Fiberglass Jon Boat W/ Shrouded Drain Plug

[NYBOATER]

Hi Crappie.com,

I'm working on getting a 12' fiberglass Jon boat into the Hudson and in addition to the transom drain plug leaking, I have an additional leaky drain plug on the bottom of the boat inside the middle seat which has a hinged access panel on the top of the seat. Does anyone know what this shrouded drain plug is called? I'm wondering if this is something I can just change the rubber seal on, or should I just use sealant? I have attached a picture of the bottom view.

Thanks