There are a wide range of aluminum
alloys out there and they behave very differently. The best alloys constructed with care are remarkably rugged, low maintenance
and long lived. While aluminum lacks the abrasion resistance of steel
and the strength when measured on cross sectional area basis, aluminum has a significantly lower density which in turn allows for a much thicker plating for a given weight. Designers chose to use the weight advantage in a variety of ways including matching the weight of steel plating and framing, which produces a significantly stronger (aluminum) hull
, or reducing the hull
weight, and so depending on the particulars of the boats in question, can produce and equal strength hull that weighs substantially less. That weight savings can be applied to some combination of greater carrying capacity, greater ballasting, or simply reduced weight which can have its own advantages in terms of smaller rigs, engines, hardware
Depending on the yard, the availability of the alloy in question, and the specifics of the design, an aluminum hull of similar design and finish level can be the same price
or just a little bit more expensive than Steel. Aluminum is generally seen as being less expensive to maintain and depending on the alloy used, generally does have the problems of internal corrosion
which is considered to be a critical problem with steel hulled boats.
Finding qualified welders who can work with aluminum tends to be harder than for steel. Cutting and shaping aluminum precisely is easier than with steel.
Industry studies on construction costs for one off boats suggest that cold molded/ composite construction still offers an initial cost advantage over aluminum and will result in lower long term maintenance
costs. This is of course subject to change given some of the new aluminum alloys which do not require painting, and the spike in the price
Aluminum is less ductile than steel and so will not stretch as far as steel in an impact situation, but since the plating and framing is likely to be thicker in section, depending on the design may still offer similar puncture resistance. Depending on the alloys involved in a general sense. aluminum tends to be more prone to electrolysis
problems than steel.
There seems to be a greater acceptance of aluminum boats in the marketplace perhaps because most aluminum boats built to date have been built by premium builders giving them a certain cache'.