Dismasting - a heavy seas lesson


Good night on parachute anchor

Waterbird got to an intense low pressure system on May 1st 2010 on 46°S 126°E on the way from Kerguelen to Hobart.

Forecast the day before: 40-60 kts (over 50kts on grib), storm centre passing south. (240 NM south according the last forecast I had on board.)

Wind on grib files

Meteorologists in Kerguelen use a following correction for grib file forecast: Winds less than 15kt, no correction. Winds 20kt to 30kt, add 5kt. Winds 30kt to 40kt, add 8 to 10 kt. 40kt to 50kt, add 10 to 12 kt. There is no guarantee that exactly the same applies for the location where Waterbird was dismasted but it is a known fact that grib files tend to underestimate windspeed in the Southern ocean area. I have no anemometer on board except a little handheld windmeter of poor accuracy and working only up to storm 10 force.

I hove to on STB tack. (parachute anchor was in the cockpit ready to use and I went to sleep). Waterbird behaved well in similar storms before and always giving some warnings before sea-anchor became necessary. This time things were different. No warnings, first unusuall wave turned the boat over.

The boat was properly hove to with the bow pointing about 50 degrees to the approaching seas. I was in my bunk, woke up by the the heel which was just getting bigger and bigger. The lines over the bunk hold me in - no flying around the cabin, no injuries. The boat was in mast down position or very nearly so and immediately returned back not making the complete circle. The mast was on deck in 3 pieces.

The interesting fact is that the rollover was not just sideways but rather backwards (bow up, turning around the stern in the first stage). I concluded this because of the way the things flew inside. The mast broke at the tabernackle pin first from the water impact i.e. towards port side and forward but finally falling on the other side (to stb and back) when the boat righted herself. I did not see the wave but I think it could be something between 12 to 14 mts. Forecast showed waves up to 12 mts at that moment. (In theory individual wave can be up to 1.87 times bigger than S.W.H.. Such a wave would be over 20 mts. But I think it was less. My guess is a steep wave - in the first stage after build up - could do it).

Wave height in grib files

 

The rollover happened 7 hrs after the wind reached gale force, blowing around 60 kts at that moment. It is much earlier than I would expected from my previous experience. According to grib files, (which I saw later) there was approx. 1000 NM area of 40-60 kts winds to windward. It was a developed low pressure system. Minimum gale force winds (reaching severe storm 11 at the top) lasted about 30 hours according to grib files.

Pressure according to Australian archives

The boat took nearly no water. She was well prepared for a rollover. The mast took the selfsteering down and damaged the liferaft box and bracket. The liferaft went away soon after. It was inflated and stayed by the boat for some time. When it was drifting away it was quite distorted. I do not think it lasted long in that kind of wheather. Two days later I was able to raise a jury mast. I changed course, heading north as fast as possible to get out of the frequent bad weather area.

A lesson: Hove to was a mistake. It pays out to be a chicken and to use the parachute rather too early. I did so in previous heavy storms. I simply got used to strong winds and heavy seas but the boat and her mast did not. Too much confidence resulted in a costly damage.

I believe I have survived two worse storms in South Atlantic on an improvised seaanchor but I can not be sure. It is hard to estimate furious seas. There is so many factors including luck. It might be just one wave in its very bad moment...

A group of pilot whales came nearby in the huge seas soon after I cut away the wrecked rigging. It was a pleasing moment.

Storm survival notes:

I rely on sea-anchors from the bow in extreme conditions but finding expensive parachutes unnecessary. Improvised anchor made of a storm jib worked well. A cubic meter fertiliser bag was perhaps too small but two of them might be as good. as parachute (I found that a trip line on Paratech anchor is not much usefull but very dangerous. It caused a complete failure in a storm, tearing the parachute in pieces.)

Seaanchor from the stern would probably work but I am almost sure that my selfsteering would be damaged from the breaking seas. (They bent some steel on my bow. What would happened to aluminium selfsteering if the stern was exposed to the same forces?!)

I never tried running in extreme conditions. There might be something good in it. I met two experienced sailors who rely on it. Both were capsized but still convinced that they ended up better than if they were on the parachute. Personally I am a bit scared to try and too lazy to steer for many cold and dark hours or even days.

Once I was in a situation when the breakers started to be disturbing even with the seanchor. However it is a fact that seaanchor prevents the destructive breaking seas to reach the boat for an amazingly long time. I have heard about boats capsized with parachute anchors but only from seccond hand. It would be great to learn more. I would guess that phenomenal seas could do it.

After dismasting the seas developed well over 12m. Broken mast helped to stabilize the boat and another capsize did not happen. The highest seas were not as scary as the early ones. (Probably as the waves get longer they are not that dangerous and, of course it is much harder to capsize a dismasted boat).

A nonsense idea: mast on the tabernacle PIN! It makes the mast weaker, deck stepped hinge would be much stronger. Or no tabernacle at all.)

The boat: S/Y Waterbird, steel sloop, Bruce Roberts 36 (11m), 12 tons, long keel, cutaway forefoot.

Jury rig

Jury cutter rig. It can be converted to ketch very easily if a helmsman has a hankerchief. (The original boom worked as a mast very well. With inbuilt sheeves I had 4 first class halyards. Unfortunately only one jib left. The orange staysail has a babyboom instead of a stay. The mainsail was used without cutting it. It is reefed around a whisker pole and (still too long!) shortened by what I call "David Lewis´s knot" (the first sailor I know who used it)"