Is your boat a masthead or fractionally rigged M17? I browsed the boat model and found many examples of both rigs. Owner conversions appear common.
I you have a masthead rig... go with the smaller cut headsail. If you have the fractional setup already... then you're good to go.... because you can depower the main much more efficiently by bending the mast with the backstay.
The "sheeting angle" is what you're talking about... it is the horizontal angle created between the boat's centerline and a line from tack to the jib block location. A barber hauler is a device used to change headsail sheeting angle..... so you can rig something simple on your boat to experiment with the athwartship block positions before drilling more holes.
Good post by Joe.
Do consider and 'experiment' with the barberhauler option first. It will allow even further 'slot open distance' options than simple 12-14° tach-clew angle (from the centerline). Also, barberhauler will also allow even closer sheeting angles when the wind is very 'light'.
For a
12° tack–clew line: draw
72" long pencil line back from the tack ON the centerline, then at the end of the 72" line draw a pencil line at 90° from the centerline for
14.9". Draw a line from the end of that 14.9" mark back to the tack = that last 'line' is 12°
For
14° that perpendicular line is
17.4" long.
Extend that 'third' line all the way back to the 'rail' .... your 'static' fore/aft fairlead position should be near/on these extended 'third' pencil lines at the rail.
Better is athwartship jib tracks (run @ ~90° to the boats centerline) and permanently applying a 'clew iron' (multiple holed aluminum plates) at the sail's clew (replaces the clew D-ring or cringle ... needs sailmaker installation). Instead of moving the fairlead car back and forth, you simply change hole positions on the clew iron to get proper fore/aft fairlead setting. Barberhaulers can tangle/jam jib sheets (flogging) in high wind conditions during tacking/gybing.
Do websearch for M20 or Inland-20 Scow for concept of athwartship jib tracks .... the positioning of the athwartship jib track must be precise before you drill holes into the deck. See item #17 in below attached .pdf
The 7/8ths 'hoist' is a jib whose luff is 7/8ths as long as a full hoist jib - keeps the slot more 'open' at the head of the jib - good idea for high winds.
Backstay should be ~20% tension when @ 20+kts. If you have a tension gage, instal it (tie it on so it cant fall overboard) when sailing in 20+kt. ... you dont want that backstay to go much, or often, go above 30% tension during max. heel and in heavy gusts --- or you'll risk premature forestay/backstay failure.
Also for jib sheet control: consider large Harken hexaratchet cheek block somewhere on deck, with Double block shackled to clew-iron for 2:1 jib sheet purchase thus: ---- jib sheet to hex - to fairlead block - to double block on clew iron and terminating back to becket on fairlead block. Very quick, 2:1 power advantage, easy to hand control when 'blading out' a small jib in 'gusts'. Tail end of jib sheet controlled via cam cleat or (instant open cam-type) 'trigger cleat' (
http://www.apsltd.com/c-313-harkennashtriggercleat.aspx).
I am out of my depth here (no pun intended) and would rather not drill a bunch of bolt holes in the wrong place so any advice would be much appreciated.
