Why Aluminium?

A lot of your queries will be answered in the frequently asked questions section of our website, however, on this page we hope to try and give you some more in-depth information regarding certain matters.

Why Should Your Boat Be Made Out Of Aluminium?

The boating industry is no difference to any other industry and is constantly demanding the latest technology and materials. Aluminium has many great qualities which make it the perfect choice for your boat. It resists corrosion, is light-weight and is good for welding retaining its strength even after welding.

Aluminium has found a high demand in the boating industry. For over 50 years now it has been used and developed for a wide-range of marine applications and its success has led to other industries now starting to use the aluminium alloys that the boating industry has enjoyed it's success with.

The first use of aluminium in the boating industry stretches back to 1891 when a partly aluminium boat was first constructed. It was not until 1940 when the first vessel made completely out of aluminium was constructed. With this creation, the use of aluminium in the boating industry has gone from strength to strength with many fine aluminium alloys being developed.

After many years of research and development, it was discovered that marine grade aluminium alloy was the most appropriate. It offered safety, reliabilty, and the ability to withstand the stress that the marine environment would present it with. Marine grade aluminium alloy is used in a wide variety of vessels ranging from fast ferries and yachts to the fine aluminium boats built here at Sea Otter. At the recent European workboat show, 85% of boats present were constructed of aluminium. These professionals know a thing or two.

Proof Of The Strength Of Aluminium

Many people have mis-conceptions about the strength of aluminium believing it to be soft and nowhere near the strength of steel. We could waffle on for line upon line about how this isn't the case, however we feel the best way to prove this to you is with real-life proof. The following article, highlighting the true strength of aluminium in boat construction, is taken from the Hazegray naval history website.

There are many misconceptions and incorrect stories regarding the use of aluminum in warship construction. One common story is that HMS Sheffield, a destroyer sunk during the 1982 Falkland War, was lost because her alleged aluminum superstructure made her more vulnerable to damage. This story is completely untrue, because Sheffield's superstructure was not aluminum. Like all ships of her class, her hull and superstructure were entirely steel. Aluminum played no role in her loss. Two Royal Navy warships lost during the Falklands War did have aluminum superstructures, and their loss is incorrectly attributed to this feature. Ardent was hit by seven 500-1000 pound bombs, plus at least two more bombs which failed to detonate, and sank some six hours after the attack. Any warship of her size, regardless of aluminum or steel construction, would likely be sunk by this many bombs, so aluminum cannot be blamed here. Antelope, another aluminum-superstructure ship, was struck by two bombs, which lodged in the ship but failed to explode. Later, while one of the bombs was being defused, it exploded, blowing a major hole in the hull and starting a large fire. The fire eventually reached the magazines, causing these to explode. Again, an aluminum superstructure appears to have little connection to the ship's loss, which was caused by the explosion of the bomb and the magazines.

Several commentators have written that modern warships with aluminium structures are definitely strong enough to sustain major battle damage. The example of this particular frigate would suggest they were right. 'I was amazed how strong she was, she had taken one hell of a hammering,' commented Alan West. Later the board of inquiry into the loss of Ardent would establish that she had been hit by no fewer than seven 1,000-pound and 500-pound bombs which exploded, and at least two others which lodged inside her but did not go off.

If this example doesn't prove to you the strength of aluminium, we don't know what will!

Aluminium Vs Steel

An aluminum hull structure, built to the same standards, weighs roughly 35-45% less than the same hull in steel. If high strength is needed, the alloy boat can be built to the same structural weight as the steel vessel, and then be considerably stronger. For smaller vessels, steel is less optiumum as one must resort to a large water plane and a large displacement to carry the weight of the structure.

Aluminium has a far greater structural efficiency (ratio of a material's stiffness to it's density) than steel. This basically means that if an aluminium column and a steel column were designed to the same stiffness, the aluminium column would weigh roughly 57% less. For beams and panels designed to the same stiffness, an aluminum structure will weigh 48% of the equivalent structure in steel. Some people will argue that the strength of a steel structure compared to that of an equivalent aluminium structure is greater. This may be true but the difference is a marginal one, however one must take into account that the aluminium structure will weigh rougly one third less in weight than the steel which is a massive weight difference. If the two boats were built to the same weight then the aluminium structure would have a far greater strength than the steel structure.

Another major benefit of an aluminium boat is that if the correct grade is used it will, to a large degree, resist corrosion. The boats produced here at Sea Otter do not even need painting as the shell is virtually resistant to corrosion. Any paint seen on a Sea Otter boat is purely to make it aesthetically pleasing. On the other hand, steel boats require annual re-blacking and the certainty is that corrosion will diminish the steel rapidly.

One factor that many people wish to know is the price difference between an aluminium shell and a steel shell. An aluminium shell is rougly twice the price of a steel shell, however this is only a portion of the overall boat cost. This may put some people off aluminium, however the saying "you get what you pay for" is very apt when talking about aluminium. You may pay more for an aluminium shell, but the money you will save in maintenance will more than match the original higher price. Sea Otter boats realise economies of scale and a finished boat is only slightly more expensive than an equivalent quality steel boat. A final advantage of an aluminium boat is that it has a far higher re-sale value than that of a steel boat.