Parachute Sea Anchors and Drogues – What's the Difference?
There is still much confusion between sea anchors and drogues. Here we look at the differences, and how to safely deploy and retrieve a parachute sea anchor.
The original sea anchor (an admiralty cone shape) is a time honoured invention that will perform adequately as a drogue - but not as a true sea anchor. There is a vast difference between the loads that can be applied to a boat by a sea anchor and a drogue.
The resistance created by a parachute sea anchor of 12ft diameter when deployed is clearly much higher than that of a smaller conical-shaped drogue.
The parachute sea anchor has taken modern airborne technology and converted it to be used at sea where its performance has no equal.
A sea anchor must always be used at the bow of a vessel whereas a drogue is best deployed from the stern.
A drogue is most effective at slowing and controlling a vessel when running before the wind, whereas a sea anchor can be used to secure the vessel in the worst conditions, giving comfort, security and relief from the considerable impact on the crew of sailing a vessel in gale or storm force conditions.
How the Parachute Sea Anchor Works
A parachute sea anchor inflates just like a parachute when deployed and exerts an iron-like grip on the sea as the wind and current makes the vessel drift. Once inflated, the pull of the wind and swell-driven vessel is balanced out by the sea anchor, therefore reducing drift so much that it is barely measurable.
A vessel will react to a parachute sea anchor in a similar way to hanging on a conventional bottom-set anchor.
As with conventional anchoring the size of a parachute sea anchor is important. Under stress a boat will drag an under sized anchor and lay her beam to the weather. Marginally over sized is fine, as it gives an additional level of security. But substantially over sized is simply a waste of money.
It is therefore important to have a parachute sea anchor that is sufficiently large to hold your vessel 'bow on' in all conditions. As a guide, refer to this Size Chart
How to Deploy a Sea Anchor
There are several ways of deploying a parachute sea anchor - but a simple, safe and effective method is to rig the system before the conditions become too challenging.
It is extremely important to use a suitably-sized deployment line (anchor rope). A minimum of around 100m of nylon braided rope is recommended. You should use:
- 16mm rope for vessels up to 32ft
- 18mm rope on vessels up to 39ft
- 20mm rope on vessels up to 55ft
- 24mm rope on vessels up to 65ft.
The anchor rope is best connected to the vessel by setting up a rope bridle secured to the major strong points of the boat - such as the primary and then the secondary winches. The apex of the bridle is then lead forward and out through a bow roller or stem head fitting.
Do ensure that the bow roller cannot chafe the bridle as the boat yaws and pitches. The main anchor line can then be shackled onto the loop at the head of the bridle. Always ensure that your bridle is the same diameter, or larger than the main anchor line.
Secure the anchor line from the bow outside the stanchions and lifelines, by fastening it to the toe rails or stanchion bases with small plastic cable ties, and then lead it back to the cockpit where it can be made secure to the nearest stanchion base.
When the parachute sea anchor is required, simply shackle all lines to the appropriate parts and deploy the retrieval line and floats over the windward side, quickly followed by the parachute sea anchor in its self-deploying bag.
Allow the parachute sea anchor to inflate in the water and once all the lines have deployed and the boat has stabilised, check it is all secure and that there is no chaffing.
How to Retrieve the Sea Anchor
A sea anchor is retrieved using a simple trip line. The parachute anchor retrieval line consists of a polyester floating line about 15m in length, shackled to the stainless steel chain at the apex of the parachute anchor. The other end of this line then leads up to a small primary float (or fender). From this primary float, a second 25m buoyant line is attached with a small pick-up buoy on the bitter end.
This second pick-up buoy will naturally be carried down wind from the primary float. To retrieve the parachute sea anchor the boat motors up to and retrieves the small pick-up buoy. With load applied to the line the parachute sea anchor will collapse and it can then be carefully pulled on board.
To see the range of parachute sea anchors and to view the sizing chart, click here or for further technical advice, contact the Safety Marine technical team on email@example.com or call +44 (0)2380 226300