A structure for stabilizing a barrel on a pontoon vessel includes a deck structure. First And second hull frame members are affixed to the deck structure and extend therealong. In spaced relationship to each other. A first and second conduit extends along a respective hull frame member; the first conduit being spaced from the second conduit by a distance to receive a portion of a barrel therebetween and each conduit contacting the barrel above a barrel central line. A strap having a first end anchored near the first conduit, and tracing a path from the anchor beneath, and in contact with, the barrel disposed between the first conduit in the second conduit, along the second conduit, and returning to the first conduit by tracing a path from the second conduit to the first conduit beneath and in contact with the barrel.