Detail of “Walker’s Bird’s-Eye View of Provincetown” from 1910. [Boston Public Library / Norman B. Leventhal Map & Education Center Collection / Call No. G3764.P78A3 1910. W3]
The current naval mooring field shown in green circles. [National Ocean Survey, Provincetown Harbor, No. 13249, 8th Edition, 17 January 1976, National Oceanic and Atmospheric Administration]
Updated on 19 January 2013 | In the early 20th century, Provincetown thrilled every July to the arrival of a small armada from the Navy’s North Atlantic Squadron. But dozens of large warships (or large vessels of any kind) present a logistical challenge all their own: how can the ships be moored in such a way that they will not collide with one another while riding at storm?
“A vessel properly moored in a tideway occupies, in fair weather, but little more space than that in which she can swing freely; but in order that she may ride in perfect security at all times, she ought to have room enough to enable her to veer out the whole length of the cable, in bad weather, in any direction from which the wind may come,” Henry Mitchell of the Coast Survey wrote in 1869. Given a standard cable length of 720 feet and deducting that part of the cable that could not be fully paid out, Mitchell determined that circles with radii of 631 feet would suffice for 12 “first rate men-of-war riding at storm anchors in the basin of Provincetown.”
“It may be objected to my manner of reckoning swing room that since vessels at anchor are swept by the wind in the same direction, the whole estimated circle is not required in each case. This criticism would be just if in practical experience we could pack vessels into the port as carefully as we plot their circles upon our chart, and if vessels were all built alike, so as to have the same hold upon the water, and thus be liable to yaw over equal corresponding sectors.”
The current naval mooring field off Long Point is composed of 19 large circles with 900-foot radii (a clear space of 183 acres in which each vessel can swing around unobstructed) and 24 circles with 450-foot radii (yielding 46 acres). Now all we need is the North Atlantic Squadron.