NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Noisy Sea Surface
From: George Huxtable
Date: 2003 Nov 15, 20:36 +0000
From: George Huxtable
Date: 2003 Nov 15, 20:36 +0000
My observations of noises from "clickers" off the South coast of England are similar to those of Keith Williams in New Zealand. That is: they are certainly individual clicks and not at all drawn-out "scrapes". They are heard from below decks, the sound being transmitted through the water and the hull, and not (or at least, very attenuated) from on deck. I have heard many clicks per second, but these seem to be from multiple sources, from all around the hull, not just from one or two clickers, clicking madly from one place. Often, sounds are heard from below, in the cabin, transmitted through the water, that would never be audible from the cockpit. For example, when the Navy is exercising nearby, what I presume to be anti-submarine sonar, with all sort of whistles and warbles. Or the rumble of the chains from a chain-ferry a mile or so away. I presume that if the sound has an undervater origin then it gets transmitted best underwater. I shouldn't give the impression that such clickings are predictable or frequent in our waters. I hear them only rarely, but most often from certain anchorages. They don't occur often enough to make for an easy research project. In Worbarrow Bay (a few miles East of Portland Bill), where I've noticed these clickings most often, there's an additional hazard when anchoring for the night. The shingle beach is a popular spot for night-anglers, who set up with an umbrella and a beach-casting rod. My anchoring spot is usually just about casting distance from the beach, but we have an anchor-light and they usually avoid us when casting. I mention this, because the presence of anglers usually (but not always...) denotes the presence of fish. I've never asked what they were after, though. Next summer, I will. My guess has been that the clicks came from lovelorn crustacea who are exploiting the sound-carrying properties of water to attract the opposite sex. But I have no real evidence to back up that hunch. I know that boat-hulls are attractive to certain fish, and my home berth (fishing not allowed) has a plentiful resident population of grey mullet, some really large ones. These graze, most efficiently, on the weed and fouling on the hulls, leaving a pair of parallel clean lines where their lips have tracked across. I doubt whether grey mullet make good eating at the best of times, but these must take in a good helping of antifoul with their diet, so I wouldn't fancy them. George. ================================================================ contact George Huxtable by email at george@huxtable.u-net.com, by phone at 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ================================================================