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Sea Anchors on Catamarans

S/C-10 Catamaran, Iroquois Mk II

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S/C-10

Catamaran, Iroquois Mk II

30' x 14' x 3.5 Tons

12-Ft. Dia. Sea Anchor

Force 8-9 Conditions

 

File S/C-10, obtained from Rudolph L. Kirse, III, Palm Desert, CA. - Vessel name Banana Split, hailing port Palm Desert, Iroquois Mk II catamaran, designed by McAlphine Downie, LOA 30' 6" x Beam 14' x Draft 5' 6" (18" board up) x 3.5 Tons - Sea anchor: 12-ft. Diameter Para-Tech on 500' x 1/2" nylon three strand tether and bridle arms of 40' each, with 1/2" galvanized swivel - Full trip line - Deployed in a gale in deep water about 200 miles east of New York with winds of 40-50 knots and seas of 18-20 ft. - Vessel's bow yawed 10° - Drift was about 5-6 n.m. during 15 hours at sea anchor.

Rudolph Kirse III, singlehander, mariner and author, was sailing Banana Split to Bermuda from Montauk, Long Island, when the barometer began to fall. The first paragraph of the following is an excerpt from an article entitled Gunkholing, by Rudolph Kirse III, appearing in the March/April 92 issue of Multihulls Magazine (reproduced by permission). The second paragraph is a transcript of the feedback Shane Victor received from Rudolph Kirse III:

By 4 p.m. a storm had sprung up off the south New Jersey coast. It was traveling north, winds gusting to 45 knots and creating 20-25 ft. seas. By 5 p.m. all sails were down, and I was running before the wind... back to Long Island. With a lee shore fast approaching and night setting in, I decided to come about and set a para-anchor on 500' of 1/2" line, with an accompanying float and trip line. It did all, and more, of what it was supposed to do. According to both the GPS and the Loran, I drifted no more than a third of a mile per hour, with the bows held into the waves and only spray coming on board. By noon of next day, the storm had passed (later I learned that three boats had sunk, and one person was lost).

Neither I nor the boat would be here without the sea anchor. This storm came up with no warning (VHF, NOAA, Fax, etc.). Everything worked well on deployment. Boat rode easily with some pounding on hulls (lee boards half down as per your suggestion) rudders up & lashed, virtually no pounding on cabin underside. Chafing was solved on bridle by putting "poly-tubing" on line, 3' sections before eye-splicing, then held in place by whippings. Float was 3' inflated ball type anchor float. At approx. 1:30 p.m. a commercial fishing boat ran over and cut the [full] trip line. Later on had many problems trying to get anchor in - dislocated my wrist while trying to winch in the parachute. Anchor was finally brought in by removing bridle from bow and floating it off, tied to four life jackets [then powering up to the recovery float].

 

Sea Anchors on Catamarans

S/C-5 Catamaran, Walter Greene

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S/C-5

Catamaran, Walter Greene

50' x 30' x 5 Tons

4-Ft. Dia. Sea Anchor

Force 9 Conditions

 

File S/C-5, obtained from Walter Greene, Yarmouth, ME. - Vessel name Sebago, catamaran, designed by Walter Greene, LOA 50' x Beam 30' x Draft 7' (20" board up) x 5 Tons - Sea anchor: 4-ft. Diameter Shewmon on 250' x 3/4" nylon braid tether and bridle arms of 50' each, with 1/2" galvanized swivel - No trip line - Deployed in a whole gale in deep water in the middle of the North Atlantic with winds of 40-50 knots and seas of 25-30 ft. - Vessel's bow yawed 45-60° - Drift was estimated to be 30 n.m. during 48 hours at sea anchor.

By way of a brief digression we should perhaps mention a previous experience of renowned multihull designer Walter Greene, an experience that ushered in a new era in SAR (search and rescue). Indeed the experience marked a point in maritime history when it became possible to ensure the safety and survival of human life at sea to an extent never before possible.

On 10 October 1982 Greene was sailing his 50' trimaran Gonzo to St. Malo, France, when it capsized in a violent North Atlantic storm 300 miles south-east of Cape Cod. The boat had been running before 30-ft. seas without a drogue when she was picked up and thrown by a huge wave - she broach-capsized when one of her bows dug into green water. Once over the initial shock of the capsize, Greene and his well-prepared crew jumped into action. In no time they had donned their immersion suits, lashed themselves to the upturned, floating, hull, and switched on the EPIRB - Emergency Position Indicating Radio Beacon.

It was the navigation officer on board TWA's flight 904 that first heard the lonely wailing of Gonzo's EPIRB (the signal is swept audio tone, sounding like a miniature "wow-wow" police siren). The information was immediately relayed to the FAA's Oceanic Control at Islip, New York, which in turn informed Atlantic Rescue at Scott Air Force Base in Illinois.

At that time (1982) SARSAT - Search And Rescue Satellite-Aided Tracking - was not quite operational, but a participating Russian satellite, Cospas, was known to be overhead. Scott AFB obtained an uplink and sure enough, no sooner had Cospas signed on than it confirmed a "hit." The satellite then provided data and telemetry needed to pinpoint the position of the distressed vessel. Atlantic Rescue then broadcast an urgent All Ships Bulletin, and the tanker California Getty was diverted to the scene. At the same time, the Coast Guard Air Station at Elizabeth City North Carolina was briefed and advised to launch a C-130 search plane, which picked up Gonzo's EPIRB signal, homed in on it and dropped two datum marker buoys (which transmit additional homing signals on a different frequency).

The tanker California Getty was the first on the scene, but failed to effect safe rescue in the 25 ft. seas, standing off to windward to provide a "breakwater" for the disabled trimaran. And there she stayed, "like a big Saint Bernard," until the 210' Coast Guard Cutter Vigorous arrived on the scene.

One by one the three survivors were taken off to safety, concluding one of the most remarkable rescues in maritime history -one of the first in which a satellite played an instrumental role. (A quick reminder that SARSAT is now fully operational in most areas of the world and any sailor with a Class A EPIRB can access the grid to get a distress signal through to international Search & Rescue agencies).

Walter Greene happily went on to design many more multihulls and four years later used a sea anchor on board his 50' catamaran, the infamous Sebago. The 4-ft. diameter Shewmon sea anchor was deployed off the bow, but was too small to do a satisfactory job (the same sea anchor did a lot better when used off the stern - see file D/C-1.) The bows of the big catamaran yawed past 60° at times.

Shewmon sea anchors are available in many sizes, up to 33 feet in diameter. Literature published by Shewmon, Inc. would seem to indicate the need for an 8-10 ft. diameter Shewmon sea anchor for a boat the size and weight of Greene's Sebago.

Why did Walter Greene choose a 4-ft. diameter sea anchor instead? Likely he was worried about a bigger one being too "unyielding." Victor Shane ran into this same apprehension among other multihull sailors. To this day some of them will react with alarm at the very idea of tethering their boats to a large diameter, "unyielding" sea anchor in a gale.