Adjustable traps seem to be too much to screw with to me. I just use the standard dog bone. If I want to trap low, I use the low hole. I want to be higher, I use the high hole.

Plus, the more parts you introduce to a system, doesn't matter what it is, the more parts there is to fail. You could probably do away with the block too. Just use a sailmaker's thimble there. Other parts of that part of the trapeze will probably wear out before the wear from the thimble becomes an issue.

This is all I use, clean and simple:


I don't shackle the block on any longer, I just use a Harken 504 (I think that's the number) and put it through the thimble when I make my trap lines.

I used to always make them from the top down. I'd make the splice that attaches to the mast first, then set my handles and do the eye at the bottom. Where the handle meets the thimble it creates a wear spot and I think the solution to that is to just tie a stopper knot, (probably just an overhand knot would be sufficient), in the dyneema for the handle to stop against and have the thimble with the block an inch or two below that knot. Should be wicked durable that way.

I've taken that dogbone to the teeth a few times, which is why I prefer that wire loop with the plastic insert. Even when the insert/spacer fails, the wire loop remains viable.

But your setup still looks sweet. What size is that trap line to the mast?

Jeff,

Maybe you've been following my thread on that other beachcat site. I had the same idea, and ordered the parts. The official Nacra and C2 double blocks used in the adjustable setup are ~$55 EACH. The ronstan double block is a ~$25 part. There is a knock off of the Ronstan/Harken part but I don't trust knock off's in a safety critical application, when the name brand guys see failure.

So I went with the shock blocks at $16 a pair from a local supplier (sorry Rick I might return these don't want to double pay shipping). My intention is to splice them together to form a double block using dyneema. To be fair to Ronstan I don't think this is the intended purpose but others have done it with Antal rings. My concerns are the following:

1) MWL; in a 2:1 setup I'm 185lbs wet so you're looking at 370#'s of load on the block. Other have pointed out you may see 2-3g's of acceleration occasionally so you may apply up to 3x that number, 1110 lbs. That exceeds the breaking load of the shock block. However, it's an aluminum block so it won't just snap. It'll likely deform and since you are only applying high loads for temporary periods of time. Finally, one must remember Ronstan designed these for similar applications/load cases on kite boards.

2) Friction. I went with 3/16" (5mm) diameter line which is commonly used in adjustable trap setups. Somewhere I saw (Murrays?) the shock block ideal line diameter tops out at 1/8". Now that I've seen that I'm going to go down to 4mm (another reason to shop locally) line, which actually increases my line cost. Previously I spec'd Excel Pro which has a 1511$# tensile strength in 3/16" diameter, but a mere 695# tensile strength in the 5/32" diameter (4mm). Hence I'll switch to a dyneema cored line, FSE Dinghy Control Line which is a nice running line and has decent price/performance ratio. In 4mm this has a tensile strength of 1574#'s. I want the blocks to explode before the line does.

I'll post photos and reviews of the system when I'm done. I'm doing this right but trying to save money where it makes sense. Also want a reliable system for ocean racing so if the shock blocks don't work they'll get returned.

What size is that trap line to the mast?

3mm. I think I'd like to go smaller, but I use that same size all over the boat and I usually buy it by the spool. A spool of 2mm would last me a lifetime just using it on trapeze parts.

The 2.5mm (7/64") Amsteel is fine for trap lines. Just be ready for it to have some initial stretch. My a-cat lines stretched about 4-6" before taking a final set.

Jake how many sails and how many times did you adjust before it locked into a range +/1 1/8 of stretch (ie Final stretch point)

Karl,
Why not just get rid of the small microblock (H224) below the handle and just run the line through the thimble. I do this and it works flawlessly. Clean and simple.

What is everybody else doing up top to prevent chafe, or are you just leaving it bare?

I have 6 inches or so of lacing at the top

how hard was it to re-splice once you tensioned the line?