A Bosun''s Chair is one of those necessary pieces of sailing gear that really need to be treated with respect.
Here are a couple of events involving them, one is an interesting story, the other from personal experience.
The story: I heard this one sitting around with a bunch of sailors swapping tall tails and feats of daring do. It involves an older couple on a 40-something foot sloop in the caribe. The wind had piped up as they approached their intended anchorage. When they attempted to lower their genny, it became appearant that the halyard was jammed and the sail would not come down. They spent the next hour or so reaching back and forth at the mouth of the anchorage with the wind at a steady 25 - 30 kts. The vessel was making a hardy 10kts+ as it sped back and forth. This drew the interest of some of the folks on shore, who watched with binoculars. With no way to get the sail down, and no way to get up the mast, they seemed to be in a pickle. The skipper''s ingenuity kicked in as the folks on shore watched as he rigged his drogue to one of his spare halyards. Then he hitched himself up with the Bosun''s Chair and had his mate toss the drogue over the side. Once the drogue bit, the skipper was launched at 10kts+ up the mast! His rapid ascent up the rig was too fast for him control and he was wedged, forcefully, between the backstay and the mast head. I believe he broke his collarbone, along with some nasty cuts and bruises. The folks shoreside scrambled immediately to assist.
The personal experience happened to me about 100 miles SE of Newport RI. I was young, and stupid, and quite lucky, as it turned out. It was around 1977 or so, comming up during an Annapolis/Newport race. Wind was about the upper teens to low twenties, with seas in the 8 foot range, nothing much for the 47'' sloop I was on. Due to a wind shift, we had dropped the ''chute and were close reaching on the genoa. Running the foredeck, I was concerned about the forward halyards. We had gybed the chute in the night, and when we hoisted the genoa, we had pretty much crossed up the halyards and someone would have to go aloft to straighten things out. No big deal, I hopped below, grabbed the Bosun''s Chair and prepared to go aloft. I had three crew on the main winches and things would be fixed in a moment or two. I was going up on one of the spinnaker halyards, with the offending halyard clipped to the same bail on the chair. As I went up, I noticed the increased motion as the higher up the mast I went, the greater the arc of motion from the 8'' seas. As I reached the upper spreaders, I had to clear the halyard from the jack stay we had rigged to prevent the mast from pumping. No big deal. I had the crew stop hoisting me and I stood, stradling the mast on the upper spreaders, probably about 50'' off the deck. I reached down and unclipped the halyard to be cleared from the chair and.... OH MY GOD!!!! I unclipped BOTH halyards and the Bosun''s Chair slipped past my knees and dropped to my ankles. OK, so now I am 50'' up the mast, standing on the upper spreaders, being whipped back and forth in 20kts of wind, I could not wrap my arms around the mast as the main used a bolt rope on the luff, one hand held both the halyards, and the Bosun''s Chair was at my feet! Much swearing and screaming (by me) ensued, as I tried to explain to the crew on deck that they had to ease both halyards, slowly, as I tried to get my hand to clip at least one of the halyards back on the bail on the chair. To this day, I still don''t know how I was able to do it. All I was thinking was that if I lost my grip or balance, I would have to make sure I shoved off hard enough to clear the deck and hit the water. Better to be MOB in the Atlantic than smashed on the deck! I somehow clipped one of the halyards to the chair, got the crew to take up slack, got both halyards on, finished going to the masthead to clear the cross, and made it back to the deck, alive.
The moral of these stories? First, THINK before you do ANYTHING and make sure you are aware of EVERYTHING that could go on as you go aloft. While the story of the skipper using his drogue may or maynot be true, it shows what can happen when you don''t think a bright idea all the way to it''s conclusion.
In my case, in the scores of times I have gone aloft since, I ALWAYS duct tape the shackle closed on the halyard I am going up on, weather at dock or at sea. No point in tempting fate twice.