I used an adjustable drogue one time in a storm on the way from Gibraltar to the Canary Islands. This may answer your question about adding to the drogue for more power.
In this incident, we had winds between forty and fifty knots, but since we were running downwind, it was not problem for our catamaran. The wind had a long fetch and the seas got up to about twenty feet, but they were still not a problem as long as we controlled our speed. In this particular storm, we trailed warps behind the yacht and slowed the speed down to four and a half knots. You can see a video of this on our maxingout.com home page in a VIDEO entitled "WARP SPEED" at the bottom of our home page.
In that storm, we trailed a drogue for three days to control our speed and to prevent broaching which would be a major disaster in a catamaran. The drogue that I used in this instance was a homemade drogue that I call the "Abbott" drogue, because I made it up on the spot using readily available components on my boat. (My name is Dave Abbott)
This drogue consisted of an 180 foot long warp of one inch three strand nylon that I looped behind the catamaran, with one end of the loop going to a starboard winch and the other end of the loop going to a port winch on the stern. But the loop is more than simply a loop of rope. On this loop I install carriers that I slid down the rope to increase the pull of the warp and thereby create the drogue effect. What are these carriers? I use four foot sections of plastic water hose as the carriers, and on these carriers I wrap anchor chain, dingy chain, dingy anchors, or whatever, and I lash these heavy weights securely to the hose carriers. Electrical ties can also attach the weights to the carriers. I then slip the plastic water hose carriers onto the loop of rope, and then slide the carrier down the rope and into the water. The carrier with attached weight immediately slides aft to the middle of the rope loop that I am trailing in the water.
If I want more drogue effect, I put more carriers and more weight on my warp and then let them slide down the rope loop and slow the boat down even more. The "Abbott" drogue is an infinitely adjustable loop of rope in which you can send as many carriers and as much weight down the warp as you need to use in order to control your speed when running downwind.
I like the "Abbott" drogue because it does a couple of things.
1. You can adjust the power of the drogue. If you need more drogue power, you simply send another carrier with attached weights down the rope loop to increase the drag in the water.
2. You can adjust the distance of the drogue from the boat by simply letting out more warp or taking in more of the warp loop using winches. The drogue should be consistently on the back side of any charging seas so that you are pulling the drogue through the wave rather than out of the front of the wave and losing drogue effect.
3. You can easily retrieve the drogue when you don't need it any more by winching it in with your cockpit winches. And when you winch it in, the carriers and the attached weight stay centered in the warp loop as you haul it in. That means you don't lose drogue effect and at the same time it's easy to retrieve once it's right behind the yacht.
4. You can construct an "Abbott" drogue using materials that are already on the yacht, and it's not expensive. You need at least 200 feet of line, and three or four pieces of flexible plastic water hose to use as carriers, and anchor chain and dingy anchors to attach to the carriers with shackles and ties.
5. The drogue is essentially chafe free out in the ocean because the heavy weights are riding on the plastic hose carriers rather than chafing directly on the warps.
If you want to see how it really works, go to my web site and view Surviving The Savage Seas on the home page or captains log archive 27. SURVIVING THE SAVAGE SEAS. There you will see a picture of two warps behind the catamaran in 40 knots of wind and eighteen foot seas out in the Atlantic. The "WARP SPEED VIDEO" shows how the catamaran behaves with the drogue in position and doing it's thing. For the three days that we were using the drogue, the autopilot did all the steering and we survived without any problem.
You will notice in the pictures that we actually had two warps behind the boat. One warp was eighty feet long with about 35 pounds of anchor chain shackled in a ball in the middle of the warp. The second warp is 180 feet long, and it had dingy anchor and chain attached to a water hose carrier. I liked having both short and long warps behind the yacht because I felt that if one drogue pulled out of a wave or failed for some reason, the other would be there to take over. Together, they held my boat speed to a consistent four and a half knots downwind. The two monohull yachts that we were sailing with arrived twelve hours sooner in the Canaries than we did, but we took less of a beating because we were sailing at a slower speed. One of the monohulls accompanying us filled their cockpit with water and had two inches of water in the galley - at least that is what they told us over the radio after it happened.
This post has been edited by maxingout: 27 December 2007 - 03:01 AM
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