I am trying to mount an inboard tank, (tempo 36t, 36 gal, 16" x 9.5" x 69.75"), The instructions say to allow for 3% expansion. To me this means that the tank will expand about 2.5" in length, 1/4" in height and about 1/2" in width. <br /><br />How can this be?? It is a square tank and I don't want it flopping around in the hull.<br /><br />My questions are:<br /><br />What is the best way to secure this tank and still allow for expansion.<br /><br />Also, there seems to be an issue with wear of plastic against fiberglass (I read a study of fuel tank failures on USCG site), what material is recommended as a barrier.<br /><br />This tank is being mounted in the bilge space of a 18' Mitchel. There is plenty of clearance on all sides and I can pretty much make whatever mounting would be required.<br /><br />Any help is greatly appreciated.<br /><br />Trying to get it in the water. Ed