TIMBER FOR NEW BUILDS
availability in lengths of up to 40ft (12.2m) and good
widths. It is known as defect free, easy to work with and
relatively cheap, whereas khaya is more suitable for
smaller boats. Yellow cedar is also used by some.
Although it is more expensive than the mahoganies, it is
extremely durable and very light. Touchwood has
supplied yellow cedar for the planking of a variety of
boats, from big Nova Scotia schooners to 8-Metre yachts.
In the USA it has long been common practice to build
boats with two layers of fore and aft planking, normally
of different species, a typical combination being yellow
cedar for the inner layer and mahogany for the outer.
Clinker boats have different requirements. “Normally
the planks are wider so it needs to be something more
stable,” says Tristan Stone of Stones Marine Timber.
Khaya is often favoured for this, as it is close grained,
light and can take a fair amount of twisting and bending.
For many years Cornish pilot gigs, in which weight
saving is essential to make them competitive when
racing, have been built with elm planking which is just
(^5) / 16 in thick. “The grain in elm intertwines,” says Andrew
Nancarrow, “so it is possible to plane it thin and it is
unlikely to split. That means the ribs can be kept light as
well.” Elm isn’t particularly durable, but the gigs tend to
be stored under cover.
In 2011 Marcus Lewis built a clinker Mayflower
dinghy which was predominately planked in spruce, but
he gave it a khaya sheerstrake, partly for a pleasing
visual contrast but also for structural reasons. “Canadian
spruce is likely to split if the boat is heaved around by
the gunwales as it is so straight-grained,” says Marcus,
“whereas mahogany is a bit more resilient.”
GLUED CONSTRUCTION
In theory, the timber species used in a strip-planked hull
don’t need to be as durable as those in a plank-on-frame
hull, because it will all be sealed with epoxy. But, as there
is always a risk that the epoxy will be damaged (however
thoroughly it is applied) allowing water to get into the
timber before the damage is discovered and repaired, it
would be foolish to completely ignore a timber’s
durability characteristics.
Western red cedar is the most popular strip planking
material. It is light, durable, readily available and bends
well (but sometimes not very fairly). Yellow cedar,
although more expensive, bends more fairly and is
harder and more durable. In many cases, large areas of
the hull planking will be visible on the inside of a hull,
and yellow cedar (which has a fairly consistent colour) is
generally considered to be more visually pleasing than
western red cedar (which can vary from a yellow colour
to dark brown). Star Yachts offers both species for its
Bristol range of motor boats and, according to proprietor
Win Cnoops, it is entirely a matter of customer choice.
Spirit Yachts builds its racier boats (such as the new
52D Oui Fling) with yellow cedar but otherwise uses
old growth Douglas fir. Although Douglas fir is heavier,
it is stiff and still not excessively heavy, and available in
lengths up to 39ft (11.9m), especially useful on a boat as
big as the Spirit 111 in build. Fairlie Yachts also used
Douglas fir on the three new 53ft-60ft yachts it built.
In 2011 Demon Yachts built a new Windermere Class
Yacht. The class was formed in 1904 and it was in the
early 1980s that strip-planked boats were first allowed,
but only if the hull construction complied with a
Clockwise from
top left: khaya
launch in the
foreground; Nigel
Irens design in
yellow cedar;
Danish oak
fishing boat
launched at the
Boat Building
Academy; a sipo
trunk being
milled