Solar Powered Cat Conversion From A-class

For anyone interested - I am converting an old A Class cat into a solar powered cat. Bad Dog becomes Moondog.

Original boat built by Jay Booth for his son Mitch to sail the 1990 Australian A-cat titles (don't think he did too well on that occasion). The boat is VERY deep, has lots of rocker, which meant it was lethal in the light conditions and dry in chop, but that's about all there was to go on for sailing. Not at all competitive, and too heavy now too. Needs a lot of weight fwd, which is fine for this arrangement. It is foam/epoxy/e-glass & kevlar, so pretty hi-tech construction for its day. A good platform for a conversion.

The 'new' boat will have hard decks built of honeycomb ply/box girder, with carbon/vinyl ester stressed bottom skin, ply is 4mm hoop. A kind of low-tech/hi-tech hybrid, with some sustainable materials (arukaria) mixed in with 'days are numbered' resins etc.

The A-frame PV support frames are an old A-cat aluminium mast cut into 4 bits, works out nicely for 2m standing headroom below PV array. The frame head universal joints took some figuring, to allow idiot-proof raising and lowering, but I have made them from scrap aluminium from my copious collection (see - bower birds rule!).

We intend to use a Torqeedo electric outboard, either the 1003 (1kW) or Cruise 2.0 (2kW). Testing showed the 1003 gave the boat a max speed of 6.3kn drawing 840kW, a higher pitch prop may lift this a bit. I suspect the 2.0 would not drive it any faster, but may give it some extra punch in a sea - but maybe not. We'll find out.

The PV array is from an International Class race boat I helped build with my kids' erstwhile school. It is a lightweight 480w array, with the panels made by Solar Sailor - 10 years old but still great. It tilts along its centreline axis, so we can pick up a bit of extra power early/late in the day.

See drawing here somewhere....

 

ps - the original solar race boat is for sale - well, bits of it: the drive leg and control gear, and the hull. On ebay:
http://cgi.ebay.com.au/ws/eBayISAPI...49508&ssPageName=STRK:MESELX:IT#ht_500wt_1156

 

On a solar boat, where the amount of energy available is much lower than on a traditional fossil-fuel–powered vessel, efficiency is of the utmost importance, says Jeff Morehouse, head of the Solar Splash intercollegiate solar boat competition and professor of mechanical engineering at University of South Carolina in Columbia. In addition to its double-hulled design, which means the boat has much less drag when it moves through the water compared with a single-hulled boat of similar size.

 

480 watts is about 2/3 of 1 hp and your going to get max output for only a fraction of the daylight hours, say 6. Then you've got storage efficiencies to deal with as well as motor efficiencies. call that say a 25% drop minimum. so if your running right off the panels you have about 1/2 hp available to you at best and zilch at worst

Batteries are there own nemesis as about the only viable storage unit for the time being are lithium ion and I don't suppose I need to mention how expensive those are

not to be a stick in the mud but if your going to be fighting wind and current as well as occasional low light conditions and low storage volume on such a high aspect vehicle you might want to install one of these http://www.centralmainediesel.com/order/yanmar_4kw.asp?page=yanmar_4kw and add a bit more motor and a few more panels lower with a seated arraignment under the canopy

I cant imagine 1/2 hp being a safe enough cushion for getting off that lee shore in a breeze

just a few thoughts
B

 

Scepticism vs confidence

Hi Boston,

Your scepticism is welcome - we always need to check our assumptions. I have two reasons for confidence: the "high aspect" is basically empty space - there is very little windage if the array is set to level. Secondly, we have already tested it, so I kinda cheated there! ;-) We rigged the Torqueedo 1003 on the unconverted A-cat, and tested it against a headwind with two adults aboard, measuring power consumption, VMG by GPS, and battery range.

We got the results posted above, which showed we were not using all the motor's power, thus the comment about the higher pitched prop.

The initial set-up will not commit us to the 1003 (1kW) motor. If real world experience - like rounding West Head into a southerly buster - shows it tyo be inadequate, then we can swap it for the Cruise 2.0, but this would only make sense with a high pitch prop.

Another confidence boost comes form the 8 years of campaigning our old International Class race boat. It was a dog to manouver especially in a cross wind, but once under way, could handle a stiff breeze with no trouble. It only had a 0.5kW motor!

 

Solar A

Very interesting, BD. I like the (foot) wheel steering. Looks like it could be a lot of fun-good luck and thanks for posting the drawings.

 

nearly there

This project has consumed most of my time since the original post - barely time to sail my 'new' A-cat on Saturdays.

We have done two float tests - one with the Torqeedo Travel T1003 electric outboard. Drawing 800w we got hull speed into a 5kn headwind, so it shows that we only need a 1kW motor, although I am keeping options open for an upgrade to the Torqeedo Cruise2 2kW motor if rough water and stronger breezes need a bit more thrust. Drawing 1000w pushed it along at over 6kn, and drawing 400w - the continuous output of the solar array in full sun - will drive it at about 5kn, drawing no battery power at all.

The other test was a trim test, to check that she wouldn't float bum-down. That was the reason for extending the deck forward of the main beam. Seems to be about right.

Everything is as per the original drawings. The old alloy A-cat mast made great A-frames. So far, 85% of the boat is either reused, recycled, or offcuts. The outboard will change that % though.

Formal launch is the Canberra Traditional Boat Festival at the end of April. Hey - what's not traditional about solar power? It built the planet and everything on it!!! ;-)

Latest pics attached here somewhere...

 

ps - the boat now has a name too.

Moondog. Don't think about it too hard, but this cat runs on pure sunlight.

 

Have you seen this, from 1998??

http://www.solarnavigator.net/history/first_solent_crossing.htm

You may also find the rest of the site of interest

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Thanks for the reminder on that site - I had not looked at it for a long time. The trans-At was a particularly gutsy effort!

we're going to do the first complete on-water trials this week - pouring rain forecast for Sydney all week - oh good! So the photos might be a little grey.

 

BTW - have you seen http://www.solarsailor.com/

This Sydney based company started by Rob Dane, a GP from NSW south coast surfing town of Ulladulla, with a stretched Stingray with massive hybrid solar panel sail-wings, 1997 Winner - Advanced Technology Boat Race Canberra Australia. This was the race that we won the International Solar Class for 7 years with the PV array going on the new boat.

Solar Sailor is also the name of the coolest (hang on - this is apparently now spelt kewlest) cruiseboat on Sydney harbour: http://www.captaincook.com.au/home.asp?fleetid=C188240BB400C0A8&pageid=5562BD355DD2416E

 

first real trials today

The rain held off for long enough to run a real trial on the Duck Pond, Pittwater. Light southerly about 10kn, smooth water (it is the Duck Pond).

Good runs - hit 6kn, using the Torqeedo Travel 1kW motor and its internal battery (still waiting for the main reserve batt to be delivered). More importantly for all-day touring, it was doing 4kn drawing about what the 400w solar array will put out.

Mass with all equipment on board is a tad under 200kg. Add two blokes, dog - looking at about 400kg.

So - off to Canberra this weekend for the Trad Boat Fest.

Pics attached - upload system going dead slow, won't load Mp4 movies, so I'll try another way, hopefully a movie will appear tomorrow.

 

Pretty damn cool! Congratulations....

 

Moondog On Lake Burley Griffin

Canberra Traditional Boat Festival last weekend...

Moondog made her debut on the lake below the House of Hot Air (that'd be Parliament House - look for the flagpole in the background). A few people said "that's not very traditional!" and it was great to be able to say "No but it sure is ugly."

Actually, the official line round here is that solar power is VERY bloody traditional - it made the planet and all life on it, one way and another. Anyway, it's a prototype, so it HAS to be ugly, right?

Who cares? It was the fastest boat on the lake that day, and with the little Torqeedo 1kW motor. Looks promising, testing will continue...

 

and some stills