A ship's tender, usually referred to as a tender, is a boat used to service a ship, generally by transporting people and/or supplies to and from shore or another ship. Smaller boats may also have tenders, usually called dinghies.
For a variety of reasons, it is not always advisable to try to tie a ship up at a dock; the weather or the sea might be rough, the time might be short, or the ship too large to fit. In such cases tenders provide the link from ship to shore, and may have a very busy schedule of back-and-forth trips while the ship is in port.
On cruise ships, lifeboat tenders do double duty, serving as tenders in day-to-day activities, but fully equipped to act as lifeboats in an emergency. They are generally carried on davits just above the promenade deck, and may at first glance appear to be regular lifeboats; but they are usually larger and better-equipped. Current lifeboat tender designs favor catamaran models, since they are less likely to roll in the calm to moderate conditions in which tenders are usually used. They typically carry up to 100 to 150 passengers and two to three crew members.
Before submarines and destroyers "grew up" during the Second World War, they were heavily dependent upon tenders to perform most maintenance. Their hull classification symbols in the US Navy were, respectively, AS and AD. All of the destroyer tenders have been scrapped, the last two submarine tenders are the ships of the Emory S. Land class. Emory S. Land and her sisters are forward deployed in the Pacific Ocean and Mediterranian Sea regions to support US naval interests in those regions.
Two tenders, SS Nomadic and SS Traffic, were built for the White Star Line by Harland and Wolff to serve the liners RMS Olympic and RMS Titanic at Cherbourg. Nomadic survives as a museum ship, and is the last remaining vessel built for the White Star Line still afloat.