Agree with John...
I think John has the right method, if you're able to work your way into that space from that angle. Otherwise, you may be able to pass the tank out through the starboard lazarette opening, once you get it out from under the ice box. The previous owner of my H25 replaced the original flexible water tank with a 25 Gallon bladder, and put it in the same location that the old tank came out of. To do so, he apparently used a jigsaw and cut a 30-inch wide section out of the lazarette wall, just to the left of the water fill port. Makes it easy to get to the bilge, but storing anything in the lazarette is a challenge! If you'd like to see pictures, e-mail me at jonbastien@yahoo.com- I'll shoot a few for you next time I go to the boat.--Jon BastienH23/H25