30+ Mast Compression Post/Bulkhead Repair Ideas

[bigd14]

Today the mast was unstepped and the boat was hauled out. I removed the mast step and found the area beneath it had been slightly compressed. I sounded it with a chisel handle and it was immediately obvious that there was a void under this area. I figured this was due to plywood core that had gotten wet and rotted. So I decided to replace the core with G10. I cut a small square to start that would be hidden by the mast plate. The square popped off easily, revealing…an aluminum plate embedded underneath!

The compression I had observed was due to a void in the fiberglass between the top skin and the aluminum plate, which can be seen in the photo below. So the fix will be to reinstall the top skin with thickened epoxy, glass the seams and then paint. The whole repair should be mostly hidden under the mast plate.

I’ll also add the support described in a previous post to the compression post.

 

[bigd14]

The step area has been repaired using the cutout top skin applied to the aluminum plate with thickened and reinforced epoxy and tied to the rest of the deck with a layer of fiberglass cloth and finally, a fairing coat applied. Yes the sanded area around the cutout could be bigger to better tie the area together and I could have used thicker fiberglass fabric. If it fails I’ll just make it a bigger project in the future. The main challenge was maintaining the tapped bolt holes in the aluminum plate. This was accomplished using mold release wax on the 4 bolts and working around them with the cloth and epoxy. Final fairing tomorrow and maybe paint if time allows.

 

[Prairie Schooner]

. . . Yes the sanded area around the cutout could be bigger to better tie the area together and I could have used thicker fiberglass fabric. . . .

I find I'm constantly making those decisions. It seems there's always a more complete or robust or professional or etc. way to do something. One of the great things about this forum is reading accounts, "I did such and such, and it's held up really well." or "That didn't work." Your choices here seem reasonable to me. Nice surprise finding that plate in there! Good luck!

 

[bigd14]

This little exploratory project is now complete and once the mast plate is on and the blocks in place nobody except me will ever notice it unless they have read this post or are a future owner cleaning the area with a toothbrush. Since it will be hidden I didn’t try for perfection on the fairing so there are a couple small irregularities highlighted by the setting sun. But it’s actually better looking than it was two days ago! Most importantly there will be no more leaks through the mast step.

I will probably not add the block to the compression post as discussed earlier because I don’t think there is actually a problem. I’ll monitor the area for any changes.

 

[bigd14]

Final installation including two Scanstrut deck glands to run the mast wiring through the deck. Any future leaks can be easily addressed now that the wires exit the mast and no longer run through the step.

I added a piece of clear tubing as a chafe guard after this photo was taken.