Age limit for Navy in WW1?

[AngelaR]

I've been trying to make sense of a few service records downloaded from the National Archives and am a bit puzzled by this one 

My great uncle joined the Navy in 1915 but gave his date of birth as one year later than it actually was. He would have appeared to be just under 25 years of age, when in fact he was nearly 26.

Was there an upper age limit for joining the Navy at this point? I would have thought it was rather low for that, but can't think of any other reason for lying about his age in that direction.

Can anyone shed light on this for me please?

Thanks

Angela