saw it go straight into her arm . In the UK you have no idea what happens with your blood , '' she added . The `` Africa Mercy , '' currently docked off the coast of Benin , West Africa , also operates as a floating hospital with medical facilities including six state-of-the-art operating theaters , an ophthalmic unit , two CT scanners and 78 hospital beds onboard . The Mercy Ships charity began in 1978 and since then has been credited with providing medical services valued at $ 748 million , performing more than 41,000 operations and impacting approximately two million people . Mercy Ships CEO Samuel Smith says the charity has been able to help so many people through what he calls a `` unique business model . '' Thousands of volunteers join the ship every year , and they not only do it for free but also have to pay for accommodation aboard the vessels ; some like Herbert , pay around $ 600 a month . See more images of volunteers onboard the ship '' `` This allows almost all our resources to go into state-of-the-art medical facilities , '' Smith told CNN . It
LONDON , England -LRB- CNN -RRB- -- Ali Herbert has spent the last seven months being `` a walking blood bank '' aboard one of the the world 's largest hospital ships . Thousands of volunteers join the massive hospital ship `` Africa Mercy '' every year . The 50-year-old nurse and grandmother from the UK resigned from her position in a hospital to volunteer aboard a ship that provides free medical treatment to some of the world 's poorest people . Like any of the 450 volunteer crew members currently aboard the Africa Mercy , Herbert can be called on at any time of the day to give blood , as the ship has no facilities for storing blood products . Instead the ship operates a system where there are usually 30 donors for each blood type . Herbert says she recently helped a young woman who needed an amputation . `` This young woman required a below-the-knee amputation , but was very weak so I was called in to give her blood as our blood groups matched , '' she told CNN . `` It was an amazing experience because two minutes after giving my blood , I