WHAT EXACTLY IS THE rubbery material beneath your pulpit bases, sealing your thru-hulls, or gripping your port lights? What type of goop is holding that fitting to your deck? Maybe you know if you are the one who put it there, but if it came with the boat, or was applied by someone else, you
probably don’t know. Only when faced with separating component parts will you
learn the true nature of the sealant.
Why does this matter? Because some sealants permit easy separation and
renewal while others turn de-bedding into a contest of will. If the sealant is
a bedding compound (e.g. Dolfinite), acrylic caulk, butyl rubber, silicone,
polysulfide (e.g. Life-Calk), or even the more tenacious polyether sealant, separation will normally just be a matter of prying to break
the bond or stretch the sealant beyond its elongation capacity. However, if the sealant is polyurethane, particularly the
ever popular 3M 5200, any attempt to separate the components by simply prying them apart is likely to end in
the damage of one or both of the joined pieces.
So how do you separate parts bonded together
with adhesive sealant? Start with step 1 and stop
when the fitting comes free. However, if you’re
trying to remove plastic fittings that you know
BREAKING UP IS HARD TO DO
What to do when that fitting doesn’t want to let go By Don Casey
were bonded with 5200, you’ll get less frustrated and do less damage if you skip down
to step 6 right now.
1 extraCt meChaniCal fasteners: Even this can be a challenge when they
were originally installed with a coating of
polyurethane. Bolts should be unscrewed.
A big screwdriver, perhaps with a wrench
on the shank, can normally deliver adequate force. For more torque, try a manual
2 try separating the parts By pulling or prying: Continuous
pressure will be more effective than hammering and carries a lower risk of damage. It
gives elastic sealants time to resolve internal
stresses and either elongate or release. If the
sealant does neither, it is probably polyurethane. More force is not the solution. Plastic
and cast parts will break and machined parts
bend. The grip is even strong enough to rip
away gelcoat. Time to move on to step 3.
3 Cut the BonD: You’ll need a sharp blade – a razor knife, carpet knife, or
single-edge razor blade. If you can reach all
sides and the sealant is thick enough, slicing
the perimeter weakens the bond. Pry just
enough to allow your blade farther into the
joint and keep slicing deeper until you cut
the components apart. If whatever tool you’re
using isn’t working, try a wire saw, simply a
foot-long length of thin wire – leader wire,
guitar string, braided fishing line, what-have-you – with rings or dowels at each end that
will allow you to saw the wire back and forth
between the bonded parts. Wedges or prying
behind the wire can assist in sawing completely through the sealant pad.
4 try some stress: If you cannot cut he components apart, try putting the
adhesive under moderate stress, then giving
it time to elongate or release. For a piece of
deck hardware, that might mean driving a
couple of chisels or other wedges under one
edge sufficient to deflect but not bend the
base, then leaving them for a day or more.
As separation allows, tap the wedges deeper.
PRACTICAL BOATER | DO IT YOURSELF
74 | Boatu.s. magazine JUNE | JULY 2014
hold fittings to
your deck needn’t
deter you from