LETTER OF THE MONTH SUPPORTED
BY OLD PULTENEY WHISKY
TREVOR WILKINS
Letters
Much-travelled Four Square
Hollow soul
40 CLASSIC BOAT MARCH 2016
I
n the history of yachting the impact of hollow masts and spars is rarely mentioned, which is peculiar because they are central to the story. Reducing the
making it safer and usually easier to sail; this is especially true in smaller boats, and the arrival of reliable hollow rig weight of any yacht increases her stability, so
masts and spars from about 1890 onwards was in no small part responsible for the popularisation and spread of the sport in the late 19th and early 20th centuries.
used, because it is certain to have been in antiquity. Bamboo was recognised as a good material for spars It is impossible to fix when hollow spars were first
wherever it was available, and continues to be employed to good effect even now. But bamboo has limitations; it is fairly readily available up to about 20ft long and six
inches in diameter, but larger sizes are rare. As yachting developed away from bamboo’s natural habitats, it seems to have only ever been used in relatively small
craft. It seems, too, that in the 19th century there were no imports of bamboo to the USA, which prompted the boatbuilders there to develop hollow spars somewhat in
advance of their counterparts in Europe.c1820 but even by the 1850s they were still rare; Hollow iron masts (for ships) had been tried from Great
Easterndiameter at deck, and over 100ft long) that were, like many aspects of that ship, much remarked upon. Dixon (1859) had three huge iron masts (3ft 6in
Kemp mentioned that hollow steel yacht spars were tried c1863, which is about the same time they started to appear on ships, but that after “two or three masts were
carried away rather suddenly” the experiment was abandoned, for yachts anyway. Towards the end of the 19th century a few yachts had steel (lower) masts
(Columbiadefender races) and booms (schooner of 1898, had a 91ft long main boom “of ’s snapped in 1899 during the America’s Cup Rainbow, GL Watson’s fine
special steel”), but in general steel spars were seen only on the largest yachts. From the very start of yachting until after the Second World War nearly all yacht masts
and spars were made from wood, and from the outset they were usually solid.The benefits of hollow spars were clearly understood
long before their construction was practical. The science of struts and columns bending and buckling was convincingly defined in mathematical terms by Euler in
the 1750s, but an instinctive grasp of the benefits is clear from the example of hollow timber lances written about as early as the 9th century. The advantage of a hollow
mast over a solid one was clearly demonstrated by Skene in his diagram illustrating the point nicely; a 10ft long hollow Elements of Yacht Design where he produced a
round mast 4in diameter with a ½in wall would have equal strength to a solid one that was 3ft (i.e. only 9 per cent less), and the hollow one would (^5) / 8 in diameter
weigh about 53 per cent of the solid one. Alternatively, if the weight were equal, the solid mast would have to be only 2 (^5) / 8 in diameter and would be 74 per cent weaker (in
buckling). If the outside diameter of both were 4in, the solid spar would actually be 50 per cent stronger than the hollow one, but at the cost of being 128 per cent
heavier. Masts in particular are designed to be stiff enough to resist bending and buckling, but also as small and light as possible. On the basis of weight or stiffness
the hollow spar wins (nearly) every time.According to the Hollow spars could also offer other possibilities. Aberdeen Journal of 15 January 1840,
From bamboo to the early America’s Cup, Theo Rye tells a story central to yachting’s
development, but one curiously overlooked
THE HISTORY OF
HOLLOW SPARS
Oregon pine by Brasker Masten Mast built of
in Holland
FACING PAGE: BRASKER MASTEN
(9.05m)29.7ftLOA
DESIGN WL25.9ft (7.9m)BEAM
6.99ft (2.13m)DRAUGHT 5.9ft (1.8m)
DISPLACEMENT 1.59 tonnes TO DWL
(1.78 tonnes loaded)287sq ft (26.6mSAIL AREA )
Ericus (Ricus) van de Stadt designed Black Soo in the
new marine plywood
62 CLASSIC BOAT APRIL 2016
A 29ft offshore racing yacht, lighter than a dayboat built in 2016, and she could plane
THEO RYE
B
lack SooCowes in 1957 for Michael Pruett. In period she was described as a development of van was built by R&W Clark of East
and along a fair distance again with this radical design and Fair Megde Stadt’s of 1955; but van de Stadt moved things Zeevalk (his fi rst design, of 1949)
her near sister, around hard-chine construction in plywood; the fiZeevalk, was effectively an advertisement for van de Zeeslang. All of them were based rst,
Stadt’s friend Kees Bruynzeel’s new marine plywood, and she proved a weapon under the right conditions, coming second in class to the overall winner Yeoman
in the 1951 Fastnet. The early post-war period was an era of exciting and rapid developments in lightweight design, with Laurent Giles producing Myth of Malham
and the remarkable trend had slowed by the late 1950s, the attractions of the type were by then well established. Sopranino, and even though the Zeeslang (design
number 58) was also for Bruynzeel, but (number 59) was destined for a British owner. She was described as “the nearest thing to a planing boat in the Black Soo
RORC fl eet”, and indeed with a good breeze on a deep reach, given a helpful wave face (and despite her narrow beam), she could be induced to plane, with some
remarkable claimed speeds resulting. Her total displacement was about half the weight of just the ballast keel of her contemporary Cohoe III, which was also 26ft
on the waterline and of “moderate displacement”. Even today a 30ft yacht for offshore racing would rarely displace as little as 1.6 tonnes; the modern J88 dayboat
at 29ft 3in LOA (8.90m) displaces 2.2 tonnes, which puts the 59-year-old design of Her cast iron hollow fi n keel with a swept tip bulb, Black Soo into perspective.
described in 1958 as at “the limit of narrowness”, weighed 760kg, giving her a ballast ratio of nearly 48%. It demanded clever design and no doubt a high level of
boatbuilding to keep her down to weight. Notwithstanding that the hull was effectively comprised of fl at panels, her fi ne scantlings would have needed a
careful touch. Thanks to her very narrow beam her wetted surface area was minimal despite the immersed chine, and she was very easily driven; even the mainsail
from a 14ft dinghy that she took as a stormsail on the Fastnet proved too large. Her dead straight sheerline and fl at panels gave her appearance an angular
modernity, and her good rise of sheer forwards must have helped prevent nose-diving as she ventured offshore, but even so she must surely have provided
her crews with a wet ride. The relative lack of flthe sections probably gave her a useful ability to ride on the chine when heeled, using the immersed topside are in
area to resist leeway. The combination of fland the hard chine gave her a hollow entry on the waterline, but as Herreshoff’s Alerion and others at panels
demonstrate, this is not necessarily a disadvantage.sections underwater to help avoid slamming when There looks to be just enough angle on the forward
upright, but as she heeled over that may not have been true, and the qualities of Bruynzeel’s plywood must have been tested at times.
excess weight. This was a narrow boat, no question, and had a very limited interior with, as some wit noted, “full In the original form there was ruthless elimination of
crawling headroom”. The four GRP Royal Cape One Designs based on the same design had a nod to convenience with a modestly raised doghouse at the aft
end, but the original with transparent plastic panels. With a second tiller extending into the aft end of the cabin, the helm could sit Black Soo had a low coachroof
below to steer and still see up to check sail trim. the 1957 Fastnet that caused She was tough; she sailed through a Force 8 gale in Bloodhound to heave-to
overnight and winches. Ironically electrical problems; an early example of a problem we DrumbeatBlack Soo to retire after wrecking fi then had to retire due to ve
might consider a modern curse. Ireland for many years from 1962, but as the doyen of yachting correspondents Winkie Nixon noted, she Black Soo was based in
“eventually succumbed to the Irish weather which is murder for even the fi nest plywood” and was broken up sometime around 1999. Her near sister, Zeeslang, was
luckier; after racing in South Africa for 50 years she was restored and is now a “cherished classic” in Switzerland, exhibited at the Düsseldorf Boat Show in 2014.
BLACK SOO
VAN de STADT
CLASSIC DESIGNS
Theo Rye’s article on hollow spars is just the kind of article I
like to see. My Albert Strange yawl Nirvana has a 40ft mast
which takes four people to carry. If it were hollow it might
weigh about half as much. I’d like to hear if anyone has
experience of swapping a solid for hollow mast or even solid
for alloy. Clearly the heeling effect would diminish but the
rolling motion might quicken.
My grandfather’s (now my brother’s) AS yawl Firefly has a
beautiful McGruer main gaff as illustrated in Theo’s article. It is a
beautifully made and incredibly light spar. It is oval in section
and tapers at each end. There are two questions: how did they
“roll” a thin sheet of semi-quarter sawn spruce to produce the
tapers? And secondly what glue did they use in 1922 that still
survives 84 years later?
My own yawl has a 16ft gaff made the “Noble” way – eight
quarter sawn pieces with a bird mouth cut on one edge of
each, as shown at the top of the title page of the article. I have
made four of these at various times and find them very
satisfactory, however, whilst immensely strong and light, I
would next time increase the diameter in order to reduce the
flexibility. Another slight drawback of this system is that the
internal flat sides are not exactly opposite one another, and so
making a plug at the compression points, say at the hounds or
in the way of a mast band, is quite awkward.
Pete Clay, via email
McGruer hollow mast praise
I owned for over 20 years, until recently, a 1926 23ft Broads
half-decker which had a McGruer hollow mast and was rigged as a
high-peaked gaff. I added a second shroud to protect the mast
downwind. The mast is still going strong to this day. Because of the
high standard of the remaining spars I can only assume they were all
McGruer spars. The boat was a joy to sail.
Adrian Jarman
Zeeslang alive and well
Thank you very much for mentioning the sister ship of
Black Soo, Zeeslang, in your April issue! I enclose a photo
of her sailing. She is still in very good condition and yes she
is still a ‘cherished classic’, as you can see.
Michael Baumann, Switzerland
The article about Black Soo (April issue) brought back many
memories.
A further much-travelled sister ship was Four Square,
amateur-built in the late 1950s by Brian Smart at
Barnehurst, Kent. Leaving the UK after the Fastnet Race in
1961, she went first to the Caribbean then on to New York,
where she was laid up for the 1962/3 winter. Brian then
entered for the 1963 Trans-Atlantic race but the entry was
refused on grounds that can be summarised as saying she
was too small. Nevertheless as the sole British entry, the
race committee offered the race facilities and she sailed
alongside the fleet. I had the dubious pleasure of being one
of the crew as conditions on board can best be described
as spartan.
Back in the UK, she was laid up until 1967, when I agreed
to be one of the crew as far as Lisbon, but for various
reasons had to jump ship in Brest. Sadly I then lost direct
touch with Brian but believe he pushed on via the Panama
canal and West Coast USA before finally selling Four
Square in Australia.
Ron Watts, Pin Mill, Ipswich