putting larger metal washers on CB pivot bolt

I have identified at least one source of my bilge water - the pivot bolt leaks on both sides. I left the access ports open and let the boat get really dry in the Nevada sun, and then when we launched in Pyramid lake I stuck my hand down there real quick, before everything got wet, and sure enough there was leakage. About a gallon in three hours on the water.
So I ordered two new rubber washers and they arrived today. Some previous owner used silicone between the rubber washers and the cb trunk, but I don't really want to go that route. Shouldn't the washers do the job by themselves?
The metal washers on the pivot bolt are smaller than the rubber washers. Does anyone know whether washers of the same size make a better seal? Seems a shame to let all that rubber go to waste around the edges.
Gabe
So I ordered two new rubber washers and they arrived today. Some previous owner used silicone between the rubber washers and the cb trunk, but I don't really want to go that route. Shouldn't the washers do the job by themselves?
The metal washers on the pivot bolt are smaller than the rubber washers. Does anyone know whether washers of the same size make a better seal? Seems a shame to let all that rubber go to waste around the edges.
Gabe