Sunday, 10 February 2013

Slowing down - making a Jordan series drogue

I've seen more than my fair share of storms. I used to think that a cruising boat should be able to take anything the sea could throw at it and that I should be able to handle a boat in any conditions, and so I paid far too little to weather forecasts or even the seasons. That youthful, optimistic adventuring spirit lasted through the ownership of several boats before being at last knocked out of me by one avoidable storm too many. I have a friend who has sailed several times around the world, much of it single-handed. He has rarely seen a gale, and once got right the way round the world without encountering one. That's the way to go!

Well, anyway, now dedicated as I am to choosing the right season for a route, and watching the weather as closely as possible, I still regard a gale or more as almost inevitable, and even if I have nothing but smooth sailing for the rest of my life, it will be pleasanter sailing if I have some confidence that the boat can handle some severe weather.

Part of the preparation for long distance sailing has been to strengthen areas, make sure every joint and connection and seal is water tight, simplify things, chuck out unnecessary weight, complication, and through-hull connections. That's all the same for any boat.

I've found that the way a boat behaves in rough weather depends very much on the boat. Each one handles differently in rough weather, so it's difficult to adopt a single strategy that will cover all possibilities. Sailing in storms is a big subject, but it is covered well in 'Heavy weather sailing' by Adlard Coles - a book I've read through and through, and was pleased to find that a new section has been added for multihulls in the latest edition.

Here's one storm strategy that isn't in the book that worked for me. 30' trimaran, single-handed, Gulf of Genoa, January 1st, 1982(?) (told you I failed to bother about the season). Sailing west from Viareggio with the wind behind me, all was well until it very suddenly increased. I got the mainsail down entirely, and was left with the working jib up. By the time the main was all snugged up, the boat was surfing fast steering with the Autohelm. I steered by hand and very soon, I realised I didn't dare re-attach the self-steering gear. We were going far too fast for that, and single handed, bound to the tiller, it would be difficult to drop the jib. Also, I was now going very fast in the right direction, so I continued with that setup - for the next 12 hours (until I'd sailed into the middle of the low, and the wind just stopped, as if someone had switched off the fan). The waves grew big and steep, and it seemed there was almost always a wall of surf behind me.

I don't know what the wind speed was, but I remember thinking the boat speed log was broken, because it kept showing 2, 3, 4, 5 knots, and I was clearly going much faster than that. Most of the time, the speed was showing in the mid-teens. Then I realised the speed log only goes up to 20 knots, and so those little readings were 20 knots less than they ought to be. I'd reached a top speed of 25 knots! This on a boat that I'd rarely seen go faster than 8 knots in 2-3 years of sailing!

Yeah, the wind speed... so the boat was going downwind at 15 - 25 knots. I had a Rutland wind generator. If I was anchored in a gale, that put out 4 amps. I'd never seen more than that. It was now frequently putting out 6 amps, and it sounded like a helicopter.

So that was a lot of wind, and the sea was quite shallow, so the waves were very steep. Maybe I did the right thing. No wave came into the boat. Of course, I was sailing on the edge of catastrophe. One wrong move with the tiller, and I'd have broached and capsized for sure. Or if the rudder hit anything in the water, or just popped up (it was a lifting rudder). But it went fine, that time.

That strategy might have been good considering the steepness of the waves, but usually, you need to slow down in a storm. Stop perhaps, with a sea anchor. However, Richard Wood's experience with a sea anchor has put me off that idea, as well as imagining lying ahull in bad weather trying to set an parachute in the sea off the bow attached to a bridle, and having that all work out just fine (probably in the dark, alone, tired and in the rain too...). Tricky to deploy correctly. So anyway, I've settled for a series drogue.

This kind of thing, attached to the back of the boat:

I made my own - instructions are here.

Here are a couple of things I learned that will be useful if you also make your own.

The cones aren't hard to make, but I needed 140 of them, so I bought them ready made on ebay. There was enough work involved attaching them, but after a bit of practise it took 4 minutes each.

There are several types of double-braided rope. I got some cheap, and struggled to attach even one cone. Turns out this type of rope (used for cod-ends on fishing nets) it much stiffer and more compact than the loose soft stuff you need for making a drogue. Check with your supplier than the rope will be suitable for a drogue.

Splices are easy. Here's how:

Stainless thimbles can twist and distort under great strain. A twisted thimble can fray your rope. Add a lump of weld to the inside of the thimble to close the loop.

Here's the bridle and finished drogue:

The drogue is no use without something strong to attach it to. I have some little cleats at the back - good for attaching a dinghy painter, but not a drogue. So I had some stainless steel plates made up and attached them to the hulls. The hulls are foam sandwich, so first I removed the foam from the inside:

and replaced it with plywood epoxied into place. The plywood is well glued to the outer skin:

Then a couple of layer of glass over that to join the ply to the inner skin:

Then bolt on the steel plate:

The 10mm thick tab at the aft end is for attaching one leg of the bridle. The loop at the for end is just something I can use to tie things in place on my aft platform (like a sit-on canoe I'm thinking of buying, for use as a second dinghy, to go fishing, and exploring creeks).

I don't expect this work to make the boat now prepared for any eventuality. But perhaps one day, in the right kind of storm, I'll attach my drogue, throw it off the back and sail slowly and safely downwind till it's all over.

Update, 3 years and many thousands of miles later: The series drogue remains in the bag. I once moved it from its locker to the cockpit, and that seemed enough to quell the storm, and all was well. However, I still regard it as my ultimate backup. When it all gets too much, I'll hang it out the back, tie off the tiller, close the doors, and stay inside. I haven't had to resort to that yet, but I have used an Abbot drogue quite a bit, and the results of that suggest to me that the series drogue is going to behave just as predicted.

The Abbot drogue, attached to the same plates has been great. See my trans-Atlantic log for details of that.

One other use of these plates: I use a Galerider drogue on a bridle over the stern whenever the boat surges about at anchor. The worst conditions I experienced were in Northern Spain, when I had a F6-7 blowing against 3 knot current. No fun at all. I had a lot of scope out, so the boat had lots room to sail about, and according to my GPS, we hit 4 knots before sailing ahead of the anchor and snatching to a stop, only to drop back downwind, and then surge forward again on the other tack. I hung a Galerider off the stern on a bridle, and the boat just stopped! Almost dead still. The anchor can cope very well indeed against a steady pull, so I wasn’t bothered about the bit of extra drag caused by the drogue, but I was very pleased not to have the anchor, the boat and me snatched about from one side to the other. I have three drogues on board – I have the Galerider specifically for anchoring in wind over tide conditions.

No comments:

Post a Comment