Biplane Rigs

[great white]

This site just keeps getting better and better! Quick question. Catamaran, sharpie hulls, potentially with biplane rig. Avoids compression stress, buries the mast (unstayed) deeply. Easiest rig to single hand? Wife and I are both handicapped - can get around, but without much agility, plus she's tiny. Thanks in advance for both the warm welcome, and the uncannily accurate answers.

[Aramas]

Biplane rigs have a broad 'dead zone' in which one sail is blanketed by the other. Also the non-existent sheeting base more or less requires a sprit/wishbone boom, which can be awkward to rig and reef.

The junk rig is definitely the easiest rig to singlehand, but it is heavy and does have a lot of bits of string.

The heeling of a monohull can be a little scary if you have trouble getting around, but once you get used to it the motion is actually a lot more comfortable and predictable than multis. They can also be self righting even in very small sizes - check out Uffa Fox's Flying Fifteen - basically a keel dinghy.

A junk rigged keelboat can be positively bouyant, self righting, managed entirely from one position, have a slow comfortable motion and can have plenty of room for sleeping onboard. Small multis are more sportboat than cruiser.

So what is the intended use for the boat? Where will it be used? Do you want to trailer it or leave it at a marina or mooring?

[TimothyB]

As a quick aside, I read about a fellow whom setup a rig like this on his cat with an additional 'yawl' sail for balance, but what he did was set a full size sail on each hull (junk sails) as if the cat was a sloop, each on opposite sides of its mast, and would use one sail or the other depending on his tack position and wind.

Extreme, but then hey life without oddities would be pretty dull!

--T

[great white]

Thanks for the quick answers. First, intended use is Great Lakes, liveaboard, most of the time coasting, gunkholing and fishing. Need storage for bulky but light. Some photography work and writing. Considering that we will never be far from safe anchorage, that we will never be in a hurry and that we will have aux. power, I wonder if blanketing will be a problem. Wind is almost always 'something' westerly or 'something else' northerly, and pretty steady, so easily allowed for. I was inspired by the Wharram designs. Brilliant. But I need a faster build, which means simpler. Which means no cold molding, etc. Junk rig is reportedly easiest to handle, but I agree about the 'strings'. Further comments eagerly solicited.

[Dave Hadfield]

What's a biplane rig, an unstayed mast from each hull, setting a sprit-boom/wishbone rig?

[great white]

Yeah, Dave, that's what I had in mind. Read about it, not much, but some. Seems like a better idea than downforcing the middle of a beam by sticking a mast in the middle of a cat deck.

[brian.cunningham]

I agree with the "shadowing issue. Biplane rig have a narrow window where they work well.

As fas as mounting the rig on the deck, the stays distribute the load.

If you want to see a biplane junk rig look here:
http://tenchiki.net/reality/fun/dragon_wings.html
http://tenchiki.net/reality/Art/sail/dragon-wings-07.gif

[Frank E. Price]

Why step the masts abreast each other? Why not step one forward and in the other hull, aft? Plenty of torque I reckon.

Frank

[Lucky Luke]

"Biplane" rigs have been experimented in offshore racing cats (JAZ, Ostar race), speed record attempts (ENSTA boat, France= over 40 knots...quite easily..), all with various success. It is a fact that these rigs do have a "blind" angle, but this is not that bad as, with any speed, the apparent wind becomes very soon close reached. On a "slow" cruiser, that may be more embarassing, but just consider that many rigs have some "blind" angle too, schooner being the worst.
For your project, you could either choose a (patented) rig with two (buoyant) unshrouded masts and a "wishboned" sail on each, or (non patented= shrouded masts (complicated if mast need to turn), or a rig with one self taking jib on each mast (and better without main), roller furling. This will oblige you to have outriggers for the sheeting. It is EXTREMELY easy to use, adjust, and furl. Mast must be supported with two backstays, and a compression bar between masts. Expensive.
Good luck

[Hwyl]

The ultimate biplane rig must have been Pete Goss' Team Philips, built for "The Race" which started on the turn of millenium.

"Team Philips" was extremely innovative in almost every area. Offset biplane rig, unstayed masts. Wave piercing hulls, limited crossmembers. High tech materials.She was huge. She was unfortunately a catastrophic failure.

[great white]

There appears to be much about this biplane concept that I didn't know. Of course, there's lots about sailing I don't know. Still, I don't like the idea of several tons of down force through the mast onto the center of a single span that could be twenty feet between hulls. I realize that this is exactly what happens on a whole raft of successful hulls and thousands of beautiful designs, but I don't like television, either, and look how successful that is. Is there another way to avoid the compression from the stays and the consequnt overbuilding of the spans?

[Hwyl]

Originally posted by great white:
. Is there another way to avoid the compression from the stays and the consequnt overbuilding of the spans?That's why we have trimarans (and proas)

[great white]

Hwyl, good point. But the articles I've read about tris usually say that they have less room, rather than more, with the amas useful for storage and little else. With a cat, the hulls can be beamier, hence more useful, at least, so my research says. I freely admit that I don't know from first hand experience, which is why this board is so great a resource.
There's another consideration, too. A tri has three hulls, which is one more than a cat, and one of the hulls requires a whole different setup to build, which means more time and expense.
Your comment about the proa is a good one. I had thought about a crab claw sail with an A-frame mast rather than a biplane rig, but I couldn't understand how you would adjust the canvas on different points of sail, as when tacking or gibing, specifically, what happens up front.
Guess it would help to have a ton of sailing experience, and salt water in my veins...

[Hwyl]

Great White, I guess I was being facetious. You are right. The tri has much less space and the outer hulls ought only be used for bouyancy, even more true with Proas. One of the ways designers have overcome your dilemma is to have a strut under the mast with shrouds to either hull. I still don't think it's an elegant solution.
Many cats have "pods" (especially with the Prout cats)which make them nascent trimarans. I have not really though about the structural issues. The pods make a great place to put an outboard motor, steering wheel etc. There are multihull discussion groups. The guy to go to on your crab claw proa idea would be Dick Newick. He would shoot you if you even sugested putting wight in the amas. http://www.wingo.com/newick/

[ 12-08-2003, 05:08 AM: Message edited by: Hwyl ]

[Aramas]

There's no point worrying about stresses on the main beam of a cruising cat. They have a much wider staying base than a mono so the stresses are lower anyway - that's why they don't usually have spreaders. A 'conventional' rig for a cat is a 3/4 riged sloop with a forestay and 2 shrouds - usually a rotating mast and fully battened roachy main. You could simplify the headsail handling with a roller reefer, but they're notoriously expensive and unreliable. About the only reefing option for a big roachy main is batten cars and slab reefing - more of a pain. There are numerous 'whacko' configurations, like an A-frame rig that has the main on a central stay. There's actually a 40' Wharram with one of those near where I live.

Junk rigs aren't very good for cats because of the quick motion and acceleration/deceleration. From what I've read from people that have used them (in Seapeople Magazine - a mag for Wharram sailors) they tend to pitch the wind out the sails (whatever that means - lol)- I assume they mean that the (heavy) rig exascerbates pitching and the sail flops around a lot and never really establishes clean flow.

I'd have to agree that Wharram cats are the easiest to build. They're basically a boat shaped triangular tube made from ply/epoxy. Cheap and simple - even moreso than a sharpie. Imo they're also slow and butt ugly, but it takes all sorts smile.gif

I would suggest that before you consider buying a multi that you actually do some sailing on one at sea. While it's true that they can be fast and they don't heel much, some people absolutely hate the quck, jerky, unpredictable motion. If you have trouble getting around then the only way you'll know how it works out is if you try it. While you're at it get some sea time on a traditional heavy displacement cruiser with a junk rig and compare. I know what I'd choose but I was born lazy ;)

[great white]

Aramas, thanks for the insight. Singlehanding is a vital part of the concept, which means that the sails have to be easy to reef and hoist and handle. Especially since my wife of 35 years is arthritic, although eager.
I read about the Wharram designs, in fact, they inspired me a lot. I really appreciate the KISS concept, and it seems to me that these designs embody that to a degree that few others approach.
I originally passed on the concept because, as is pointed out elsewhere on the board, the finished craft has no center deck. Since this boat will be a retirement home for us, and an occasional vacation spot for several other couples, I need a considerable amount of room. Everyone aboard will be professionals in some rather intense fields... film making, photography, jewelry design, computer stuff... and they will need both private space and work space of their own.
However, with the insights that I have gathered from yourself and other sailors, I am thinking that it would probably be wise for me to go back to the Wharram designs... which I love, BTW :)... and see about adapting them by building a cabin deck between the hulls.
And, in conclusion, I suppose that a conventional rig... though still unstayed... would probably be the wisest choice.

[brian.cunningham]

Looks like a review of the basics is in order.

Get yourself a copy of "THE CRUISING MULTIHULL" by Chris White.
http://www.chriswhitedesigns.com/images/scover.jpeg
http://www.chriswhitedesigns.com/books.php

And by all means get on the multihull boat builders mailing list
http://www.multihullboatbuilder.com/

[ 12-08-2003, 05:47 PM: Message edited by: brian.cunningham ]

[great white]

Thank you brian. Will do both.