Inspection plate aft fresh water tank

[ken emigh]

1996 Carver 380
The aft water tank is leaking and it appears it is at the inspection plate cover. Because of its location I used an inspection mirror and did not see a crack around or near the inspection plate. The plate cover appears to be a screw type however it won't turn at least not by hand. It looks to be sealed? The cover has vertical nubs on the edge, is there a spanner wrench for these plates? Or can I just use more sealant around the plate? What type of sealant would work,5200?

Thanks in advance.

 

[RamSport47]

There is an o-ring around that "nubbed" cap. I've always been able to open them with large channel locks.

 

[ken emigh]

Will give that a try in spring as boat has been stored for winter.

Thanks

 

[Carvervirgin]

An open end oil filter wrench works well for that job.