Orbit II rolled over at about 1600 UTC, Friday, Sept 6, 2002. Position was about 58 degrees, 55 minutes N, 18 degrees, 37 minutes W, at least, that is the GPS position I remember being displayed after the roll. I believe this put us over Hatton Bank (not named as such on the chart I had, but some charts name it this way). Depths went quickly from about 1028m (3370 feet) to 503m (1650 feet). I think the change in depths explains the sudden, steep, high waves (the one that knocked us down, and the one the rolled us over).
Average seas were about 20-25 feet (7-8m) before and after the roll. Neither of us saw the wave that rolled Orbit, so I cannot guess at its size, other than to say it was obviously bigger than the average seas, and very steep, as we did not recall being pushed in any direction, just rolled suddenly. Do not recall hearing the sound of a breaking wave, so think that if the wave was breaking, the noise was not excessively loud (but this is difficult to be sure of).
I have been through about eight Force 8 or greater gales with Orbit. Orbit always seemed a safe and secure boat in rough weather. Usually, I hove-to, with or without some sort of sea-anchor off the bow (to hold it closer to the wind & waves). Either a reefed (or double-reefed) foresail, or a storm trysail off the mainmast were set, and the helm lashed down (to head the boat up into the wind). I have used various types of sea-anchor, mostly makeshift arrangements of anchors and sails, typically varying what was used in each gale, in an effort to figure out what was best. In this gale, I was using the old staysail, about 20 feet (6.5m) of chain, a swivel and 5/8" 3-strand nylon anchor line.
Though I once had an 18 foot (6m) diameter sea anchor, it was too big to use as an assist in heaving to. I tried to buy a 12 foot (4m) diameter sea anchor from a marine store in America (I was then in Ireland), unfortunately, there was a delay in sending it, and when it did ship, it was incorrectly addressed, so it was returned, and by then I was leaving and had no other address, so I was back to using makeshift sea anchors.
Limit of positive stability:
For those fond of knowing the static limit of positive stability number, it was supposed to be 120 degrees. When I was searching for a boat, several years ago, the choice (of used steel boats) ended up coming down to two Tom Colvin designs, Orbit (a Tamarack) and a 37' pinky. My intention at the time was to get a boat suitable to sail to Baffin Island (northern Canada, just west of Greenland) in. I discussed the two boats with Tom Colvin, and he felt the Tamarack (Orbit) design would be more suitable, because there was room for some sort of deckhouse (which would certainly help creature comfort in cold waters) on it, where there was no such room on the pinky. I asked about relative seaworthiness, and he said the pinky, with its deeper forefoot could keep *sailing* longer in rough weather, but both were equally seaworthy. He told me that both vessels were designed with static positive stability of 120 degrees, also pointed out the mass of the heavy rig increased the force required to roll it (high roll moment of inertia) and that none of his designs had ever capsized. He also emphasized that what really mattered was how closely the boats were built to plans, as he could only comment on the design, not on the actual vessels as built.
As far as I could tell, in all significant ways, Orbit was built to plans (I was the third owner, not the builder). I have no reason to suspect that she was not ballasted as designed (since the ballast is sealed under welded steel plates, I don't know how one could confirm that).
Differences from plans:
Construction details that proved inadequate:
The deckbox, built of 3/4" (18mm) plywood, with the joints backed by 2x2 lumber, glued (epoxy in some places, polyurethane in others), screwed and nailed together, with a curved top of (mostly) 3/8" (9mm) plywood, was not strong enough to withstand the roll. The box broke apart at the joints. Never saw the lid afterwards.
The doghouse, built of 3 pieces of Honduras mahoghany laminated together (2.25" (56mm) total thickness) and 1/2" (13mm) polycarbonate (Lexan), with 1" (25mm) stainless steel channel where the dropboards go was destroyed. The stainless steel channel was still attached (it was welded to the cabin sides), just badly bent. The lower dropboard was still in place, the upper dropboard was not being used (the doors were closed instead). The only piece I saw of the rest of the doghouse was one side piece, which had been broken in half, roughly diagonally. The sides of the doghouse measured about 20" (50cm) long by 14" (35cm) high.
The cabintops were laminated together from two sheets of BS1088 (marine) plywood, 1/4" (6mm) and 1/2" (12 mm), then bolted to the cabin sides with 1/4" (6mm) bolts on 4" (10cm) centers, and screwed to the laminated mahoghany cabintop beams. Chocks for the dinghy seemed to transfer a huge downward force to a section of the cabintop, causing it to rip free of its attachment to the cabin sides (the 1/4" (6mm) bolts). I had made the dinghy chocks of cheap softwood, intending any significant side loads (thinking of a boarding wave) to cause them to break, rather than transfer a big load. The load transferred by the chocks seems to have been more of a downward load, causing the chocks to merely split, but still transfer the load.
Two of the 7" (18cm) opening ports had their glass smashed. Don't know how thick the glass was, but in no way did it ever appear weak.
The dinghy was broken into several pieces, and seemed to have been mostly affected by a downwards load, not a side load. As the dinghy was also the liferaft, this meant we had no liferaft either.
The handrails where the dinghy had been double-lashed to snapped off where the rope was. These handrails were made from a mahoghany 2x4, and were much stronger than the type of flimsy teak handrails seen on most production yachts. They were secured to the cabintop with 5/16" carriage bolts.
The Edson worm gear was missing large parts of its linkage (this device had broken a few times before, though never as completely as this time), despite the rudder limiting line being tied in such a way to take some of the rudder's load directly.
Incidentally, none of the broken wood (masts, hatches, cabintop, deckboxes, handrails) was rotten in any way.
Conclusions and otherwise:
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