Kahana Bay Beach Cruiser
Hi Chris, it’s good to see the interest the one sail only layout is creating. Proas have many disadvantages but they are unique and it’s great to try to take advantage of that uniqueness.
Your fully battened idea does this but I think furling/unfurling is much easier than raising/lowering and reefing becomes problematical. But if you want to take the idea further how about a double skinned sail with ribs instead of battens, a wing.
I have not seen a rig that I would prefer over my Flight rig for all but strong wind conditions, that is 90% of our sailing, and I suspect if others come to grips with its simplicity, there are two lines only that need tending to shunt, they would look at it more seriously.
In most other configurations, as well as adjusting the sails, the number of ropes for the sails varies but probably more than two, there are rudder up/down adjustments, another two ropes? and mast rotation adjustments to make, another two ropes?
I do have a video of Flight in action on an old cassette which hopefully I will be able to post one day.
All the best
John Pizzey
The thing I don’t like about it is the track. It’s a spendy item. I need to look into the relative cost of two furlers v the track—not that those are the only options. The other thing I don’t like is a loss of luff tension when shunting. Lots of folks have talked about how nasty that can get in rough conditions.
I certainly vouch how expensive tracks are, I was blown away costing a 1.4meter straight one.
I also can confirm that pulling a un tensioned luff from one end of a proa to other is problematic. I briefly used this on TP01 and the flogging jib would shake the craft very violently.
Bit left field but what about an inflatable tube in the luff like a surfer rig. Might be daft idea but easy to do some dirty test.
Tink
Furl jib, shunt along track, unfurl jib. Done.
Bit left field but what about an inflatable tube in the luff like a surfer rig. Might be daft idea but easy to do some dirty test.
That’s actually a super interesting idea. That’s how a muscular hydrostat works. Elephant’s trunks, octopus tentacles and your tongue work that way! The two basic elements are a tensile member in the middle (usually muscle fibers running lengthwise) and surrounding bands that squeeze around the outside like a tube. Contract the middle and it gets shorter, contract the tube and it gets longer.
Biomimicry proas. Does it get more cool than that?
But if you want to take the idea further how about a double skinned sail with ribs instead of battens, a wing.
Got a sketch of that? Sounds cool.
I have not seen a rig that I would prefer over my Flight rig for all but strong wind conditions, that is 90% of our sailing, and I suspect if others come to grips with its simplicity, there are two lines only that need tending to shunt, they would look at it more seriously.
A boat like this could be set up with an isosceles sail, but not unless the rig cants, right? As far as I can tell it has to to keep the foot of the sail relatively flat and shift the CE forward. Is that right?
I do have a video of Flight in action on an old cassette which hopefully I will be able to post one day.
I’m sure that I’m not the only one who would love to see that.
Furl jib, shunt along track, unfurl jib. Done.
True, but you have to tension the luff too. I think its more like Furl jib, shunt along track, tension luff, unfurl, done. Maybe its easier to have to nice tight furlers so that you furl one, unfurl the other and done. But I don’t know.
Here’s a version with the mast stepped on the windward gunwale. It has lower shroud/stays, and a simple 23’ tubular mast, showing 120 sq ft of sail. The idea here is two furlers/sails, synthetic rigging and an aluminum pole. Where is the best place to put the tacks of the jibs? What is the best cant of the rig for specific contitions? BTW its 15 degrees to leeward here.
The good news is that all that could be adjustable, as John pointed out. A nice development rig.
It might just make a nice little raid boat, as long as the reinforcements that allow us to step the mast on the windward gunwale don’t prevent us from having a hobie mirage auxiliary.
My biggest question with this type of boat (beach cruiser) is how does one person right the boat after a capsize? If I’m going to take my kids out on this, I need to be able to get it back up if it flips over.
You mean turtle? What Gary Dierking does is make the safety ama detachable. Then you can lift the ama with a righting line, and put the safety ama back on after you’re upright.
I always loved the way my Nacra 5.8 would right itself in a fresh breeze just by standing on the bow. But I never went turtle because of the 5gal water jug zip tied to the top of the mast. Dorky, but effective if you have to rescue yourself.
Kahana Bay developing nicely
I like the new staying arrangement and windward mast, looks right.
I also like the idea of furling the sail and moving it down the track. I have a few thoughts.
The last two foot of the track could be radiused to the luff radius so it self tightens and allows some movement of CE
Long and bent tracks are VERY expensive what about a block at the foot of the jib and a wire strop from bow to bow. The furled jib is pulled from one bow to the other and then tightened up. I have a few ideas in my head about that, but first the rub.
There has to be a rub, it would be boring otherwise. The furling sails I know all require something fixed to the deck for the furling line. Obviously there are other systems because for one AC72 any many other race boats have furled sails lying from the bowsprit onto the tramp, I will have an investigate.
TINK
See below for simple fairlead and cleat attached to furler. I will draw up my simple strop control later, I am sure you can haul to new bow and pile on luff tension with one action when shunting.
1) Furl sail
2) Release old bow haul line
3) Pull to new bow
4) Unfurl
5) sheet in and off you go, smile
The thing that has not been said I don’t think is that you would not always have to furl.
Possibly under force 2 no furling, force 2 - 4 half furl and above a 4 full furl.
Also still thinking about a Biomimicry inflatabable luff BIL, you could have more than one tube to give an aero foil shape and or combine with furling the sail quarter of a turn to create a better luff shape.
TINK
PS ‘Optional cam arm brackets and snap shackle adapters fit onto Schaefer System 550 and 650 furlers to make it easy to give your staysail a whirl! ‘
Furl and then unfurl still seems simpler. It has fewer steps and one of those steps is NOT tensioning the luff.
The weight and windage aloft of a second sail is a pain, but so is all that hardware.
What about vertical/helical battens like a hobie bravo to put some leech in it?
See below for simple fairlead and cleat attached to furler. I will draw up my simple strop control later, I am sure you can haul to new bow and pile on luff tension with one action when shunting.
Taking that idea a bit further, make the strop a little loose, so at the end of its travel it sits a bit above the deck . Then have the line which pulls the jib from 1 side to the other, put it into a cleat on a floating block with something like 16:1 or however much purchase you want. (This same 16:1 could be used for both sides saving money.) Give that line another pull. You could do this after unfurling perhaps so you don’t loose any time.
Even better: attach it to the halliard. I’ve seen it on a hartley 16.
-Thomas
Bit left field but what about an inflatable tube in the luff like a surfer rig. Might be daft idea but easy to do some dirty test.
There seams to be quite a few people interested inflatable wings,
TINK
Here’s a little progress on the KBBK (which needs a better name).
I’ve been thinking about the sail that they use on hobie kayaks and the hobie bravo.
http://www.hobiecat.com/sailboats/bravo/photos/
It uses little diagonal rod shaped battens to give the sail a little square head, but the battens wind up around the mast when it furls. I’m not sure this will work with the smaller diameter of a headsail furler, but I really like this idea. Shown here it has 140sq ft of sail on a short, 22 ft mast. I like the shape of the sail. It looks fast!
I’ve also added a little stick built ring frame/mast step in the middle of the cockpit. I’m disappointed to have an obstruction in the cockpit, but I think it needs the rigidity here.
I’ve also modified the tiller so that they come readily to hand. They also get out of the way of somebody sitting on the cockpit sole while the boat is under Hobie Mirage drive power.
Shunting would be as simple as easing the sheet and furling the old sail, raise the rudder that is right next to you, then you swing around the mast to the new helm position, lower the new rudder (that is right next to you) unfurl the new sail and sheet in. No luff tensioning.
This could be a cute little RAID boat. With a simple, VERY reefable rig, and the powerful hobie mirage auxiliary, it feels like a good little camp cruiser.
Plus, it feels very buildable. The CNCed foam bottom and amas make quick building of compound shapes. The amas on my Wa’apa are CNCed building insulation, and they were a snap to build, light and strong. The rest is a dory that can be built on a flat table, some box beam akas, a tubular aluminum mast with riveted on fittings, the dagger/rudders and cases (probably the most challenging parts)...all pretty straightforward stuff.
Best,
Chris
some more
same thing, but with the mast upright.
It’ll be fascinating to compare the performance of the rig canted, vertical and maybe even canted to windward. What might be best for racing and cruising might not be the same thing.
chris
I love it! I agree about needing extra support under the mast step. It looks like a really fun raid boat.
Kimbal.