Fitting to convert 2" fuel tank screw cap to 2" filler hose?

[ReedMikel]

Hi,
Just bought a small used 4-stroke 30hp pontoon boat. It came with a 6 gallon portable type gas tank strap-mounted to rear of boat (exposed to elements). I have a brand new low permeation 12 gal tank that has a typical screw off cap (with built in vent). I'd like to install this new tank inside a rear compartment. Already bought a stainless steel outside filler and gooseneck filler hose. But I need to convert that screw cap (2" dia threads) to one that would allow me to clamp on a standard filler neck hose (hose is 2" ID). Does such a fitting exist? I searched Amazon, but didn't find anything - probably because I don't know what it's called

TIA,
-Mike

 

[Chris1956]

That 12 Gal tank is likely not rated to be installed inside a compartment. It would need a permanent vent fitting to a thru-hull vent. Has it got one?

 

[ReedMikel]

You're right - on the 12 gal portable tank the vent is part of the cap and needs to be manually opened/closed. So, I decided to purchase a Moeller 14 gal permanent style tank with vent, sender and 1.5" fill inlet. Also ordered a plastic fill cap to mount on exterior (which has a vent connection).