"By "water deck iron" do you mean the third item in this stove accessories page:
Stove Accessories "
Yes the 4 inch bronze is pictured .
Water is poured onto the deck iron and will remain outside in the fitting .
The unit keeps the deck temperature at the fitting below combustible.
Mostly required for larger HOT wood burning ranges.
The limited BTU output of most of these units may require more than one unit for severe cold.
The most common is an oil fired galley range and one or two round units fore and aft.
All depends on the size of the boat and temps.
Warm shades work well on large glass areas.Wool rugs on the cabin sole , with a bathroom carpet on top works well.
The bathroom carped is machine washable , so visitors with mud & snow covered boots are less hassle,
Stay warm!!! 22 years full time in the NYC area.