Workshop team crafts vessel models for ice tests

Did you know that every scaled-down vessel model used in our ice model tests is custom-made? Find out how our workshop team produces the perfect model for each cutting-edge test in our latest article presenting typical positions and tasks at Aker Arctic.  

In the heart of Aker Arctic’s building in Helsinki, adjacent to the ice model basin, lies a workshop furnished with a wide array of wood- and metalworking machines, tools, painting supplies, electric appliances, electric motors, scaled ship parts, and other equipment. Here, every custom-made miniature hull replica is finalised, coated, and outfitted before each ice model test.  

The core team responsible for the workshop and models, which are used to test and verify vessel designs, consists of Tomi Auvinen and Ville Kuivainen (Model Outfitting Specialists), and Henrik Strand (Measurement Engineer) – each an expert in their respective field – supported by Topi Leiviskä (Team Leader, Model Tests and Facility). 

Aker Arctic’s ice model testing facility is one of the few in the world where ice-capable vessels can be tested prior to construction. Also, various hull form options can be evaluated to choose the most efficient design for the final vessel concept. The facility serves both in-house vessel designs and external customer projects.  

Every model is custom-made 

Each scaled-down model used in Aker Arctic’s tests is custom-made according to specifications from the naval architects to precisely replicate the designed hull form.  

Since beginning to offer testing services in 1970, all models have been numbered, with the most recent being number 524. Every model used in the tests is as unique as the ships they represent. 

Originally, the models were manufactured from abachi wood and occasionally from fibreglass. However, in the 1990s, wood was replaced with PVC foam, which is light, easy to work with, and has excellent mechanical properties. The basic shape is milled by a supplier, but the critical details such as the coating, painting, outfitting, and instrumentation are done on-site at the workshop.  

Four surface layers to target friction 

When the basic vessel form arrives at the workshop, its first stop is the painting room, where Ville covers the model’s surface with four distinct layers. The final layer is a special bespoke friction coating.  

“This important stage optimises the friction between the model’s surface and the ice, which is an essential feature in the model test,” explains Ville. 

After the final layer of red paint is applied – a colour chosen to contrast with the white ice in the tests – the friction is measured and documented. The goal is to achieve a friction coefficient that accurately reflects the real friction between sea ice and a new vessel. The closer this coefficient is to the actual conditions, the more reliable the test results will be, thereby aiding ship designers in their work. 

Detailed equipment list 

The next stop is the workshop, where Tomi equips the model with the electric motors, propulsion, and other equipment specified on a detailed list received from the model testing engineers. 

“We have a large number of propellers in stock to choose from according to the diameter and type needed, but the shafts usually have to be manufactured or modified to fit properly,” Tomi says. 

Pod covers, rudders, ice knifes, bilge keels, and other smaller parts are manufactured with a 3D printer, then post-processed and painted – a more flexible and cost-efficient method compared to earlier techniques.  

Sensors to measure results 

Henrik is responsible for the instrumentation of the model with all the sensors and equipment needed to record the results during the ice model test.  

Once the model is fully equipped and ready in the water basin, weights are placed  inside the hull to achieve the correct draught, trim, and stability.  

“Before the actual ice model test, everything is thoroughly verified to ensure that all components are firmly in place, motors and propellers are working, and all appliances and sensors are functioning correctly. For every ice sheet, there is only one opportunity to perform the test, so everything must be perfect once it begins,” Henrik highlights. 

Ice recipe for each test 

Tomi, Ville and Henrik are also part of the model testing team preparing the test ice according to a specific recipe received before each test. During the actual test, Henrik handles the test carriage located above the model, ensuring that the sensor data output is correctly recorded.  

When Tomi and Ville are not tied up working on the models, they participate in tests requiring special solutions, such as ice floes, ice ridges, or brash ice channels, which are part of their expertise.   

“For example, we have built a Saimaa Canal in the basin, various jetties, obstacles and other constructions. One of the most memorable projects was an artificial island, for which we brought in tons of rocks,” Tomi recalls. 

Challenges are welcome 

The Workshop team enjoys challenging projects requiring creative ideas, although most models and tests follow a well-established, straightforward pattern, developed over decades of model testing and close cooperation between departments.  

“Figuring out how to construct a model for testing a detachable bow, an icebreaker breaking ice from below the surface, how to create shallow water tests, or testing models with interchangeable bows and sterns have all been particularly rewarding,” they say. 

Maintaining the facilities 

In addition to outfitting models and preparing for ice model tests, the trio manages the maintenance of the property, the refrigeration machinery and equipment. 

“When time allows, we do the servicing ourselves or liaise with outside service providers. During summer, we have interns to help. Regular maintenance is necessary to keep everything in prime condition,” Ville emphasises.  

All three joined Aker Arctic at different times and have varying educational backgrounds and experiences that complement each other. At the same time, they stress that there is no formal education for their work – learning from each other and through hands-on experience is the best way. 

“The wide variety of tasks is what makes our days interesting,” they highlight.  

Text by Catarina Stewen