The best book I am familiar with is Earl Hinz's "Heavy Weather Tactics using Sea Anchors and Drogues. However it has the weakness that most material has it that it addresses sailboats and small power boats. Remember that the first really good publication on Sea Anchors was written by Captain John Voss in 1949 voyaging in a , sailing Tilikum a 38 foot carved log Canoe from British Columbia. This boat was low freeboard, and had a removable outboard rudder (the rudder had been broken in early experiments when drifting backward to a conical sea anchor. ) A sea anchor was necessary for survival of this frail craft. The other classical books--Dashews "Surviving the Storm", Adlard Cole's (updated by Peter Bruce)Heavy Weather Sailing, Rough Weather Seamanship for Sail and Power by Roger Marshall, and the "Annapolis book of seamanship vol 2, Heavy Weather Sailing --but again most of these focus on smaller boats or sail. The series drogues, popularized by Jordon were also used on small boats. Both Ken and Phil have hit on the problems--there is little information on the use of these devices on large boats. The Para-anchor is used frequenty by smaller fishing boats who will shut down and drift at night while sleeping (should have at least one watch stander as a lookout). The Series drogue is to keep the stern to the waves, and prevent both broaching and pitchpolling. The shorter drogues have the problem of comming out of the water, being out of sync with the waves and the boats and not giving adequate drag, plus the danger of entanglement in the running grear. (A friend had a 65 foot 100 ton wooden Colin Archer power boat --had been vessel which the pilots lived aboard off the the entrance to Bergan Norway. He was caught in a hurricane on an Atlantic crossing, and eventually put out a drogue--it was tires, fenders, chain, wooden beams etc. A large wave swept the drogue toward the boat--and tangled the 2" diameter cable in the running gear--so he was helpless). In our own experience, we crossed the North Atlantic before the Series drogue was popular. The three boats which were in VHF contact were about the same size (55 to 62 feet and displaced 30 to 50 tons). The two other skippers were professional delivary captains and we all agreed that even in the circumstances of 40'+ waves we were most likely safer continuing on under power rather than attempting to put out a drogue. I envision the sea anchor as a respite to try and get rest or repair gear if possiable during a storm. Or if it is an ultimate storm, as a survival technique. I now of one tri which broke apart even though bridled when riding to a sea anchor. The boats will generally not lie directly bow to a sea anchor (at least my experience in smaller boats). The question is what is the size at which one would fit the sea anchor. I personally would be more likely to fit series drogues (with a winch in the cockpit--which I think is essential in any ocean passagemaker for a number of reasons). I probably would pass on the sea anchor for the larger boats, but with a smaller boat use one. Another set of questions are turning a boat from the running attitude to a bow into the wind/seas attitude. This becomes dangerous and difficult as the seas build. When is the key. I have been in situations where I was sure I would roll the boat if I went beam to seas, so continued down wind. As noted the problems of setting the gear associated with para-anchors--both the rode, the chain, the anchor and the trip line. The series drogue--although longer, would be easier to set--but again you are leaving a more vulnerable part of the boat exposed to the sea. There are two issues--one is the flat aft run and swim step exposed to the face of a wave(lifting and tending to broach)--and a boat which has good sized aft deck/lazerette/doors to the saloon exposed to a breaking wave (water boarding and smashing aft items). Certainly a situation one wishes to avoid. (and in most of the tradewind routes at the right time of the year, it is avoidable). Bob Austin