Marriage Savers
The only thing I can add here is that 'marriage savers' are, I believe, a generic name for a communication device which allows 2, or more, individuals to converse at normal tones and volume with each other while being in different parts of the boat.
We purchased ours at the Annapolis Boat Show, forget which 1, but I wish we had gotten them sooner, they are quite a great addition to the safety items we have onboard.
These items allow us to converse while driving the boat, we do so exclusively from the bridge, when 1 of us leaves for any reason.
I have used them from the engine room while dealing with a problem when underway, while my wife drove up the coast of NJ.
I have not experienced any lag time in communications, nor any extraneous noise while using them. I also wear hearing aids and they do not interfere with their use.
We have the SENA Bluetooth which are light, no additional items other than the headset itself and easy to use.
Also, and an import issue, support is a phone call away. I have called a few times and the phone was answered immediately and answers were provided immediately.
Additionally, there is a company called Cruising Solutions which sells the product and provides great support.
I also believe, IF you are a member of the AGLCA (American Great Loop Cruisers Association) there is a discount available.