Monday, September 29, 2014

One fun project - Masthead plate

I realize that reading about a boat project may not be that exciting, but boat projects have been pretty much my world for the past couple months, so that is what you get to hear about!  This project was one of the many unplanned projects.  It is amazing to me that stuff that had been working for years (in this case, about 30 years!) suddenly decides to break now, just as we are trying to whittle down our long list of planned projects.  Maybe I should chalk it up to the fact that we are inspecting all aspects of the boat more carefully now than ever before ... and obviously it's better to be able to fix it now than try to do it in Mexico.  So I should be happy about it, right?!

Breaking welded extension on mast top
plate for halyard mounting
So, anyway, I was up at the top of the mast about two weeks ago, cleaning up some loose wires, and I noticed a rather disturbing thing -- a welded aluminum plate was about to break off!  This piece is an extension off the front of the mast top plate, which holds a U-bolt, onto which is mounted our spinnaker halyard.

For about a day I just ignored this problem, and didn't even mention it to Jolanda!  There was just too much other stuff going on.  But eventually we decided we had to address the problem.  If this thing broke while we were flying the spinnaker, it would allow the sail to drop in the water, likely going under the boat and getting destroyed, and possibly causing significant problems (like bringing the boat down)!   There is no way we could get a welder up to the top of the mast to fix that part -- the only way to fix that part by welding would have been take the boat to a yard, drop the mast, and do the work on the ground.... and this was way more hassle than we had time/money to deal with now.  Instead, I decided to cut off that broken section, and have a new aluminum top plate fabricated to take it's place. The new plate would be just screwed into the exiting mast top plate.

I quickly took some measurements, made a SketchUp design (BTW, I love SketchUp ... I couldn't do this kind of project nearly so well without it), and called up some local machine shops to see who could make a new top plate quickly.  Craig at Metal Magic in Oakland was able to get the part fabricated and powder coated in just a couple days.
SketchUp model of new mast top plate
Mounting the new plate was not really an easy job, but fairly straightforward.  Working at the top of the mast is always a bit of a hassle, but I really dislike hauling heavy tools up there.  But in this case, I had to use my right-angle grinding tool with a cutoff wheel to cut off the broken section.  Then I had to drill and tap four holes -- I was very cautious to avoid breaking a tap.  But it was relatively easy ... after working with stainless steel, doing work in aluminum is sort of a treat! Below is the before and after photos.  Note that, in addition replacing the previous port-side U-bolt, I also added a new starboard-side U-bolt -- not sure if we will ever use that, but it was basically free so I thought it would be worthwhile to add that.

The original mast top plate, with the
broken extension plate
The new mast top plate, with two shiny new U-bolts
 mounted, and the original spinnaker halyard block back
 in place.
A couple more picture of the view from the top of the mast.

N-dock at Berkeley Marina

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