No hurry. 
I'll wait before I shorten the mast, because there could be a pilot house in my future, which would make me want to raise the whole sail higher.  I need to put out some of these immediate fires before I even consider going there.
I'll want some rake, at least, so that I can rely on the sail bundle swinging out in light breezes.  The Brunk's mast is reverse raked, and when the winds are light the sail will fall back amidships, a most unhandy occurrence. 

First off, I drew up a rough sketch of Seablossom's new mast and partner location.  It's in my photo albums in a Seablossom's Sail... album

David Tyler wrote:Here we are again, with that tricky job of matching up the rig, the boat, the skipper and the waters. Seablossom has the kind of hull form that has given problems with the flat HM rig, which loses power too quickly as you begin to tack, and doesn't regain power quickly enough as you come out of the tack. She needs a more powerful rig. I don't think I would recommend a totally flat Fantail rig. I would always put some rounding on the head, which is where it does the most good, and I would always put just a little rounding on the edges of panels, where there is a seam under a batten, so that the luff and leech stay tauter and  the middle of the panel is not "starved". But I think that's as far as you need go. As long as you're not looking for the last tenth of a knot to windward, but are content to sail well, and reliably (which is not the same thing as sailing fast) then the Fantail rig will suit you. If you want to sail fast, you have to add more power by cambering the panels; but if you simply want to get to where you're going, reliably, stay with the simpler sail.

I'm not known for speed.  Built for comfort, as the old blues song said.  So sailing less fast than others is not an issue to me.  Getting stuck in stays is an issue.  Make that a disaster, from my perspective.  On the Brunk I can just lean up and back the sail, but I certainly don't want a real cruiser that fails to tack.
If I understand this post properly, what you are saying is to make a sail that is more generously cut than an out-and-out flat sail cut from whole cloth, but without the liberal camber Arne might choose.  It would occur to me that in 19th century and before, in China, rigid flat fabrics would have been unimaginable, so that sounds like it might go with the reality of the Chinese tradition.  All worthy of thought.
Many of those who sail conventional plastic pointy sail cruisers on Stockton lake (and yes, they are there, up to and beyond 40 feet) tend to sail downwind and motor back, but I don't want to do that.  If I do sail the lake - not a foregone conclusion, but possible - I definitely want to be able to sail back to where I started from.

Paul Thompson wrote:

Jeff, you have a heavy displacement double-ender a type of hull that could not be more unsuitable for a flat sail than if you set out to design the most unsuitable hull for a flat junk sail. You need camber and doubly so if you sail on inland lakes where the winds are predominantly light. Without camber you will most likely have trouble tacking and light air performance will be poor to nonexistent.

A Fantail style sail with camber would work for you but at a cost of a more complex sailmaking process. Arne's method could of cause be applied to a Fantail style sail which would help simplify things a bit.

However if you want a sail that will "just work" and has a simple proven sailmaking method, I suggest that you stick with the Arne type sail that you were originally keen on.

PS. If you have mislaid the drawings, I can resend them to you.
PSS. The fact that I designed the Arne style sail for you does not come into it. It's just fact.

All true, and all noted.  I must confess that the look of the Fantail sail is so attractive to my eye that it's worth extra consideration, and even extra work.  I seem to be leaning right this minute toward an Arne / Fantail hybrid, although I guess that David's sail is already that, so perhaps I'm using too many words.  Ah well, I do that.  :-/

Here we are again, with that tricky job of matching up the rig, the boat, the skipper and the waters. Seablossom has the kind of hull form that has given problems with the flat HM rig, which loses power too quickly as you begin to tack, and doesn't regain power quickly enough as you come out of the tack. She needs a more powerful rig. I don't think I would recommend a totally flat Fantail rig. I would always put some rounding on the head, which is where it does the most good, and I would always put just a little rounding on the edges of panels, where there is a seam under a batten, so that the luff and leech stay tauter and  the middle of the panel is not "starved". But I think that's as far as you need go. As long as you're not looking for the last tenth of a knot to windward, but are content to sail well, and reliably (which is not the same thing as sailing fast) then the Fantail rig will suit you. If you want to sail fast, you have to add more power by cambering the panels; but if you simply want to get to where you're going, reliably, stay with the simpler sail.

David Tyler wrote:Back to pondering Seablossom's rig : if you're really interested in a Fantail sail, Jeff, could you let me have a look at a drawing of where the mast partners are now, and give me an idea of what mast rake might be possible? 

I'll scrounge around and print up a profile drawing of a Nor'sea 27 to draw on as soon as I can, but for now my printer is down and it looks like it will be the 27th before I can correct that. Just verbally, the center of the hole is 460 mm forward of the cabin top in the foredeck.
As far as rake goes, the step isn't planted so it's whatever I / we decide. I was thinking in terms of about 4 degrees, but my bury is a bit stingy, and additional rake will equal additional bury, and every little bit can help, so I'm certainly open to any increase you think would be appropriate.
As I think of it, as far forward as the partners are, the keel is rising up toward the forefoot, so I will gain bury not just by the additional length of the hypotenuse of the narrow triangle created by the rake, but also by landing further aft on a descending.curve of the keel, so (a) the more the merrier, and (b) how much rake do you think I can get away with before it starts to look awkward?
As I mentioned in another post, I have ordered metric tape measures for this project. My country may continue to pretend that we are on the British Imperial measurement system, but I'm not going to play any more. This sail will be my first all-metric project.

David Tyler wrote:

Jeff McFadden wrote:

Barry & Meps / Stellrecht & Schulte wrote:... snip ...

I believe that 2:1 and especially 1:1 mix epoxies have some sort of "filler" in there and aren't as strong as the 5:1 compositions. But I should probably go check my facts before I spout off about it too much!

Speaking of people who ought to check their facts (meaning me :-)  )... I thought West System was 5:2?

Er, no. You buy 4 litres of resin and 800 ml of hardener as a matching set. Maybe imperial packaging is supplied in the States, but the ratio will be the same.

Yeah, Imperial measurements are used in the United States, which results in resin and hardener containers with very weird quantity measurements, with decimals to two places.
I just ordered two metric tape measures.  I'm trying to join the rest of the world.