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Aluminum Chambered Boats 32
by Roger McAfee
Military tough, recreation ready
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Almost all who see the boats ask the obvious question: "If it looks like an inflatable, why not just make an inflatable?" To say that an aluminum chambered boat, as built by ACB, does the same job as an inflatable, is like saying an Indy race car does the same job as a Chevy. The only thing an inflatable and a chambered aluminum boat have in common is that they both float.
ACB has received a lot of press lately because of the relatively large military orders it has received, and many think the company had its start as a military supplier, which is not the case.
"We started business nine years ago, with four staff and a 1,300-square-foot shop," said ACB founder and CEO Larry Wieber. "Initially we supplied serious sport fishermen and fishing lodge operators. We received our first military order in May 2002, and we now employ 110 people and occupy more than 200,000 square feet with a state-of-the-art production facility." The ACB plant is located in Bellingham’s Fairview district in the same complex as a famous former Bellingham builder, Uniflite.
ACB’s boats are unique in one respect — thanks to their chambered design they are reportedly the only production hard boats made that are certified without the use of foam flotation. The aluminum "tubes" that are obvious to everyone seeing the boat are actually all-welded, airtight compartments that are pressure tested at three different stages of hull manufacture. These tubes, which have chambers with bulkheads and run from bow to stern, provide the flotation required should the vessel take on water.
While ACB’s core business is building tough mission-purpose boats for the military and commercial sector, we’re glad to see the company offering the same kind of mighty hulls with a number of civilized touches for recreational boaters.
Military Specs
It’s easy to see why the military would want vessels without foam. In case of a fire the boat occupants don’t have to worry about the dangerous, and potentially fatal, fumes gassed off by burning foam. Nonmilitary users, of course, gain the same advantage.
The aluminum chambers — more or less circular in shape — bring a major structural advantage over typical monohull deep-V boats. Generally speaking, one of the strongest structural shapes is a tube, assuming the proper wall thickness. It’s also one of the stiffest and lightest if engineered properly. This means boats built in this manner are strong and light.
They are also very stiff, which is an important factor if a vessel is to be used in rough water. I was once on board a 65-foot government fiberglass vessel that was so strong it was bulletproof — literally. We got caught out in a bit of a blow and the boat was twisted and wracked so badly it cost almost $250,000 to repair torn-out bulkheads, hatch coamings, windows and doors. The boat was heavy and strong, but not stiff enough.
Almighty Aluminum
There are a lot of “downstream” benefits to this type of construction. The first is light weight. The 32-footer we tested weighed in at only 13,500 pounds. Therefore, less power is required to achieve the same speed as a heavier boat. That means better fuel economy, which is an obvious plus given the endless rise in fuel prices.
A lightweight boat can be easily trailered and, in fact, can live on a trailer when not actually in use. This means no slip fees and a reduced maintenance regimen compared to a boat that lives in salt water — combined this can save thousands of dollars a year.
ACB boats are made of marine-grade aluminum, which does not corrode in salt water. Once it develops an oxide coating — that dull gray look of unpainted aluminum — no further oxidation occurs. Aluminum oxide is chemically similar to sapphire, and is, therefore, very hard. Except for antifouling paint, marine-grade aluminum does not need to be painted for protection. Unlike those who own a fiberglass boat, the owner of an aluminum boat does not need to worry if his or her boat gets scratched during use. The "wound" heals itself.
Reverse Chine Rules
Below the waterline the hull is a combination of a traditional deep-V with a 21-degree deadrise. However as the bottom runs out toward the chine it flattens horizontally and then, at the chine, it hooks down slightly. This hull design feature is known as a reverse chine, and it brings a number of advantages. The first is that it creates a larger planing flat than the traditional deep-V, and this allows the vessel to come onto plane quicker, with less power.
However, the main handling difference is noticed when a reverse-chine boat goes into a sharp corner. With a reverse-chine bottom, the chine bites into the water and the boat carves the turn without skid or skip like an Olympic-class slalom skier. Also more of the boat is submerged as the chine is forced into the water during the turn — this increases buoyancy and the turn is generally flatter than with a traditional bottom.
The same feature makes the boat very stable while at rest since as weight is applied to one side, more of the hull is forced into the water, increasing the buoyancy along the weighted side.
Civilian Touches
We were the first to test the new “civilian” 32-footer. Her hull, like all of ACBs other boats, is produced to the same specs as the military hull.
The 32 is not finished in the traditional “yacht” way. Welds are not ground flush; there’s no flashy paint and no fancy exterior wood trim. All windows, doors and hatches are commercial grade. In short, the 32 is finished, outside, much like the thousands of tough, purpose-built, commercial aluminum boats that have been earning their keep for many years along the coasts of the Pacific Northwest, British Columbia and Alaska.
Access to the cockpit is safe and easy. The cockpit itself is open and uncluttered — a good fishing space. Access to the foredeck is easy, but would be made more comfortable with cabin-top handrails. They’ve probably been added by now.
The interior of the vessel is fairly traditional for boats of this type — galley and countertop along one side and head and settee/dinette along the other. The main salon is quite large for this size vessel and provides 360-degree visibility. The full stand-up head/shower bulkheads contain windows with pull curtains for privacy.
Designers have been able to create a long cabin on this boat, because they fitted the foc’s’le with a V-berth arrangement rather than an island double or queen bed. ACB’s arrangement recognizes that boaters spend most of their time in the salon, not the “bedroom.”
Access to the command bridge is easy and safe and the visibility from there is outstanding.
Performance
We fired up the twin Suziki 250 outboards and idled away from the dock out into Bellingham Bay, which is a nasty body of water even at the best of times — and our test day was not the best of times. It was blowing and the combination of wind, current and tide created a confused 3- to 4-foot sea.
With four on board and the engines running at their rated top rpm we topped out at just more than 43 mph into the wind. The vessel handled the conditions easily without slamming or banging, although the metal hull was slightly noisier than a glass hull in similar conditions. We ran across the sea and downwind with no problem, and our speed picked up slightly when we weren’t fighting into the headwind.
Because of the inherent ability of a reverse chine to carve turns at high speed, we threw the vessel into tight turns at full speed — she handled them without fuss. We came to rest in a beam sea and, once again because of the inherent stability of the reverse chine in such conditions, the boat also handled them without problems.
As we bashed about on the bay it became apparent the ACB was a dry boat — much drier than expected in such conditions. Any spray that came on board cleared easily.
Despite the sea conditions and the speeds we were running, nothing clattered or banged around. No doors or drawers rattled or popped open, and we could move around inside in safety.
In summary, the ACB should be on the short list for anyone looking for a tough boat with a good turn of speed and superior handling that won’t break the bank for routine maintenance.
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This article first appeared in the August 2007 issue of Sea Magazine. All or parts of the information contained in this article might be outdated. |
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