The royal national lifeboat institution (rnli) is the largest charity that saves lives at sea around the coasts of the united kingdom, the republic of ireland, the channel islands and the isle of man, as well as on some inland waterways.there are numerous other lifeboat services operating in the same area.. founded in 1824 as the national institution for the preservation of life from shipwreck. Tamar – kit code ms-30 model scale 1:16 length 1000mm displ. approx. 7.5 kg: the tamar class is the result of several years of research and development by the rnli to produce a slipway-launched lifeboat, which is virtually unsinkable.. A rescue lifeboat is a boat rescue craft which is used to attend a vessel in distress, or its survivors, to rescue crew and passengers. it can be hand pulled, sail powered or powered by an engine. lifeboats may be rigid, inflatable or rigid-inflatable combination hulled vessels..