Delamination is not spelled d-o-o-m

Story and photos by Bill Sandifer

Article taken from Good Old Boat magazine: Volume 1, Number 3, November/December 1998.

Deck delamination conjures up images of free falling straight
through to the bilge but it need not frighten the most resourceful
among us

The word “delamination” causes instant visions of a good old boat coming apart at the seams.
Worse, those visions may be equated with an unsalvageable hulk lying
in the mud of a river bank. Bad jokes have been published of a prospective
buyer falling through a deck or into the bilge. These visions and
jokes ring somewhat true sometimes, but does a delamination problem
predict the end of a good old boat? Is there useful life after delamination?
Let’s examine the causes, effects, and eventually the cure for this
common good old boat problem.

Layer below the fiberglass

The rotted core just below the fiberglass was not a pretty site.

Delamination is the separation of layers of fiberglass cloth and resin
from each other or from the core sandwiched between the layers. The
cause of delamination is usually physical stress to the fiberglass
surface. This ruptures the surface skin and allows water to enter
the laminate and migrate into the core. Delamination can also occur
from repeated surface impact even if the skin is not broken and water
does not enter.

Most delamination occurs on the decks or in the cabinhouse structure
of a boat, although it is possible for delamination to occur in the
hull itself, particularly if the hull is cored.

Some builders used cored hulls for rigidity, as well as for sound
and temperature stability. The core material (usually end-grain balsa
squares, occasionally plywood, and sometimes foam) separates from
the fiberglass skin above or below. Once the separation takes place,
the core deteriorates from water intrusion or turns to dust with repeated

When an area is delaminated, it is substantially weaker and
will feel soft when walked upon. An easy way to check for
delamination on a horizontal surface is to walk barefoot on the
surface and to dig your toes into the deck or cabinhouse. A soft or
giving feeling will indicate potential areas of delamination. These
can then be critically examined. A solid deck should feel like a rock.

Depending on the size and location of a good old boat’s
delaminated area, a cure may be possible, affordable, and prudent. It
is never cheap or easy. Commercial boatyards charge exorbitant sums
just to attempt repairs and usually will not guarantee their work.
The reason is that without totally disassembling the area, cleaning
out the damaged core, and recoring the structure, it is often
difficult to assure that all of the area has been repaired.

Easy fix?

Several technical publications recommend an “easy fix” which involves
drilling a series of holes through the top skin of the deck and
forcing epoxy resin into the holes until it fills the void and
emerges from another hole. This method is unsatisfactory for the
following reasons:

  • The delaminated area must be completely dry for the epoxy to bond to the top and bottom skin. There is no way, even if core samples are taken, to know if all of the area is dry.
  • Due to working “blind,” you cannot be certain that the epoxy completely fills all the voids./li>
  • A small solid, non-delaminated area may form a dam and restrict the epoxy from flowing into all areas of delamination.
  • The cost and physical effort required to attempt this cure are not justified, given the unknown final results.

There are two other methods to solve the problem and, though
costly in time and material, will guarantee a successful result. Depending
on the construction of the vessel, one or both of these methods may be used
to make the repair.

My own 1961 Pearson Ariel is a good example of both. In a nutshell, the
entire main deck and cabinroof were one spongy mess that gave under a person’s
weight. The foredeck aft to the chain plates had been destroyed over a number
of years by “deck apes” jumping on the deck in race conditions. The forward
cabin under the foredeck did not have a liner installed, so the underside
of the deck was fully visible. The sidedeck and main cabin area had an interior
liner which precluded direct access to the underside of thedecks and coachroof.
The side decks were delaminated as a result of improperly filled holes when
the genoa tracks were moved. The coachroof was delaminated due to the roof-mounted
winches, cam cleats, etc., being mounted, moved, and remounted without properly
sealing the original holes.

The mast was deck-stepped and had sunk three inches into the deck due to water-induced rot in the mast support beam. This was caused by poorly sealed fittings around the base of the mast.

If you have read this far, you’re probably saying, “What did this nut see in a totally destroyed boat? He must be crazy!” Well yes and no. I had very
little money (less than $2,000) and wanted a capable sailboat very badly!
The price was right. The Ariel was the boat I wanted, and I had a plan.
The boat’s past racing life, which had caused much of its problems, also
provided the method to afford the rebuild.

First the good news

The boat had eight good racing sails. I sold the six I did not
want for more than I paid for the boat. I made a $300 profit and
became the proud owner of a Pearson Ariel with an Atomic 4 engine,
(More about this in the January/ February issue of Good Old Boat),
a good mainsail, a good 120 genoa, hull, mast, boom, and rigging.
The only problem was the deck, maststep, and, oh yes, the bunk had
rotted out, and the galley area was trashed.

To get the boat home, I fixed the engine and felt I should be able
to sail (in case the engine quit). I used 4 x 4s and a hydraulic
jack to support the mast and push it back into its correct position.
And on April 1, 1990, (April Fools Day/Ship of Fools!), my wife
and I departed the New Orleans Municipal Harbor for home on the
Mississippi Gulf Coast, 11 hours away. Since I am writing this article,
we obviously succeeded in completing the voyage. Would I do it again?
Of course! There is little enough adventure in this world, and taking
the tried and true route is no adventure at all!

We were towing a dinghy with a motor to provide a third method of
propulsion (or lifeboat, if need be). We had picked a bright sunny
day with a good forecast, filed a floatplan with our children, had
a VHF radio onboard, and stayed close to shore in about eight feet
of water. We figured we could fill up but not sink below the surface.
You may be asking, “What does all that have to do with delamination?”
Everything. It shows that a boat can have an extreme problem and
yet be saved. Here’s how.

Start with the worst case

Side deck cleaned and ready

The side deck was cleaned, sanded and ready for a new core.

The first task was to remove the mast and all of the deck fittings, lifelines,
bow pulpit, and so forth. The foredeck was the worst case, so I tackled
it first. I determined what the camber (crown) of the deck was and laminated
wood beams to conform to the curvature and length required to span the
deck on the underside.

Once the beams were made, I cut out the entire underside of the deck fiberglass
laminate and core from below. I scraped all the coring off and sanded
it so only a very thin (1/16-inch) fiberglass skin remained. I cut waterproof
K-inch mahogany plywood panels into four sections in the shape of the
deck. Then I fitted new beams and plywood to the underside of the deck
and prepared to push them up against the underside of the foredeck, forming
a new wood deck beneath the old skin. I assembled the beams and panels
in the V-berth area, screwing and bonding them together with epoxy. After
a “dry fit” to assure that all was well, I coated the new deck with a
mush of epoxy mixed with chopped mill fiber (at a mayonnaise constancy),
raised it up, and propped it in position against the deck skin.

Working from a dink in the water to avoid putting any weight on the fragile
deck, I set stainless steel screws through the top skin of the deck into
the deck beam to assure complete contact between the interior wood deck
and the exterior fiberglass skin. The old deck skin was so thin it was
possible to be sure that there were no air bubbles to interfere with full

When the epoxy cured, I removed the props and taped the beams to the hull
sides for final strength. Next I removed the stainless steel screws and
filled the holes with the epoxy/chopped mill fiber mush, faired the deck
epoxy, sanded it, and painted it with non-skid paint. I used the same
method to refurbish the coachhouse overhead in the forward cabin.

Next side decks, roof

New core installed

The new core was installed on the side deck.

The sidedecks and main cabinroof area could not be worked from the
inside, due to the liner, so this time I started from the outside.
With a circular saw (carbide blade), I carefully cut the sidedecks
and roof out in one rectangular-shaped piece each. I lifted them off
as three pieces (two sidedecks and one roof). I scraped each clean of
the wet balsa core and set it aside. I removed the ruined core down
to the outside of the inner liner, sanded each area clean, and
allowed it to dry.

I cut strips of K-inch mahogany plywood about three inches
wide and the length of the area to be filled, taking care that the
strips landed on a solid support surface or bulkhead fore and aft. I
cut and fitted enough strips to build up the new area to the level of
the old roof and decks, with the exception of the “saved” pieces of
deck and roof. The strips were numbered, so they could be replaced
exactly where they had been fitted.

With all in readiness, I mixed the epoxy/mill fiber mush
mixture and coated the outside of the liner. I wet out the strips
with unmodified epoxy (no mill fiber filler), and set these into the
mush on the liner. I followed this process until I had reached the
desired height.

I coated the roof and deck panels with the mush and returned them to their
original positions on the hull. I allowed the epoxy to dry, taking care
to assure a complete bond between the strips and the underside of the
old panels.

The reason for using the old panels is twofold. First, it saves material
and, if carefully prepared, reduces fairing of the surfaces to the original
camber. Second, the roof panel incorporated the rails for the sliding
hatch which would have had to be remade in wood, bedded, and so forth.

I simply removed the mast step beam and replaced it with a new beam when
the coachhouse roof was replaced.

The final finish work was not as hard as you might imagine, due to the
reuse of the old skin panels. After a good fairing with a long board and
80-grit sandpaper, I rolled high build epoxy primer paint on the panels.
These were sanded and primed again, sanded a third time, and then painted
with three coats of polyurethane one-part deck paint, sanding between
each coat. I mixed the final coat with non-skid compound for a non-slip

More good news

Original deck piece replace

The orginal deck piece was replaced.

Did it work? The answer is a resounding “Yes!” After eight years of
12-month-a-year service, averaging three days a week, there have been
no failures, no leaks, and no soft spots. I’ve repainted the deck
once more for cosmetic and aesthetic value.

Was it worth it? Again, “Yes.” The boat became ours April 1,
1990, and we motored it out of the harbor. We have motored, sailed,
motorsailed, and used the boat ever since. The work on the deck was
done during intense weekends over a two-month period. The boat was
“out of commission” for two-week periods as each stage was
accomplished. The deck, beam, interior, and so forth were done afloat
between uses.

prioritized the work. The foredeck came first, mast beam next, bunk and
interior third, side decks and coachroof last.

Since we live in a southern climate, it was possible to complete all the
work over the span of one year. The non-structural work – replacing the
pulpit and lifelines, putting in new port lights and running lights, etc.
– was worked in as time and budget allowed.

When I review the refurbishment work done over the past eight years, the
volume seems overwhelming, but when viewed in small segments, it was achieved
and has not been onerous.

I had the assistance of family and friends some of the time, but the bulk
of it was done without help. Having the use of the boat while working
on it was a big plus and kept my spirits soaring. I believe if I had chosen
to lay the boat up until everything was complete, I would have become
discouraged and lost interest and momentum.

My wife loves the boat but hated the project “mess.” For this reason,
I kept one or two areas neat so she could feel comfortable while I messed
up the other areas. The V-berth area was torn up considerably, but the
main cabin and cockpit were usable and neat. Doing the sidedecks did not
mess up the interior, and the V-berth was completed and “neat” by that
time. The same is true for the coachroof.

Today, the boat is in excellent condition. Motor and sails are without
problems, and it looks great. Now, if I could just figure out how to stretch
the boat to a 36-footer in the same condition. Hmmmmm.

Bill Sandifer is
a marine surveyor and small boat builder who has been living, eating,
and sleeping boats since the early 1950s when he assisted at Pete Layton’s
Boat Shop, building a variety of small wooden boats. Since then Bill has
worked for Charlie Morgan (Heritage), Don Arnow (Cigarette), and owned
a commercial fiberglass boatbuilding company (Tugboats). Bill and his
wife, Genie, restored a Pearson Ariel from a total wreck. They are now
sailing an Eastward Ho 31.

Join Our Sailing Community. Subscribe Now!

Complimentary monthly supplement

  • featured articles
  • news from the helm
  • mail buoy
  • book reviews
  • sailor photos
  • and much more

Good Old Boat News Flash!

Our website is getting some long overdue improvements! has merged with

Thanks for your patience while our website is under construction.