[C38] floor cracks base of mast.

[Tom T.]

Hello Bill,

It sounds like you have a soft mast step base.  I  had the same problem a
few years ago.

The support between the hull and mast step is wood on our boats and it can
soften with age from being in the wet bilge.  The only way I know to fix
the problem is to remove the mast.

The ordeal goes something like this:

1.	Mark a grid on the deck around the mast with tape so you can reposition
the mast in the exact same spot, or if you want to make any adjustment,
allow for that with the tape grid because once you rebuild the mast step,
you won't have any reference for replacing the aluminum mast step.

2.	Once you get the mast grid marked on the deck, spray PB Blaster around
the aluminum mast step remove the mast.

4.	Remove the aluminum mast step if it's still attached to the deck. (It
may have been pulled up with the mast if it was too badly corroded for the
PB Blaster to release it.  

3.	Clean around the mast step and mark a line about one inch inside the
recessed deck where the mast step was and cut this portion of the deck out.

4.	Get a drill and augers and start trying to remove as much of the soft
wood of the mast compression base as you can.  Finish with chisels and
hammer until the base is clean to the hull.

5.	Sand the area of the hull where the compression base was and build a dam
using light wood to make a mold for a new compression base.  At this point,
I installed 3 plastic electrical angles in the mold so I could route 3
ground wires to the bilge, one forward to a keel bolt and two aft to keel
bolts and engine.  These conduits will also allow the new mast step to
drain any water directly to the bilge so the mast will not corrode in the
future.

6.	Start laying up woven roving and resin until you have filled the mold
making it flush with the old recess.  When you build to the height of the
old deck, carefully finish laying up with finish cloth and grind it to a
perfect finish.  If you don't make the deck with some way of repositioning
the step properly, you won't be able to get the mast back where it should
be.

7.	Dress the mast step with a wire brush and install it on top of the new
compression base.  The bottom of my mast was so corroded I had to cut 1/4"
off of the base of the mast to get a clean surface.  I cut a piece of 1/4"
aluminum plate to fit in the recess to compensate for the plate.  I bedded
this plate to the deck and new compression base.  My deck step looks like
anyone else's but there is aluminum showing around the base of the mast
instead of the original fiberglass.

Grease the aluminum mast step with a waterproof trailer bearing grease once
you have it in place.  You will have to make  holes through the base for
any conduits if you elect to install any but in any case, allow for water
to seep into your bilge so it can no longer accumulate in the mast step
causing corrosion.  If you don't install conduits in the lay up process,
you can drill a weep hole at an angle through the base plate and lay up
since the new compression base is totally glass and resin and no longer
vulnerable to moisture.  The original mast step had no provision for any
accumulated water to drain so corrosion is a problem.

8.	If you elected to install mast grounding wires, install then now in the
mast and grease the connections well.  I grounded my aluminum mast step to
a forward keel bolt and ran two very large electric cables aft through two
conduits giving my mast three ground paths through the keel.  By using
plastic electrical conduit 90 degree angles in the base, you make any
ground wires have as large as possible radius improving lightning
protection.  I don't remember what size cable I used for my mast grounds
but they are about as large as my index fingers.

9.	Replace mast or get drunk, depending on your success.


I have some pictures of the procedure if you are interested.  It's a lot of
work but fairly easy actually.  If you make your cut in the deck slightly
smaller than the aluminum mast step, the finished project will not show any
of your repairs.  You could prefab the new compression base and bed it in
the hull if you want.  I formed mine in place but either way will work. 
Which ever method you use, I highly recommend building into the base the
electrical angles for both grounding wires and a drain for water.

Grounding out the old wood is a chore but the softer it is, the easier the
project.  If you pre-drill the wood before chiseling like I did, use a
drill stop so you don't hit the hull and find a geyser shooting up from
your bilge.

Good luck,
Tom Troncalli
The Renata #95 

> [Original Message]
> From: William Knowles <william_k_19810 at yahoo.com>
> To: <listserve at catalina38.org>
> Date: 7/8/2008 2:21:50 PM
> Subject: [C38] floor cracks base of mast.
>
> While cleaning our bilge and shower sump area and head after much nagging
by the first mate I discovered that the floor at the aft base of the mast
had a large crack with a downward angle. I stuck my head in the bilge and
the post to the keel seems straight and strong. But a photo I took looks as
if there is a tab that attaches the floor to the post and that seems to be
cracked. Has anyone else had this problem?  The mast is sound and appears
straight the boat sails great. I do have photos but the site would not
allow me to post to large. Any ideas and  is this a major or minor problem
that can wait to winter haulout. Thanks in advance for your help.
>
> Bill Flying Goose
>
>
>       
>
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