Overview
Severn Swan

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.

Ferro Can be Beautiful....

Go to next page

Previous page

Go back to top of page

Hull and Construction

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 hull today.

 

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!