Velorum #215: Frigging in the Rigging

The boat was originally rigged with Navtec rod rigging and even though it lasts longer than wire and is lighter and stronger than comparable wire (diameter), it was time to replace the almost 40 year old rig. In a perfect world I would have replaced all of it with new rod rigging, but there are 4 problems with that:

Very expensive
Rod rigging needs specialized presses to 'head' the rod to length (more expense)
Specialized fittings on the mast and deck that aren't easy to find (and expensive)
Navtec is out of business so sourcing everything would be difficult (and expensive)

Fortunately for me, when I bought the boat the previous owner left me a big spool of 7mm compact strand wire, a box of all required Stalok fittings, and newly designed tangs to replace the old Navtec rod rigging fittings on the mast.

All the parts are there, but some assembly required!

Of course, having all the parts doesn't mean that the rig is complete, the existing rod rigging needed to be carefully measured before I made the first cut on the new wire. Ultimately, each fully built new shroud needed to be the same length as the old shrouds, so I know the final answer, but in order to get there, a bunch of measurements needed to be done.

I put a bolt on the outside of my shop where I could hang one end of each piece of rod rigging and tension the other end with a come-along attached to the hitch of my car. Once I tensioned up each shroud, I measured the length with the turnbuckles at their midpoint to get the total length of each one (center pin to center pin).

I created a spreadsheet and entered the total lengths and then measured all the pin to pin lengths of the rod turnbuckle assemblies and subtracted that from the total length to get the rod length. In theory, this should be the same as the wire length, but because the new shrouds have different fittings that connect to both the mast and chainplates, these had to be measured and subtracted from the total length as well.

The fittings in question that need to be added to the spreadsheet and subtracted are:

Stalok Eye: 1-1/4"
Stalok Turnbuckle: 10-5/8"
Deck Island (completed May '24): 1/4"
Correction Factor (Identified by previous owner on some shrouds): 1/2"
Tangs (Engineered and beautifully machined by previous owner, see schematic below): 3.5"

So all told, this added up to quite a bit more than the original chainplates so the final wire length was several inches shorter than the original rod rigging. The forestay will have to wait because I'm not sure if I'm going to replace the rod on the forestay yet because it may require me getting a new roller furler if I can't snake the new wire through the foil. The backstay I'm going to save because I don't really know the length it should be. The boat used to have a backstay adjuster which cut a few feet out of the total length, but I don't know the exact measurement. The manual has a number 48' 7-3/4" but I don't know if that can be trusted. I may wait until the mast is stepped to cut the tail for that one.

Final wire length calculations

With the spreadsheet completed with lots of measuring and re-measuring I measured out the first wire to cut and marked it with tape. Armed with a brand new 32tpi hacksaw blade, I centered the wire in a piece of wood with a v-cut to hold it steady and made the first cut. The hacksaw blade works great as long as the wire is held steady and is probably faster than a power tool (and makes less heat that could work harden the wire).

A quick cleanup with a metal file to get rid of any burrs and it was time to assemble the first Stalok fitting. I've used mechanical fittings in the past Stalok and Hayn HiMod and while slightly different, they use the same principal and are really nice to work with. In a nutshell, these fittings split the wire with a wedge and then form the outer strands of wire around the wedge using compression from the screwing the 2 parts of the fitting together. The mechanical connection is reportedly stronger than the wire itself.

The process is simple: take apart the fitting, remove the wedge and slide the socket over the wire (in the correct direction... ask me how I know). Then using a sharp screwdriver or chisel, unwind the outer wires and expose the core. The wire (especially compact strand wire) is pretty resistant to unwinding so expect to poke your fingers a few times with a sharp chisel before getting the hang of it. Once you do though, it's kind of amazing stuff. Because the wire has 'memory', it retains its shape even when unraveled.

Once the core is exposed, slide the wedge over the core and allow 1/8" of the core to poke out the top. Then just twist the wires that have been unwound and the will collapse back over the core. The one tricky part is that you need to lay the wires back down over the core so none of the wires fall into the tiny slit in the side of the wedge otherwise it won't be able to compress.

Once you have them all lined up nice and even, slide the socket up as far as it will go over the wedge and screw the terminal fitting (contains the wire former) onto the socket. When it's cranked down tight, unscrew it again and inspect the wires to make sure they wrapped around the wedge. Put it back together with a tiny bit of locktite and the fitting is done. Rinse and repeat for each shroud. Unfortunately, I won't know if my measurements are correct until I actually step the mast next spring, so I'm keeping my fingers crossed. Visual instructions along with videos are here: Stalok Fittings.