Re: standing rigging question
Rig tuning is a complicated and detailed subject. Here are the general guidlelines for a basic tune (does not include rake, bend, prebend, etc).
Others are telling you how to check to see if your mast is in column (same distance between port and starboard chainplates using a halyard is the way to do that).
Also check to see a halyard run against the back of the mast follows the luff groove of the mast. Any deviations would indicate a pull to port or starboard by the lowers. Adjust them until it's straight in column all the way up and down.
Next snug up the uppers (turn each side same number turns), and release any adjustable backstay (set rake now, whatever that is, by hanging a weight - hammer say - from the main halyard, the distance the hammer falls away from the back of the mast measured at the gooseneck is rake).
Now you can tighten your uppers to recommended Loos tension (generally it'll be with a light twang, for those of us without Loos guages).
If you have a single lower (sounds like it), then tension both lowers to snug with light backstay on, again tighten evenly, check for in column, and also check for straight against the luff groove... Bring the tensions up to the recommended tension by Loos, or with slightly less tension than your uppers (by feel).
NOW you sail (with light backstay on)! Sailing on a windward starboard tack in light-moderate breeze, tension the leeward shrouds, first the upper (assuming it's flopping), and count the number of turns it takes to take the slack out of it. Do the same on the lower.
TACK! Take the same number of turns on the opposite side now (it'll be easier sailing doing this as most tension should be off of it).
You now should have a decent basic tune on your boat.
Some hints... More rake isn't always better, but SOME rake is usually designed into the cut of most sails. How much rake your boat will perfer will be dictated by the boat first, then by the sail manufacturer.
If for some reason you don't have an adjustable backstay it's Ok, tension it enough early on to JUST take the slack out of the headstay and perhaps 1 extra turn, to do the rest of the tune (this assumes you have one upper and one lower per side, therefore you have swept spreaders, so the backstay isn't the only thing keeping the mast from falling forward).
when you set rake you'll need to ease the forestay and backstay in concert, keep in mind if you set a lot MORE rake all your shroud tensions will ease some.
AS the winds pipe up you'll want to bring up tension on a windward tack to take out that slack.
As for floppy shrouds in light winds... well sort of? If you don't want to tune every time you sail, you'll likely want to tune for JUST above your average winds for your area. Floppy in light air allows more power for sure, but if your winds pipe up a bit, a pumping mast is tough on rigging.
By the way, your sail manufacturer should be able to give you a tuning guide for your boat. They might be able to give you ballpark loos settings, and also rake, bend and prebend settings.
Hull #68 S2 7.9 on our little landlocked puddle, Lake Wallenpaupack, PA, it's cheap, trailerable, and paid for.