| Wow! What a great time we
had today, this boat is awesome!' you think as you step off of your new
boat and onto the dock at the marina. Filled with pride and contentment
you browse around to see who else is around watching your homecoming with
your new cruiser. You reach for your significant others hand to help her
off the boat, then the kids. With everyone off the boat and standing
safely on the dock you take in a deep breath and with a smile, and you
sigh. You stand with your gaze fixed upon the new boat, unable to
break your eyes away, regardless of the impatient pleas of the kids to
get going, and unaware of "the look" your lady is giving you as she looks
at you, then the boat, with her arms folded with a wry look on her face.
If looks could kill! But really, you do intend to pay attention to her
again at some point in the future! One more quick scan across the surface
of the boat and you will get going. With another deep breath and
a sigh, you turn to walk away with the family. But after the first step
you take in the other direction... something stops you. You quickly turn
back to the boat, eyes wide and face flushed... what the heck is that...
that crack! You step on the boat and rush over to it for a closer look.
But wait, there's more! One here, one there, and one over there... and
one in the sink too! They weren't there this morning when you left the
dealers!
Unfortunately, the scenario
above realistically, does happen all too often. Little hairline cracks
appearing here and there on the surface of the boat. They can appear
anywhere, in and around hatches, sinks, shower stalls, bridges, steering
columns, decks, transoms... you name it.
The cause
The causes for stress cracks
are much the same as for blistering. We won't go into great detail
here, but suffice it to say that stress cracks occur because of voids under
the surface of the gelcoat, and or a lack of strength in the underlying
fiberglass or compounds used in the sub structure of the boat. For
more details on some of the things that can go wrong in the fiberglass
during the manufacturing process please refer to the blistering article.
(Click
Here).
When these voids are present, or when the fiberglass is lacking in strength
because it was not mixed properly, or because enough fiberglass was not
applied it paves the way for stress cracking. Your boat body will
flex some even during normal use. Fiberglass is strong, and if mixed
properly, and if enough is applied, the fiberglass will take up much of
that flexing. But gelcoat is very brittle and has no strength to
it. When the boat flexes and twists, the fiberglass flexes and twists.
When that happens, the gelcoat can't flex with the fiberglass, it just
cracks. Hence you get these little hairline cracks.
What must be done?
Once a stress crack begins,
it can travel for great lengths. Sometimes a short one or two inch
stress crack can travel the length of the boat. This is because once
that fiberglass underneath has flexed, and once the gelcoat has given way,
the bond has been broken. A separation has occurred. Then simple
heat and sunlight is enough to cause that gelcoat to continue it's meandering
course across the surface of your boat. Stress cracks can be successfully
stopped however. The crack must be ground out thoroughly. It
needs to be ground deep enough to reach good fiberglass (fiberglass that
is not whited out or "shattered") and it needs to be ground out wide enough
to reach the good fiberglass on either side and end. For voids, (a
void is a place where the fiberglass had a low spot in it and the gelcoat
didn't touch the fiberglass to bond with it) they need to be ground out
and followed down through all the way till the end of the void is reached.
Then new fiberglass must be applied. And of course followed up with the
finishing touches of shaping and regelcoating. Normally this process
will do away with the stress crack.
Sometimes a stress crack
can reappear though, even if all the repair work was done properly.
Sometimes if large surface areas are compromised underneath, in the fiberglass,
stress cracks can reoccur. Though the portion you had fixed may be good
and strong now, if that fiberglass surrounding the area is weakened and
not properly wetted, then it is going to flex more than it should and problems
are going to continue. |
