Here is a how I made a new gas bottle locker that is gas-tight with a drain out through the hull. I used the Boat Safety Scheme Part 7 technical literature and other info mined via the Web in order to set it out.
This is the connecting pipe where is goes from flexible hose to copper before vanishing through the bulkhead on its way to the stove. There was not one clip along its entire length and too many joints.
I decided to make a gas-tight box and install it in the same locker with a drain out through the yacht's side. Here I am deciding which plank to put the skin-fitting in.
A box was made to fit the space to carry the 4.5kg bottle out of 9mm marine plywood.
Trying the box for size - there was just enough room for it to stand in the base of the cockpit locker and for the lid to go over it - just!
The regulator wouldn't fit but a little modification gave a space for the flexible rubber hose to run.
The box was completely sheathed with GRP and painted. Here it is with the hose taken through a protective sleeve in the side of the box. In the base of the box is an in-fill to keep the bottle central. Still to be fitted is a webbing strap and clip to hold the bottle down.
This picture shows the drain from the bottom of the locker. It is a requirement to have a minimum of 19mm internal diameter on the drain hose and fittings so I used 3/4" fittings. A 'fall' is needed all the way from the box to the outside air and this was a fiddle to achieve...
As can be seen in this picture as water is caught in a low point of the pipe. A clip now holds this up to continue the downward 'fall' of the drain pipe. The seacock is shown closed in this picture. We close it when sailing as water fills the locker as the boat heels, leaving it open when she is moored un-occupied.
Here is the drain outlet - just above the normal water line. I was not keen on having to bore another hole in the yacht's hull but such is the price of safety regs compliance..
A new copper gas pipe was run in one run, clipped with non-corrosive rubber lined P-Clips to a batten fastened to the hull. The flexible rubber tubing lengths were kept to a minimum length and the whole of the gas pipe line is visible for inspection.
I fitted a shut-off valve adjacent to the stove. A looped length of flexible rubber hose allows the gimballed stove to move.
The main problem I had with the installation was buying tubing and fittings. It was possible to buy BSP fittings, but only for metric tube, its seemed, and then impossible to find a source of metric copper tube in reasonable lengths. In the end I used 5/16" tube bought from one supplier and fittings from a couple of others including our local Chandler's - this took more time than actually doing the job!