Updated 18th May 2003

How To Build a Ferro-Cement Boat in Easy(?) Stages

The boat is the yacht 'Noidea'. (In case you're wondering about the name, it comes from "What are you going to call your boat?" - answer - "No idea").

It's a 57' ferro-cement ocean sailing cruiser, about which the following statistics may be interesting (then again, they may not be - in which case just skip the next bit): length 57', beam 16', draft 8'6", displacement 45tons (all up). In the course of the construction we consumed 9 tons of sand, 18 tons of cement, 1.3 miles of 1/4" steel wire, 1.3 miles of 1/6" steel wire, 100000 wire ties, 40 sheets of 8' x 4' 3" square 1/6" wire mesh, 3500 square yards of 1/2" chicken wire, 6.5 tons of scrap metal, countless 10000s of screws & bolts.

If you're wondering how we went about the construction of a 57' (17.5m) ocean-cruiser, then this might give you some idea.

The first stage involved fabricating cross-sectional trussed frames, out of 10mm steel rod. The boat contains 17 such frames, spaced 38 inches apart. Each frame was reinforced with horizontal & vertical pieces of angle-iron, fixed to the frames with u-bolts.

The vertical piece of angle-iron on each frame was extended with ½ inch studding, which was passed through a hole in the centre-beam of the building frame. The frames were secured to the building frame by nuts on the studding, which also allowed vertical adjustment. The horizontal angle-iron on each frame was afixed at the same vertical level, allowing easy visual confirmation of correct alignment.

Once the frames were in place, a stem piece of galvanised pipe was shaped & welded to the bottom of each frame - thereby fixing the horizontal spacing of the frames:

The piece from the stem to the rear of the keel was a single ¾ inch pipe. Two parallel ½ inch pipes were used from the rear of the keel to the transom - spaced far enough apart to allow the passage of the propeller shaft between them. The transom was also constructed from shaped pipe, overlaid with square mesh, to form a classic curved transom shape.

The tops of the frames were joined together with steel bar, from the point of the stem, along the deckline, to the top of the transom.

At this stage a reasonably rigid construction existed. Onto this were tied the stringers, consisting of ¼ inch wire spaced horizontally every 3 inches. Another layer of 1/6 inch wire, was tied over this (also at 3 inch spacing) to form a rigid 3 inch mesh. The wires were tied together at every crossing point:

Once the hull was completed covered with the rigid mesh, it was then covered with ½ inch bird-netting. Five overlapping layers were placed over the outside of the hull, and 5 overlapping layers on the inside between the frames. The frames were also covered with netting. ½ inch reinforcing rods were inserted fore & aft along the length of the bottom 1 foot of the keel, which was then cemented, and filled solid. Once this had set, supports were inserted under the keel, allowing the ground to start taking the weight, rather than relying on the whole structure 'hanging':

The whole hull was then tied at 3 inch spacing, to hold the netting in place, and to form a good key for the cement. Then (in a single 11 hour operation) the outside of the hull was cemented by a team of four plasterers, and one labourer:

As the day progressed the boat changed from being a see-through 'ghost', into looking like a solid boat:

Once the outside of the hull had set, the cementing of the inside started. For the more difficult to access places (such as inside the skeg, shown below) it was necessary to vibrate the cement into place, using a vibrating poker:

The inside of the hull (done by us, rather than a professional team) was plastered one frame section at a time:

Once the hull was completed, the decks were constructed in the same manner - notice the use of angle-iron tied to the outside of the deck, holding the structure in place whilst the underside is cemented (notice also, how little children have no fear of heights!):

After the decks, the cabin sides & roof get a similar treatment, although the flat surfaces here allowed the use of sheets of square mesh instead of having to tie rod together:

As the structure started to take on strength, so braces could be fitted to the underside of the hull, and the vertical supports (the angle-iron pieces) could be removed. Once the verticals had gone, so that part of the building frame could be removed. It's during operations like these that you lose your fear of heights (in the photo below I am sitting on a 6 inch wide beam, 22 feet above the ground):

With the though-deck angle-iron verticals removed, and the underside of the deck cemented, it was then the turn of the topsides of the decks & the cabin sides:

Simlar treatment of cabin tops, with lemonade bottles providing the perfect tool to cast nice round holes in the cement:

Once the main structure was complete, it was then necessary to fit the ballast. 6.5 tons of scrap steel (in the form of old chain, storage-heater blocks, sash-window weights, etc.), buried in cement in the keel. The keel was divided into sections, and the ballast had to be divided into measured weights in each section:

Timber cross-bearers were fitted to the webs (formed from the frames), on to which could be laid the plywood flooring:

By this time, the removal of the building frame was starting to reveal something that really looked like a boat:

The entire building frame had to be cut off above the height of 7 foot (to allow access for the crane). The outside of the hull also required painting:

The rudder needed to be fitted in place. On a boat this size rudders are quite big! The rudder stock is 2.5 inch diameter stainless steel rod, and the whole assembly had to be lifted into place with a chain-hoist:

To lift a big boat, you need a big crane. This particular beast had a 200 ton lifting capacity, and if you're wondering how it got the boat past the tree (in the middle of the photo below) - simple, it lifted it over it! Cranes this big make 37.5 tons of boat look like a feather:

A load this big breaks a number of road-traffic laws: too wide, too high, too heavy. To transport something like this requires a special licence from the department of transport, a police escort, a telephone company escort (the top of the boat being higher than the telephone wires). For many parts of the journey, the transporter either had to drive down the middle of the road, or sometimes on the wrong side, in order to avoid various obstacles. It is quite understandable that they only allow you to move loads like this on a Sunday:

A three-hour, nine mile, journey later, and the boat arrives at Shoreham Beach wharf. A quick re-assembly of the crane, and the boat can at last take to the water:

Two and a half years of most evenings, weekends & holidays, and finally we were afloat!

Our boat in Brighton Marina: