Radar and Rigging

Lower Port Shroud

The guys form Maritime Electronics fitted the new radar cable on Friday morning and got the radar working again. 

I found a card at the companionway when I arrived at the boat and it was from Edgar Vitte, Pachuca's rigger here in Australia.  He gave the the surprising news that I had broken wires in both of my lower shrouds.  As luck would have it Edgar was working at a nearby boat so I asked him to drop by when he was finished at that boat.

I started off by complaining that the rigging was only about 20 months old, installed by what was reputed to be the best rigging team in S America, and using top quality materials.  I then told Edgar that the riggers in Argentina had told me that I could expect 14 years of service from that rig and I recalled telling myself that I would be happy with half of that expected time. 

To my untrained eye the shrouds looked OK at the swage, though on closer inspection I could see that the pattern of the wire was not quite right at the wage.  Edgar leaned over and picked the broken wires out with a small screwdriver. 

Edgar told me that there was nothing wrong with the rigging: the materials were good and the proper tools had been used.  Given what he knew of the history of my rigging problems he had to concluded that there is a design problem.  First of all, the boat is very stiff with her heavy keel and tumblehome hull.  This means that she resists heeling which results in a lot of load on the rigging.  This exacerbates the fundamental problem, which is that the deck fittings of the lower shrouds are not far enough from the mast (1.1 meters in fact).  He told me that having the shrouds so close in results in enormous loading and that moving them even 200mm out from the mast would have huge reduction in this loading.  

Lower Starboard Shroud

I told him that I had blamed my earlier problems on running the rigging too loose, but since Argentina I had kept everything tight with a carefully maintained log of the number of half turns at what date.  Edgar shook the rigging and told me that it was just right - tight, but not too tight, and certainly not too loose.

Edgar presented me with 2 options. The first option was to replace the 10mm (3/8") wire of the lower shrouds with heavier wire.  However, this would require larger toggle pins and turnbuckles, which would cost serious money.  The second option is to use 10mm "Dyform" wire (see http://www.s3i.co.uk/1x19-Dyform-stainless-steel-wire-rope.php) which is a guaranteed 30% stronger than conventional wire.  This is achieved by filling in the gaps between the wire strands with smaller wire strand, resulting in a more solid wire. 

Edgar will replace the lower shrouds with Dyform wire in the coming week and will also check the rest of the rigging for me.

I consider myself lucky because I felt so confident in my nearly new rigging that I had not bothered to check it closely, either personally or through a professional.  It was by my good fortune that Edgar had enough interest in Pachuca to have a quick look at her rigging.