How wide a paddle slot in the aka nets?

[brian.cunningham]

It turns out the latest nets only weigh in at .02 lbs/sqft!
So, I've tryed I've redesigned thing a little taking this newer technology in mind. :)

http://www.imagestation.com/picture/sraid222/p04f73ab130eb761590340481a9a7c706/eb2d31ba.jpg

I really like the looks, and it makes hiking out more of a leisurely stroll.

I'll have to leave a slot in the nets for the paddle. The question is how much of a slot do I need. I thought about running the nets above the akas(crossbeams), so I'm sitting below them while paddling. But I need to be able to duck under the boom, let it live up to it namesake. :)

[Woxbox]

Well, the short answer is a lot of space. In fact, I can't image a double paddle working at all. While one blade is working, the other one goes up pretty high. If you follow through with this plan, I think you're going to have to be able to slide the bar holding the net outboard quite a bit to be able to paddle, and then slide it back in for sailing.
I noticed the earlier post looking for comments, too. I can't see any need for three pairs of amas. There seems to be unnecessary weight and windage in it. A boat can't be too simple!

[Bruce Hooke]

My experience is with paddling canoes, so that is the perspective I bring to the matter. When paddling straight ahead you really need very little space -- a foot would be plenty I think, and you could probably get by with 9". However, if you need to do a sweep stroke or anything similar then it is easy to be reaching out over two feet beyond the gunwale. However, I don't see a sweep stroke doing you that much good on a boat as directionally stable as this boat is likely to be. Still, it might be nice to have at least some option for wider strokes.

By the way, I assumed you were planning to use a single-bladed paddle. A double paddle would obviously use most of the space that is currently filled with nets, and it might well also hit the akas. A single paddle is also going to be a lot easier to stow.

[brian.cunningham]

Ah, yes, sorry for the confusion, I meant a canoe paddle, the nets won't allow a kayak paddle. I've got a friend that owns a Discovery 20, and when he races, he leaves the motor behind and uses a canoe paddle to tie up.

I did a hiking board study, and no matter which way I place the board, fore&aft or port to starboard, it winds up adding too much weight, and winds up being either hard to get to, or too close to the cockpit to do much good, though I could use a kayak paddle. Hence the switch to the nets.

http://www.imagestation.com/picture/sraid222/pc0a55b193f8dda52d62709e332bd71c2/eb26ac8f.jpg


Another alternative is to pull up the rudders horizontal, and use the to skull it.

I've got 3 akas ( crossbeams ) since I'm not comfortable with just 2. I really want support under each mast. But I need a 3rd since having one under each mast places them to close together.

http://www.imagestation.com/picture/sraid222/p119187ac3a802d447516ba0012ca0af2/eb26a00c.jpg

I'm still running the #'s. It's one of those drag added vs weight added things.

[Woxbox]

Well, Brian, the three aka version would cut short the paddle stroke an uncomfortable amount as you have it drawn. But I wonder how much force you expect that mast to generate.
You've probably seen this from Chesapeake Light Craft. That's all it takes.
http://www.clcboats.com/images/boats/sailrig3s.jpg

[brian.cunningham]

Yes, I've seen CLC' SailRig, that's what my boat started out as. :)

CLC's rig is a free standing mast, so there's a lot of torque at the mast step, but hardly and downward force. Also the floats are relatively small, you'd never fly the kayak, so you don't have to worry about supporting it.

I've got
8,000ft-lb of righting moment.
60,000ft-lb of torque on the akas (crossbeams)
2,000lbs of tension on the windward stays and
2,000lbs of force on the maststep!
and that's if I run the stays all the way out to the amas(floats)

If I just run them out to where the curve starts change that to 3,000lbs.

[rbgarr]

I'd think there would also be a huge strain on the bow with that jib, the central hull won't float your weight, the rig, the outriggers, etc., and at any real speed under sail your cockpit will fill right up with water.

[Tom Robb]

Stupid question time again:
If you sail fron the kayak cockpit, what are the nets for?

[Keith Wilson]

Try not to be too bound by tradition; try something new once in a while, OK? ;)

[brian.cunningham]

Stupid question time again:
If you sail fron the kayak cockpit, what are the nets for?

Not stupid at all. When winds are light, or I need to paddle up to a dock, I'll be in the cockit. When winds are strong, I'll be out in the nets.

I've added a lot or reenforcement to the kayak to take the loads.
http://www.imagestation.com/picture/sraid222/p1468fa475f22176fa1ed22ed9a936b66/eb20778f.jpg
http://www.imagestation.com/picture/sraid222/p36e44ee4bdaf0b78c6cb12750a999df5/eb20779a.jpg
There will also be bracing lines to the akas (crossbeams) to help take the jib loads.

It's really more of a catamaran with a central pod than a trimaran. Each float has 610lbs of displacement, the kayak has 700lbs. I'll be sailing with the kayak just kissing the water. If I can get the hydrofoils to work, than it will really scream. :)

Here's the Windrider Rave to give you an idea.
http://www.youtube.com/watch?v=FO-NdFYiYa8
http://www.sailingtexas.com/picwindriderraveca.jpg


Try not to be too bound by tradition; try something new once in a while, OK? ;)

LOL :D

[Dan St. Gean]

Brian,

Having just built a Gary Dierking Ulua as a tri with some teething problems, I know where this design spiral is headed. I added a wee bit of sail area since I had built the boat at 21'. That made the mast a wee bit longer, so I made the mast step a wee bit stronger, the akas a wee bit bigger, and the amas a wee bit bigger to stand up to the added sail. My end result? Too much weight for the canoe to handle without swamping in a chop. The design spiral didn't work in my uneducated position. I needed more freeboard or more capacity to float all that additional weight and more ama volume than I built to stand up to that much sail. The canoe tended to twist alarmingly since it wasn't designed to support a 23' freestanding mast or 128 square feet of sail. Short solution--go back to what Gary Dierking designed and have Chris O. design a tri to use the tri akas and the sail.

As for your question, you could use about 18" between the gunnel and the pola to swing a canoe paddle. I'd try to give it a go without the third aka--it will interefere with a paddle stroke for sure. How big are your masts going to be? You might be able to go freestanding like many other small craft without the attendant downward forces. With a bulkhead or perhaps a pair surrounding the mast, you'd be fine.

Dan

[brian.cunningham]

Dan,

Nice to see I'm not the only one trying to kick up the power on one of these little boats http://www.woodenboatvb.com/vbulletin/upload/images/icons/icon14.gif
http://homepages.paradise.net.nz/garyd/compositePhoto.jpg

Did you keep it a Proa, or did you turn in into a tri?
How much volume was in the amas?

While sitting still, both my amas will be in the water helping it float. ( a triple dipper ) This changes when is starts to heal. I've got the ama's pickleforked to bring more buoyancy up front. I've thought about added a false bow that could also act as the forward aka mount. Sounds like I should go ahead with the idea. Ideally I'd like something like a Dick Newick winged aka, but alas the weight would just be too much. Though it would support the torque on the amas better....

Twisting of the hull is why I went to a stayed rig. The other reason is that an unstayed mast would wiegh 70lbs each! :eek:


The boat is rigged for light winds, and I don't plan on running a spinnaker.
The foremast is 23ft, the main is 26ft since it doesn't have to support a jib.
Sail area
Jib 69
Foresail 120
Main 138
total 327

Better ability to paddle would be nice, so would being able to get at the rear hatch underway. I'm going to re-crunch my numbers again and see what I come up with.

[Woxbox]

Sail area
Jib 69
Foresail 120
Main 138
total 327

Wow. The C-class cats are limited to 300 square feet and they sail on 25-foot hulls. And with that they are extremely fast. I didn't realize how far you're planning on pushing this design. Those masts are taller than I figured from the sketch, too. All in all, that's a heck of a lot of sail for the boat underneath it. I'm thinking that Dan is right. That much power and potentially the weight of the boat and rig will need more hull volume. What do you figure the dry weight and displacement numbers will be? To reliably keep the windward float from diving, that hull by itself should be half to two-thirds the displacement of the boat. (Some multi designers will go less, but most don't.) So if the amas displace 610 pounds each, your all-up weight is, hopefully, in the 300-400 pound range. I don't know what you weigh, but if the boat is built to be sailed by up to a 200-pound person, you've got about 200 pounds max left for the boat and gear.

[Todd Bradshaw]

The Ulua isn't a proa, it's a tacking outrigger.

[Gary Dierking]

On my Wa'apa and Ulua outriggers, I use hiking seats that can be quickly pivoted outboard when you wish to change from sailing to paddling. The seats can be made like mini-tramps with fabric stretched over a frame, and would be lighter than the ones shown.

Gary
http://farm1.static.flickr.com/103/294191004_9a379ad37c_o.jpg

[Tom Robb]

Gary D's idea sounds like a good answer to my why the nets question.

[brian.cunningham]

Nice looking boat Gary!

I also like how they did the Holopuni OC3/S Sailing Outrigger Canoe
http://www.holopunicanoes.com/oc3s.html
http://www.holopunicanoes.com/tahiti2005/images/Huahine.jpg
http://www.holopunicanoes.com/tahiti2005/images/3steerH5.jpg
You can see how they use the slot in the nets here.
You can also see the kayak style skirts they use to keep the water out.
http://www.holopunicanoes.com/tahiti2005/images/5sail-LV1.jpg

How about this idea, use the nets so I can hike out all the way to the amas(float) but install 'hatches' to use the paddles.

I've got some pics of a new 2 beams design, with a raised bow. Unfortunately ImageStation seems to be actind up. :rolleyes: If I can get it to work, should save me about 40lbs.

If swamping an issue, have you though about raising the sides or covering the forward section with canvas? The OC3's use kayak style skirts.

BTW How do you like the steering paddle?
Can you skull with the rudder?

[brian.cunningham]

I got ImageStation to cooperate today.
Here's my latest 2 beam design.
The raised false bow is just in case. I'm hoping I won't need it with the hulls pickleforked.
http://www.imagestation.com/picture/sraid223/p03e1546de77842c56ad2f456df498136/eb12b387.jpg

[Dan St. Gean]

Brian,

You will need above all to keep things light if you are going to get the craft foil borne. I did pump up the sail area to the Ulua as a trimaran, but with mixed results. I am going back to a tacking outrigger as designed. I had tons of hull twist since I nearly doubled the sail area with no more hull reinforcements than a berefy step. A stayed rig is a good idea for you. I used the Holopuni idea for the tramps as well. Actually, I was looking to replicate the Holopuni initially at 21' but I didn't do my homework. I needed larger ama displacement to counter the 128 square foot freestanding rig and a more robust hull to take the twisting forces. I'll be using the Wa'apa rig on the Ulua hull as gary had designed. Scaling back on the sail area will allow the boat to perform as designed.

Designing from scratch is a different story. I had too many cooks in the kitchen. As long as your boat is an integrated system that is designed from the outset to work together, you will be fine. There are several foil borne craft to model yours after as you well know. Is there any reason for the schooner rig? Affectation? Lots of strings?

Anyhow, Gary's idea is great as is the Holopuni idea. Leave yourself 15-18" to swing the paddle. Will you have enough freeboard to aviod swamping the cockpit? That was an issue with mine once I loaded it down with heavier amas, akas, mast and two big guys.

Dan

[brian.cunningham]

Is there any reason for the schooner rig? Affectation? Lots of strings?


Keeps the sail area low, it's really a prototype for a bigger boat. Splitting the sail area up would make the sails easier to handle. Also two short sticks wieght less that one big one. Besides I really like the looks. Nothing like a schooner!

If it starts to swamp, I can either raise the sides of the kayak as well as the nose. Or add more displacement to the amas via raising their decks.

EDIT
I agree with you, the lighter the better.

[brian.cunningham]

Project has grown just a little from my 1st design.

This show the original batwing sail rigged design with sliding akas (crossbeams), alongside the current gaff rigged design.

http://www.imagestation.com/picture/sraid223/pe099efc7364d62bd11958fd08fbc699a/eaff5374.jpg