PJR suggests 5.2 oz/sq yd or 177 gsm for this size of sail, when conventional sailcloth is used. This is plenty strong enough for the whole sail.

I have found that the cloth breaks down in three main areas:

1. At the throat of the sail, due to cyclical loadings, first on one diagonal, then on the other. The answer is not heavier cloth, but patches that put the threadlines at an angle to the panels. Sailcloth can withstand a pull along the line of the threads, but is not so good at withstanding diagonal pulls.

2. Down the leech, fluttering and flapping will cause breakdown. This happens more in the lower two panels than in the upper panels, because there is little or no tension in the cloth. The answer is to add a doubler all down the leech, about 300mm wide, if you want to make an ocean-going sail. Again, there is no point in using over-heavy cloth throughout the whole panel, and for cambered panels, lighter cloth will take shape better in light airs.

3. Threadlines should be close to parallel or perpendicular to the edge of the sail, where the loads are concentrated, or the cloth gets distorted and will break down.

I have never seen cloth breakdown in the top panels, once the peak and throat have been reinforced with patches, in the conventional sailmaker's fashion. So I don't think there's any need to use heavier cloth here.

Hi David,

many thanks for your opinion, I think I will make both sails same with area of  12,5 - 13m2.

The other idea about sails that bothers me - how if making the lower romb panels of lighter fabric (say 220g/m2)  and three or two top ones, which often work as a storm sails, of heavier - like 340g/m2 ? I think it is quite logical...

Hi everybody, I think I made my homework - see attached - and my new sail plan that includes suggestions (many thanks :) ) is more proper. Basically, the main and the foresail are the same and of 12,5 m² each. However, despite quite high AR 2,7, having seen the Badger sail plan I drew additional panel making the main 14,6 m² with AR as high as 3.1.  Assuming total displacement of loaded boat of 1.600  ton this will result with 17 m²/ton. With such a factor I hope for being able to plan downwind. Please comment, ;) 

Thanks David for your opinion. Yes, I have good few reasons on my list to keep two masts, so I definitely will give it a try. But I'm going to plan carefully the rigging and go down with the chord to some 2.4m, as you have suggested. What, in the terms of degrees, would be in your opinion the difference in performance between one and two mast rig? 

Thank you very much for your comments and advise. Sail plan as shown is in a very initial state. Certainly it requires some play  with Chord - now 2750mm, and the mast height. Definitely, I prefer single sheets on both sails.

With displacement between 1.2 - 1.6 tons fully loaded for a long range cruise I'd love to have enough sail area to take advantage of hull shape and go planning in the trades. Will a 28 - 30 square meters be enough?