I have heard the argument that concertinas were a bit more of a middle-to-upper class instrument. They were rather expensive and made with a degree of precision that may not have done too well under the rigors of a life at sea. If you've owned any of the basic, early, instruments you know that they're delicate, and not just because of age. Far more delicate than the vastly more expensive Aeolae and Edeophones that professionals have loved and sought after for a very long time now...and which would then, as now, been out of reach for most laboring folk. Oh, and they're quiet--- much more at home in the parlour or drawing-room than on deck.

A workaday melodeon, on the other hand, is made to much larger tolerances, and of cheaper materials. It's a loud, raucous, thing that was made with "the masses" in mind.

Think Hohner poker-work and some imitators. They take a lot of abuse and keep on playing, and can be field-repaired with readily-available materials.

In the day, the concertina was to the melodeon as the fine pocket watch was to the cheap alarm clock.

They were, as I used to tell my demonstration attendees, "the Casio keyboards of the 19th and early 20th centuries." Almost "throw-away" instruments.

They went to mining, railway, and lumber-camps, barn dances, and everywhere in between. It makes sense that they'd find their way among the working people at sea.

Would they have received a lot of mention? Probably not. Not much more than shoe-laces, straight-razors, or other things people took with them where they went.