Join Date: Dec 2004
Location: Alameda, San Francisco Bay
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First, a little common terminology: Your “sliding blocks” are known as “fair leads” or “jib cars” (west coast and east coast folks tend to use different nomenclature). The track is either a “fair lead track” or a “jib track”. Whereas the general principals apply to all boats, what specifically works on my boat may not work exactly the same on yours, so you will have to work it out on your boat. We call this “dialing in” the boat and once we get the optimum setting, we either mark it down on the track or make note of it somewhere.
I’m assuming that your C25 only has one fairlead track on each side of the boat? Your initial setting will be when sighting up the jib sheet, your LOS will be exactly halfway up the luff of the sail. Move your fairlead up or down until this imaginary line is halfway up the sail’s luff. Your 150 will have a different position on the track than say, your 110 lapper jib. Now for the fine tuning: while sailing, move the fair lead up or down the track so all tell tails are streaming aft. Then, slowly luff your boat into the wind and watch your genoa tell tails. If the upper one breaks first, move the fair lead forward. If the bottom breaks first, move the lead aft. You want all the tell tails to break at the same time. This “fine tuning” adjusts for wind speeds.
Other adjustments: Moving the fair lead forward closes the leach and moving it back opens it up. If the winds are building, you can move the fair lead way back (opens the leech) and this will help in controlling heel. Moving the fair lead forward will “power up” the boat and give you better acceleration (but the downside is you will experience greater heel). If you have two tracks on each side, use the inner one in lighter winds. Move to the outboard track if the winds are building and you see compression on the mainsail (a “bubble” depressing the luff area). If you are using the outboard track, you will not point as high into the wind. We tend to go to the outboard track only in very windy conditions and when we are on a reaching leg.
Ulta light air sailing is an art form and it is easier to show you on the water than writing about it. Generally, you will not be able to point as high and you will need to move your mainsheet traveler up to compensate. Both jib and mainsheets will be fairly taught as is your halyards and outhaul. Think of slow moving air molecules as being lazy and you need a smooth sail with a flat camber to keep them attached as they slide along the sail.