Hiya,
As already stated 6knt tides and deep water are not common, most of the deep (down to 630') areas I fish tend to only have surface tides (top 50') of less than 1 knt. Even in 300' of water 1knt of tide makes it very difficult to fish with anything less than 2lb of lead.. and that aint fun
I did get caught out once while fishing a mark in 350', the tides decided to not play fair and instead of the expected 1knt of flood tide I was hit with 4knts (on the paddle wheel). It was totally impossible to retrieve the anchor using the Alderney ring and I ended up having to buoy the anchor off with 3 large dhan buoy's which were promptly pulled under by the force of the tide when I cast off the anchor rope. I had to wait another 3 hours before the buoy's surfaced and when they did it was like the scene from Jaws the way they popped up
Because of the size and shape of the boat and some quick thinking I got away with it OK but I wouldn't have liked to have been caught like that on a small boat.
As for precautions, check the charts and make sure the area you want to anchor in is not a Submarine exercise area; these are very common in the deep water areas. Im not sure about the area you are going to be in but up here the Coastguard broadcast the list of live exercise areas along with the weather forecast.
Anchoring wise you will need to at least double the amount of chain you have on the anchor or if you can manage it treble the length. When lowering the anchor you need to slow the rope down or the weight of the chain will sink faster than the anchor and result in a nice big knot
Also always make sure you have easy access to the anchor rope at all times and have a sharp serrated blade knife handy just in case you have to cut the rope.
