
A frenzy of preparations: no matter how long you prepare, I think setting off for a sail like this always ends this way - desperately getting spare fuel filters, organizing a little bit more food, and Greg trying to find his special wind-stopper fleece hat.
Over the last couple of days we've been at a boatyard having two padeyes installed on the stern. These aren't just rusty old D-bolts, they're super strong Harken units that have a breaking load of 20,000lbs. They're bolted through one-inch thick solid fiberglass and have large stainless steel backing plates that give them a huge load bearing capacity. To put this in context, the whole boat weighs just over 20,000 lbs (about 9,000kg), so we can almost hang the boat from the stern off either padeye (a potentially novel way to save on winter storage costs)!
The reason for all this is a device called a Jordan Series Drogue. In essence this is a 200' long piece of rope. The start of the rope connects to the boat (the new padeyes) via a bridle and some giant stainless thimbles; above is a photo of one next to a quarter . But the key to it lies in a series of around 120 small parachutes, each a small drag device, that run down the rope. In series they provide a huge amount of resistance.
It's one of those things you hope you never use (having paid for it today, I thought just for a moment: we'd better use this damn thing. But it's a day or two before we leave and I'm getting superstitious - I took it back very quickly and hope nobody up there heard).
You see, a potential risk to a sailboat like this comes from large breaking waves. Big waves are fine, we just sail over them, but breaking waves can sometimes, when they're big enough, catch the boat and propel it like a surfboard. The boat takes off, essentially in a falling body of water flying down the wave, and can hit 70km/h before crashing into the wave's trough. I'm told this is not recommended. Either the boat breaks up, or the bow can plant into the trough with the following wave flipping it end-over-end, a situation known as pitchpoling. I'm fairly confident that is not recommended either.
So this is where the drogue comes in. It keeps the boat's stern to the waves. When a big wave hits, it allows the boat to accelerate a little (diffusing the impact) but then gradually the chutes open and - like a bungy going tight - you're pulled back through the whitewater and over the wave's top. That each side of the bridle needs to be rated, in our case, to 14,000 lbs gives you a sense of the loads potentially created. There are other versions in more common use - one giant parachute etc - but this one intuitively sounds safest to me: the loads on any one chute are small, there's almost nil chance of the series getting reversed (a risk with just one chute), and it's so long there's little chance of it being in the same place on a following wave.
So it's a pretty useful device. My friend Dan, a willing volunteer to Bermuda, spent a good part of today helping connect the chutes to the line. We've done about 30....only 90 to go...
...but for now it's not so much a problem that we're still finishing off our preparation. The weather in the stream is awful. It looks like we'll be here another day or two at least. Here's the forecast for the offshore waters outside NY...not even in the gulfstream yet [1 Fathom is 1.8 meters or 6']:
GALE FORCE WINDS EXPECTED SAT INTO SUN
FRI
WINDS BECOMING NE AND INCREASING TO 15 TO 20 KT
LATE...EXCEPT W OF 1000 FM 10 TO 15 KT. SEAS BUILDING TO 4 TO 7
FT. HIGHEST WINDS AND SEAS SE.
FRI NIGHT
NE WINDS INCREASING TO 20 TO 30 KT. SEAS BUILDING
TO 7 TO 11 FT.
SAT
N TO NE WINDS INCREASING TO 25 TO 35 KT...EXCEPT E OF 70W
TO 35 TO 45 KT. SEAS 8 TO 12 FT...EXCEPT E OF 1000 FM BUILDING
TO 12 TO 19 FT. HIGHEST WINDS AND SEAS SE.
No comments:
Post a Comment