G'day,

Thought you may be interested in the recent launching of Elementarry, a 7.5m/25' proa with 4m/13' windward hull.

Schooner rigged, unstayed carbon masts, telescoping beams (2.4-4m/8-14'), 22 sqm//235 sq' sail, and weighing 120 kgs/266 lbs, although the next one will be considerably less.

A few issues to be resolved, mainly with the sails and me getting fit enough to move around quickly, but so far it goes pretty well.

For pics and the story so far, see http://www.harryproa.com/Elementarry/SailingPhotos_4.htm and the previous 3 reports.

Regards,


Rob

wierd looking. It would be interesting to see it up against a beach cat. I figured by looking at the images, that in order for it to sail both ways, the vessel has no stern or bow? as both ends can act as either OR?!?!? also the sails have to rotate all the way around?

Looks killer, and kinda scary. Just like those C clase

catamarans.

ooooaaaahhh please explain this photo?

the boat is sailing in reverse, but not really? the sails are inverted? confused!!!

mate, looks like its sailing in Albany harbour.. Probably not but....

also in Perth

G'day,

Weird indeed, but actually just a cat optimised to not have anything surplus to requirements.

Should do well against the beach cats as it has the same sail area and righting moment as a Tornado, but is 25% longer, 25% lighter with a lower centre of effort. What it does not have is a gun crew or the benefit of 30 years development by the world's best scat sailors.

It is double ended. The crew always sits to windward, so this hull can be very small as it is only required when not flying a hull. The rigs rotate through 360 degrees, the rudders through 270. To shunt (equivalent of tacking), the double ended sheets are released, and pulled in at the other end. The rudders are rotated and you head off in the other direction. We are at the stage where we can go from hull flying to hull flying at about the same speed as a cat, but with practise should be fatser. Downwind is the same technique, but at this stage, slower. In both cases, the maneuver is totally reversible at any stage, which should make starting a whole lot of fun.

In the photo, the boat is running near enough square, approaching the beach. The aft sail is doing all the work, the front one is in it's shadow. Going wind and wing is one option and gybing downwind another.

Stewart, the picture is on Coff's Harbour. Should have it over here later this summer. Let me know if you want a sail.

Regards,

Rob

If your downwind speed is high enough the front sail will not be in the shadow of the rear one and the two combined can actually make a quite powerful rig. The rear sail will have to be sheeted in further because the front sail will skew the angle of attack of the rear sail. Be sure to put tell tales in your sails and sheet you sails to those.

WOuter

Coffs? Ok. just looked like the rocks in the bays down south. But Coffs is nice, lucky buggers..


Im wondering about the centreplate. O understend or think I do about the mechanisms employed with the rudders. But not sure how your pulling off doing a rotation on the plate. Any clues?

First thing I noticed in all the pix was the bad wrinkles in the mainsails.., not enough downhaul.., even when sailing off the wind when you cannot be oversheeting.

Also, I was privileged to sail on an outrigger in Saipan. It was sailed by real natives with all the parts tied on with local woven weed. It was quite an experience.
And in tacking it did the same thing that you have described. But, it was a very, very slow procedure.

How can you swap ends with the rudder that quick and claim it will tack with modern beach cats?
Just curious,
Rick

Why can't you just have a rudder at each end and have the one that is not in use pulled up out of the water? When you swap ends, you pull the old rudder up and put the new rudder down?

G'day,

No centreboard. Just 2 oversize rudders in daggerboard cases hung off the side of the boat. A fixed centreboard makes shunting too slow and adds weight and cost as you still need 2 rudders. Two foils are all that is needed, and if they both rotate, they work much better. Can even angle them both slightly to force the boat to windward. Experience so far is that this is very costly in terms of speed, but handy when jamming for a mark, or stopping someone going past to windward.

Regards,

Rob

G'day,

The luff tension is inadequate. Not enough purchase, too much friction from the batten camber inducers. Working on it. May also be some luff round issues?

Not sure what you mean about swapping the rudders? All we do is rotate them through 180 degrees. The helmsman has 2 tiller extensions. When the boat is stationary he pushes one, pulls the other and round they go. The slow part is coming to a halt, although reverse sheeting the sails does this pretty quickly. With practise, we should be able to luff head to wind until nearly stopped, then sheet in the new aft sail, move crew forward and spin the boat round to hard on the wind on the new tack. This will be slower, but should have better vmg. Hope this is clear. We will be making a video next time we go sailing which may be a bit clearer.

Tacking from reach to reach we are definitely quicker, although this is not a whole lot of help!

Tacking downwind we are definitely slower, but crew weight movement will speed this up.

Regards,

Rob

Rob,

Can't wait to see the video!

G'day,

You can lift the front rudder, and many proas do. I don't as
1) Two rudders in permanent use can be half the size of one at a time
2) Control with a bow and a stern rudder is awesome, particularly during a shunt where speed is slow
3) Lifting and lowering is more work, at a time when you are already busy.

We do only use one downwind, and as we get better, will only use part of that.

Regards,

Rob

sound interesting. Give me a tickle when one is here..
How much leeway does she lose?

G'day,

Will do. Leeway? Don't have a proper idea of the tacking angle, much less the leeway. However, based on previous boat to similar designs, not a lot.

regards,

Rob

Harry,

You mentioned that it is difficult to slow the boat down prior to changing directions - do you use the two rudders to help slow the boat? It would seem that you could put them both at 90 degrees to the direction of travel and add quite a bit of resistance.

G'Day Rob,
First of all, congratulations, I strongly admire people who think out of the box.
My question is how did you decrease the weight/surface area relation, for example comparing to a tornado. On light winds I can see the advantage, as you basically don´t need the weight of the winward hull, but on strong winds I believe that the extra weight of the cat would be an advantage, because the weight of the winward hull and the weight of the rig are helping to reduce heel. In this boat, all the weight of the boat, except for the crew and the small hull do not counterbalance heel.

G'day,

Rudders at 90 certainly slow it down, although nowhere near as quickly as sails at 90. Both waste inertia/energy/whatever it is that keeps you going forwards. With a bit of practise, we will kill the speed by luffing head to wind. Unlike a cat, where this is done as quickly as possible to maintain momentum through the tack, on a proa it can last a lot longer. Once the boat is stopped or nearly so, then rotate the rudders, sheet on the aft sail, move crew forward and spin it round onto the new tack as quickly as possible. Maybe not as good vmg as a cat, but should be close, with no chance of getting into irons.

Regards,

Rob

G'Day Rob,
First of all, congratulations, I strongly admire people who think out of the box.
My question is how did you decrease the weight/surface area relation, for example comparing to a tornado. On light winds I can see the advantage, as you basically don´t need the weight of the winward hull, but on strong winds I believe that the extra weight of the cat would be an advantage, because the weight of the winward hull and the weight of the rig are helping to reduce heel. In this boat, all the weight of the boat, except for the crew and the small hull do not counterbalance heel.

G'day,
Thanks.

By increasing the beam. A Tornado has rm of half it's weight (80 kgs) x it's beam (3m) plus 2 crew (160 kgs) x beam. RM~ 720 kgm

We have 2 crew (160 kgs) plus ww hull plus half the beams (20 kgs)x 4m beam RM~720 kgs.

The weight cost of increasing the beam is offset by the weight saving of not having to support the mast in the middle of the boat and not having a boat which has to sail on both tacks.

Regards,

Rob

Very clear. The lack of trapeze would also be a need to add some cm to the beam, or some wings, doesn´t it? Anyway, adding beam to this boat doesn´t seem to affect it´s performance as it would on a cat (particularly on it´s turning ability).
Other things that called my attention are:
- The lack of stays, that must be a very special and expensive mast?
- The front rudder is just left free or is it necessary to fix it while sailing?

Rob,
When going upwind, what happens when the boat is sideways to big chop as you are turning it? It does have to be broadside to the waves temporarily, doesn't it?