Ship models are an important part of research at MARIN. Even with the increasing potential offered by computer programs, model trials are essential in predicting the behaviour of a ship at sea.
All models are made to scale. The first model was made in 1932 and is known as model number 1. Recently we made model number 10,000.
We have our own model production workshop in Ede. Originally, the models were made of wood but nowadays we use newer materials, such as polystyrene and carbon. The weight of the actual ship determines which materials are used in the model – the lighter the ship, the lighter the material.
Building a wooden model starts with a rough model that is built up of 50 mm layers of wood glued together. We use abachi wood because it is relatively cheap and is available in wide pieces. A CNC milling tool is used to make the parts 10 mm larger so that there is enough wood to make the model precisely to size.
The final shape of the model is made in a computer-steered milling machine. This machine capacity is 25 x 5 x 2.75 m and a model can be millded to size in one action. Model milling takes on average 2 days, sometimes operating at a speed of 40 m per minute. The models are five-axis milled, that is the milling chisel is at right angles to the surface. As a result, the surface requires very little finishing. The milling machine also bores the holes in the model to attach, for example, the thruster, propeller shaft and the rudder.
A new development is plastic models, which are less labour-intensive than wooden models to make. First, the core of the polystyrene is milled and then carbon mat on which a layer of paste is applied. This is then milled to size. Plastic is used for smaller and less complicated models.
Carbon is a lighter material that can be used for models of shallow draught vessels, such as catamarans, trimarans and rescue boats. First, a mould is made of the exterior of the hull. A carbon fibre cloth is placed in the mould over which the resin is injected. After which, the mould is vacuum sucked and left for 2 days to harden.
When the models have hardened, they are sprayed MARIN yellow. This bright colour is easy to see in the water, in photos and on film.
Did you know
the milling machine can operate up to a speed of 40 m per hour?