I know it's a daft question, but the subject line asks it: How old did you have to be to join the Royal Navy in 1866?
Thanks for your help.

The minimum age for entry for a rating was established in 1843 as 14; "No boy is under any circumstance to be entered under the age of 14..."

Boys as young as 12 could be accepted as a Naval Cadet at one of the naval colleges, such as Osborne; however he would not go to sea until he was 15 or so.

OK, thanks. This is related to family history research. I've come across an ancestor who apparently joined the Navy at 17 (in 1866) but cheated on his year of birth to pass himself off as 18. Was there an interest to do so? - Going to sea quicker, better pay?
Thanks again.

I would suggest pay - in the 1860s a Boy 2nd class (on initial entry) was paid 15 shillings and sixpence a month; after one year he would be made 1st class and pay would be 18 shillings.

At 18 he would be entered as an Ordinary Seaman, and pay would be £1 18s. 9d per month

Seems like a good enough reason to me.
Thanks for your help.