Tom, if you have a fixed position gooseneck, and the end of the boom droops low, then I think a) you aren't hoisting the main high enough, b) the bolt rope in the luff has shrunk considerably. Like, seriously shrunk. I've never rigged a Javelin, so I can't speak from experience, but "within a foot of the top of the mast" doesn't seem hoisted high enough. On a fixed gooseneck, you could sweat the halyard. Pull as tight as you can, then wrap the halyard around the cleat enough to give you friction. Then, push or pull against the halyard perpendicular to the mast, which will stretch the luff. Then, pull out the slack at the cleat. You'll have to do this several times to get the luff good and tight, and to put a correct amount of stretch on the bolt rope.
And if it's a sliding gooseneck, with a shrunk bolt rope, then you need to hoist the sail to the proper height on the mast, then pull down on the boom to slide the gooseneck and stretch and tighten the luff. There should be a thumbscrew on the sliding gooseneck to lock it in position on the sail track (one of my GP14s was set up like this.) My other GP14 has a fixed position gooseneck, but there's a pin the boom slide into. Hoist the main to the black band at the top of the mast, then pull the boom down to fit the gooseneck pin into the boom end (and then Cunningham handles luff tension adjustment.) Or maybe there's a downhaul line on the gooseneck to help with this - there is on my 192, and this is what holds the gooseneck in position.
Remember never to hoist the main with the main sheet cleated off. Having the main sheet cleated can cause the leech of the sail to tighten first during a hoist, causing the luff to stay slack. You want the luff to get tight first.
If the sail has batten pockets, then it needs battens. Just about every sail does. You'll note the leech of the sail curves aft of an imaginary straight line drawn from the head of the sail to the clew. This extra curvature is called roach, and it gives the sail more sail area. But it's unsupported, so battens are added to allow the body of the sail forward of that imaginary line to support the roach after that line. For a very roachy sail, without battens, the curvature will just wrap around the sail, and will flog in wind. You need battens. You can get batten stock, cut to length with a hacksaw (watch fiberglass splinters...) and then use electrical tape to cover up the ends.
However, if your boat is circa '74, and you've got this amount of trouble with your sails, I think it's far more likely that these sails are old, tired, stretched and/or shrunk, and I hesitate to suggest you spend any money on them. For example, usually batten pockets have a bit of elastic in the forward end of the pocket. This allows the batten to stretch the elastic while inserting, and then the elastic pushes the batten aftwards so that it's held into a pocket. If you really have such old sails, the elastic in the batten pocket will be shot, and this can allow the batten to flog its way out of the pocket. And, of course, old, soft, baggy, stretched sails do not sail well at all. They will not allow you to depower, and will cause the boat to heel more than to drive the boat forwards.
You might be at a point where new sails are in order. And, yes, you are looking at $800-900 for a new main and jib.
Usually bagged sails cause weather helm, as you are unable to bring the draft position of the main sail forward. As for lee helm, this indicates that the mast is not raked far enough aft - or you are not lowering a pivoting centerboard down far enough. Lee/weather helm are caused by the balance between the center of effort of the sails (grossly controlled by mast rake) and the center of resistance of the boat in the water, which can be effected by pivoting the centerboard. So, if the COE of the sails is too far aft with respect to the COR of the centerboard, you get weather helm. (some weather helm is good, because if you let go of the tiller, it's good to have the boat head to wind and depower.) If you lift a pivoting centerboard, it also causes the board to pivot aftwards, which also reduces weather helm (but can induce leeway, or side slipping...)
If you have turnbuckles on all 3 stays, then it sounds like you need to loosen the forestay, and tighten the shrouds to rake the mast aft. How much depends on how the boat handles: adjust, sail, then readjust as necessary. If you don't have turnbuckles on the shrouds
But before messing with mast rake, I think you need to get that sail straightened out, and set correctly.
Hope this helps,
Brian
