My copy of DDDB, picked up in a boat swap in Nuku Hiva, Marquesas
(thanks whomever!) was published in 1998 or so ...
There are 41 case studies of monos and sea anchors off the bow, 21 trimarans and sea anchors, 20 cats w/ sea anchor
, 9 power boats with sea anchors, 19 monos with drogues off the stern, 10 tris and drogues, and 9 cats and drogues. Extensive discussion of common findings etc. Can't comment on the Jordan Series drogue
comment, but case studies cover many types of drogues and sea anchors.
I have a fully-rigged sea anchor
as follows, ready for deployment in less than five minutes, and I plan to pre-attach the bow bridle
before my major Indian Ocean
crossings, running it back to the helm
station, so all I need to do is deploy the balance of the rig in less than 1 minute from the helm
One of the things I've heard time and again is that the simple act of deployment is the most dangerous part of the exercise, and that the decision to go from "offense" to "defense" is the most important decision you make as a skipper
I have a 44' cat, Fountaine-Pajot Orana
. Pre-rigged, I have 2x90' bridles of 3/4" double braid nylon, each end terminated in a thimbled splice, connected by a 12mm x 70mm s/s ring -- said ring rated at about 11,250 SWL.
is attached to a 45' length of 3/8" BBB chain using a 3/8" Hi-Mod S/S shackle, rated at 8,360lbs minimum breaking load.
The chain is pre-attached to a 300' length of 3/4" 3-strand nylon tether, again using a 3/8" Hi-Mod S/S shackle.
The tether is attached to a 18' Para-Tech Sea Anchor
, using a Para-Tech supplied oversized s/s shackle and a massive s/s swivel shackle.
I will use a 24" fender
ball to serve as the primary float for the parachute -- it's essential that the parachute never be permitted to hang straight down, so the Para-Tech rig comes pre-equipped with a length of nylon to which one attaches a float buoy.
The overall length if the tether is thus 90' + 40' + 300' = 430', about the minimum recommended 10x length of my boat. It's important to have the parachute synched up to the wave period, so that the boat is at a wave peak when the parachute is at a wave peak, and trough = trough. It may be that I'll need a longer tether for seas which are further apart than 400' or so, which is a distinct possibility.
Thus, I have an additional 210' 5/8" nylon rode
, with thimbles spliced into each end and appropriate shackles if sea conditions are such that I need a longer rode
One of the major issues on these rigs is chafe, and we installed dedicated cleats
at the very tips of our two bows, with backing plates
, to avoid rope-on-boat chafe, and I also carry thick diameter reinforced plumbing
hose to deploy if necessary.
I stress the following: THIS IS ALL BOOK KNOWLEDGE -- I have NO practical experience in deploying or using these storm management strategies.
I will say that two areas required significant research
, and I'm still not 100% sure I've got things right. First, the entire rig will only be as strong as its weakest link ... the stresses can be enormous, and I spent a fair amount of time trying to synch up the shackle strength to the rope
and chain strength. I think I have it mostly right. It turns out that manufacturers use several metrics, including:
- WLL, the apparently preferred metric by standard-setting agencies -- Working Load Limit;
- SWL, the Safe Working Limit, cited by many marine stores, etc.; and,
- MBL, the minimum breaking load, also cited by many marine stores.
I had to mix-and-match a bit as I sized the rig, by in short, I stayed away from galvanized shackles, since they are not strong enough for the diameter.
The second area of uncertainty was/is the appropriate length of chain between the bridle and the rode ... it's essential that the parachute stay in the water
, and Para-Tech recommends the chain, which also serves a dampening role as a result of its concatenary sag, be no more than 20 percent of the length of the rode. Some have suggested longer chain ...
That's it folks -- a novice's effort to be prepared ... lots of this is available for free at the Para-Tech website ... several comprehensive downloadable PDFs ...
Comments/reactions welcome ...