[The remaining components are not supplied by Bartels, but for our purposes need to be considered as part of the same system:-]
5 - The Sail
As mentioned, the genoa fits onto the spar by means of a concave groove in the back of the aluminium section. The sail needs to have a luff rope (bolt rope) of suitable diameter sewn into the leading edge rather than the usual luff wire. The groove has a maximum diameter of 5mm within the extrusion, which dictates the bolt rope diameter, (not forgetting to allow for the thickness of the sailcloth around it).
A good sailmaker will be able to convert an existing sail, although this may not furl as neatly as one designed for the purpose; this is because the standard sail is likely to be cut too 'full' to roll neatly around the spar, free from creases. A purpose-made sail can be cut flatter than usual, and can have the other modifications to the head and tack, such as the addition of tape loops (as shown) or cringles for sail attachment 'designed in' from the start.
I originally requested cringles for attaching the sail to the spar, but the sailmaker (Mike McNamara) was very reluctant to use this method, preferring to use tape loops (mainly because they are flexible, I think). Because I leave the sail on the spar virtually all the time, this works well. The lower tape loop is tied closely to the lower end cap ring, with strong 2- 3mm line. The upper loop (at the head of the sail) is attached to the upper end cap ring, and pulled just tight enough to take the slack out of the sail's luff without introducing any vertical creases, before being tied off. If I wanted to adjust the luff tension regularly, it would be necessary to shorten the upper tie a little to leave room for this adjustment at the lower luff. (It is important to remember that luff tension and rig tension are entirely separate parameters.)
An alternative method (which I would guess would work better with cringles than tape loops) would be to fix the lower luff (tack) and use a halyard passing through the upper end cap ring to raise the sail and maintain/adjust the luff tension. This would have the advantage of ease of adjustment, and would make it possible to remove the sail independently of the spar, even afloat if necessary, making the sail potentially available as a trysail, as described elsewhere. (This kind of genoa is particularly suitable as a trysail because it already has a luff/bolt rope, which can be slid into the mast groove.)
Other factors to discuss with your sailmaker include:-
1 - Compensating for the unusually high tack position caused by the furling drum.
2 - Fitting a shaped lightweight foam insert sewn behind the bolt rope to help take up the fullness from the middle of the sail when it is partly or fully furled. I decided to try such an insert and duly specified this when getting a new genoa made, but it has not been a total success, having taken on a permanent curve across its width (from being furled away in the same direction for so much of the time). This disrupts the airflow just behind the luff, particularly on port tack, and makes the tell-tales appear to lift more or less constantly. (It would be simple enough to remove the foam – it's held in place by a sort of 'blister' or patch of extra sailcloth [see photo, right], which could be unpicked and removed.) This problem seems to relate to certain types of foam, as others have reported no curvature, even after several years.
<-- Back to previous page - "the Forestay"