Saturday, 19 November 2016

Working with shock cord

Another candle lit, the spinnaker pole rebuild triggered an investigation into shock cord.

Buy it.

It's not easy for the novice to tell good from bad.  What I managed to learn was that a dacron cover has superior life to nylon and is one of the indicators of a superior product, as is the amount of elongation that the product will permit.  Try it.  Cheap stuff does not stretch as far as the better stuff, and feels quite different.  OK, not exactly the definitive guide to things Bungee, but it's a start.

Cut it, terminate it.

To cut it, tape first with masking tape then use a hot knife.  I bought a soldering gun with a cutting tip on kijiji, and it works well enough. 

To terminate, use stainless hog rings and the appropriate crimp pliers.  Was not able to find these easily in Toronto, but in fishing communities where lobster traps are used and maintained they are commonplace, as are the better grades of shock cord.

Easy.   All the right stuff is in the photo below, followed by a shot of crimped hog rings on the original shock cord.

Old vs new.

When I dismantled the spinnaker pole and looked closely at the original cord, I could see a construction quite different than I was used to seeing.  See below.   The old stuff, (white) with two layers of braid looks as though it would have greater ultimate strength   and perhaps a more specific extended length than the new stuff.  the rubber cores are different as well.  Though obviously expired, it had not failed in use.  I expect the newer stuff would have snapped.  Perhaps this older style material still exists?

Monday, 14 November 2016

Spinnaker pole repair

This winter is focused on sails and running rigging:  new lines, two sails, a few other items.   One of which is the spinnaker pole, which I believe was original.  Its issues are plain to see:  It was damaged by being pressed against the baby stay at some point in its life, and the topping lift bridle is well past its retirement date.

How can I straighten the bend in the tube, and possibly (somewhat) press out the dent?

Tubing is anodized AL, 3" o.d., .080" wall, 2.83"I.d..   

This pole had no lower bridle.  Some do.  Should this one have one?


Was quoted around C$250 for a replacement anodized tube from a local chandler, but in a rare flash of inspiration I remembered an automotive tool called a pipe expander - meant for dealing with steel exhaust tubing.   C$35 later I was able to do a passable job removing the dent using an el cheapo  tubing expander from Princess Auto.  Misted it with silver paint as well, just 'cuz.

So far, have replaced the shock cord as can be seen above.  See tools and some detail below.