Camelotwenz on Family Tree Circles

I have been unable to find any death records for my great, great grandfather Thomas McLean who was the first of our line to arrive in New Zealand. I don't have any information of his arrival, only his marriage to Mary Brynn in Thames, New Zealand in May 1876. Thomas was a mariner and the info I have is that he was "lost at sea", in 1877, the year after my great grandfather Thomas William was born (1876 - 1946), but I have been unable to find anything to support this. I'm a complete novice when it comes to genealogy and I'm not sure where to go next to find any more info. I would be very grateful for any help in pointing me in the right direction. Many thanks.