Now, is it just the jargon that's considered arcane, or the actual practice of removing fenders when cruising? Because I've always considered that to be good practice, and rather looked down on people chugging along with their side fenders trailing in the water - or even dangling just shy of it. I assume it's side fenders we're referring to here; the sort of things that 'real' narrow boats, unless I'm very much mistaken, never had.
Tickles me, thinking back, how we used without any hint of embarrassment to keep to the naval way of doing things.
Fenders were brought inboard on leaving the wall - woe betide any helmsman caught proceeding down the cut with fenders out: the penalty being to buy the first round at the first 'up spirits' stop - 8 pints, probably cost something like GBP2:40 in total then.
Warrior's fenders live in front and back lockers, and only come out when moored to a rough wall or noisy piling, or tied to another boat, or sometimes when sharing a lock with the sort of boat whose owners look like they might appreciate not getting too intimate with our blacking. At other times, I feel much happier with them out of the way of the risk of getting snagged in locks, collecting debris and generally looking untidy. I've always viewed cruising with side fenders down as a solecism on a par with hanging the rope on the tiller pin; the preserve, of course, of Daily Mail readers who own semi-trads with bowthrusters.
There. That'll find out who my friends are.