It depends what you want them for. If the phone
is just for talking, then any used phone will do. If any of your friends don't have any old leftover phones then just buy the cheapest one. If you want a portable computer, get a smartphone.
Choice between tablet or laptop also depends on what you are planning to use it for. If you plan on doing any "computer work" (type a lot, etc.), get a laptop, typing more than a short email
on a screen
can be quite frustrating. If you only plan to browse the internet
, then tablet can be more convenient to use. I have no idea about how available marine software
is on iOS/Android vs. windows.
Also, I'd consider a netbook instead of a laptop(netbook is type of smaller and more lighter laptop), which can be quite cheaper.
Most netbooks are quite underpowered. HP dm1z and Lenovo x120e two best ones. Avoid anything with Atom processors. dm1z has better speakers, Lenovo has matte screen(more readable in direct sunlight) and that awesome nipple mouse.
On tablets, Apple still makes the best ones, but you will pay a considerable price
premium for that. Samsungs tablets are also pretty good
Wow, you can get a brand new phone for €16? Prices sure have come down.