Intercom is a better invention than "sliced bread":

This is another of the great tips we've got from other Outbound owners. We spent a week with Kurt and Pamela on "Big Frisky, Hull #32" in Morehead City, NC waiting for a weather window to go offshore to the Caribbean. We had a blast together, and they were kind enough to share stories and what had worked for them cruising and living on Big Frisky for 4 years. One of their "must have" was interestingly enough a pair of Bluetooth intercoms. How stupid is that...

But they insisted, and referred to all the times we've heard people yell at each other on the boat whilst docking or dropping anchor. We tried to tell them that we were masters in hand signaling (which was not really true). They were convincing enough, so whilst stuck in bad weather we've ordered a pair (yes, do buy 2). We have never regretted it, and now see them as an essential item aboard. So to the point that we bought an extra pair, if we would lose one or two. Which is really handy when you are three or four aboard (yes the do work with several people).

Use cases:

Some of them are easy to imagine, like docking and anchoring. But they also work wonders whilst up the mast. When one of us are up the mast doing stuff, the other one can be below puttering around with other shores, and we can have a normal conversation.

A true test came about half way over the Atlantic. Suddenly, the auto-pilot stopped working. Anette took the helm immediately, got my attention, describing the situation. Not knowing what was wrong, we put our headsets on, and Anette continued to helm the boat whilst I got into the garage, and into the steering compartment. During this, Anette and I could still talk to each other as if were next to each other. To be honest, even better. So me down below, and Anette steering the boat, I told her that a pin on our auto-pilot broke. The intercoms did not solve the problem, but took a ton of stress off of the situation. Any task where we have to be at different places in the boat is just so much easier when you can talk, without shouting.

The range is 900 meters, so that can also be used if someone is close enough ashore doing something.