[C38] boom failure

[Tom T.]

Hi Glenn,

I can't name a good replacement for your boom but before you do that, let
me tell you of another experience I once had that may help you.

We had a highly modified South Coast 22 once that I used for design
experiments.  It had a very efficient hollow steel keel that was bottom
weighted with lead.  The keel weighed 550 lbs, same as the original iron
keel but my center of gravity was much lower because of the bottom weight
of the new keel.

We were sailing in a stiff breeze and really flying when my mast pumped
forward in a puff making the mast fail at the spreaders.  The whole mast
and sails came crashing down and we slowly retrieved the sails, shrouds,
boom and mast halves and motored back to port.

I salvaged that broken mast.  We made a splint of wood and clamped the two
pieces of the mast together and welded them back together.  Then we took a
piece of another mast, slightly larger than ours, and cut diamond shaped
pieces to overlay the welded area to permanently splint the damaged area.

After we repaired the mast, it looked like the factory had made the mast
with the reinforced section welded at the weak spreader area.  Not only did
we salvage the mast, it was now much stronger than originally and not prone
to future failure.

The key to this repair is the diamond shaped plates made from another mast
to overlay the repair area.  The reason for diamond shape is to not
concentrate the weld area of the plates.

In my opinion, all masts and booms should come from the factory with these
diamond shaped reinforcements.  The failure point of any mast or boom is
usually where either the shrouds meet on the mast or the vang meets on the
boom.  Those points are the highest strain points weakened by holes drilled
through them and the diamond plate weld procedure makes those points  
stronger than the rest, as they should be.

You don't personally have to own a MIG, TIG, or any other type of welder to
do this, the preparation is the key element of a good repair.  Anyone can
make the wood splint, find a piece of old mast or have some aluminum plates
rolled and fabricated from a metal shop if not successful in finding a mast
stub for the metal overlay splint, and grinding a good fillets on the weld
edges of all pieces.

Once this preparation is done, any good weld shop equipped to weld aluminum
can weld the mast together at a minimum of expense.  Like an auto collision
repair, it's the preparation that cost the most, not the final painting of
the car.  Same here, prep the mast properly and make a good splint from
some straight wood and the repair price should be very small compared to
the price of a new boom, let alone the fact that your repaired boom would
be actually much stronger than a new boom.

Email me if you want more details.

Tom Troncalli
Renata #95  

> [Original Message]
> From: Glenn Terry <Glenn.Terry at Sun.COM>
> To: Catalina 38 Listserve <listserve at catalina38.org>
> Date: 7/18/2009 11:42:52 PM
> Subject: [C38] boom failure
>
> I had a rookie at the helm and he executed a perfect uncontrolled jibe.  
> The boom broke at boom vang mount.
>
> Can anyone give advice in the replacement of the boom?
>
> Regards,
>
> G!enn
>
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