basic help for a newbie
Any 12 v battery will do, but you will get better service from a deep cycle - you can buy a marine DieHard at Sears to save money, get one small enough to hoof home to recharge.
You don''t connect an alternator to a outboard, you buy an outboard containing an internal alternator. You might want a 2-4 HP engine for a 21'', you may not be able to get alternators in such small engines, so you may want to investigate a solar panel (can''t help there!).
Loose shroud is a big ??
- first make sure both shrouds are the same length and also the correct length, find another SJ 21 if you don''t have specs.
- then learn to tune your rigging - use the main halyard to to both toerails to ensure the mast straight side-to-side, adjust the shrouds to remove slack, go sailing to fine tune - find more detailed instructions elsewhere .
- if one shroud is still too long try to figure out whether your mast step is sagging, which may get you to your last question - the soft cabintop. I''d take the question about repairing a cabintop to a San Juan owners email list, I doubt you''ll be the first owner to find this problem. I wouldn''t think there will be any easy way to reinforce a cabin top, depends on what has gone soft. Also see if there''s a San Juan web site.