Mast stub plug

[bruce]

This simple DIY project may be useful for a Mastendr sailor, especially if you're chasing a mystery leak. The issue is, when the mast is folded down the mast stub is open to the elements. How much rain can enter there is up for debate, but it can be comforting to eliminate it as a potential source.

At least on the PC, the fasteners for the hinge are at least a 1/2" from the cut, so I sourced some 1/2" rubber sheet (#1370N19) from McMaster Carr, suitable for use outdoors. I chose Neoprene because it was cheaper, and was available with a durometer rating of 30A, softer being better for conforming to the inside of the stub. Other suitable rubbers were typically 40A, or higher. 40A is probably still OK.

I also found a nice 18-8 SS elevator bolt (#92361A463) with a large head that would spread the load well, but any bolt with fender washers could work.

I rubbed chalk on top of the stub and transferred the shape to the rubber. The rubber cut OK on a band saw, but a hand fret or coping saw would work as well. The rubber did machine sand well, so curves could be faired readily. I punched a hole for the bolt, and added a fender washer under the nut. Rubber doesn't drill well, but again, a pilot hole could be faired and enlarged with a round rasp or abrasives. I slipped the assembled plug into stub and tightened the bolt expanding the plug. Nice tight fit. Back off on the nut, and the plug can be easily removed.

I don't have wires in my mast, but I think a short section of plastic tubing could be used as a conduit through the plug. Punch a second hole towards the track for the tubing, and seal the wires in the tube with putty or caulk at the top. If the wires are already run, it may be possible to slice the tube along one side, spread it open, and slip the wires in. The plug could then be sliced between the new hole and the track and the conduit/wire bundle snapped in place. Expanded, the plug should seal around the conduit, and close the cut, at least in theory! The third photo shows a possible layout.

[Gerry]

This is exactly why this forum is so valuable.  Learning the solution to problems is the basis of great owners forums.  Thanks.

[kickingbug1]

   you would have thought that hutchens would have thought of that

[brackish]

really good idea Bruce.  Did you cement the carriage bolt to the bottom of the plug or just shape the square seat?  Does it try to spin at all in that rubber?  That looks like a great way to make a compression seal for any oddball shaped opening.

[Jon898]

When I had a replacement sail cover made by Lonesome Pines Canvas (link at the bottom of Keith's site here : http://sailboatrichlands.com ) they included a separate canvas cap that velcro'd to the main cover and sealed off the mast stub, including the sailtrack.  Seemed to work fine.  See this thread: http://cpyoa.geekworkshosting.com/forum/index.php?topic=7118.msg52087#msg52087

Jon

[bruce]

Hey brackish, neither. I intended to cut a square seat in the rubber, and had a chisel in hand, but cutting the rubber neatly to a depth wasn't going to be easy so I just tried it and it worked fine. The bolt didn't spin. Once you've got some compression it's even less likely to spin. I did use a 5/16" punch, for the 5/16" bolt, but it was still tight. I might have had some slippage if the hole was looser, a 1/4" hole would have worked. If it did spin, I think I'd just cut a slot in the end of the bolt so I could insert a screwdriver to hold the bolt as I tightened the nut from the top.

I've made up a few plugs for the drainage holes of large garden pots that I want to make into water gardens. Even with access to both sides, I can usually just tighten the nut to compress the plug, no slippage.