 ton Ketch.
When I started this endevor, the boat weight was around 11.5 ton. After removing the Old Volvo MD17 and fuel tanks I lost alot of weight. I repowered with Scott at Electric Yachts. yes I have had a few bugs to work out but over all, Im very glad I converted. We are sailboats and really the only reason we should use the motors is to enter and leave the marina or if maybe we need to make up some time befor a storm so we motor sail or just try to hold a lee shore. Many people who sail today (and please people dont be offended) motor more than sail due to many reasons. But over all rely on a internal combustion engine than say electric.
The way I look at it if you have room for batteries then go electric.
If you use the boat on a regular basis it will pay off to go electric. If your a weekend sailor or say use the vessel a few times out to the year. It might cost more than its worth. Everyone has thier own idea's of what to do but you know better than any of us how you use your sailboat.
I kno Electric Yachts can double up two motors on one frame and will be ready to drop in, I know that new 10kw motors are out and avail now. So maybe Scott can configure something for you. So you would be running 20kw and if you can go to 72vt with two banks you should be fine.
Also if your insured you might wish to check with your provider. If not do what you feel is the best. As I always say follow your gutt regardless of what the mainstream has to say. They have enough problems tending to themselves. In the end its your boat, your life and your problem.
Cheers
--- In electricboats@yahoogroups.com, "KetchNomad" <KetchNomad@...> wrote:
>
> Eric,
> I appreciate the candid and no BS reply to my inquiry. It has given me much "food for thought", these are the types of things I like hearing. To date, my correspondance has been with turn-key manufacturer's of these systems ......and naturally, their reports and products all glow with their capabilities!!!
> Thank you very much,
> Matt
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> >
> > Hi Matt,
> >
> > There are two common conversion formulae to size an electric conversion. The first is to divide the existing engine hp by 2 or 3 to determine electric hp. Unfortunately, this has to be vague to accomodate the wide ranges of installed engines. For example, many 30' sailboats have engines with more hp that your 39' ketch which would lead some people to consider your boat underpowered. Alternatively, the other conversion ratio is 1kW per ton of displacement. Since this relates directly to the boat itself, I find it much more reliable. Personally, I would find a 10kW drive marginal for your size boat and would look for something closer to 14kW from your description.
> >
> > Higher power drives come with additional considerations. A 48V drive would draw 300A to deliver 14kW, 96V would halve that, but systems above 48V should comply with ABYC's requirements for high voltage systems addding cost and complexity.
> >
> > Lots of people want regen, but I have yet to hear of anyone that has reliably generated more than 100w at 5kts. It is my opinion that it takes at least 7 to 8 knots of boat speed to generate any significant amount of electricity back into a battery bank. Most people are getting better results from PV solar panels, again adding cost and complexity.
> >
> > Realistically, I would never recommend an electric conversion as a way to save money on a re-power. If you're thinking about building a DIY electric drive, you should be comparing that to a DIY install of a good used or rebuilt diesel. If you're using the cost of a turn-key professionaly installed diesel repower, compare that to a turn-key professionally installed electric system. Of course, many people will bring all the money you'll save over the next 10 years, but you still have to pay up front just to get sailing again.
> >
> > Lastly, when you think about sizing your batteries, every 10kWh of battery bank roughly equals 1 gallon of gas. Once you have an idea of the size of your prospective bank, consider if you would sail your boat with that size gas tank, most electric conversions have less than 2 gallons of equivalent energy storage. I'm converting my 30' ketch because I can accept that I've got about 3/4 of a gallon (8kWh) when I'm full up. Many other boaters would not make the same choice. It all depends how you use your boat.
> >
> > Your boat is a little larger than the "sweet spot" for electric conversions, which translates to bigger parts, higher voltages, more complex systems and more money. Don't get me wrong, it can still be a good idea, but you should be able to make an informed choice because its your boat and your money. There's nothing worse than learning some of this after you're already thousands of dollars into the game.
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
> > --- In electricboats@yahoogroups.com, "KetchNomad" <KetchNomad@> wrote:
> > >
> > >
> > > My NOMAD is a 1950 steel hulled 39' ketch (monohull) with a full keel of a J. Murray Watts design built in Hoerneke Boat Yard (WI), estimated at approximately 13 tons (probably a bit more). She is powered by a Universal Gas (not an Atomic 4 but its predecessor) 25 HP engine at 2500 RPM with a gear reduction of 2.25:1. The prop I believe to be a 19" 3-blade with an 11" pitch.....not 100% sure on this....found various old literature on the boat concerning the prop by the previous owner.
> > >
> > > I have only recently been researching my various options in electric drive, but generally the consensus for pushing this much bulk is about an 8-10 kw motor, and I would prefer a regenerative system. Commercial applications are appearing rather pricey........
> > >
> > > Any tips, advice, comments, or suggestions would be greatly appreciated.
> > >
> > > Thanks,
> > > Matt
> > >
> >
>
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