As I recall
, the original design called for the cones to be made of rip-stop nylon, and the attachment "strings" to be made of folded up ripstop.
Some years ago I built a very small series drogue to use when towing our big inflatable
(bad practice, I know!). Idea was to keep it from surfing and getting too much slack in the tow rope
. Not having a clue, my first attempt had 6 cones, standard dimensions. When I first tried it out whilst motoring at about 4 knots in the dinghy
, it nearly pulled me overboard
before I could throttle back! Wow! So I ended up with two cones, and it worked a treat... still does, for that matter. But, the nylon soon was reduced to tatters. If you stop to consider, when you use one with 120+ cones on a yacht, the speed will never get above 1-2 knots and the stress on the individual cone is small. In the dinghy
drogue we could and did exceed 10 knots whilst towing it. This trashed the nylon. So, I made some new cones out of Herculite vinyl material, and they've lasted ever since... circa 15 years.
So, I suspect that you could indeed get away with your blue tarp stuff, but as in a previous post, I think it might be a foolish was to save a few bucks. For one thing, I wonder about the ageing qualities of the tarp stuff. It could be years before you needed your JSD, and it would be a shame if it blew apart when you deployed it. You might wish that you had spent just a little more on material!
All that said, I think that they are a great device, and applaud your determination to build one.
Jim and Ann s/v Insatiable II lying Broken Bay, NSW, Oz