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

Anonymous wrote:

Hi Jim,

We converted our ANNIE in 2018 (a 30' Cornish Crabber, now for sale with her gaff rig soon to be re-fitted). She was transformed and we loved the confidence that the rig gave us. However 50sqm plus is quite a thing to handle even in JR form, so I would encourage anyone thinking of this size of rig to try to find a similar one to sail first. Like you, we wanted to keep the accommodation and deck hatches as much in place as poss, but ended up moving the mast forward nearly 4 feet which made her a real cat-boat though the balance turned out to be perfect to my eternal relief and joy. Thanks to Arne in that respect - I followed his instructions for finding the right place for the mast to the letter! So her mast was in the eyes of the ship, wrecking the spacious head compartment - which was an excessive luxury!

I made the solid D fir mast myself (I'm a sawmiller) and, on a 6ton boat the (estimated) 190kg stick gave her a lovely slow roll, so my advice would be you don't necessarily want to make a super-light mast on such a vessel. Too light a mast may give her a sharp motion? Incidentally, our 5.9m battens were ali tube, as was the yard. The whole bundle was a big lift for 2.

She sailed like a dream!

It's a great thing you're planning. Good luck!

Pol.

Hi Pol, thank you for that reply, very informative! Your Annie does look good in the photo. 

I agree with having a heavy mast. Her present one is and she has a lovely motion. The construction method I am thinking about is not for lightness but strength. I intend to keep building up the layers of glass and carbon untill it is a similar weight or a bit more than my current mast. I imagine the finished mast will be very stiff, is that a problem do you think? I was thinking of carbon battons like Ming Ming 2. He described his sail as being virtually flat at the top and then each lower panel has gradually increased  camber which sounds interesting. Does anyone have any views on his lower two panels being removable. Seems sensible as easier to make at home and they could be removed in areas with strong wind.

What are your mast dimensions and sail area please. 

Thanks, Jim 

Anonymous wrote:

Jim,

now I tried my hand on it, using a standard Johanna style sail with the yard angle lowered to 60°.  The resulting sail in yellow lines is the result.
My guess is that the original JR (retraced in black) should work just as well as the one I drew up, so all I can say is good luck!

Cheers,
Arne

PS: The full size drawing is in my album, Arne’s sketches Section 7, photo 13.

Thank you Arne for spending the time to draw this, I like it! Possibly I should place the mast more towards the bow but for structural and access reasons I have placed it aft of the fore hatch, which is why I've drawn a taller and narrower sail that projects in front of the mast a bit more than normal to compensate.

I've explored using a suitabley strong existing aluminium pole for a mast but drawn a blank. I am now nearly decided on building a thin walled (22mm) Douglas fir mast, then wrapping glass tape around and and around to the truck. Then carbon tape layed side by side all the way up longitudinally which should give good torsional strength, then repeat glass then carbon. Perhaps 5 glass and 4 carbon plus glass taping the inside. Perhaps aiming for a walk thickness of 18 mm. If it's convenient maybe vacuum bagging each layer. The above is a not very educated guess but I think the principle should work. I was thinking to carry on taping till too strong people could only just lift the spar. My current rig is heavy and she is slightly down at the stern since fitting a 36 hp buhk so a heavyish mast will be ok. I would very much appreciate your and any one else's thoughts on the prospective construction.

At the moment the planets are aligned as I have someone who is interested in buying my entire rig, I can use space in a mates workshop this summer and a boatbuilding friend is going to give me a hand with the build. All the best Jim

Jim,

now I tried my hand on it, using a standard Johanna style sail with the yard angle lowered to 60°.  The resulting sail in yellow lines is the result.
My guess is that the original JR (retraced in black) should work just as well as the one I drew up, so all I can say is good luck!

Cheers,
Arne

PS: The full size drawing is in my album, Arne’s sketches Section 7, photo 13.

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