Erik and Evi Menzel Ivey wrote:

Boom/batten angle - I think that with cambered sails, batten stagger is less controlled by the batten angle but rather by the various parallels, including Hong Kong if used. 10 deg. seems to be standard but I am considering 7.5 deg or less to avoid too much rise of the boom. 

Erik

Not entirely true, Erik. I once made a series of calculations of how much the angle to the horizontal should be increased when cambered panels were used, but I can't find it now. I do remember that an increase in the order of two degrees was needed with a heavily cambered panel. That is, nearer to twelve degrees than ten.

Darren:  We own a Freedom 40 Cat Ketch and I have struggled with similar issues as you are regarding sail size, panel size, boom/batten lengths, and Dm.   I am generally following Arne's designs including equally sized panels and batten lengths.  I by far not an expert, but maybe some of this is helpful.  And hopefully the real experts can chime in, too.

Lead - I have been able to sail our boat in various conditions and I think we have a litttle too much weather helm when both sails are full size.  The new sails will have a COE approximately 50cm further forward.  Not sure if that is a lot or little, but it is pretty easy to adjust helm balance on our ketch by trimming the two sails differently, and once you are reefing you get to pick which one to reef first, so to balancing the boat will be easier then, too. I've decided not to worry about it too much.

Sail size - Going smaller makes everything else easier.  We have approximately 73 sqm split between two sails.  I'm thinking of going as large as 86 sqm, equally sized, 7 panels.  But they may end up a tad smaller to help with other constraints.

Boom size - similar to yours, at about 4.6 meters

Yard angle - 70 deg.  I like the look. others are possible, esp if the yard is made shorter.

AR - approx. 2.6

Boom/batten angle - I think that with cambered sails, batten stagger is less controlled by the batten angle but rather by the various parallels, including Hong Kong if used. 10 deg. seems to be standard but I am considering 7.5 deg or less to avoid too much rise of the boom.  I would like to be able to reach the clew when the sail is reefed. Also the large empty space between the boom and deck looks awkward to me.

Sheets - I currently sail with a 3x1 on 6 m long wishbone booms.  Total sheet length is 30 meters.  It ends up being a lot int the cockpit.  I would really like to avoid longer sheets.  The 3x1 gets you to a 5 point attachment setup on the junk sails, thus the 7 panel sail.  If the twist can not be controlled adequately, I could see going to two sheets before a 5x1, but that means adjusting 4 sheets during maneuvers - maybe OK for ocean sailing, not so much in close quarters.  

Dm.  This is a struggle, esp. with me trying to keep the booms low.  Shorter booms help, but either the sail area drops or the AR goes up when I try for more D.   Kurt Ulmer on this site suggested varying the panel height in order to reduce the Dmin.  My sheet arrangement has a Dmin of 1.75P.  I have drafted a sail plan for an average P of 1.44, but the lowest P is 1.2 m, and the next two are 1.6, then back to 1.2 and 1.6.  This gives a D min of 2.3 m  vs 2.52 m.  The varying P doesn't look too weird, either.

Material.  I've looked the Weathermax80 and really like it compared to the other standard options.  

Erik

My sheet has occasionally fouled the windvane, despite having more drift than yours.  It often happened when I was tacking in stronger winds and the sheet blew aft, rather than when gybing as expected.  I have significantly improved the problem by putting a restraining horse or deflector across the cockpit just above the sheet.  I used an alloy tube lashed across the pushpit.  This deflects the slack sheet as it comes across and inhibits its tendency to catch the windvane. 

Gybing created other problems.  I rarely do an all-standing gybe except in the lightest airs, preferring to leave the sheet cleated, but haul the slack out of it, flaking it down on the cockpit bench then letting it run out through gloved hands as it goes over.  (Provided the sail is squared right off before executing the gybe, I find that this is easy and stress free, but then my sail is only 35 sq m!)  When gybing with a slack sheet (all-standing), there is a lot of slack there and if it can find anything to take a turn around the damned thing will, in my experience.  Putting a lot of thought into eliminating snags on deck is well-worth it.  I have almost succeeded by this time but it still hooks under one edge of my cockpit roof occasionally.  I am thinking of ways to resolve this.  If I am successful, then I should finally be able to tack and gybe (and reef) on the blackest night with impunity, which is the required standard for offshore voyaging. 

Your new sail plan has a higher aspect ration than PJR recommends but if you have some camber in the panels that should not be a problem.  Actually, I have a friend with flat-cut sails with the same aspect ratio as yours.  His sails develop a lot of twist but still seem to have plenty of drive to windward.  He has a very heavy boat so high performance sails probably would not make much difference.  Good luck with your project!

Thanks David and Asmat,

I suppose I knew I was being too greedy about sail area and I was just in need of an intervention to make that reality apparent.  We do have a brand new Beta-50 and 230 gallons (870 L) diesel capacity, so motoring through the calms is an option.

I have another JRA member visiting tonight, but tomorrow I'll need to take some measurements to see if I could make the sheeting to the pulpit work.  The Dmin would be much shorter, but the sheeting angle better.  Hopefully, I can leave sufficient clearance for the windvane.  I now understand why David's windvane has the vane mounted remotely on the davits...

Darren,
I have to agree with your line "I may have been a bit too greedy in trying to fit in 1200 sq ft (113 m²) sail area". Whenever I've "been a bit too greedy", I've ended up regretting it. Taking the displacement as 14 tons and aiming for SA/D = 18, a sail area of around 1100 sq ft seems to be more than enough to carry out your mission statement. Tystie has a great deal less, and yet was at no disadvantage during my four Pacific crossings, the first stage of your planned voyaging - I do feel that a small but reliable iron topsail is a lot more useful and versatile than that extra 100 sq ft. A small diesel will get you trickling along economically at 2 or 3 knots when it's not an option to sit and wait for a wind. When you get away from the BC Inside Passage waters, a wind-free zone in summer, I venture to suggest that you'll find 1100 sq ft enough. Personally, I'd be happy with 1000 sq ft.

And, of course, scaling down the total area to 1100 sq ft, with a batten pitch of around 1280mm and a batten length of around 4860mm, eases all of your design problems. More halyard drift, or shorten the masts a bit (4in top diameter seems really quite small when you're up at that height in a bosun's chair), and more sheet drift.

With eight sheeted points on the main, and seven on the foresail, I feel that upper and lower sheeting is not only desirable, but essential. You have room for three-point spans - just - so it would be possible to use five-part single sheets; but I fear that you wouldn't get good enough control over twist. Nevertheless, since the amount of rope and hardware is much about the same, it's not too costly an experiment to start with single sheeting. Don't be too worried about over-stressing the battens with unbalanced upper and lower sheeting, I never found this to be a problem.

I think you can move the foresail sheet deck blocks back a bit. That, and a dinghy with a raked transom, should allow reasonable foresail sheeting. I tried port and starboard sheeting, but found it to be unnecessary on the foresail.

Can you sheet  the mainsail a bit further back by putting the deck blocks right back on the rail? Looking at my photos of Leeway, I think you can.

I think you should consider a lightweight extension to the yards, to make sure they stay aft of the lifts. Nothing too big, maybe 2in diameter  at the most.

You'll be aware that hinged battens are out of the question with so much foresail balance area, but you might consider them on the main.