It is interesting to note how boat construction has changed over the centuries.
Thousands of years ago, boats were crudely fashioned from hollowed out logs. Over the years boat building became more sophisticated and boats were built from wooden frames, with planks nailed in place to form the hull.
There were two types of planking. The oldest process was called clinker, where planks were made to overlap each other. This process was used successfully by the vikings and made the ship lighter overall.
Carvel was the more modern version of the two, where the planks were laid edge to edge with a small gap. The gap was filled with soft, fibrous substances and latterly these were combined with a resinous substance and known as caulking.
Unfortunately culking would get worn out and the boat would leak. If a boat was out of the water for a long time, the planks would shrink and this would also lead to leaking and expensive repairs.
Over time the planks were made smaller and glued edge to edge before being sanded to a smooth finish.
Today there are several different ways a boat can be constructed
Wood and cold molding
This is the process of using several layers of wood veneer. A special jig is made in the shape of the hull and the veneers are then glued over the jig, using a special boat expoy resin glue.
This is a time and cost saving process, because the jig is fairly simple to construct and can be easily changed when a different shaped hull is required.
A layer of veneer is glued over the jig to form the shape. Once that has dried, a second layer of veneer is glued to the first layer. The grain on the second layer runs in the opposite direction to the first layer and each layer thereafter goes in the opposite direction from the last. This gives the hull great strength and rigidity.
Once the glue has dried. Fibreglass may be added for addtional strength and the whole thing sanded down to a smooth finish, after which the hull is varnished (with several coats).
This is now the most popular way to build a boat. It is actually a reinforced fibre plastic that is added in layers.
The process is more expensive for individual builds, because of the expense of creating the mold. However if the mold is going to be used in mass production, the cost is greatly reduced and this is combined with lower maintenance and great strength.
A female mold is created in the shape of the boat. The mold is firstly covered in a releasing agent, so that the finished product can be easily removed. Once this process has taken place, a resin gel cost is applied over the mold. This is the finished layer that you see once the process is complete. It is tough, shiny and must withstand years of sun and water.
Before the gel has completely dried, a catalyst epxoy resin is applied and then the layers of fibreglass are added, alternating between resin and fibreglass to build up the layers. Wood and foam inserts can be added as fixing points, or to add increased strength in key areas such as the bulkhead.
The latest technology combines fibreglass with modern composite materials like corecell. The advantage of modern technology means that the rigidity and strength is kept, but the weight of modern composites means the overall weight is greatly reduced.
Most companies using this method still use a jig, however the wood veneers are replaced with the composite material and these are glued in layers much like veneers to provide the shape and strength of the boat.