Classic Refinish
by Story by Lee Wangstad and Marty Loken
December 1, 2007
You’ve found the perfect classic boat … or what appeared at first glance to
be perfect. It’s the right year and model, and is even the color you’re looking for. But after
having searched for this particular boat, you find that its condition isn’t exactly ready for prime
time. It’s in tough shape, and you know it.
Once the hook has been set, you’ll probably go ahead with the purchase of your dream boat,
no matter what. But you have some serious decisions to make: Will the dream deteriorate into a
forlorn-looking mess out behind the garage, or will a plan of action deliver your project to the
water in style by the next boating season? If you’re buying the boat, you need to make a commitment
to the project, setting some ground rules and hopefully a timeline for the boat’s repair or full
restoration.
There are times, of course, when the best thing to do is turn the job over to a
professional. But for many of us, having the work done by others is out of the question. In terms
of cost, we’d really prefer to do it ourselves — and perhaps learn some new skills and gain the
rewards associated with bringing the old boat back to life with our own two hands. Two of the most
common problems found on neglected classic fiberglass boats are weak transoms and rotten plywood
floors. There may be lots of other issues, but these are the most critical elements — and not
beyond your ability to repair, if approached carefully.
These structural repairs can be done at home, but remember that if you attempt this kind of
work, you become responsible for the integrity and strength of the boat. If something structural is
removed — especially a transom — something of equal or greater strength must take its place.
While you may not give floors a second thought, they’re integral parts of the structure of
most boats, working in close conjunction with stringers between the floor and bottom of the hull,
or with the keel itself. Either way, floors are an important piece of your boat’s backbone, giving
the hull its maximum strength. Again, transom and floor repairs can be left to professionals, but
you can probably accomplish these tasks on your own. Here are some things you need to learn, or
consider:
What To Look For
The first thing you need to do is evaluate the condition of the floor and transom. Floors
are usually easy to check: If it feels solid under your foot when you stomp on it, it probably is.
But if the plywood is rotten or delaminated, you’ll notice
softness in spots or separations of the floor from the underlying stringers or
keel. Transoms can be trickier. Almost all transoms in fiberglass boats from the 1950s and 1960s
were made of plywood, sandwiched just inside the hull’s thin fiberglass skin. Usually, but not
always, the plywood transom is also covered on the inside by a layer of fiberglass matting, which
means you may not be able to easily inspect the plywood. So, how do you know if the inner ply core
has problems? The first clue will usually be a bowing-out of the transom in the center area, under
the long-term weight of an outboard motor, indicating weakness or rot in the plywood core. Rotting
in transoms starts either at the bottom, where bilge water has seeped into the wood; at the top, if
the plywood’s upper edge has been exposed to water; or sometimes in center areas, when transom
through- hull bolts haven’t been adequately sealed from outside moisture.
If you can’t easily detect rot, but you suspect the transom is weak, there are a few ways to
sleuth out the soft spots. First, gently tap the transom with a small hammer or wooden mallet,
moving slowly across from side to side and top to bottom. Where the transom is solid, you should
hear a crisp, consistent "bonk," and the hammer should bounce back at you. If the tone changes in
one spot, or in a whole area — from a lively "bonk" to something resembling a dull "thud" — you may
have found rot, or at least delaminated plywood that’s lost strength. If tapping on the hull doesn’t
tell you enough, you might want to drill core samples — literally boring 1/2-inch holes into
suspicious areas of the transom. Either the wood that curls out on the drill bit will be dry and
fresh-looking, or it will be a dark and moist pulp, indicating rotten plywood.
Demolition Time
Once you’ve determined the floor or transom have problems, you need to begin surgery. It’s
fairly easy with the floor, since some floors are so bad you can literally peel them out of the
boat after getting a grip along an edge near the
transom or sides of the hull. If it’s not that easy, you’ll want to
bring out your main surgical tool — the circular saw. If you don’t know the exact thickness of the
floor, begin by setting your blade at 1/2 inch and make a cut across any section of the floor that
needs to be removed. If you’v e been able to cut through the floor on the first pass, just make
your way around the perimeter until you can lift the entire floor out, in one piece or in sections.
If you weren’t able to pierce through with the blade set at 1/2-inch, adjust it to 5/8-inch. Try
again. If you need to go deeper, just work your way toward 3/4-inch, which should be deep enough to
cut through most runabout floors. You don’t want to go any
deeper than necessary, in order to avoid cutting through stringers, or worse, though
the bottom of the hull. With transoms, if you can determine the rot is confined to just one area,
cut out only portions that are actually rotten or delaminated. Rot is often confined to just lower
portions, or only upper sections. In such cases, try to make a straight cut from side to side,
leaving as much good wood as possible. If you’re using a circular saw to cut into the transom on
the inside, be sure not to cut through the outside fiberglass shell of the hull, since the outer
casing is critical to the hull’s integrity. You’ll probably find you can come close to the outer
skin, making horizontal and vertical cuts until you’re able to pry or chisel out smaller sections
of weak or rotten plywood. In the end, you’ll most likely be working with only a sharp chisel and
hammer or mallet, cutting all remaining fragments of soft ply out of the boat, making sure you get
down to nothing but nice, healthy plywood.
Replacing the floor
Once you’ve successfully removed the floor and transom (or portions thereof), and you’ve
cleaned up and dried out the mess, you can start the rebuilding process. If you’ve found rotten or
broken stringers under the old floor, you’ll need
to begin by replacing the bad ones. If you’re lucky, you’ll be able
to use the old ones as blueprints. If you’re not so fortunate, the task of shaping replacements,
fitting and glassing them to the inside bottom of the hull becomes a more tedious process. Let’s
assume the floor is the only part needing replacement, since that’s usually the case. Following
removal of the old floor, or a section of floor, you can often make a good pattern for the new
piece(s) by simply measuring the opening, assuming it’s a neat rectangle or trapezoid. Once you
have the dimensions, you might want to "prove" the shape before cutting into an expensive new sheet
of marine or exterior-grade plywood, by instead using cheap 3mm doorskin or 4x8 sheets of cardboard
— just to be sure the measured shape fits the opening. Once you’ve cut the new sections of
floor and they fit tightly in the space, you’ll want to thoroughly seal both sides of the
replacement panel with either a one-part toluene wood sealer or two-part clear penetrating epoxy
sealer (CPES) before screwing and epoxying the pieces onto subfloor stringers. If sections of your
new floor lie adjacent to old flooring in-between stringers, where there’s no support for the new
flooring, you’l l want to epoxy butt blocks along the undersides of the old floor, so the new
plywood has something to land on. This will give the new floor more strength between stringers and
increase its longevity. After screwing and gluing the new sections of floor in place, you’ll have
to overlay the work with a 6-ounce, resin-saturated fiberglass cloth to give the floor more
strength, durability and water-tightness.
Filling the void
A final step you might want to consider, when replacing rotten floors, is to fill all voids
under your new floor with floatation foam. You can buy two-part closed-cell foam kits (not to be
confused with the spray foam for household insulation) from companies specializing in fiberglass
and epoxy products such as Fiberlay (www.fiberlay.com). When you mix Part A with an equal portion
of Part B, the magic happens. The epoxy expands to more than 30 times its liquid volume, filling
all cavities with foam that cannot be penetrated by bilge water. Filling all sub-floor areas with
floatation foam will make your boat virtually unsinkable in the event of an accident, and will also
add stiffness and sound insulation to your new floor, giving you a quieter ride on the water. When
you pour the thoroughly stirred A and B portions from your foam kit, you need to give the foam some
elbow room. It’s going to expand rapidly and with
considerable force, so you have to give it a few escape routes to ensure it doesn’t expand
by lifting your new floor skyward. We use 1 1/2-inch vent holes between each row of stringers, at
16-inch centers fore and aft. By tipping the hull up during your foam-pouring adventure, and by
starting at the low point and working uphill, you’re able to completely fill all voids under the
floor. At the same time, you’ll give the expanding foam an escape valve when it overflows.
Transom Work
Most of the procedures described for floors also apply when you’re replacing transoms, or
sections of transoms. After test-fitting your pattern, cut and fit the new layers of plywood, then
seal all wood surfaces, especially the edge grain of plywood, before epoxying the sections of new
transom in place. All of this is pretty straightforward if your old transom is completely flat. But
if there is any pronounced curve to the transom (viewed from above), you may need to build up your
new transom with several layers of thinner ply, bending, clamping, gluing and screwing each
successive layer into place. The way to start is with the layer that butts against the fiberglass
skin of the hull, but how do you securely hold the replacement panel tight against the curving
surface of a 15- to 25-inch deep transom? Assuming you don’t own a collection of giant, long-armed
woodworking clamps, one solution (here you must show bravery) is simply to drill small pilot
holes all across the outer face of your boat, 10 inches or so apart from one another, sinking
dozens of No. 12 by 3/4-inch panhead screws, backed with 3/4-inch washers, right through the outer
transom layer and into the epoxy-gooped first layer of new plywood. You may need a friend to apply
pressure to the plywood from the inside, while you run screws in from the outside. This is often
the best or only way to make sure the new wood makes full contact with the hull’s outer skin, which
is important to the longevity of your new transom. When the epoxy has cured, simply back out the
panhead screws and fill the pilot holes with a sandable two-part filler such as Evercoat Lite.
Additional layers of new transom plywood can then be epoxied and screwed onto the previous
layers from the inside, until your new transom has reached the desired thickness. While most
runabout transoms from the 1950s were only 1 to 1 1/2-inches thick, your objective should be to
make the new transom stronger than ever — ideally 2 to 2 1/4-inches, with the exact thickness
determined by the plywood used. I like to go with three layers of 3/4-inch plywood for flat
transoms, four layers of 1/2-inch ply for slightly curved transoms, or six layers of 3/8-inch ply
when you’ve got to deal with some real curves.
When you fit and attach the new sections of transom plywood, you’ll no doubt have gaps
around the bottom and side edges of the new ply. Not a problem — just mix some two-part epoxy, and
thicken it to a peanut butter consistency
by adding silica power (available at marine supply stores), and trowel the thickened goo
into all voids. You want it thick enough that it will not run or sag when worked into the crevices.
Ideally, you’ll have time to use the angled edge
of a paper cup to trowel in a nice smooth radius, maybe 1 1/2-inches in diameter, where the
new transom meets the sides and bottom of the hull. Once the epoxy fillet has cured, slather on
some fiberglass resin and apply 6 ounces of fiberglass cloth, using 3-inch fiberglass tape to cover
the corner joints and larger precut sheets to lay over the rest of the new transom upper lip. You
may need to use more glass-cloth tape, 2 to 3 inches wide, to wrap over the upper edge of the
transom. Just be sure you make it watertight, since you don’t want to repeat this act five years
from now.
Other Details
Some of the processes described may have to be altered for your boat, depending on its
design. For instance, if the boat had transom knees in the past, they’ll perhaps need to be removed
to easily install the new floor and transom. If you remove old transom knees, you’ll want to
replace them with stronger ones, perhaps larger in size, and better adhered to the transom and
bottom. A lot of 1950s boats had no transom knee or only a small one down the centerline. There’s
nothing to prevent you from rebuilding the boat better than when it came from the factory, so feel
free to use two knees instead of one, or beefier under-floor stringers than the broken, split
and/or rotten stringers you’re pulling out of the boat. Remember, these were simple production
boats in their time, never intended to be in use half a century later.
Finishing Up
Once your construction work is done, and you’ve sanded the new transom and floor sections
smooth, you may want to fill any remaining hollows, fiberglass-tape edges or other voids with more
of the sandable fiberglass filler, such as Evercoat Lite. After everything is smooth, use a good
two-part primer such as Interlux Primekote, and finish with a one-part polyurethane paint, such as
Interlux Brightside or Pettit Easypoxy, or Interlux’s two-part Perfection paint. You can brush
these paints, or use the roll-and-tip method. This requires working with a partner. One person
rolls paint onto the hull using a thin-nap, yellow-foam "weenie" roller in a horizontal pattern.
The other person follows behind with a semi-dry bristle brush, gently brushing the rolled-on paint
smooth, using top-to-bottom vertical strokes. You can reverse the pattern on successive coats if
you wish. You can also spray the paint, but that’s another article unto itself.
Considering Gelcoat
You may ask, "Well, don’t I need to use gelcoat to make my boat look original, since it had
a gelcoat finish at the factory?" The short answer is no, don’t bother. Gelcoats are harder to use
and more
expensive than most paints. And when cured, they don’t immediately look
glossy and beautiful; they’re dull and ugly, until you’ve applied tons of elbow grease tediously
rubbing out the gelcoat, finally developing the gloss you’re looking for. Modern urethane or
polyurethane paints can give you an appearance just like gelcoat in a fraction of the time and for
less money, so keep the whole job as simple as possible, while obtaining results that look
absolutely professional.
Marty Loken specializes in the restoration of classic fiberglass boats together with vintage
wooden boats, and he’ll be happy to help you, if possible. If you run into trouble and need advice,
just take digital photos — if they’ll help explain the problem — and e-mail your questions to
Marty@islandboatshop.com. If you’re not an avid e-mailer, send queries to Marty Loken, c/o Island
Boatshop, P.O. Box 216, Nordland, WA 98358.