20 Aug. 2012
I went up the mast to re-install my lightning rod and found that the starboard inboard spreader had developed "stretch marks" and had almost a tear on the trailing inboard edge (see photos). I've been watching the lower spreaders for some time now but this is the first serious deformation. It pretty much has put any sailing plans on "hold" until it has been fixed.
The "root" is the aluminum casting that the airfoil butts up against. It is supposed to rest on the shoulder of this casting and have the force evenly distributed about it's circumference. The root is attached to the mast by a floating tang of heavy aluminum which is attached to the two stainless mast bases by 5/8" clevis pins. A smaller (1/2") clevis pin holds the tang, root and spreader arm together. I think this pin should not be load-bearing; it serves mostly to hold the assembly together in a loose fashion.
If it is bearing a load then the spreader will pivot and one edge or the other will be point-loaded and start to spread apart. This is what I think happened. You can see in the photos below that the spreader does not rest evenly on the root. Both upper and lower starboard spreaders exhibit this problem. The port spreaders are fine.
I have noticed that with the rig tuned to the appropriate tension (see the Tuning page) the leeward side of the rig was fairly loose. It is possible that the rig should
be progressively tightened (with caution) to the point that even under high winds the downind shrouds are still tight. (Note: click here for a diagram of standing rigging terms)
27 Aug 2012
We are moored in the quiet and pristine Pinta Bay in the Kuring-Gai national park north of Sydney. Seemed like a good spot to take off the spreaders. I had been thinking about lying in bed, doing the work in my head, and decided we could easily remove the two damaged lower spreaders to start with, then proceed to re-rig the boat and possbly fix the upper spreaders as a progresive project later on.
28 Aug 2012
Today we took the spreaders to my Niall's cousin Paul who has a soda-blasting business. Niall lives in Sydney and is the new owner of KP44 Ubuntu (currently in Puerto Vallarta).
It took Paul almost three hours to clean the linear polyurethane paint off the spreaders. Tough stuff. I think the only other way to remove it is by sanding or heat.
In the afternoon we took the spreaders to a specialist welder and instructed him to grind off about 5mm square to the axis of the spreader and then weld it to the root casting.
29 Aug 2012
The welding is finished. The welder ground down a few mm of the distressed material on the starboard spreader and a matching amount on the opposite spreader. Because some material had been remmoved the holes no longer were lined up so we had to re-drill the holes in the root and tang to match up with the holes in the spreader.
This left some sloppy looking oval holes in the tang but since the purpose of the 1/2" (12mm) holes is to simply keep the assembly together (i.e. they should not be load-bearing) this should not matter.
I might have wished for a neater welding job but it will be up the mast and not visible. This same day we dropped the assemblies off to be painted. We are fortunate in that
the spraying is being done as a favor and I only have to pay the cost of the paint. It was supposed take about a week plus a couple of days to cure but it turned into well over two weeks.
26 Sep 2012
Once I remembered that the wing-like cross section determined the leading and trailing edge the spreaders went up fairly simply. Kathy hoisted the spreader using the staysail halyard clipped underneath to the flag halyard ring and wrapped over the top to allow the spreader to be mostly balanced with the top up. The trick was to start at the tip of the spreader (the outboard end). The rig was tight enough to allow me to hang on to the shroud. My biggest fear was dropping the rigging pin, but it slipped in fairly easily through the fork on the spreader tip and the connector plates. Next I moved to the root. Kathy slacked the shroud wire to allow me to push the spreader base out and back into the stainless base fittings on the mast. The spreader was now in place and I just had to drop in the clevises. I used a nylon spacer washer to fill in the gap in the base.
Before sailing next I will have to tune the rig, of course. I did notice that with the re-built spreaders in place that the tips are naturally more forward than the were. The chainplates are in line with the aft edge of the mast and travel to the center of the mast at the spreader. I don't know if this is commonplace and intend to look at any other KP44's I encounter to see if the chainplate positioning on Beatrix is normal.