What kind of plugs can I expect on transatlantic cruise ships?

Question

When searching for cruises, there are usually descriptions of the rooms you can book but in the list of amenities there is no mention of power outlets. As spending a week or more on the sea requires to have some activities (and today we use a lot of electronic devices), I am wondering first if there are multiple plugs in the rooms, I expect at least 2 since the rooms are for 2 people.

I am also wondering what kind of plugs there are, i.e. is it the North American, UK or European plug system (or a different one) that is used? I expect that some shops will sell that on board of the cruise ship but I would prefer to be prepared.

So to sum up, are there multiple plugs in transatlantic cruise ships, and what type (North America/UK/Europe/other) are they? Or is the plug type depending on the country the ship was built in?

EDIT: As asked, let's say for example the cruise would be on the Costa Luminosa

Answer 1

Very much depends on the cruise ship, and it's often based on their country of origin. Here are some examples:

in the help of P&O cruises (a British-American cruise line) :

Oceana and Britannia also have US 2 pin sockets in addition to UK 3 pin sockets

The standard electrical supply in the United Kingdom is 50HZ (cycles) and 240V.
The supply on board is:

Adonia -220V / 60HZ
Arcadia - 220V / 110V / 60HZ 
Aurora - 220V / 60HZ
Azura - 230V / 115V / 60HZ
Oceana - 220V / 110V / 60HZ
Oriana - 220V / 60HZ
Ventura - 230V / 115V / 60HZ

and Iglu, a UK cruise agent, lists many cruise lines :

**Cunard**

British three-pin, 220v sockets and 110v two-pin sockets are available.

**Costa Cruises**

Continental Europe 220v two-pin sockets

**Cruise and Maritime**

Continental Europe two-pin, 220v/110v sockets

**Disney Cruise Line**

US two-pin 110v sockets

**Celebrity Cruises**

A 220v Continental Europe two-pin socket and multiple US 110v two-pin sockets.

**Fred. Olsen**

Both US 110v two-pin sockets and Continental Europe 220v two-pin sockets

**MSC Cruises**

Both US 110v two-pin sockets and Continental Europe 220v two-pin sockets

**Norwegian Cruise Line**

US 110v two-pin sockets.

**P&O Cruises**

British 220v  three-pin sockets.

**Princess Cruises**

US 110v two-pin sockets

**Royal Caribbean**

US 110v two-pin sockets

**Carnival**

US 110v two-pin sockets

**Holland America Line**  

Equipped with both standard 110v and 220v outlets

Answer 2

It will depend on the ship. Cunard seems to have one US + one UK plug officially, and if you search around you find some more (by unplugging TV etc.), but they have tons of British customers. Other cruise ships might have US + European.