Both hull and deck are ferro cement and she is undoubtedly one of the best examples
of a ferro boat.
As can be seen from the photographs, she is very fair and smooth and remains in very
good condition with virtually no rusting. If you are new to the world of ferro boats
please visit http://www.ferroboats.com/
Severn Swan measures 54 feet (16.4 metres) on deck, 50 feet (15.2 metres) on the
waterline. She is 66.6 feet (20.3 metres) over the bowsprit and boomkin.
The entire hull is thickly coated with Jotamastic 87 two-pack epoxy. Below the waterline
this is followed by zinc-based tie coats (Jotun Vinyguard) and antifoul., whilst
the topsides are Hempel Enamel.
The interior of the hull is insulated throughout with13mm closed cell nitrile foam
sheet (which looks and feels like wetsuit neoprene) of a thickness which was calculated
to prevent condensation under virtually all conditions, which it does most effectively.
There are many myths about ferro boats, the most prominent of which seems to be that
ferro boats are the heavyweights of boat design. In fact, a traditional wooden ocean-going
yacht is usually heavier than a ferro boat of the same length. While writing this
we are moored alongside a traditional wooden pilot cutter which is a little shorter
than us but weighs virtually the same. The reason for this is that the ferro hull
is only about 20mm / ¾"thick and its strength is in the armature not in the heavy
frames that a wooden boat needs. Ferro cement is of course less dense than steel.
Many early ferro boats were pretty awful either because of the lack of competence
of the amateur builder or because they were built to designs not intended for this
material. Severn Swan is a Sampson C-Lord. Sampson and Hartley (eventually amalgamated
under the Hartley banner) were the two largest designers and builders of ferro boats.
Over 11,000 boats have been built to Hartley designs. Ferro has been a popular choice
in Australasia where many were built and are still sailing. The C-Lord was one of
Hartley’s most prestigious designs and Severn Swan appears in the Colin Brookes “Hartley/Sampson
ferro"Bible" (Ferro Cement Boats” by Colin Brookes, 2005) as a fine example of its
type (photo from the book above). We have been contacted by a number of other C-Lord
owners who share information and we believe that there are at least 40 in existence.
She was built by a marine engineer who had already built a number of successful boats
and the proof of his abilities can be seen in the state and fairness of Severn Swan's
Another myth is that ferro is brittle. This probably stems from a comparison with
poured concrete. Steel reinforced concrete on the other hand is very tough. If you
have ever tried to break up a reinforced concrete drive or garage slab you will know
how tough it is. The strength and toughness of either reinforced concrete or ferro
cement depends on the amount of steel and how well it is distributed through the
thickness. Drives and floor slabs typically only have one layer of steel in a 3 or
4" thick slab, but are still very hard to break. A ferro boat is a tight mesh of
steel with a plastering of cement. The steel is distributed throughout the thickness
of the hull as much as is physically possible. As a result it is both incredibly
strong and also flexible. There are a number of examples of ferro boats being run
aground on reefs and remaining intact where a wooden or GRP boat would have been
smashed to pieces.
Ferro cement is not the same as reinforced concrete. Reinforced concrete is a mixture
of sand, cement and gravel poured around reinforcing bar. It is an excellent material
for use in heavy constructions such as buildings, bridges and foundations. Ferro
cement is a matrix of reinforcing bar and layers of fine mesh plastered with a specialist
mortar. The mortar is very rich, 2 parts cement to one part sand, and uses a sulphate-resistant
cement and also includes pozzolan (pulverised fuel ash or volcanic ash) which is
very fine and fills the interstitial spaces between the grains of sand. This results
in a very dense, hard and waterproof mortar. It provides great strength in a relatively
thin structure, high impact resistance and flexibility.
Serious impacts tend to result in deformation and crunching of the mortar leaving
an intact matrix, rather than a large hole. The matrix can be more readily filled
even while underwater.
Ferro cement is one of the easiest materials in which to effect a permanent repair.
There are many other advantages of owning a ferro-cement boat. For example she is
fireproof. A major fire in a GRP or wooden boat could quite likely lead to destruction
of the hull and having to take to a liferaft. With a ferro boat the interior may
be lost but the hull will remain intact and floating.
Ferro boats do not rot nor do they suffer from osmosis. They are watertight and
give you dry bilges unlike many wooden boats.
Ferro boats get stronger with age. A 40-year-old ferro boat is stronger than the
day it was built because cement continues to cure and get stronger (slowly) over
its life. The oldest ferro boat in existence was built in 1848.
Ferro boats are quiet. Even when the wind is howling in the rigging, all is quiet
and peaceful down below. A friend of ours that used to own a ferro boat and now
has an aluminium one, comments on the noise in his new boat ," it's like living in
a tin box" he says.
Ferro boats have a larger thermal inertia than other boats. They heat up and cool
down more slowly, which is part of the reason they are comfortable to live in and
are make such good live-aboards.
It is true that many ferro boats were not pretty but a well built one looks as good,
as beautiful, as any other type of boat. People hardly ever ask if Severn Swan is
ferro. Most assume she is timber, until they get close and cannot see the plank
lines. They then guess GRP or steel. Yachties will walk past the row of Moodys
and Oysters, registering only that they have a high price tag, to come and admire
and talk about Seven Swan. With the exception of the occasional multi- million dollar
traditional wooden schooner, we never see a boat for which we would swap Severn Swan.
Above all, ferro boats are stonking good value. To get the ocean going capabilities,
space and luxury of Severn Swan in a GRP boat you would probably be talking more
than £500k. If you seriously intend to spend the next few years living on and sailing
the world I challenge you to find a nicer boat to do it on - at any price!