WishBone Sailing Rig

[brian eiland]

Two More Examples

I have recently received some Emails that reference a couple other examples of 'wishbone', or 'bi-pod', or 'A-frame' shaped masts. So I thought I would post them here for reference to the discussions.

1)The Valkyrie catamaran Stevenson Projects' Experimental Boats https://web.archive.org/web/20120420081437/http://www.stevproj.com/Carz/XBoats2.html
( original link: www.stevproj.com/Carz/XBoats2.html )
...excerpt, The rig was a bipod of 36' aluminum tubes which could be raised or lowered in 15 minutes (we had a lot of practice by the end of the project). There were four sails: two jibs on Harken roller-fouling (which worked nicely), a staysail on a central catwalk between the cabin and the front crossbar, and a loose-foot, fully-battened main flying on a luff-wire from the cabin.

2)Kolika monohull motorsailer kolika https://web.archive.org/web/20110826144123/http://www.sail-works.com/KOLIKA/html/kolika_10.html
( original link: http://sail-works.com/KOLIKA/html/kolika_10.html )
...have a look thru the picture gallery, Picture Gallery https://web.archive.org/web/20080914182111/http://www.sail-works.com/KOLIKA/html/picture_gallery.html (original link: http://sail-works.com/KOLIKA/html/picture_gallery.html )
...excerpt, Pros and Cons of an A- Frame Mast-System
Analyzing the compression loads on a mast, you will find that an A- Frame Mast will only see half the compressive load compared to a single mast. That allowed us to build lighter masts than a single wooden mast, which would weigh about 600 lbs. - ours being only 200 lbs. each. The extra windage is greatly reduced by foil shaping the mast. An A-Frame with the genoa overlapping the mast, has an another benefit: we can sheet in the genoa closer than on a conventional rig where the protruding spreader usually prevents it. The A-Frame mast rather conforms to the angle of the sail. The ease of unfurling both sails made us take advantage of almost every puff of wind. Even when motoring the mainsail is controlled by a light weight wishbone boom that is completely out of the way. The only disadvantage may be, that you can not control sail shape with as many adjustments as on a conventional mast. You can tighten the stay by hand wheel right below the Harken Furler for flattening the sail or tighten the outhaul via a double Pulley tackle from the clue to the end of the Boom. No other adjustments needed. The 2 short whisker poles can be pre-rigged in special chokes on the bow Pulpit so that you can even single hand a spinnaker with Sock or fly 2 same size genoas.

...this rig certainly reminds me of the original Procyon rig configuration
PROCYON project........a Bold experiment https://www.boatdesign.net/threads/procyon-project-a-bold-experiment.10771/
and particularly this illustration, PROCYON project........a Bold experiment https://www.boatdesign.net/threads/procyon-project-a-bold-experiment.10771/#post-79362

 

[Pericles]

Brian,

Reading the Steve Clark comments July 2004 about the difficulty of maintaining sufficient headstay tension with a forward raked mast, what about something like a flying buttress to prop up the mast. A lopsided "A" frame mounted longitudinally is one image or a fishing rod rest type of support with the feet located on the gunnels.

With reference to your wishbone boom mizzen sail, if the luff stay could be raked further aft, would the lift generated be beneficial to boat handling? As for down wind sailing when crossing oceans, would you consider a Kiteship traction sail? http://www.kiteship.com/outleader.php

Kiteship also had a link to the Bat Ship.
http://www.dcss.org/PopSci_May_06.pdf

Your articles are always worth reading and I look forward to seeing many more. You will have read the latest copy of PBB, I wonder if the Paraglass advertisment caught your eye. Their 3D fabrics could be applied to internally reinforce stitch and glue Epoxy/Marine Ply Composite monocoque hulls. The ParaGlass 22 infused with epoxy resin, scales in at 12 ozs per square foot and UK prices for the fabric are the equivalent of $5 per square foot. Greatly increased strength for very little weight and not too much money. http://www.parabeam.nl/

Regards,

Pericles

 

[brian eiland]

With reference to your wishbone boom mizzen sail, if the luff stay could be raked further aft, would the lift generated be beneficial to boat handling?

Negative, there would be virtually no lift generated this far aft.

As for down wind sailing when crossing oceans, would you consider a Kiteship traction sail? http://www.kiteship.com/outleader.php

Don't see a problem with these if you wish

 

[brian eiland]

Variations on the Mast Aft Rig Concept

By now many of you readers are aware of my affinity for the mast aft or aft mast sailing rig concept. For the most part I am content with this being a singular mast column, stepped a little further aft on the vessel, and canted forward approx 10 degrees.

However, I’ve had more than a few people interested in alternative rigs ask about my rig and bi-podded rigs in the same questioning. Now, I was always enamored with bi-pod mast rig aboard Olaf Harken’s ‘Procyon’ vessel. And this wishbone shaped mast rig in my photo gallery also intrigued me.

So here I present some variations of the mast-aft rig configured with a wishbone/bipod mast column. There is a wide based version, and a narrow based one. And with each of these there are two different spreader arrangements that affect the very important cap shroud angle. Modern mast and rigging materials could very well make these unusual rigs a viable entity

 

[yipster]

Brian, are these the pics mentioned in your gallery?
i more than agree on your filosofie and see planty of possebillity's.
for a power-sailer-cat i like to learn more on carbon tubes, pricing, perhaps a top bracket, forces, construction, paralel sails, drag, and much more

 

[brian eiland]

Photos

Brian, are these the pics mentioned in your gallery?

No, they are not. Somewhere on one of my computers there are some other photographs of that tall wishbone rig sent to me by a fellow out on the west coast several years ago...I just can't find them at this very moment

I also was contacted by the gentleman who purchased the shorter rigged version of this design not long ago, and I tried to encourage his participation on this subject forum apparently without success. When I get a little more time I will try to find him again.

I like to learn more on carbon tubes, pricing, perhaps a top bracket, forces, construction, paralel sails, drag, and much more

Sorry, never got into this detail on the subject as there was not a paying or buying client to do the work for.

 

[yipster]

thanks for the reply, take your time but remember i'm interested
like to work out my version of a perfect cruiser one of these day's
and it makes sence to be a bit more precise eventho its only for fun

 

[brian eiland]

The Valkyrie catamaran
http://www.stevproj.com/Carz/XBoats2.html

Don't know if anyone happened to have noticed their claim as to the pointing capability of their vessel?..."Ullman Sails had a hard time figuring out how to run full battens without a mast to push against, but they figured it out. The main really pulled well without a mast in front to screw up the airflow. The Valkyrie could outpoint any boat it came up against"

 

[brian eiland]

No, they are not. Somewhere on one of my computers there are some other photographs of that tall wishbone rig sent to me by a fellow out on the west coast several years ago...I just can't find them at this very moment

I also was contacted by the gentleman who purchased the shorter rigged version of this design not long ago, and I tried to encourage his participation on this subject forum apparently without success. When I get a little more time I will try to find him again.

Well he found me. I received a couple of eMails from him and most recently a couple of photos under sail.

 

[yipster]

thanks for the photo's, looks like a pure sailing machine
still wonder bout wishbone vs bipod, is that a boom on the second sail
is that a canvas cabin, like to hear more if possible
have to read up on matches on a valkyrie search first
did consider asking stevenson some things, i'm just not that far -yet-

 

[brian eiland]

Photos & Misc file located

Somewhere on one of my computers there are some other photographs of that tall wishbone rig sent to me by a fellow out on the west coast several years ago...I just can't find them at this very moment

Bonanza!! I found the photos of the tall rig version, a whole bunch of them in fact. I'm going to think about the best way to display some of them rather than posting them all. Turns out they are the original photos themselves rather than images on my computer that were taken by, and so kindly supplied to me by Dennis Pickard.

And in the same paper file I found a lot more info on the bi-pod masted vessel Procyon that I will also post once I scan the info

 

[brian eiland]

Olaf Harken's reply

...And in the same paper file I found a lot more info on the bi-pod masted vessel Procyon that I will also post once I scan the info

I posted this additional info and sent a letter to Olaf Harken. You can see his reply here: http://boatdesign.net/forums/showpost.php?p=112067&postcount=33

 

[brian eiland]

Designer of Wishbone Rigs

Well he found me. I received a couple of eMails from him and most recently a couple of photos under sail.

The new owner of the shorter version of these two wishbone rigs recently sent me this note:
message: I noted your thread on rigging loads. Enlightening in a candle in the wind sort of way. Thanks.

The designer of the Orca and Relentless Wishbone rigs was a Boeing engineer. I have not been able to find any of his published writings and did not know if you have a way to search the lit that I cannot.
Fred Greenway was his name. Died last year. Built this in 90 so should have been active in 60's and through maybe the 70's.

On occasion it seems to be more like an aircraft than a ship, but at times these forms are very much in sync Fair dinkum, Kojii Bangs

 

[brian eiland]

Orca Owner Report

Sails very well in light air. Not had it over 15 kts of wind yet due to various refitting . Very responsive, tender only at the dock. Underway very comfortable ride. Cuts through 4-5 foot waves as advertised.

Windshield (1/2"acrylic bulb) disperses deck water over sides.

This hung at 22k - 11k in teh keel - 3/4 cutaway very Amerca Cup-like from 80's I guess.

Wishbone rig flex is a little difficult to get used to for a Bermuda rig sailor... about 2" to leeward mid wishbone (between 2 crossmenbers) at 20 degress of heel in 10-15 kts of wind. All sails out. Sorting that out before any venture into higher winds. Scary to some people. Not familiar enough with carbon yet to know myself what to expect in terms of how far it can flex before the big blow I hear so much about.

Yarns along luff of genoa were pointing up about 30 degrees as advertised. Bow hardly moves at all. Amazingly even ride.

Wing and wing was a bit of a challenge but works. Staysail tended to fly away with the boom.

Hydraulic steering takes a little getting used to but very sweet once you do.

This rig (vessel) is not for everyone due to long snug quarters below, but very fun to drive. Head room very good for me. I am 6' 4".

Sister ship is Relentless documented out of Klamath Falls - also Oregon.

More later. Still trying to get photos to work -

 

[Guillermo]

Aft mast cutter/ketch trimaran sail power calculator

Brian,
Did you know this?:
http://www.barefootsworld.net/windwalker/aftmastsailingcalc.html
What's your opinion?
I've just found it.
Cheers