Hi Chris,
I am not sure that yours is the right question as SeaHawks have slightly different rigs depending on the age of the boat. Originally your boat (#154) would have had a rig that reflected that shown on the sail plan shown at:
http://www.seahawk17.org.uk/reviews/yw.htm#sailDon't take too much notice of the text there as it does not reflect current knowledge on sail plans and is more concerned with an earlier debate about the vintage of the article.
I now have a full sized copy of the original draftsman's drawing from which that image was clearly taken (Drawing: 477/4). From the photograph of "Wintin" at the top of the page at:
http://www.seahawk17.org.uk/description/sails.htmit is also clear that that rig was still the one being supplied as recently as the early days of Moore's boats. Note the short luff and long tack strop.
With regard to your query, the important factor is that this drawing shows that the rake of the mast should be set so that its top is set back from the vertical by 6". (I haven't done the calculation to determine the angle from the vertical, or length of the forestay, but the mast is shown on the drawings with the hounds at 14ft).
Equally interesting, for anyone considering fitting roller reefing, is the fact that the drawing was passed to me by David Cornabe, the guy who, in 2004, was considering starting to build SeaHawks again. He also passed a further full-sized drawing to me, both of which were obtained direct from John Bennett himself. This is drawing, 477/5, the one reproduced further down the page beneath the photo of Wintin. Note that the original date for this is November 1987, around the time that Moore's started fitting the larger furling Genoa as standard, and shows a genoa with a far longer luff, on a mast with hounds set a foot higher.
On the print I have of 477/4 there are marks in red ink referring the user to 477/5 with further red ink marks indicating the changed boom and hound height. The important point being that there is no suggestion that the rake of the mast was changed.
Further, you say nothing about the age and source of your headsail. Your boat, #154, appears to have an original mast, with lower hounds and consequentially, a shorter forestay than later boats would have, so there may be an issue over luff length to consider if you have obtained a used sail from a more recent boat.
Although it is not an ideal photograph, for this purpose, take a look at the one of "Jemima" at Oulton Broad Yacht Station:
http://www.gregafloat.org.uk/broads/jemima1976.html#oultonIt seems to indicate that the genoa supplied new with the boat in 1973 had a luff short enough to need the strop used with the standard jib. Although I don't say so in that cruise report, I recall that when the strop was not fitted the pulpit fouled the bottom of the sail, completely destroying its shape, at any time other than when closed hauled, so was a very necessary fitting.
Finally, it only occurred to me recently, that one reason why I might have had so much trouble with the genoa on "Just 17", believed to be a 1973 or 1974 boat, is because of the change in the mast on later boats. Mine is hanked on, I have no furling gear, with a makers logo showing "Fylde", so is certainly not an original. The luff is so long that I cannot use the strop and even then I can't get it as taught as I think is right. However, I took it to Jeckells and asked them to measure to compare it with one of their sails, with a view to having as much as foot taken out of the luff, so I could use the normal tack strop.
They reported that it seemed to be made to the standard SeaHawk dimensions. At the time I left baffled, taking my sail home unaltered. Now I realise that the records that my sail's measurements were compared against were probably those of more recent boats with the revised mast. Even these will be over twenty years old by now and very few older boats would have been supplied with the hanked on genoa, making it quite rare. Furling gear had become the norm, when a genoa was specified, for quite some time before 1986 when the genoa with furling gear began to be supplied as standard.
Locked
