yellow jack

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yellow jack

2. A yellow nautical flag formerly hoisted to warn of disease on board.
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References in periodicals archive ?
As you enter each port, fly the yellow quarantine flag and notify Customs of your arrival immediate!) Only the captain is permitted to leave the boat until the vessel has been cleared.
A yellow quarantine flag has to be flown as you enter the port and Customs must be notified of your arrival; contact the dockmaster at your chosen destination on VHF 16 for instructions.
We can talk of the good old days when life seemed simpler, but we often forget the quarantine flags draped on front doors of those critically ill.