No sealant is necessary.
The front handles (and maybe the side handles) are through bolted with stainless steel hardware and washers with neoprene/rubber attached to the back. The rear (and maybe side) handles are bolted with well nuts, again no sealant and no awkwardness with trying reach through a hatch to get the nut & washer back on.
"Water is life's matter and matrix, mother and medium. There is no life without water." -Albert Szent-Gyorgyi
"No man ever steps in the same river twice, for it's not the same river and he's not the same man." - Heraclitus