Posted on February 16, 2023
Rotational molding takes powdered resins, dyes, heat, and specialized equipment to create hollow objects in a variety of industries. For those of us in the marine industry, that means creating the floats that give floating boat lifts their buoyant properties.
HydroHoist floating boat lifts are made through a manufacturing process called rotational molding (also known as rotomolding, rotomold, or rotocasting). While this production process gets used in many industries that need hollow parts of any size, it works especially well for creating floating boat docks, which is why we use the process.
Most rotational molding is done with polyethylene materials, which has been the case since around 1961 when polyolefin powder had its first public demonstration. Other materials have been investigated, including polypropylene, nylons, polycarbonate, rigid polyvinyl chloride, and many others, which can all be reinforced or foamed with fiberglass as well. Many companies that do rotomolding will also have or use grinding services, which expands the range of materials that can be used.
Polyethylenes, as a broad class of material, have great processability, numerous useful properties, and have a low cost considering their benefits. HydroHoist floating boat dock tanks and ports begin the rotational molding process as polyethylene. The raw materials have dye added to them before the rotocasting process begins.
So how do the raw materials become the hollow products that rotocasting produces? The raw materials start as a powder, and by the time they’ve gone through the rotational molding process, they’ve become a resin in the desired shape. The raw materials are added to a mold in powder form, which is then heated and slowly rotated both horizontally and vertically inside an industrial oven to ensure that the insides of the mold are completely and evenly covered. When the inner surfaces are covered with the melted resin, the mold is cooled off, and the finished product is removed and ready for use.
HydroHoist injects the dyed raw polyethylene into the tank and port mold. The mold is heated and rotated to ensure full dispersion before cooling and removal. The majority of the HydroHoist dock tanks are single-piece units, which means no seams to ensure water tightness and rigidity, even in harsh marine conditions. Our ULE tanks consist of two of our biggest tanks fused together, which means that those will have a seam, but the seam won’t compromise the quality of the materials or construction.
Why go through the trouble of rotationally molding a boat lift when there are so many boat lifts that are bolted together or made of different materials on the market? Because there are some waterfronts where only floating boat lifts will work, and rotocasting is the best way to create those docks. For water that’s especially deep, fluctuates often, or has a rocky, muddy, or otherwise difficult bottom to work with, a floating boat lift is a great solution that ensures that the dock is always at the right level. For boat lifts and even entire dock systems that use electricity, a floating setup is also a great idea to keep the electrical components from getting submerged in a bad storm or when the water level gets too high.
A rotationally molded floating boat lift system is also good, even if you have other choices. Floating boat lifts will be easier to get in and out of the water than comparable models on piles or legs, making them great for seasonal boaters. The rotational molding process ensures there aren’t seams, which eliminates weak points in the design that could compromise the buoyancy of the boat lift in the event of an accident. Also, rotationally molded boat lifts are more environmentally friendly, and the polyethylenes HydroHoist uses are UV-resistant to avoid degradation. Because the floats are hollow, there’s nothing inside that has the potential to leak out and harm the environment.
Are you interested in learning more about different types of boat lifts for your waterfront? HydroHoist is a great place to look. The peace of mind that comes with having a high-quality boat lift made from the right materials with innovative engineering methods makes it easier to enjoy your time on the water without worrying about whether your dock will break down. If you have questions or want to start creating a waterfront with HydroHoist, get in touch with our team online.