Fiberglass and Aluminum

First vessels were built of wood. As time came, lead and copper plates were used to protect the wooden hulls. Beginning to the mid-19th century, the mass production of steel boats began in earnest, especially in military and commercial shipbuilding. These older steel boats were safe and reliable, but heavier steel travels more slowly, or requires more resources to increase speed. That is why lighter materials, such as aluminum and fiberglass, came into play. 

Both aluminum and fiberglass are not only light, but also quite durable, which is why they are commonly used for modern recreational shipbuilding. However, their qualities are different. Every company that looks to build quality boats that suit the needs of their customers need to decide which material, aluminum, or fiberglass to use best. To make the correct choice, one needs to look deeper into materials’ qualities and features.

Each material choice has its benefits and drawbacks. A heavier boat has higher displacement; it can carry more and has better seaworthiness. On the other end of the spectrum, a lighter boat can potentially enhance speed and mobility. Aluminum is resistant to corrosion, but might be too light for some applications. Fiberglass has plasticity, which makes it easier to mold to shape, but is brittle for some applications. So, your material of choice will define which type of naval architecture you will implement, what kind of boats you will be making, and which tasks these vessels will be capable of handling. Finding the right material means discovering balance.

Aluminum is the most used nonferrous metal on the planet. Lightweight and silver in color, it is the most widespread metal that does not include iron on Earth. As a result, aluminum is popular in shipbuilding. It allows the creation of lightweight and fairly durable boats. Notably, however, this material is very costly. (Djukanovich, 2016). 

The most popular aluminum alloys for use in corrosive environments such as seawater are the 5xxx and 6xxx series alloys, which demonstrate adequate strength and good corrosion resistance. The traditional and the most often used Al-alloys in shipbuilding are 5083 type Al-Mg alloy for plates and 6082 type Al-Mg-Si alloy for extrusions. These alloys are generally reliable in marine service as well as during manufacturing. (Ertug, 2015)

Considering manufacturing and refit, aluminum might be tricky to work with. There are not that many specialists who know how to properly weld aluminum, and the equipment is not that widely available. The material has to be cleaned and prepped for welding; the welder has to be aware of aluminum thickness to avoid burn-throughs, and because of its high sensitivity, the weld must be protected from air and dirt contamination. Tungsten inert gas (TIG) and metal inert gas (MIG) welding, two most popular methods of joining aluminum parts, as well as laser beam and electron beam welding, resistance welding, and shielded metal arc welding, all require complicated equipment.

Aluminum is a good reliable material for numerous applications that should be considered by boat builders who are looking for its specific benefits and prepared to overlook its shortcomings.

Fiberglass is a composite material created from a plastic base and reinforced by glass fiber. Production of fiberglass uses different plastic materials such as epoxy, polyester resin, vinyl ester resin, and can employ a number of fiber layouts such as random arrangement, flattening into a sheet, or woven into a glass cloth. This material is light, reasonably durable, and non-corrosive. It is heavier than aluminum. The chemical base for the fiberglass is silicone SiO₂ with an addition of aluminum oxide, alkali oxide, calcium oxide, magnum oxide, boron oxide, and other composite materials to create a large number of combinations and proportions. Many types of fiberglass are produced to fit different tasks.Importantly, however, one of fiberglass’s biggest shortcomings is its susceptibility to mechanical stress. 

There is no “marine-grade fiberglass.” One of the most widely used types of glass fiber in naval construction is E-glass, which is aluminum-borosilicate glass with less than 1% alkali oxide. Pultrusion, the process of manufacturing fiberglass, has silica (glass) heated until molten, then it gets forced through superfine holes thus creating extremely thin glass filaments. These filaments get woven together into different patterns, and then various resins are added to the woven mat. During the process, fiberglass parts can be molded into desired shapes or forms.

With hundreds of applications and the high plasticity of the material, fiberglass creates relatively lightweight and durable boats. Though it responds well to the outside environment, when damaged, fiberglass might not be easy to fix “in the field”. However, if the workshop has all the necessary materials and equipment, the repair process is relatively easy. 

Boat function defines the materials that are used to build it. As a general rule, a pretty and speedy boat will be made from fiberglass. Fairly sturdy and speedy – from aluminum. There is one issue that has to be considered first, how safe is your boat? How resistant is she to impact, fires, and the extreme elements? At Bering Marine, we believe that both fiberglass and aluminum have enough benefits to be considered a safe material of choice to create multipurpose RIB and catamarans. This is why we use both materials to deliver a second to none experience to our customers.