This job occurred due to a loose mast heel and broken mast goose neck attachment. The x2 rivets holding the heel to the mast had loosened and slightly elongated  the holes in the mast.

Once removed I noticed that the x2 small halyard pulley wheels which are secured into the mast heel fitting had broken edges [not good for the ropes]. These plastic wheels are held in place by two quarter inch stainless steel rods. Soaking these rods in anti rust did not un seize them and the shafts fit into blind holes so you cannot punch them out.

I had to break the plastic wheels off, place a pair of vice grips onto the quarter inch shaft and gently heat the mast heel with a gas axe to remove the x2 quarter inch shafts.

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Fitting the new plastic wheels was no problem but I coated the ends and sides of the new shafts with a product called Duralac anti corrosive joining compound .The commercial mast/rig builders use this on all fittings that they attach to their masts that are of dissimilar metals.

There were x2 cracks visually detected on the mast heel where the boom vang shackle attaches itself to, this was rectified with alloy welding but had the potential to fracture when in use and sooner than later by the look of it.

I removed all of the stainless steel pop rivets and fittings from the mast and boom, removed the corrosion and salt build up, applied the Duralac to all rivets and fittings where contact occurs and used Fosroc Silaflex MS [ life of 20 years +] to act as a filler in the spots where corrosion had pitted the alloy. This was on the advice of a mast/rig builder of many years experience.

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I used monel pop rivets with steel mandrels [ the metal shaft of the rivet ]. Unfortunately a marine retailer had informed me that monel rivets have stainless steel mandrels but this is incorrect so don’t inconvenience yourself trying to locate any. This means that the steel mandrels require tapping out [? corrosion or rust stains] and then lift the mast head up to remove them from inside the mast. Removing the mandrel does not weaken the strength of the rivet according to the commercial mast/rig builders.

I admit that I did not feel comfortable taping the steel mandrel out as advised as the pop rivet curves over the top of the mandrel when pulled tight.  Instead I coated the whole pop rivet with the Duralac, allowed it to semi dry, fitted it  to the mast and applied the Silaflex MS to the mandrel hole to prevent salt water access to the steel mandrel. I also replaced the other x4 plastic halyard wheels while these fittings were off the mast.

Lastly I refitted the mast heel by drilling x2 new 3/16 holes to secure it to the mast. Monel rivets have a corrosion factor of 6 when used with dissimilar metals ie monel on aluminium, where as stainless steel has a factor of 28 out of 36 when used on aluminium.

This fitting has three short metal sections welded across the main metal section, which is in turn pop riveted to the mast. Each one of these short metal sections had cracked at their adjoining welds on the main metal section, which in due course would have detached when under pressure one day. This was welded, welds filed smooth and refitted to the mast