Hi Meryll
I think you need to post the sections you need help with. There were a few military prisons, but most sentences were in civil gaols for both the army and navy. A year's imprisonment was a bit long for desertion of a few weeks, unless he had done it before. Although most men would desert wearing their uniform, which was then 'lost', so time would be added for that. the sentence should also be IHL - imprisonment with hard labour. It could be that it was for a civil offence.
18/622 looks like the standard ‘man’s number/ship number’. But I have not found a list of ship’s numbers. The only ship I can find starting Dio appears to be Diomede, which was cancelled (in 1867 as it happens) before construction was started.
‘Glasshouse’ in the army was the guardroom, used for more serious confinement than ‘CB’ – confined to barracks; and longer sentences in gaol. I believe the navy only had the ‘brig’ and gaol. The normal use of the hulks was to hold prisoners awaiting transportation, but they could be used as overspill gaols. My guess is that they tried not to use the hulks for service men, as it may have permanently ruined his health, and the RN would want him back after serving his sentence to complete his length of service.
Ken