C27 Mast Inspection and Repair

When I bought it , the boat had new SS spreader brackets, new u- bolts for the lower shrouds, and new standing rigging (and reciepts to show the new standing rigging was less than one year old), but something didn't look quite right at the spreaders. The lead on the port-side lower shrouds wasn't fair and the spreader bracket was misaligned. So I decided to unstep the mast and take a closer look.

The cost to unstep the mast was about $75. It'll cost about $100-$125 to restep it, because it takes longer to re-step than unstep a mast.


Bad news! Here's what I found hidden underneath the new stainless steel spreader bracket on the port side. The bottom-most hole (below the spreader cup) is elongated (as are the other two, but less obviously), and the mast is compressed about 1/8" right where the bottom hole was. I'm VERY glad I decided to inspect the mast -- this was a mast failure just waiting to happen. Those elongated holes permitted the whole spreader bracket to move with every shock to the mast, and the bolts were "egging-out" the holes.

Folks have emailed me to ask it the mast failed from compression under the spreader bracket. The answer is probably "No".

In fact, the factory-recommened compression posts had been installed. I think the holes might have been misaligned when drilled by the factory, or perhaps the bolt threads chewed up the hole, egging it out. As the hole elongated and the axis of the bolt changed, it pulled the wall of the mast in about 1/8".

From the looks of things, I suspect the damage was there before one of the previous owner installed the new spreader brackets. Only the area immediately surrounding the elongated bottom hole was dented, not the whole area under the bracket. The spreader bracket itself wasn't bent at all. The mast column itself was not buckled like you'd expect to see from it there had been compression damage.

Whoever replaced the OEM aluminum spreader bracekts with the Stainless Steel upgrades just left the damage there, and covered it up with the new brackets.

Good news: I can fix it, but it's gonna cost about $200-300 to have an aluminum patch and compression posts fabricated by the metal shop at Svendsen's Boat Works. The shop foreman told me he has sucessfully repaired hundreds (literally!) of masts on old Catalina's (of all lengths). They'll fabricate the parts and I'll do the installation myself, according to their instructions.

From my past experience with four (or more) other old masts -- This is the worst I've damage I've ever found on an old mast, but every other old mast I've ever taken apart has shown significant damage from lack of proper owner maintenance. I've found holes enlarged from galvanic corrosion (shoulda used some goop to insulate the steel bolt from the aluminum), egged-out holes from bolts that were too long (the threads were wearing the spar wall), missing compression tubes, etc. A word to the wise -- inspect your mast when you first buy a used boat, and inspect and maintain it regularly.

 


A side view: You can see how the bolt pulled the mast wall inward about 1/8" in the area immediately around the hole. Forturnately, it's just local.

Here's the final design for the 1/4" plate. I double checked with Master Rigger Brion Toss about the design and installation before giving Svendsens' Boat Yard metal shop the final go ahead for the design. Brion suggested a few refinements over and above the metal shop's suggested design for the compression posts and bedding method.

After the mast and plates are painted with LPU, the plates will be mounted to the mast wall with machine screws into counter sunk, threaded holes. The spreader brackets will be mounted with thru bolts and compression tubes directly underneath the spreader bracket. Both the mast and the plate will be painted with LPU (two part polyurethane) before mounting. All screws will be well coated with TefGel anti-gavanic compound. The plates will be bedded to the mast with LifeSeal (polyurethane-silcone combo) or polysulfide (like 3M 101)

Forward to the next page about repairing the Mast

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