Every summer, the same radio call: "Harbor, we're coming in tonight, got room?" And every summer, the same answer. Full. Except it isn't, quite. Here's the math the sign never shows.

The hidden berths

On a July Saturday, maybe eight percent of the slips in any marina are empty — a boat's out for the weekend, another's on the hard, a third slipped out at dawn. The marina says full because it can't see its own empty slips in real time.

The map fixes the answer

A live berth map turns "full" into a specific: pier A, slip 7, 6.2 m, open until Sunday. The dockmaster sees it, the boater sees it, and the fairway stops drifting at dusk.

Why we built it first

Because the berth map is the harbor's heartbeat. Everything else — the tide, the pump-out, the fuel dock — hangs off knowing where the boats actually are.