See pic. It's a zigzag model, but there's machines out there that are cheaper and are essentially the same thing. I bought this one around 6 years ago. I used it to fit out the Clipper fleet, there's pics of the stuff I've made on this machine, on my dining table in my yacht saloon on my Facebook gallery, which is linked to via my blog.
It's been so useful.
Last night I quickly adjusted a mattress protector from IKEA for my forward cabin. The day before I made a load of covers for a friend on another forum who has a classic boat.
Next week, I'll be starting on a full reupholstery for someone that I'm in the same yacht club as.
When I was sailing for my holidays the sewing machine was strapped under the table for safe stowage.
I've repaired my own sails too, when the leach ripped etc.
Can't recommend having a machine on board enough
:-)