Is there a plumber in the house?

[rjrendemd]

I have been tracking down the source of a persistent odor since aquiring my new but slightly used boat. I even went so far as to retrofit my heads to fresh water and I checked all the hose connections for leaks. On a recent gulf stream crossing I found the source. I seldom use the black water tanks but I noticed bubbles coming from the edge of the inspection ports on the top of my holding tank after getting shaken up a bit. It seems that the flange of the inspection port was screwed down but not sealed. The tank is fiberglass and the port itself is plastic. What compound should I use to seal it? 5200 seems so permanent.

[sarafina]

Funny you should ask, we DO, and her name is Peggy! There will be others who have suggestions as well, I am sure, but Peggy is the Head Honcho around here ; -D

[wsmurdoch]

If they are Beckson deckplates.

Deck Plate Installation by Beckson

[peghall]

Actually, I can improve slightly on Beckson's instructions: instead of using any sealant under the flange, make a rubber gasket. It seals better and lasts a lot longer. Rubber gasket material is available from any decent hardware store.

5200 has no place on a boat IMO.

[HopCar]

I think I would use Life Seal. It bonds much better than silicone and it won't hurt plastic. BoatLife LifeSeal Clear Tube - 1160

[sailorchic34]

Bubbles around your access fitting may be caused by a clogged or blocked tank vent connection. If the vent is open there should not be any pressure in the tank. That you see bubbles would a good indication that the vent is blocked. You'll want to check and fix that too. As to sealants, Either 4200 or Lifecaulk, or any good caulk will work there..

[rjrendemd]

Thanks for the advice. I checked the vent as a first step and it was clear. Life Seal seems to be a good choice. It appears to be a hybrid of silicon and polyurethane that adheres but not "too well."

[Charlie]

Originally Posted by sailorchic34

Bubbles around your access fitting may be caused by a clogged or blocked tank vent connection. If the vent is open there should not be any pressure in the tank. That you see bubbles would a good indication that the vent is blocked. You'll want to check and fix that too. As to sealants, Either 4200 or Lifecaulk, or any good caulk will work there..

+1 for Sailorchic's comment. If there are bubbles then the tank must be unable to vent its gases.

[Nicholson58]

I agree regarding a rubber gasket. Any port you expect to have to get open again should be sealed with that in mind. You can buy sheet gasket material from McMaster Carr on line in any material or durometer you can think of from cork to viton. Chemical characteristics are noted as well. You should have an ample supply of sheet on board anyway. Consider also owning a gasket punch or die set. Buy various sealer compounds at any automotive or hardware store. For water service, Silicones are great sealers and not permanent.

[MacG]

The rubbar gasket is IMHO the best solution. If you need to open the inspection lid again you don' t have to apply new sealant.

[hellosailor]

rj, if you use butyl tape, or get butyl rope or similar "rope" sealante from an auto glazing supplier, it conforms very well but never forms a permanent seal, so it can always be scraped off when you want to remove it.

[muskoka]

Rubber gasket. Look at all your inspection plates, deck fillers, hatches, etc. And they're all sealed with rubber gaskets or O-rings for a good reason. Rubber is used to seal against fuel, water, waste, etc. and will remain effective for years.

Rubber sheeting is readily available in a variety of thicknesses and O-rings come in varying thicknesses and diameters.

[peghall]

The gasket goes under the flange...to create a seal between it and the tank, It'll seal around the screws just fine. The cap should have an o-ring,