Thru-Cockpit Seat hole

The starboard cockpit seat has a 1 1/4" hole to allow the gas line through into the cabin. The gas tank is fastened down and secure under the starboard quarter birth. This hole is very large and contributes largely to the volume of bilge water after a rain. My solution here was to use a rubber stopper that I found while browsing the isles of Active Surplus in Toronto. The stopper already came with a centre hole and I was thinking that for a dollar, it might be a good solution to this problem.

The centre hole of the rubber stopper was undersized so I continued to drill out the center hole to the size of the gas line hose (9/16). I also have a GPS cable that shares this entry point into the cabin so I drilled a second buddy hole through the rubber stopper about 3/8".

The second part of this equation was to build a backing plate that would hold the stopper in place. I didn't want someone bumping into it while underway and knocking it out. The backing plate is made from a small piece of aluminium that is hidden on the inside portion of the hole.

Top view.
The aluminium backing plate was added to this solution. A 9/16 hole down the middle of the stopper and backing plate was drilled. 2 SS screws hold the plate into the rubber.

Side View. The stopper was 1 1/2" wide, and the hole is 1 5/16", so I add more taper to the stopper.

Cost of solution was 1$