when did he join the above mentioned navy?
25 August 1803.
William Hobson
Hobson joined the Royal Navy on 25 August 1803 as a second-class volunteer. 
who wrote the english version of the treaty of waitangi William Hobson, with the help of his secretary James Freeman and the British Resident James Busby. when was this treaty first signed? 6 February 1840. and by whom? Representatives of the British Crown and Māori chiefs from the North Island of New Zealand. what is its importance? It established a British Governor of New Zealand and gave the Māori the rights of British subjects. what are the principles of this treaty? One of the principles deals with  the exchange of sovereignty by the Māori people for the protection of the Crown. the person who wrote the english version of the above mentioned treaty, who was he? A British Royal Navy officer and the first Governor of New Zealand. where was he born? In Waterford, Ireland.
wiki:13527465
William Hobson [SEP] Early life
William Hobson was born in Waterford, Ireland, the son of Samuel Hobson, a barrister. He grew up in an Anglo-Irish Anglican family. Hobson joined the Royal Navy on 25 August 1803 as a second-class volunteer. He served in the Napoleonic wars and was later involved in the suppression of piracy in the Caribbean. He became a midshipman in 1806 and some seven years later was a first lieutenant. Between March 1823 and May 1824 he commanded the schooner , in which he captured several pirate vessels, earning himself the nickname "Lion Hobson". He was promoted to commander on 18 March 1824 and commanded between 1826 and 1828.