Anonymous wrote:

Jim wrote:

I hope this is the right area to post some initial questions. I designed and built Atlas as a gaff cutter 25 years ago in Tasmania and she is of traditional timber construction. I am now getting older and am seriously considering converting her to a single masted Junk for simplicity. I've drawn an initial rig that has a 43 foot mast (6 foot bury) with a flat sail about 550 square feet (please see attached photo). I would like to sail back to Australia so would like a bullet proof mast with some reserve. I would rather not a wooden mast but perhaps an aluminium one if possible. I imagine this rig might be at the outer limits as regards weight. I look forward to hearing member's thoughts. Thanks, Jim

I'm getting older too, and typing has got difficult, but this is an area in which I have relevant experience both in size of sail and in sailing in the Tasman (with Tystie), so should try to help.

550sq ft is big, and it's necessary to make things as easy as possible. This means:

1. High AR, to keep the battens short.
2. Yard at 45˚, and shorter than the battens, to keep the loads on the hauling parrels low.
3. Make the sail in two or three sections, joined as on Mingming II, simply because making a one piece sail in this size is hard, heavy work, especially for someone coming new to sailmaking.

So I think your original drawing is pretty close to ideal.

I echo Annie's comments on mast building. Either make a wooden staved mast with 20% wall thickness, or make a very light former, possibly of foam, on which to lay up uni carbon; but don't mix the two. Anyway, the latter is very difficult to do well, and only justified on a lightweight boat.

Actually, you can probably find a grown mast in the forests, in Tasmania. But as I've said often before, the pragmatic choice is a hybrid, with an aluminium tube at the bottom (10in dia x 1/4in wall, in this case), and a barrel tapered wooden topmast which can be either staved or solid.

Thank you David for your advice.

Yes weight of sail and battens will be an issue. I hope to use carbon battens and a lightish to medium weight cloth. Would you recommend a weight and perhaps a manufacturer. I don't mind paying a bit extra for something that will last and be UV stable.

When we sailed back from Oz we cruised in company for a while with a Hereshoff cat ketch called Pollen Path. The unstayed masts were layers of glass over hollow spars. Randy complained that they were a bit whippy at the mast head but they must have been strong as she survived the Queen's Birthday Storm, when many were lost.

Talking of old cruising friends, I wonder if anyone has heard of someone we met. I think his name was Roger and he had a green junk rigged steel Tahiti ketch called Irene. He sailed single handed and I was very impressed watching him thread his way through the reefs in Tonga. He was also a very nice chap.

Thanks again, Jim 

Jim wrote:

I hope this is the right area to post some initial questions. I designed and built Atlas as a gaff cutter 25 years ago in Tasmania and she is of traditional timber construction. I am now getting older and am seriously considering converting her to a single masted Junk for simplicity. I've drawn an initial rig that has a 43 foot mast (6 foot bury) with a flat sail about 550 square feet (please see attached photo). I would like to sail back to Australia so would like a bullet proof mast with some reserve. I would rather not a wooden mast but perhaps an aluminium one if possible. I imagine this rig might be at the outer limits as regards weight. I look forward to hearing member's thoughts. Thanks, Jim

I'm getting older too, and typing has got difficult, but this is an area in which I have relevant experience both in size of sail and in sailing in the Tasman (with Tystie), so should try to help.

550sq ft is big, and it's necessary to make things as easy as possible. This means:

1. High AR, to keep the battens short.
2. Yard at 45˚, and shorter than the battens, to keep the loads on the hauling parrels low.
3. Make the sail in two or three sections, joined as on Mingming II, simply because making a one piece sail in this size is hard, heavy work, especially for someone coming new to sailmaking.

So I think your original drawing is pretty close to ideal.

I echo Annie's comments on mast building. Either make a wooden staved mast with 20% wall thickness, or make a very light former, possibly of foam, on which to lay up uni carbon; but don't mix the two. Anyway, the latter is very difficult to do well, and only justified on a lightweight boat.

Actually, you can probably find a grown mast in the forests, in Tasmania. But as I've said often before, the pragmatic choice is a hybrid, with an aluminium tube at the bottom (10in dia x 1/4in wall, in this case), and a barrel tapered wooden topmast which can be either staved or solid.

Anonymous wrote:

Hi Jim.

Regarding your masthead, a good length of solid timber up there may be a good idea. As to the fitting, I started with Practical Junk Rig and adapted a little. It can be wonderfully simple. The spare halyard tang on the fore side of the fitting is great for lots of jobs including getting to the masthead without having to dismantle the halyard from the yard.

Regarding the step, I formed a slightly oversize step "socket" to take the tapered heel, and used a 2 part polymer resin for the neatest possible seal, which was poured in immediately after stepping. Before stepping, the heel was sparingly coated in Vaseline, and I had small string under the mast to allow an air gap in case it didn't want to leave at haul-out time. This step lasted for 3 seasons and was absolutely tight. Others may know better, but I think it would have lasted many more seasons. 

Pol.

Anonymous wrote:

Jim wrote:

Forgive my ignorance but has Arne published a book with his ideas and drawings as I would like to learn more.

Yes: Arne's Area Has his "Book" (in quotes because the original is as well) as well as other documents. There are many example conversions.

Anonymous wrote:

Hi Jim,

Thanks for yours and your compliment. She DID look fabulous with the JR!

I think I'd have been put off by the cost of carbon, glass and epoxy (had I investigated) and the complication of making the wooden mast so thin-walled. I'm a bit of a wood basher so laminating up a solid D fir mast out of 63mm x 280mm x up to 9m laminations was was more my kind of thing! The outside was carefully treated with lots of thin epoxy (MAS is wonderful, simple, non-smelly kind-to-skin stuff partly made from renewable materials) and epoxy paint from Jotun. Many junkies make the mast from a single stick which I would have done had I not had the air-dried D fir already. It was quite fast-grown stuff so not suitable for a bird's-mouth construction I didn't think. It is quite whippy at the top so I treated it like a fragile gaff topmast and it worked well. As Annie Hill said at the time, what bends shouldn't break. Well, it didn't! Now it is off to Chris Phillips, in Scotland also, for re-purposing as the mainmast in his Wylo junk schooner SERCHTHRIFT (see the current Magazine no. 91, p55). It is almost exactly the spec on his drawing, I believe, which is about 11" or 280mm square at the partners, tapering to 7" or 175mm at the heel and about 4" or 5" at the truck. It is 42' or 12.8m overall, with just over 5' 1.6m bury. 

In working out the whole sailplan I got immense help and enthusiasm from many members, Arne in particular, and initially from Practical Junk Rig without which I probably would not even have got close to thinking about such a project! 

Another way of building a wooden mast is to shape it up roughly, then cut it up the middle, hollow it out and then glue it back together. 

I don't think you can have too stiff a mast although I believe that a flexible mast is kinder to the rest of the structure of the boat and deals with shock loads better. What I liked about the whippiness of our mast is that it made us THINK like the sailors of an old Edwardian gaff-rigged yacht with a spindly topmast. It made us more sensitive to how much sail we had up for any combination of wind and sea state, and we were constantly "blown away" (forgive the pun) by how much power the 52sqm rig had, even with "only" 3 panels up, and sailed with  less sail up as a result for no drop in speed.

There is a lot on these forums about decreasing the camber the higher you go panel by panel. Arne's pages on the subject of sailmaking are a fantastic help, and there are many discussions on the forums about camber in junk sails. We followed this idea when making our sail.

I like Roger Taylor's idea of lashed-in panels, easy to remove and repair, and come the day when we replace our sails (34' schooner) I will look at that more closely. I like stuff being lashed and not in tracks or bolted etc.

I'm not the only one who will be watching your conversion with interest. Keep us posted please, and write lots with heaps of photos for the Magazine!!

 Pol.

Hi Pol, thanks for the info about your rig. Good to hear your mast has found a new home. I was considering birds mouth construction but will probably go with barrel stave using biscuits to align the joints seeing as it's more of a former. Forgive my ignorance but has Arne published a book with his ideas and drawings as I would like to learn more. I've got the Hasler/McLeod book which is good, (I've got a Hasler Mk5 ss gear on Atlas). I've been thinking about the mast head fitting design and also a secure way of attaching the mast to its step. 

I'll need to add more floors and fit a new mast step. I have a large baulk of recycled pitch pine which can be shaped down which will do the job particularly if I can notch it into the existing step.

Cheers, Jim