Blow tube Communicator, like in the movies.

On land it's a speaking tube; afloat, it's a voice pipe.


They work by airflow and echo - at least the solid ones do. You can make one out of broad thin-walled pipe (brass, copper, tin) with a funnel (or cone or mouthpiece) at each end. Speak into one end, and have someone put their ear to the other. The reason for blowing is to get the attention of the person on the other end so they can bend an ear for the message. If you're going through any machinery spaces with it, you'd want to wrap the tube in something that absorbs sound from outside it.

Having one of those would be a hoot. Just be careful if you have one end on an open bridge. It will be an access for water, mice, etc. so it would need a plug.

the copper, brass, and bronze mouthpieces i've seen on open decks generally have hinged lids to prevent weather and critter infiltration. No idea where to get such a thing, but see below for an example.

In looking around at what people have done to make their own versions, one person recommends putting a 90º shutoff valve in line. While a ball valve might perhaps work as well as a lid for keeping critters out... what of accumulated water that might sit in the tube above the valve? The person at the other end might receive a wet, slimy ear.


Oh, I forgot to mention that the way attention is gotten is there would generally be a whistle plug kept in either end - blowing through the tube would cause the receiving end to whistle, hence getting the person's attention there.