We sailors love to wax poetic about the peacefulness of sailing, but the reality is that sailboats can be about as quiet as a can of loose rocks. The various clangs, bangs, and thumps heard aboard almost all vessels not only disturb the peace, they can keep the off-watch from getting essential sleep, erode your confidence in a building wind, and make you a pariah in marinas or at anchor.
What follows are a number of strategies for muffling or eliminating the most common and most annoying onboard noises. I like a quiet boat. So will you.
Mast Noise Some sailors seem deaf to halyard slap. Or maybe they just think it is one of sailing's inherent sounds, like the gurgle of the bow wave (good) or the moan of the wind through the rigging (not good). It isn't, and if you allow your halyards to slap all night, don't expect your neighbors to hold you in high esteem.
The first step—and often the last—toward eliminating halyard slap is simply to clip the shackle end away from the mast, preferrably on the rail or the pulpit. Securing the tail of the halyard away from the mast is typically not so easy, so try pulling it away from the spar with a piece of shock cord or light line that you can attach to a shroud.
A more elegant method of accomplishing the same thing is to fit the aft or forward (depending on the halyard) edge of the lower spreader with a small thumb cleat a foot or so out from the mast. Looping the halyard tail over this cleat will separate it from the mast.