boat owner

Keel crack repair

ABOUT THE AUTHOR

INSIDE THE TRUSS CAVITY

Mark Ryan, an IT

manager for Mortgages

for Business, has

sailed all his life from

the River Medway and

now cruises with his

wife Elizabeth, two children (Sophie,

aged 1, and Thomas, aged 3) and

seadog puppy Patch on his 9m (30ft)

1970s Albin Ballad, Triola.

O

n inspecting the inside

of the truss cavity, it

was apparent that the crack

extended above and below

the area where it was visible

on the outside. Before I could

glass up the inside, this had

to be ground out back to

good glassfibre.

I filled the ground-out sections

with the same mixture (colloidal

silica, milled glassfibre and epoxy)

as I used to fill the crack in the hull.

Finally, I was ready to glass up the

inside of the hull. It was even more

important for me to do this as I

had been chipping away at a resin

block that encapsulated my mast

truss, leaving the whole area

slightly suspect: polyester resin

is very brittle and susceptible to

impact forces, as a microscopic

process called micro-fracturing can

occur. Therefore, I painstakingly

tailored eight layers of glassfibre

to fit the area inside the hull.

Once again, the surface was

cleaned thoroughly with acetone

and given a base of thickened

epoxy to create fillets around any

sharp corners and fill in any voids

before the first layer of glassfibre

went down. This time, I actually

used 404 high-density filler rather

All layers of glass applied, with peel ply on top

as epoxy is exothermic, and if
enough epoxy is present it
will create a chemical chain
reaction where the epoxy will
heat up, which will speed the
curing process, which will then
create more heat and so on! If
your epoxy exotherms it will
become very brittle indeed –
not to mention the fact that it
can catch fire and give off toxic
fumes – so it is to be avoided.
If you need to make thicker
GRP, work in stages by putting
peel ply on top of say, the 15th
layer, let it cure overnight,
remove the peel ply and
continue laying up.
Finally, apply the peel ply
over the top: make sure the
peel ply is oversized so you
will have a corner to grab once
the epoxy has gone off. Use
a spreader to squeegee as
much resin out as you can:
the less epoxy there is in the
GRP, so long as its all wetted

out, the stronger your final

fix will be. In reality, in a

complicated area like this

you won’t want to work it too

much as it is important to get

the shape back.

Fairing the hull

At this point, the repair wasn’t

quite completed. I hoped I

had done a good enough

job that I could put my

Coppercoat straight over the

top of the GRP, but after pulling

off the peel ply and sanding it

down, small bubbles and finger

depressions were apparent

that would need filling.

Once this was completed, I

patched up the Coppercoat:

you get very good at

accurately measuring small

batches of the stuff for this

process, and a helpful tip is

to get some good digital

scales. The keel is now

stronger than it ever was.

Some small voids needed filling before antifouling

Glassing up the inside

The extent of the bow crack:

the ground-out sections are

shown in yellow

The end result: all glassed in, with peel ply on top

than 406 colloidal silica as my truss

would eventually sit on top of this

glassfibre, so compressive strength

was a priority. I finished off with peel

ply once again to make the next

stage of the process easier and

avoid any need to wash off amine

blush, and to leave a keyed surface

for the next process. Finally, as with

any structural work I undertake to

Triola, I had my good friend and

marine surveyor, Alf Cackett, come

and survey the repair and write it

up for my insurance company.

Phew, job done!