Sprayed polyester is a great material for building practical and inexpensive boats, but the process can be hazardous to workers and it releases air pollution that is difficult to control. For about a decade, the Swedish boat builder Ryds Båtindustri has been using a vacuum injection technique that improves the workplace environment and cuts emissions by as much as 70 percent. On top of that, the company says it makes sturdier boats with less wasted plastic.
With years of experience and continuous improvements in the vacuum injection process, Ryds claims that few competitors among boat manufacturers are able to match the company’s environmental profile and product quality.
From serial craftsmanship to mass production
Ryds’ management decided several years ago to move beyond its traditional reliance on handcraft and begin building boats with industrial production methods. Manufacturing would also be converted to a sealed process, protecting workers from fumes and the environment from hazardous emissions.
How are boats constructed by vacuum injection molding? The first step is to spray a form with a layer of gelcoat (a hard plastic that dries to a glossy finish), followed by dry fiberglass reinforcement mats. An external layer is laid on top and attached to the form with rubber strips, resulting in a construction that is tight enough to create a vacuum as air is pumped out.
In the next stage, a container filled with liquid polyester is attached so that the form is filled as the air is sucked out. When the form is full, the input valve is closed to allow the polyester to harden. Finally, the “cover” is lifted off and the hull is moved for attachment of reinforcing braces and buoyancy material.
It takes only about an hour to complete a boat hull with the vacuum injection method, and the process is so precise that the amount of polyester used is almost exactly the same from one hull to the next—the variation is generally less than a half-kilo. The process is also less physically taxing for workers.
Stronger, lighter boats
Introducing the vacuum injection process required Ryds to make substantial investments, but the company says the returns, in several different forms, made the upgrade worthwhile:
- The sealed process means lower levels of indoor air pollution in the factory. This in turn reduces the need for continual ventilation with outdoor air, cutting heating costs.
- Labor inputs per boat built are reduced, allowing the company to maintain stable prices.
- Emissions of styrene and other volatile organic compounds are lower. While difficult to quantify in financial terms, the environmental improvement helps the company meet increasingly stringent regulatory requirements.
- The injection method makes boat hulls that are lighter, while at the same time increasing stiffness and transverse strength. Safety is improved and fuel consumption reduced.
- Less plastic is wasted, improving raw material efficiency and reducing disposal costs.
- The workplace environment is healthier, lowering the risk for work-related illness and accidents.
Growing customer interest
Boat owners are notoriously fussy, and they demand a lot from manufacturers. They also tend to be environmentally aware, taking note of fuel economy claims when making purchase decisions. Ryds Båtindustri sees a strong and growing market for boats produced with the vacuum injection method, and the company says it plans to make further investments in increased capacity so that all of its boats will eventually be manufactured with the new process.
Article published in September 2009