So there you are, walking around on the world's most advanced aircraft carrier. Everything around you is a multi-million dollar machine packed with advanced technology. Then something propped in the corner catches your eye. Is that an old wooden ladder? What the hell is that doing here?
When Newport News Shipbuilding builds aircraft carriers and submarines, they've always used a bunch of wooden ladders that look plucked from a 1940s' farm. These fire-retardant ladders, made of pressure-treated lumber, are hand-build right at the shipyard. But they aren't just there for the sake of tradition.
Once aircraft carriers get to be 300-400t, they are built outside, in the elements. Rains can pool up on the metal deck. Meanwhile, electricity is being pumped onto the ship at all sort of voltages. If one of those sources were to go to ground and short, then everything around it would carry a charge. Rubber boots are generally enough to insulate you from a current running through the deck, but if you put you hands on a metal ladder, you could get a shock. The jolt might not kill you, but letting go and falling off the ladder just might.
Have you ever climbed up a tall, extendable aluminium ladder? If so, you know that they flex a lot with every step, particularly when you're in the middle. Now, imagine you you've got a fully-loaded tool belt and you're carrying a 18kg chain fall. You would get a lot of movement with every step, making the climber feel pretty insecure. The wood they use has much tighter, more predictable flex patterns, so even under heavy loads it feels a lot more stable, even at great heights. If you need a beefier ladder, that's no problem, because...
If shipbuilders want the ladder to be stronger, they add reinforcing jacks between each rung. If they need it to be shorter, they can simply remove a couple of rungs at the top. Best of all, because these are all made right at the shipyard, they can be custom-built for their intended location and purpose. You can't get that kind of versatility with an off-the-shelf ladder.
They Won't Burn
Fibreglass ladders are a very popular alternative to aluminium and wood. They're super light, very strong, and they are also non-conductive. Just one little problem. "They have a quick burn rate," said Newport News Shipbuilding's Larry Horne. "We have experienced a few incidents where welding adjacent to fibreglass ladders have ignited the fibreglass ladder, and they burn quickly and have toxic gases in their smoke. That's partially why we use the pressure-treated, fire-retardant wood on our in-house ladders."
And They're Lovely
Nobody at Newport News Shipbuilding actually said that this is one of the reasons they use wood ladders, but they didn't have to. The raw wood is rustic, and really, kind of beautiful. It elicits a sense of tradition. A bit of nostalgia. They have a subtle but clear sense of pride in them, and why not? Yeah, these people build the world's most sophisticated nuclear aircraft carriers. But they also make these simple, practical tools. By hand, on site. There's an elegance in that. Especially in a wold of steel, concrete, wires and weaponry.
Image credit: Richard Thompson, NNS