What is a sea anchor and how to use one?

A sea anchor (sometimes known as a drift anchor, drift sock, para anchor or boat brake) is a means by which the sailor can arrest the drift of his vessel (when not underway). In large part it does the same thing as a normal anchor, except that rather than fastening the vessel to the sea bed, it deploys like an underwater parachute, acting as a brake and slowing, or even halting drift in the process.

Sea anchors have been credited with saving many a small yacht in extreme conditions. Many lighter displacement yachts do not react well to being hove-to in heavy weather and large seas and even when they do, the crew might quickly become exhausted on a small boat that is being thrown about violently. 

Running with the storm is an option, but again, a shorthanded crew might quickly become tired. This alternative also assumes that the vessel has sufficient storm sails and sea room to do this. There’s no point running flat out into a beach - or worse still, a rocky headland!

The sea anchor is usually made up of heavy duty nylon material in the shape of a parachute. The average sea anchor for a 40 ft yacht is likely to be no more than 15 feet across. It will have its edges reinforced with heavy duty webbing and the rode and lines should be strong enough to withstand the breaking loads likely in a severe gale or storm.

Sea anchors are best deployed from their own bag (unless instructions advise otherwise) as this limits the chances of the anchor filling with air and acting like a spinnaker! Not something you want to be dealing with in gale force conditions.

A robust sea anchor, when properly deployed and attached to sufficiently durable strong points should keep the vessel headed into the prevailing wind and sea, making the vessel stable and properly aligned to take the worst on offer. Make sure that you check carefully for potential chafe points and protect accordingly. It’s always better to do a test deployment in good weather to iron out any wrinkles, rather than be using this kit for the first time in a F7 with 55 kts of wind imminent! 

In truly extreme conditions, battening down the hatches, strapping yourself and your crew into their bunks and keeping a listening radio and radar watch is sensible. After all, you are now not under command and should let others know of your presence.

Once the worst has passed and you have taken advantage of the halt in sailing to get some much needed rest, you can recover the sea anchor (by using the attached tripping line) and pack it safely away for another day.  Make sure you don’t get it tangled around the keel or propellor and check for damage as you stow it.

Finally, a sea anchor is different from a drogue in that a drogue is usually a conical / funnel shaped object that is attached to the stern of a boat to slow its speed and improve stability when underway. A sea anchor in contrast, is deployed when not underway, to halt drift and keep the vessel’s head into the weather.

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Photo Credit - Ed Dunens