Originally Posted by Peter_C
I would prefer one single piece of rope, but tie a good knot and you should be okay.
Better yet, splice a large eye into each line at the connection point and feed one line through the eye of the other then through itself. Can't come apart that way (unless your splices suck.)
How much chain do you have? Also what anchor? I use a Danforth anchor with 4.5 meters of chain.
Chain is IMO more important than the amount of rode you have. Like Pete, I usually put out 2 to 3 times the depth (usually tending towards 2.) The fairly long, heavy chain ensures that the pull on the anchor is largely parallel to the seabed, which prevents the anchor working its way out and dragging.
The 7:1 scope is for large boats overnighting in possible bad weather; the all-encompassing discussions have made it the favorite figure to quote for all boating. For temporary anchorages (which is what you'll be doing while diving), 2:1 (or 3:1) with verification of set (start your dive by going down the anchor line and making sure it's hooked up) should work fine unless there's a lot of wind or swell.
How you deal with the dive flag depends on how they enforce things where you are. Where Pete and I dive (California), the diver down flag has no legal meaning (State law, as I recall suggests that when near a diver down flag to operate with caution), and is not required. Interestingly, though there is no legal requirement to fly a flag while diving, flying one while not diving is a citable offense. Go figure. In other states, as I recall, divers are required to fly a flag on the boat and remain within a radius from the flag (Hawaii; largely ignored, I think), or required to tow a flag while diving (Florida.)
I have both the diver down flag and an Alpha flag on a pole that puts them both well above the radar arch. I do not expect them to keep other boats away (though I keep hoping...)
When dropping your weight belt into the boat, do so at the mid-gunwales. Do NOT do it at the back of the boat, as everyone tends to drop the belt over the tubes behind the transom, and on to the bottom of the ocean. I've recovered one person's belt 3 times because of this (Pete: Won't mention names, but sounds a lot like "Carol".)
Other than what Pete wrote, a VHF and cell phone (assuming you have reception) in case of emergency, and you should be good to go.
And on the number, the most I got in my 14' Achilles was myself and 5 other divers. Worked, but we weren't going anywhere in a hurry. Realistically, myself and 3 was about the limit (could still get on plane, and had barely enough room to kit up and such.)
Luck and be safe;