Have you tried one Malcolm?
How loud are they?
Quality is about the same as (probably better than) the one I did years ago using an ISD chip, which is a) no longer easily available, b) cost about twice this module's price c) had to have a circuit built around it. Recording time on the original was about10 seconds, this module claims about 40 seconds. It does come with a tinny little speaker which is technically audible, but the speaker leads can be diverted to an amp, at that point, the volume depends entirely on the power of the amp and size, solidity and mounting of your chosen speaker. It does come with two switches, one for recording, and one to initiate playback, which is the one to intercept to the switch worked by the servo, or a switcher.
I would recommend a relay contact, rather than solid state, switcher as the ground line is not easily accessible, so it really isn't referenced to the boat ground line. Recording can be done via the provided microphone, playing your sound from whatever you choose, or you can get a "recording module" to connect to a PC or earphone socket.
For recording, you pretend that its a cassette recorder - press the record button, and as long as it remains pressed, its recording. For playback, a single dab on the other switch starts playback, which continues until the recording has been played.