Crab Claw Riggung On Tri

[GOTTABSOMEWHERE]

I HAVE BEEN ADMIRING "SHELLBOATS" CAT WITH THE TRIPOD CRAB CLAW RIGGING..........I WOULD LIKE TO INSTALL ON MY TRI BUT CAN'T FIND ANY DRAWINGS, FITTINGS, OR RIGGING INFO.
SHELLBOATS DOES NOT HAVE A WEB SITE NOR PLANS FOR HIS RIGGING.
CAN ANYONE HELP ME COME UP WITH RIGGING AND HOW DO YOU SAIL THAT THING ? WHEN I LOOK AT CRAB CLAWS, I SEE ALL KINDS OF SHUNTING RIGS, PRO STUFF ETC. ETC. BUT NOTHING SPECIFIC ON HOW TO MAKE THAT PARTICULAR DESIGN.
ANYBODY OUT THERE HAVE SOME HELP ON THAT RIGGING AND SAIL ?
THANKS IIN ADVANCE

[rwatson]

Just get some bendy trees and some tapa cloth, and follow your nose

Except for looks, the Crab Claw on a modern hull wont achieve much.

They only built them that way in the old days because they had to, and you always get some nostalgia buffs.

[kengrome]

SHELLBOATS DOES NOT HAVE A WEB SITE ...Sorry, you're wrong about this. Fred Shell does indeed have a website, and here's his page about his Crab Claw Cat:

http://www.shellboats.com/sbcrabclawcat.html

[rwatson]

I didnt thibk they were Crab Claw sails at Shell Boats.

The real traditional ones - like at ...

http://www.holopunicanoes.com/crabclaw.html

Comments included .
"The Crab Claw Sail is difficult to reef and the large amount of sail area up high tends to create lots of heeling force. It is not an efficient sail for reaching or going up wind."

[GOTTABSOMEWHERE]

Kengrome,

Yeah He Has A Site But No E-mail
I Talked With Him On The Phone

[GOTTABSOMEWHERE]

Thanks For Your Reply..............but Go To Shellbots And Look

Don't Understand What You Mean When You Say "up High"
Please Take A Look At Shellbots

[rwatson]

Thanks For Your Reply..............but Go To Shellbots And Look

Don't Understand What You Mean When You Say "up High"
Please Take A Look At Shellbots

Yeah - I went to Shellboats and looked - and they are not 'crab claws'!

The real 'Crab Claws' are the traditional Pacific sails that look like a tree with two branches, and cloth between the two branches.

'Up High' means that all the sail is up in the branches, not down close to the hull.

The Shellboat sails are just Lateen or Sprit sails with a boom, and most of the sail is down close to the hull where it doesnt try to tip the boat over

[GOTTABSOMEWHERE]

Rawtson
So Ok........it's Not Traditional "crab Claw"
I Still Like The Low Feature And It Looks Like A Easy Learner.
Now...........what Is The Sail Size ?............etc. Etc.

[BWD]

The tahiti/hawaii ones are vertical, most of the others are lower, some are adjustable.
Micronesian proas are/were the champs, speed-wise, it seems.
Personally I think the heavy tahiti & hawaii double canoes had vertical rigs to help keep steerage in the high seas they ran down in voyaging/migration between island groups. Maybe not so good on a modern boat 1/2 as long and much lighter.
Here's one of my favorite pictures of crab claw rigs, from New Guinea.
Look about and you can find photos of them with the sails hoisted to various angles, presumably some could be used in more than one trim.
For a tri I might go with a short mast and flexible-tipped yards with adjustable stays, rather than a tripod. Having more flexibility to adjust it might help you find the best way. Plus you could have clearer decks when all furled.

[rwatson]

Beautifull shot there BWD - they obviously have fun with their boats, and no collar and ties ....

GBSWHERE - you havt got a Tri you say?. What type, what size, has it got a sail already ? Can you post a picture?

The size, type of sail, rigging have soooooooo much to do with the size, shape and style of the boat.

[GOTTABSOMEWHERE]

Rwatson
17' Hobie Hulls...........16' Dory Between
No I Don't Have A Sail.............trying To Make Like "shellboats"
Have 16' Spars (booms ?)
Have 8' A Frame..........stayed To Hulls Fore And Aft.
Keep The Dialog Going

[rwatson]

If you converted a Hobie, you probably have the old mast and sails. If you dont, then you should be able to pick up an old set of rigging and sails secondhand for almost nothing.

Just tie the bottom of the mast to the bow of the dory, move the jib attachment fitting near the top of the mast down to the say, a halfway position on the mast, and run a rope from the newly placed jib fastening to the top (apex) of your A frame.

You may have to experiment on the position you put the jib fastening at, to allow for the current positioning of the A frame, and the space you have for the bottom of the mast to swivel about.

Then you will have to cut some sails to suit the new shape of the mast. If you are clever, you might be able to put the old mainsail on upside down, so the bit that used to to be near the boom (foot) , is now the back edge of the sail (leech).

Simple diagram attached that I hope will help.

My recommendation, if you just want to get on the water ,is to stick the old hobie rig in the centre and save yourself all the trouble and hassle.

You have to remember that these 'olden day' lateen rigs were built because they needed to create 'light' manouvarable rigs without all the advantages of modern fittings and metals. In practice, they require a lot more effort to get to work well, and are a lot more fiddly to use. Reefing is a problem for a start, and the foot of the mast has to be controlled as well as the foot of the sail.

But, you will have fun experimenting, and learn a lot trying stuff out.

[GOTTABSOMEWHERE]

Hey thanks..........
I like the idea of useing what i have but...........existing mast is 28" long.
That would stick out the stern about 10'. Maybe I should "hacksaw off"
about 10' from the bottom ? Mainsail dosen't have the right shape.............
like the "crab claw" style.
Another question (now that I have your attention) dosen't the sail/mast bump
into the forward "A" support ........or tripod?
I was going to use the Hobie's shroud line fastenting points (2 fore & 2 aft)
to stabilize the "A" and not have a tripod mast like Shellboats.
Cain't come up with a light ridgid "A", keeping with a homebuilt messabout....
so I'm looking at 8" galvanized light weight fence posts. I am assuming the two spars........big sail........lines.........etc would be quite heavy and require
an "A" of superior compression strength. Additionally, super strong/big
deck plates to accomodate the "A"
You are really helping my thinking...........
OH by the way......Putting the old 28' Hobie mat in the traditional manner
would give me the traditional problems of putting up the damn thing and taking it down. If the "A" is only 8' high I can trailer it down the highway
with the sail lashed to the beams. When I get to the water.........simply
crank up the sail.........yes?

[rwatson]

I wouldnt saw the mast shorter until you have tried it out.
Like I said, you will need to recut the mainsail - hope you have a sewing machine :-)

yes, the sail/mast does bump into the underneath of the A frame (tripod) - as do the ones at Shellboats. A most unsatisfactory arrangement in my eyes, but hey - you are the customer :-)

You dont need stays for the A frame arrangement, or even a tripod. Remember, these designs were developed by resource poor sailors.

If the foot of the main spar is tied to the bow of the centre hull, as well as to the apex of the A frame spars. it forms a tripod with the A frame.

Likewise, if you tie the main spar to the TOP of the A frame (not hang it underneath), and make sure the track of the mast faces the sky when you insert the sail, you can actually pull the sail OVER the mast to the other side of the boat for better performance on the other tack (with the purple line). The old mast will flop back and forth on top of the supporting A frame as you change the sail side.

Also, dont use steel pipe for the A frame. Get an old mast off some small boat and saw it in half. It will be plenty strong enough and a lot lighter

All so much more work for a mast/sail setup that wont be nearly as easy or effective as the old Hobie rig, even on the 'modified' trimaran.

[GOTTABSOMEWHERE]

Understand your comments on spar material of "A" frame......
Don't understand fixing main spar to bow. What you explain is nothing like I see on the "shellboats"
Understand "resource poor sailors" but there is an evolution that is happening.
"main boom on top of "A" ?????? You are kidding me right ?
I know you AUZZIES are big on kidding the YANKS but really ???
Please remember my point of not having to set-up and take-down 28' mast.
I was about to suggest you change your brand of beer to BUDWEISER
but BUD has been bought out by a Belgum company.
Alas BUD is no longer a U.S. beer.

[waltm]

I don't think he's kidding. If I follow it correctly you would be using the mast also as the forward part of the tripod, that is why you are attaching it to the bow, like the shellboats do with a third member
http://www.shellboats.com/images/cccc3_big.jpg

And as far as mounting the mast with on top of the frame with the luff track facing up you would tack the sail over the top around to the other side although I'm not sure how easy this would be if there is a large boom on the end of the sail but might work well if the sail were boom less, sort of like an asymmetric spin?

[rwatson]

You got it WaltM

My diagram was a bit crude, but I was doing it at work and trying to stop the bosses looking.

The other point is that the end of the mast doesnt have to be solidly fixed to the bow, it can run on a bit of a traveller so that when you run before the wind, it can be moved over to one side or the other to get a bit more wind from behind.

And that doesnt have to be too important, because to get top speed running before the wind, you actually want to Tack downwind like the high performance multihulls do.

Yes, a boom would prevent tacking, but usually these boats dont have a boom because there is nowhere to pivot it from, and way too long to control as it sweeps almost the entire hull.

The Shellboats method is strange because the boom prevents getting a curve in the sail from bow to stern, which is where all the lift is. If you have a boom, then all the curve is from bottom to top, and the only curve produced is by lifting the boom. The other problem is that a large amount of the sail is high above the deck, making the tipping pressure much higher for not much more 'drive'

They use a tripod, but the foot of the main spar is fastened to the bow. If they are going to have a solid leading tripod member, they could at least allow a bit of side to side movement to be able to place the sail a bit better.

As far as raising the main spar, thats a doddle. You fasten both legs to the main spar, tie foot of the main spar to the bow, and then you fasten only ONE of the spars to the side of the hull. By pushing the OTHER spar, the mast will magically raise the main spar, until you can fasten the final spar to the other side of the boat.

Get some cloth and string and bits of wood, and you will soon get the idea.

[GOTTABSOMEWHERE]

EREKA !!!!
I like the idea of "adjusting" the foot of the main spar at the bow.
What about a block there or main sheet type of adjustmant ?
Sheet adj at bow, and sheet adj on lower boom/spar. ...........WOW?

Boom /lower spar does bend somewhat and would give the list you referred to
I like it ....I like it....
If the 8' A works I can just flop it down and zip down the highway
THANKS

[brian eiland]

Polynesians sail the Pacific to save their ocean

http://www.sail-world.com/cruising/index.cfm?nid=88687&rid=11