Re: Boat ?
The plug for my boat is not accessible from the inside without removing the floor and then snaking your hand around the gas tank. I suppose you could take a sawzall to the raised deck and get at it that way, but it's a bit hard on the back of the boat! Been plugging it from the outside and never had a problem. That's kind of why the plug is screwable, so you can adjust the width so it stays snug when in position. It's also why the boat has a bilge pump.
I keep the plug inside in my Gheenoe in Florida. There's no raised floor in that boat, so the plug is directly accessible. Nice to be able to pull it and drain the boat when it's on plane.
Anyway, it works both ways.