The Coastal Craft 33 Profish is built entirely of durable, rugged aluminum, yet weighs only 11, pounds. So are many commercial small craft�below feet�in operation today, as well as ships to more than feet, where reducing weight to achieve high speeds is very important.
First, a science lesson. Manufactured from the ore bauxite, aluminum is a silvery-white, ductile metal with excellent corrosion resistance, strength and toughness. It can be easily cast and welded, melts at 1, degrees as opposed to degrees for fiberglass , and weighs pounds per cubic foot�a little more than a third as much as steel. What this means for the boat owner who runs aground at 25 knots is that the metal stretches and dents before it ruptures, which is good when the goal is keeping the ocean outside the boat.
The plating surrounding aluminum welds is about 60 percent as strong as the surrounding members it joins. In order to compensate, backing plates and longitudinal stiffeners help spread out loads, and hull plates are butted in between, rather than at the frames, to minimize stress at these structural hard spots.
And you will likely have a much better chance of maintaining watertight integrity after a hard grounding than with the average fiberglass boat. In addition to strength, toughness and abrasion resistance, another reason aluminum is used in so many commercial and military vessels is its low maintenance.
This ability to bare all includes the bilges, which are usually left unpainted. And forget about scraping and painting, or compounding and waxing gelcoat. Commercial companies love aluminum boats for their ability to withstand punishment every time they are put to work. With all that in mind, here are several things to consider when talking about aluminum boats. When comparing aluminum boats, ask about plate thickness, especially in the hull bottom and sides.
The bottom is often one size thicker, for obvious reasons. Also, look at the spacing and scantling size of the hull and deck framing. Deeper frames are stiffer, all else being equal, but they also take up more interior volume. Pontoon boats are typically made of. Aluminum and walleye fishing boats in the to foot range might have. Rock Salt Alloy Boats builds this foot center console fishing boat completely from aluminum.
While welded aluminum pleasure boats are in the distinct minority in the United States, they make up close to 40 percent of the market in Australia, according to Perrotta.
I also tell customers about megayacht builders like Derecktor, Palmer Johnson and Burger, some building yachts to feet and more. And then there are the commercial yards producing pilot boats, patrol boats, foot fast ferries, and foot offshore crew boats for the oil industry.
Welded aluminum boats on average cost more than fiberglass boats of the same size, Perrotta says. Eagle Craft manufactures this salty-looking 43 Pilothouse Cruiser.
It is made completely from aluminum. While the true condition of a composite fiberglass boat can remain a mystery even to a competent surveyor, absent destructive testing, an aluminum boat bares all its secrets. With aluminum there is no core to rot or delaminate, no fiberglass voids to blister, no faulty skin-to-core bonds, no rotted plywood transoms, no soft stringers or bulkheads around poorly sealed limberholes.
What you can see with an aluminum boat is pretty much what you get. And aluminum welds can be X-rayed. Hull-to-deck joints are welded, so there are no rivets and fasteners to come loose and leak.
These are truly one-piece vessels. Dent the hull or deck badly enough, and you just cut the abused section out with a carbide saw and weld in another. The bottom of the hull is also the bottom of the tank, and the tank becomes part of the hull structure. This eliminates wasted space between a separate tank and the hull, maximizing tank capacity and lowering the center of gravity of the fuel.
Gasoline-powered boats, however, require separate, non-integral fuel tanks, since the consequences of a leak in one of these tanks could be a lot more memorable for anyone in the vicinity. While an aluminum boat is invariably more expensive to build than a fiberglass equivalent built from a reusable mold, a quality aluminum boat might hold its value better over time.
The shapely Lekker Damsko proves aluminum boats can be beautiful. For most do-it-yourself boatbuilders, buying a fiberglass hull and deck and finishing off the boat is going to be the easiest though it is by no means easy way to go.
At its most basic, this means you buy Mylar templates that are used to mark the plating so you know where to cut frames and plating. You can even cut aluminum with basic power tools and metal-cutting blades. A better way to go, from a precision-fit and ease-of-building perspective, is to buy a kit with all the aluminum pieces precut.
You just set them all up on jigs and weld them together. This is not a bad way to go if you have the metal-working skills � or the time to acquire them�and you want to minimize cost. Keep in mind that a fiberglass kit hull and deck are laid up in a mold, so they are or should be smooth and shiny on the outside. Obtaining the same finish in an aluminum hull takes a lot of fairing and sanding, since the heat from welding distorts the metal. And it would be a good idea to find an instructor and do many hours of practicing on scrap metal before you start piecing together a boat.
Fortunately, there are plenty of aluminum-boat builders out there. Stock production boats, custom boats and a mix of stock boats with custom touches are all available. In fact, customizing an aluminum boat is easier than modifying a fiberglass model.
You can weld pieces of aluminum in place and move non-structural bulkheads, seats and other components. With glass you must create molds and fuss around with endless filling and sanding. Perrotta says electrolysis really no more of a problem with aluminum boats than it is with a fiberglass or wooden boat with underwater metal.
A limitation regarding plate aluminum is that it can only twist in one direction, so anything built of it has what are called developable curves. This makes for a less attractive boat than a fiberglass hull with compound curves creating tumblehome aft and flare forward, and more curves where advantageous in the hull bottom to optimize the running surface.
Of course, you can pay more and have the boat built of aluminum strakes, or planks oriented diagonally, which allows some compound shape to be built into the surface. This also requires a lot of fairing to get the surface smooth, but it can certainly be done. Most aluminum boats are built with a single chine Aluminum Boat Deck Screws For for ease of construction � and because a single chine makes the most sense for a planing hull. Displacement vessels can be built with multiple chines that provide a more easily driven and seakindly hull form.
What are some of the downsides to aluminum? For this reason, insulating the hull and deck to control temperature, condensation and noise for all but the most utilitarian boats is a smart move. And you have to take precautions against electrolysis and crevice corrosion. You might even be in the vanguard of a practicality-driven populist trend. How do different hull types react in rough water?
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