There is a direct relationship between sea state tolerance (survivability) and vessel alignment. When a boat is properly aligned with the seaway its sea state tolerance increases dramatically. When it falls out of alignment survivability is reduced to the same extent. The problem is this: boats will not remain aligned with the seaway unassisted. (A quick reminder that most of the random/catastrophic events that characterized Fastnet '79 were caused by a lack of proper alignment with the seaway). Boats must be forcefully kept in alignment by some sort of drag device, sails or an engine. Making the right choice in different heavy weather situations is what we call "Seamanship".

Sea anchors are used to align a vessel with the seaway bow-to, that is, facing directly into the wind and the sea. Since all boats are designed to take the seas on the bow a sea anchor should be a sailor's FIRST LINE OF DEFENSE. in other situations a suitable drogue may be towed off the stern to keep the stern aligned with the seaway as she is running or quartering the seas downwind. The two options differ widely. The proper use of a sea anchor off the bow should not be confused with the proper use of a drogue off the stern. The dichotomy between the two concepts along with documented case histories has been combined into a publication entitled the Drag Device Data Base (available from Para-Tech). Sailors planning extensive offshore passages should obtain a copy with a view towards more in depth study of the different applications of both devices.

A speed-limiting drogue is towed off the stern. Its purpose is (A) limit the speed of the boat, (B) reduce her angle of yaw and (C) provide for steering assist in strong following seas. It is a LOW PULL device that allows a fair amount of directional control through the helm. You can, and may have to, steer the boat with the drogue in tow. It follows that there is a "Catch 22" associated with any speed limiting drogue: The same low pull that allows for steering control may also allow the boat to broach, capsize and pitch-pole in the heaviest seas. The forces that pitch-pole yachts are formidable enough to yank the drogue through the water in the course of throwing the boat end-over-end. Sailors should be aware of this "Catch 22" and make allowances for it in the course of their decisions at sea.

Para-Tech's new DELTA-DROGUE TM uses this "guide surface principle". The basic design is a triangular "Delta" shape that provides strong uniform flow separation at all leading edges. Shape retention is achieved by the pressure of the water inside (similar to the "Ballute" drogues used in Aerospace recovery applications). The relatively small mouth at the leading edge of the drogue makes it highly unlikely that one will ever get turned inside out (a problem associated with cones and small parachute drogues). Additionally, the three vent holes of the drogue have the effect of increasing the drogue's drag as speed increases.