1975 Ericson 27
Mast Dimple Repair
This has been an interesting project. I contacted a well known
local rigger and told him what
I was
doing, gave him the mast material info e.g. thickness and asked to buy
a flat piece of aluminum sheet. I told him that I would take it
from
there. They were more than happy to do this,
but
there is a minimum shop charge of $55.00, and do I really want to pay
this for a $15 piece of aluminum, and BTW, they ask if I am really sure
I can do this. I respond that I can, as I have a bit
of mechanical, metal fabrication and welding knowledge from doing
automotive restoration work. As I talk to the sales contact, I
ask about
them doing
the first bend for me for the $55. He thinks that is great,
it'll probably cost a little more, but this is the best way
to go. I
bring them a tracing of the mast cross section (from the foot) and am
told it will be ready in a couple days. Well,
this is fun, I am supposed to pick it up on day x, and I talk to my
contact
the day before it is due, and it hasn't been done, but they are about
to do it,
and tomorrow afternoon should be no problem. I get a call back a
few hours later.
Ahh, wow, this is a tight radius, the lead fabricator has to do
it.
High risk of cracking the aluminum if not done right etc. Won't
be
ready until the day after tomorrow. I am perfectly happy to let
them bang on it at
this point, and I happily wait. I get the critter and am quite
pleased to talk to the
fabricator about the install. I originally asked for aluminum
rivets,
and he upgraded me to stainless for the extra strength. When I
asked
about the corrosion factor, he basically told me to forget it, I'll
have other problems with the mast elsewhere first. He told me the
ideal thing to do would be to do a complete dry mount, get it all bent,
holes all drilled etc., then coat it up with epoxy and attach it.
I
think these guys must have special mast vise grips with contoured jaws
that can clamp down and bend a big piece of metal all at once.
There
is no way, nada, absolutely not happening that you are going to do this
in this method with C clamps, pipe clamps etc. A very capable
friend and I
sat there with this pile of clamps of all sorts of shapes and sizes,
and nothing was happy about the contours of the mast (wanted to slip
off). We
ended up attaching the plate on the front and then working the sides
down. To
hold the clamps from slipping off, we put them under the mast jaws up,
placed the mast down in the clamps, and then
sat on the mast and tensioned the clamps, with our weight holding the
mast
down in the clamps. One of us would breath wrong and pop!, take
'em
off and start over. I did some prebending of the last inch or so
of
the edges to help us. Good thing I did it. Here
are the series of
photos. Keep reading and scrolling. Click on the images for
larger pop-up windows:
1) The aluminum collar as it came to me. Note on the back view
where
you can see inside the U. The metal on the center line looks like
it almost has been squished in the bending process.
2) The original mast damage. Very difficult to see the depth in
the
photos. In the second, I've held one of the companion
way
boards against the mast to show the
depth of the dimples.
3) The collar at the end of the first day of installation.
It was sundown, and we were
out of rivets. Several things to note. On the straight
edge,
with a
single rivet in the center, you can see the aluminum is under so much
tension that it bows up and out away from the mast between the
rivets. Pretty amazing given the total length of the edge
is about
9.5 inches. Also, there is enough tension here that the mast's
dimples
have actually been pulled out straight some! Believe it or not,
it's taken something like 4 hours to get to this point. This does
of course include time to scratch our heads and contemplate clamp
technique etc.
4) The collar with all rivets installed and the holes for
spreader
mounts and wiring have been drilled.
5) Spreader mount test. Not taking for granted that
everything
really does line up. It does! Note the damage to the port
spreader
bracket. It has been welded. I need to track one of
these down.
6) OK, the last 1/16 to 1/32 inch of the edge just would not pull
up
tight. A variety of factors are at play ranging from
irregularities
due to mast damage and extreme leverage needed to bend that last little
bit down. Just not happening. Some of these photos show
looking into
the gap. A lot of the gap is actually caused by the mast dimple,
not
because the metal didn't fit tight enough. Here is where the
epoxy
comes in. I used a special 3M product from their ScotchWeld
line (2216 B/A gray). It has both very high strength and
flexibility.
7) The last set of photos shows the plate at the end of the
second day
with the
epoxy added to finish it off. The Scotch-Weld has the consistency
of the all
natural
peanut butter when it is warm, somewhat runny, but much greater
viscosity than something like the West 105. I was able to take a
card
and pack a tremendous quantity of the epoxy down into this gap.
The
last photos show it at various angles so you can see the tightness of
the wrap around the mast, the epoxy fillet etc. All in all, I
think I
am pretty pleased with the way it came out, and quite happy I had the
rigger do the first bend. Don't think it is possible to do it
otherwise. I've bent a lot of steel for car body repair, and it
is not
nearly as elastic. The aluminum just doesn't want to bend the
same. A
whole lot more bounce to it.
8) The last part of this was to caulk the edges and the rivets with
some
of the 3M 4000UV. It doesn't look as neat and pretty,
but this will be good for the long term. Besides, when it's in
the air, you just can't tell that this is not the Picasso of 3M.
However, I've got to go up and redo the boots on the spreader
ends. Somehow they escaped my attention earlier.
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Last update: 4/28/04
