Santa Maria did the trade wind crossing from the Canaries starting out December 25. We left Tenerife in wonderful weather and gained self-confidence with every hour. By sunset that all changed. The wind picked up and by 11 PM it was pitch black, wind at 15 – 20 m/s and huge waves were rolling in from aft. There were all kinds of horrifying sounds coming from every part of the boat. It continued for four days.
Well, what doesn’t kill us strengthens us, and Santa Maria finally convinced us that she could take it. There after we actually enjoyed the fast ride!
To prepare, you should take down some sail before the squall hits. Since we didn’t use the main much, we took to the habit of being prepared and lessen the genoa, thus never had any problems. However, if you go lazy and fail to adjust the sails before they hit, you could easily end up with a situation and potentially lose a sail.
Note that the wind will reach you before the actual cloud does, since the wind usually beam down from the cloud in 20º-40º.
In 1999, on Everest, we climbed to 8600 meter (28000 feet) in hurricane force wind. It was cold and very exhausting, but strangely enough not too hard to stand erect. Contrary to believe, it is not the wind that causes the problem but the waves and stuff flying around. The first rule of high wind is to stay with your boat. Stay cool, minimize the sails and try to sail with the wind. A boat under sail will behave much better than without. If the wind is too high for any sails – go with bare rigging, but try to steer anyway.
A drift anchor is great for slowing down the speed and riding out the storm. In real bad situations, you might have to turn the boat toward the waves and battle the ocean. There are some great books written about the different techniques used (incl. "Heavy weather"). Again though, this kind of weather is almost unheard of on the Atlantic in the calm season.
Well, without a warning, a hurricane further north sent some huge waves - up to 18 feet - rolling into the harbor (no wind!). Fortunately we had a caretaker (thank´s Fixman!) who defied the waves and motored Santa Maria to the leeward side of the island (this normally being the windward side).