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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > Sailboat Design and Construction
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  #11  
Old 09-14-2009
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The idea of doing the whole thing from scratch sounds appealing too, as you mentioned, and with any boat one builds there is that line between interest in the project for itself, and the desire to get out on the water.

The more I think about it, the more a fully battened rig on a mast secured to the outriggers, with multiple reef points and a roller furling headsail sounds like a great way to have my go fast cake, and eat it (be able to survive stronger winds, and maintain a balanced sail plan while I'm at it) too. Is it possible to do all of this, and keep the controls mounted to the amas of the sail rig, so I can keep my kayak a basic functional kayak?

Could I take it even farther and put the big sailing rudders on the amas themselves ala catamaran, and get good steerage without mounting a rudder on a kayak which definitely doesn't need one for itself?

Perhaps I can't, but the more I think about it, the more eager I am to try it and at very least see if I can get a great story and some experience out of it. Either way, for now, the work is building the kayak, which leaves me months and months to continue to scheme and plan about the sail rig itself. =)

The first dilemma seems to be determining how much sail to carry, and how to best carry it low to the water, while maintaining a balanced rig... hrm. I suppose for that, I'd need to know a bit more about the shape of the hull and it's dynamics in the water, right? How does one start this process of designing sails for a given hull profile? What additional information do I need to bear in mind since it's a multi-hull rig?

Would it be appropriate to experiment with self made tarp or nylon sails, if I intended to eventually get decent dacron sails, or would none of the information really cross over?

Thanks

-- James
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Old 09-14-2009
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I think it is best to experiment with cheap sails. The shortcoming when changing cloth is that elasticity changes, so the cut would be different. But they will give you a good idea of drive and heeling force. Recutting old sails can be a good source, also used windsurfer sails.
I like low aspect traditional rigs like lug rigs. They give good drive for less heel, and work well with shorter spars. This makes them easier to rig, and easier to store. There are some good examples of these on the yahoo forum, and also on the woodenboat forum.
As far as reefing, you might consider different rigs for heavy or light air. I think if I got caught in a canoe or kayak with too much sail, I'd take it all in and paddle. You can use a downhaul on a marconi rig, or a lug rig's yard will brnig it down. I agree that sock type sails, and even sprit rigs, can be dangerous because they won't come down on deck. I think you'll be surprised how easily driven a kayak is by small amounts of sail. Remember you don't develope much force with a paddle, way less than 1 hp I'm sure.
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Perhaps you could help me out with this. It's been a source of confusion for me for some time.

I always presumed that Lug and Gaff rigged sails were merely an outdated means of getting more sail area lower, and that with the advent of advanced sails with full battens which allow nearly the same shape without the added weight aloft and necessary halyards and lines for the additional spar both lug and gaff rigs require, that no one would use them. Despite this, I see these rigs on a number of boats, especially small craft. Obviously they seem like good rigs to a number of people, almost all of whom know far more about this than I do.

Could you point me at some reading so I could better understand why?

Thanks.

-- James
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Old 09-14-2009
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James,

There is always room for debate about the pros and cons of the sailing performance on these various rigs.

But I think one of the biggest reasons why you see these rigs persist today, particularly on "small craft", is that lugs and gaffs and spritsails and gunters all permit the use of shorter spars. In other words, the rig can break down into easily manageable (and trailerable) components that usually all fit within the boat's length for easier storage.

If you've ever done much trailering or cartopping, you'll certainly understand how important this is. Most folks are willing to make a few compromises to achieve easy trailerability and facilitate storage.
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Old 09-14-2009
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Quote:
Originally Posted by jbarros View Post
Could I take it even farther and put the big sailing rudders on the amas themselves ala catamaran, and get good steerage without mounting a rudder on a kayak which definitely doesn't need one for itself?


-- James

You can buy beach catamaran and carry folding/inflatable/small rigid kayak for fun.
I tried to go your route some 20 years ago, modifying a kayak into fully blown trimaran. It never worked for me. Chief from Watertribe has tried to go this route without much success. Every year somebody trying to bring some kayak based paddling/sailing, supposedly fast trimaran into Everglades Challenge, I have never seen one succeeded, exept Balogh system and Hobie AI.
There are too many design limitations. To make weatherly trimaran you have to build very strong and stiff platform. It becomes too heavy very fast for one person to handle, to paddle, to cartop…
Did you look at Raptor outrigger?
Hydrovisions Innovative High-Performance Watercraft Design
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Old 09-14-2009
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The other reason that Gaff rigs still persist has a lot to do with the idea of a boat as system. For the most part, it is very difficult if not imposible to design a true gaff rig or sprit rig that will point as high as as well designed Bermuda rig, which in part results from difficulty controlling twist and in part because gaff rigs usually end up with more drag and weight aloft for thier drive.

But many small boats have hull forms and foils that are not all that efficient in going to weather, so that a small loss of rig efficiency does not hurt the boat's windward efficiency since their ability to go to windward is limited by the hull as much as the rig.

What gaff rigs do well is provide a lot of power when reeching or running without producing as much heeling force. Since the vertical center of effort of a gaff rig is lower in height than an equal area Bermuda rig, the gaff rig can can carry a lot more sail area for a given amount of heeling moment. With modern gear, this can be a pretty efficient rig for inefficient hulls.

The most modern very high performance boats have square head mainsails which offer the best of both worlds. Because they use a cantilevered batten to create the square head they are able to control twist and yet the square head allows them to optimize drive to heeling forces.

This is nothing new. In the 19th century, voyaging and racing canoes used a batwing rig which was essentially a gunter rig with a mainsail with huge roach supported on long battens that improved twist control and reefing. This rig was reefable and often carried a small jib as well.

Jeff
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One other thought, as the price of carbon fiber poles comes down in price you may be able to reduce weight and simplify the connections of the amas.

Jeff
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Quote:
Originally Posted by CrazyRu View Post
You can buy beach catamaran and carry folding/inflatable/small rigid kayak for fun.
I tried to go your route some 20 years ago, modifying a kayak into fully blown trimaran. It never worked for me. Chief from Watertribe has tried to go this route without much success. Every year somebody trying to bring some kayak based paddling/sailing, supposedly fast trimaran into Everglades Challenge, I have never seen one succeeded, exept Balogh system and Hobie AI.
There are too many design limitations. To make weatherly trimaran you have to build very strong and stiff platform. It becomes too heavy very fast for one person to handle, to paddle, to cartop…
Did you look at Raptor outrigger?
Hydrovisions Innovative High-Performance Watercraft Design
Speaking of Watertribe...

I wonder if something a bit more substantial, like these Wa'apa sailing canoes, might be more along the lines of what James needs. It's tempting to call them sailing kayaks, but they have more heft.

Incidentally, and here I'm guessing, but I believe this video was shot from Matt Layden's little Sand Flea sailing pram at the start of the 2007 E.C.

Wa'apa Sailing Canoes at E.C. 2007
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CrazyRu,

I just got an email reply from John at CLC who pretty much agreed with everything you said. They're a great way to make a kayak sail, but really never going to be a great sail boat.

John,

Those look like fun, but I'm sure I couldn't move one around with my little scion. the need to be cartopable or towable by a car with a towing capacity of "0" is a real problem when it comes to vessels looking to cross the channel.

Jeff,

I guess that was my question, why not just used a square headed full batten sail instead of a gaff or lug sail? is it just the cost or difficulty of making that type of sail? It seems like it would do everything the gaff would, including the low mast and large sail area? I'm sorry if I'm missing something obvious here.

Thanks again guys, this is proving to be quite an educational experience.

-- James
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sailing a Long Haul Maek II with a 36' HP Sport BSD Sail.

Perfect combination.

The Maiden Voyage on Vimeo

This is the story of the first 76.4 miles water journey paddling and sailing our new Long Haul Mark II Commando folding kayak in the beautiful and quite challenging Everglades National Park. Enjoy!
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