Junk rig

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oz-1

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Happy Christmas and peaceful New Year to all. I am thinking of converting my conventional cutter rigged, home built 22foot sailboat to junk rig. I have joined the junk rig association and downloaded the practical junk rig book. I think there are a couple of boats, similar in size to mine, that came with a junk rig. If there is any one out there with one of those boats, I would like to ask if they would be kind enough to give me the diameter, length and wall thickness of the mast. This is for an aluminium mast. My boat is a home built flicks ( American designed boat). Any information will be greatly appreciated. Best regards, Oz.
 
Hi daydream believer, thanks for your prompt reply. I have looked at Roger Taylor's video and iv'e searched for aluminium lamp posts with no success. I think his video is about 10 years old. I have found a company that sells 606t aluminium tube in various diameters and wall thickness, and hence my post. Best regards, Oz.
 
oz-1 said:
Hi daydream believer, thanks for your prompt reply. I have looked at Roger Taylor's video and iv'e searched for aluminium lamp posts with no success. I think his video is about 10 years old. I have found a company that sells 606t aluminium tube in various diameters and wall thickness, and hence my post. Best regards, Oz.
Click to expand...
I googled this in a few minutes
I am sure there are lots of suppliers if you look
lamp post
But this is in the Uk & I do not know where you are located. That may be the issue
 
The original Ming Ming was a Corribee, so 21' and very light. The second Ming Ming was an Achilles and had a section of lamppost for a mast, and it was extra tall because of his experience of low winds in the high arctic summer. Dunno about the Corribee, but there was actually a small junk rig boat from the same maker, called a Coromandel. Presumably the Junk Rig Association will have members who know if no one here does.
 
You can use a tree, optionally split and hollowed out.

I've also seen (on the Junk Rig site, perhaps?) composite masts made where an aluminium tube was extended with a bit of tree. This seems puzzlingly the wrong way around, with the heavier component at the top, but maybe it was for easier fittment of masthead rigging components, or they wanted to build some taper into the top.

Here in Taiwan I would have the luxury of large section bamboo, (if, say, I was building a multi-hull) but that probably isn't available for free where you are.
 
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If you really are in Oz, that's the implication, there was a development called, I think 'Gold Spars' in or around Sydney. https://goldspar.com.au/


I thought All Yacht Spars had their own extrusions made locally, though don't know if locally means near Brisbane or in Australia (there is a big difference :) - as you will know). I do note you have found a spar, or tube, maker - but AYS, and other mast builders, would be able to recommend dimensions - its part of their bread and butter.

One of the riggers at The Alfreds has a huge stack of old rigging, old spars etc, not sure what he intends - but rather than buying and dressing a new spar you might find old ones to suit, what do riggers do with old spars?

Jonathan
 
I suspect you are starting this project at the wrong end.
Unless you know the correct righting moment for your boat (@ 30 degr.) and have calculated the required moment of inertia for your mast, you will not get a satisfactory or useful answer. To note: not all 22' boats are the same, nor do they have the same stability characteristics. Small boats are considerably less stable than larger ones. Stability increases or decreases, as that may be, to the third power. Even small variations in beam, length and bilge form make a considerable difference.

Your boat was not originally designed for a junk rig. Why is this important? A freestanding spar has to be stronger and inherently heavier than a supported one and a junk sail is heavier as well.

A freestanding aluminium mast will be have to be heavier yet, due to the risk of material fatigue. The Nonsuch series had a bit of a habit losing theirs as a result and Freedom too changed to carbon and not just for weight saving.

In the eighties, when freestanding masts were all the rage, I was involved in the design and, later, build of a 50' wing-masted schooner. After many evenings of heated discussions (and copious amounts of wine) the boat was given a single, cutter rigged and conventionally stayed mast. It did wonders for her stability, calculated and otherwise.
 
As an alternative you may find it is simpler to construct your own wooden mast and wrap it in carbon fiber cloth. A good friend did exactly that for a Heavy long keel 32ft wooden boat last year that he converted from Gaff rig to Junk rig. He did that because he is good with wood , there were no suitable aluminum poles and and he says it wasn't that difficult.
 
Anyone is free to do as he likes. However a flat junk sail has the lowest lift to square foot value of any rig. In this context it has long been determined that the best marriage for a junk rigged yacht would be a light displacement, easily driven, contemporary hull, as in the Galway Blazer or Ron Glass tradition.

I know the Flicka, designed by Bruce Bingham and originally for ferro cement construction. Essentially, she is short, fat and extremely heavy with a very modest ballast ratio. Additionally, she has a SA/D lower than many a motorsailer. They are reputed to be a wonderful liveaboard in spite of their compact size and which is hardly surprising given that volume. In spite of their great weight, they are fairly tender, no doubt due to the amount of underwater volume/buoyancy necessary to float that load.

The Flicka junk rig was not designed by Bruce Bingham, but was added later by someone else. I'm not sure the Flicka planform is the best candidate for a junk rig, both from a stability as well as a performance point of view.
 
Although, being very easy to handle, junk rig does offer some opportunity to fit a very large rig to offset the low efficiency per square foot - which is anyway not relevant for downwind sailing.
 
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A junk sail does not have to be flat. Join the Junk Rig Association and you’ll get access to people who’ve designed and made cambered junk sails. Or read Roger Taylor’s later book about the conversion and rigging of Ming Ming 2. Info available online, I’m sure.
 
Years ago PBO did a side-by-side test with two Van de Stadt Sprinters, one hot racing boat and one with an experimental split junk rig. With both sailing single-handed and no extra downwind sails, the bermundan rig was quicker to windward, they were level on a reach and the junk was quicker on a run.
 
Yes I read that at the time.

Downwind the Bermudan owner was faster when he deployed the spinnaker.

To be fair, this split junk rig was quite a bit larger in area than the Genoa plus Bermuda mainsail.

I believe that the junk rig owner later had the sail cut down to restore a more favourable handicap. But I’ve not heard what happened in terms of results.
 
As I had intimidated, I have investigated and looked into various types of freestanding masts & rigs, junk rig configurations included, and I am very aware of the possibilities to improve the aerodynamics of the junk rig. I even designed one of my own, only to discover that I was reinventing the wheel.

Also, I'm not at all certain about the aerodynamic quality of the scalloping as seen on some junk rigs with shaped panels. As the boat heels, the battens and scallops tend to end up in a cross flow of the air moving over the sail.

The fact that a single, large surface has more drive to leeward is hardly revolutionary. After all, multi-masted and sailed vessels do not shine on this point either. Any owner of a catboat type rig, no matter the plan form, will tell you so. There isn't much aerodynamic science involved in this either.

On the downside however, I have been told by several Nonsuch owners that, downwind, the one-sided leverage of the single sail tended to induce broaching in boisterous conditions. A common theme with catboats.

The biggest problem, particularly for hulls not specifically designed for such a rig, is the much greater weight of the junk rig. In this context, I have observed that some of the junk rigged Benford dories seem to sail at rather sharp angles of heel. A tendency for large angles of heel is not a concept for cruising or voyaging comfort; I speak from experience over several thousands of miles

I certainly would be concerned about putting a significantly heavier rig on a hull that appears to be tender in the first place.

The big advantage of the junk is, or rather was, the ease of reefing. Much of this has been superseded by the development of furling technology on conventional rigs.
 
Hello everyone, apologies for not replying to all the kind and helpful comments about my query for changing the rig of my boat to junk rig. I have joined the junk rig association and got the junk rig handbook. There is a lot to study!! As laminar flow mentioned, my flicka is certainly tender, but once it has heeled slightly it stiffens up. My flicka is one that was slightly altered ( at my request ) by Fred Bingham, Bruce Bingham's father, so she is 22 feet on deck, 19 feet 6 inches waterline length, with 8foot beam, Displaces ( empty ) 3000 kilos with 1000 kilos lead ballast. The draft increased fom 3feet three inches to 3feet 6inches. There is a saying that there is no fool like an old fool. Well, i am old and a f..., so i will give it a go while i am still capable. By the way, laminar flow, sounds like you are on the west coast of Canada, well, i used to live in Squamish, BC. Best regards, Oz.
 
Daydream believer said:
I googled this in a few minutes
I am sure there are lots of suppliers if you look
lamp post
But this is in the Uk & I do not know where you are located. That may be the issue
Click to expand...
I get blocked, which is a mild pity, because aluminium lamposts puzzle me.

WHY? What are they for?

There doesn't seem much reason to save weight, they seem likely to be more expensive than the alternatives, and maybe vulnerable to theft.

I dont get it.
 
Hi ducked, from what i understand, aluminium street lamposts are used on junk rigged boats as they are tapered, can be obtained in various lengths, and can be had with different diameters at the base ( from about 100mm to over 270mm ), and then tapering at the top to abot 80mm or 90mm. Of course i could be talking a load of rubbish!
I am pleased to say i have sourced a 9.2 metre post. if there is any interest, i will be happy to post photos when i start the conversion, which hopefully will be late spring/ summer time. I have to complete some projects i promised my wife first! Best regards, Oz.
 
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