Discovered water in Saildrive this morning. Assuming it's the seal, although I hope the casing is not breached. https://drive.google.com/open?id=0B7GvyOr-FTQYOUg2VUx4dDZzMUk
Bugger. Don't panic, if you haven't used it much with the water in there and it still has oil to provide some lubrication it might be a simple seal replacement. I don't have much experience with saildrives (none) but I assume they are pretty robust.
Yes, hope your right about it being a seal.
I hope it does'nt have anything to do with the fact that a diver cleaned the running gear on Friday.
Check for traces of oil in the water around the boat too. I'd keep it topped up to keep the water out if that would work, and get it slipped somewhere so you can check it properly.
The saildrive boot came loose and I removed it some months back. I wonder whether that has put more pressure on the seal. The boot is not meant to be water tight so I don't see why not having one would cause the issue.
Discovered cause of leak, it was the less of the three evils, a failed seal around prop shaft due to fishing line. Saildrive was full of water when we drained it, with just a little oil left, luckily I have not run it since I first discovered issue. I filled it three times with diesel and flushed it and have left overnight full to the brim with oil. Will drain that oil tomorrow and then finally refill it. Hope it is ok.
I'm no saildrive expert but FWIW, oil and diesel will only dislodge water as they don't mix, right, so wouldn't metho which does mix with water and then evaporate be more suitable? As I said.... Just thinking?
Also, you've probably already done this but can you put it in neutral while the oil or whatever is in there and turn it by hand to dislodge any trapped water?
As I said I m no expert so ignore this if I'm wrong. 
Both the diesel and oil have detergents added to absorb water....this is the milky white substance when you get water in oil.
if when the last oil flush has lots of milky deposits, maybe it needs another go.....
Good to see you found the issue.
Hopefully its easily sorted.
I live in fear of fishing line around the prop.
Some way irrationally. ...so its good to have some support for when I go crazy about lines around the prop and carried on like a crazy freak making sure it is always completely cleared.
P.s 30 years out those seals...wow
