Peekay, I have just come across your post of Sun Nov 05, 2006 dealing with "West coast Naval defences ". I was very familiar with the area around Loch Fyne during the war, and travelled around it on many occasions. The village of Inveraray was the centre for commando training for Allied forces and at the height of its use had up to 15,000 service personnel in training there. There were many landing craft in use and also, a couple at the most, of ships for carrying landing craft. I saw many thousands of soldiers storming ashore from landing craft on the beaches around Inverary.
The above info is all very well, but it doesn't really have anything to do with your question about "West coast Naval defences ", other than to give an idea of what was available, although the forces here were involved with training, not defending. I might mention that in Campbeltown, at the tip of the Mull of Kintyre, there was also an asdic training school, HMS Nimrod, and a Fleet Air Arm drome at Machrihanish. Again, there were lots of naval personnel in the vicinity of Loch Fyne, but again, more concerned with training than defence.
I see on an earlier post by Apollo that Loch Fyne had an anti-submarine boom defence extending from Otter Ferry to the opposite bank, in the area of Port Ann. I visited Otter Ferry in early 1945 and don't recall seeing a boom defence, but it could well be that it had been discontinued by then or that i just hadn't noticed it. The steamer use to sail round the Kyles to Tarbert from Wemyss Bay, and there was never apparent defences around there... yes, i know, the 'defences' would not be expected to be noticed by the public.
I'd have said there were no naval defences around Loch Fyne; and the only boom I knew of for defence in the Firth of Clyde was the one at the Cloch Lighhouse. I recall small naval patrol boats stationed at Tarbert, and submarines and air-sea rescue launches stationed at Campbeltown. Oh there were AA batteries and at a number of locations around Kintyre, especially around Campbeltown, because of the submarines in use here with the asdic school (Campbeltown was in fact bombed in 1940, and four people killed), but i don't think they are the defences you were asking about. Rothesay was home to the submarine depot ship HMS Cyclops, and she always had a swarm of subs alongside her. There would likely have been AA guns somewhere on Bute.
I would doubt very much that Loch Fyne was ever used as a holding area for convoys. Convoys originating from the Clyde assembled north of the Cloch boom, generally spread all around the Tail o' the Bank... and there were lots of convoys assembled here!
So there's some information for you Peekay, I hope it is of some help to you. Cheers dugald.