At http://www.sailboatstuff.com/images/AB132077LG.jpg you will see a picture of a porthole. At the opposite edge from the hinges are slots. Engaging the slots are hinged rods, threaded at the outer ends to accept knobs with threaded holes. Those assemblies are the dogs. By turning the knobs on the dogs you tighten them down on the slots, thereby squeezing the porthole against its gasket and making a tight seal. The same devices are used to tighten the lids on pressure cookers; I don't know whether cooks call them dogs.

--- Joe Fineman    joe_f@verizon.net

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