Wishbone main ketches, Mizzen mules ?

Has anyone experience with a Wishbone ketch (such as Robinsons Svaap)

I was wondering how they were to windward,
how to determine the best C of E

whether they are truly a no-chafe rig when running

whether they are much better than using a mizzen mule on a std ketch rig

which would be a better option.

I have read that the mule tends to get back winded by the main when going close to windward. Maybe you have to accept a slighly more open course?

Any comments, thoughts or ideas for spreading lots of canvas on heavy big boats please.

Cheers

 

The problem with the wishbone is always the same , HEAVY WEATHER.

If the wishbone is to be kept aloft it must be restrained from taking the mast with it if it gets loose.

Large Wishbone boats HAVE been dismasted, so the trend now is for fully battened mains to get loads of area, and good shape.

The Mule usually has far to little area to bother with ,
but a mizzen staysail's area can excede the main ,and is GRAND on a reach.

FAST FRED

 

If the Mizzen is a decent size eg 20% of the sail area then the mizzen mast can be around 80% of the length of the main mast. This leaves a large triangle for a light air mule.
Ted Brewer is a fan of the mule but I have no experience.

I agree the staysail is an excellent number. All the big ketches I have sailed on have flown them, the results always delight those aboard.

The wishbone main is another thing, consider it a modern Gaff rig. Some designs allow the lowering of the wishbone for heavy weather.

Robinson's "Svaap" was successfull as was "Wishbone" both famous old yachts.

Its a pity so many of these ideas get sunk simply because of the rating rules.

Cheers

 

Mike,

Perini Navi use roller furling mules on the main backstay to gain sail area. But, the only way they could get them to work is by sheeting to an athwart ships traveler at the head of the mizzen mast. The traveler then needs its own backstays so it doesn’t twist the top off the mizzen mast.

The wishbone is okay, but hard on the wind you still have that sheeting problem.


Tad

 

Thanks for the comment TAD

It would be interesting to nail down the reason for the failure of the mule on this vessel, or what points she had problems on. I think it is best to consider it a light air sail and for fairly free sailing. I have seen a number of photos of older vessels flying the clew directly from the mizzen masthead with no problems. Probably was backwinded by an excessive roach necessitating the masthead traveler .

Cheers

 

Interested in discussion on wishbones and svaap. We own what is believed to be a sistership to Svaap, it was Alden 224B and ours is recorded as 224C, sure looks identical.

Does Robinsons book not deal with the wishbone performance?

 

Bryan
Sorry to take so long to reply to this.

Robinson waxes lyrical about the wishbone main after converting Svaap for his Galapogas voyage (after circumnavigating ). But vessel performance was not compared much between the two rigs.
What configuration is your rig ?

 

Mike & Bryan,

Roger Taylor prints a fairly lengthy letter from Robinson on his rig modifications to Svaap in his book, Good Boats, published in 1977. This letter is reported by Taylor to be recent, I assume mid 70's, and is Robinson's memories of 1928-31. Quite some time back!

After completing a RTW voyage, Robinson modified his standard ketch main to a wishbone trysail over a mizzen staysail. He first built a trial version, sticks & string, with sails sewn by his mother from unbleached muslin. He states that under this makeshift rig Svaap sailed faster and pointed higher than ever before. She also exhibited strong weather helm. He then took her to Nevins yard where they built proper spars and fittings, he had Ratsy build new sails, and he lengthened the bowsprit and added an outer jib. He doesn’t say how much the bowsprit was lengthened, but there is a picture of the boat under sail, and the bowsprit looks long.

Robinson concludes saying that he found the rig "extremely effective, adding greatly to the performance of the yacht." He also states that there are drawbacks, "The rig would be unsuitable for the singlehander. It becomes impractical beyond a certain size. It requires impeccable maintenance to avoid failure of any of its elements."

Below is a 51' wishbone ketch I had a hand in designing in 1995.




Tad

 

Thanks Tad

Chanta looks very intersting, how did she perform?

 

Mainsail-less ketch, etc

Hello Mike,
I now you are not a fan of my single-masted ketch rig concept, but in my discussion on the website there is this little hidden note:

"I once had a copy of a test on a Morgan 41' Out Island ketch , where upon removing the mainsail, the boat lost only 1/2 knot of speed, but cut its leeway in half (from 11 to 6 degrees). A staysail was then rigged between the masts in place of the mainsail, and the boat regained 1 knot of speed while retaining its decreased leeway."

I think this addresses both pointing, speed, leeway in an interesting fashion. I suggess the use of a wishbone boom on my mizzen sail to get better shape as well as to give head bashing clearance over the upper helm station, and to 'flip-up' to clear the fishing cockpit

Here's another freestayed ketch concept by Dick Newick on his design White Wings. I think he utilized a wishbone boom on the mizzen.
<http://www.dicknewick.com/WhiteWings.html>

Arabella (recently visited the Annapolis show) had some interesting rigging ideas. Here's one website but there are probably more with some technical aspects of the rig design.

I never did care for the use of 'travelers' mounted at the top of mizzen mast to control mules...gets more complicated than my rig.

And then there is the concept freestanding wishboned ketch rigs onboard the Wylie vessels: http://www.wyliecat.com/yachts/models/wyliecat_65.html

 

Mike,

Chanty II is a cold-molded centerboarder built by Zimmerman Marine in Cardinal, Virginia, on Chesapeake Bay. Her owner has a house next to the yard and Zimmerman have maintained her "as new" since launching.

LOD is 51'9", LWL is 40'10", beam 15'0", draft b/up is 4'8", b/down is 11'8". Displacement is about 50,000 lbs with 21,000 in ballast. Sail area with 100% fore triangle is 1680 sq. ft. All spars are carbon, built by GMT in Rhode Island. Her 5 sails are all hydraulic roller-furling, the trysail and the mizzen inside the masts.

The owner uses her mostly for daysailing on the bay in summer, as this is a light-air area, she has considerable sail area. It is also quickly increased or reduced, and there are no other sails to mess with. She is sailed from the cockpit with all powered winches. She is quick in lots of wind, having the stability to stand up to it, and she can ghost in the lightest airs (though not quickly). Due to her weight she is predictable, which is a good thing in a cruising boat. A comfortable sail boat, no racer.

Tad

 

Brian And Tad

Thankyou both for your interesting posts.