Midships Water Tank Vent

[britinusa]

Looks like time to rebed the stanchion (and then I can check out the vent tube at the same time)

[britinusa]

And ... yes, I have already replaced that hose clamp with a non-cutting version. 

[Noah]

Ugly site under there. Yes, IMO it's  time to rebed (with backing plate while your in there) and check others for similar nasty rusty signs of leaking and corrosion. Not fun.

[Roger Rathbun]

Hello Paul
Your picture suggests you may have some rot in the plywood in the deck. I had the same problem with the starboard vented stanchion over the galley. I removed the vented stanchions on both sides in 2012, repaired bad plywood on the starboard side, reinstalled with epoxy'd in aluminum backing plates,  and took lots of pictures. Thought you might like to see some.
The stanchions came off easily but the job grew in complexity when we found we could not gain enough access to the deck underside (stbd side). We removed the galley shelf with the sliding doors. This is quite a hassle but don't give up; it will come out mostly in one piece but it was a pain (left a few scratches). We had removed the teak trim screwed to the vertical 'lip' of the deck 'head liner' which covers the wiring running fore and aft along the hull. Working with mirrors or lying on your back across the galley wasn't working so we gave up and cut out a piece of the lip of the deck liner. This greatly improved access for sanding the underside of the deck and removing any gobs or resin left by the factory. I don't believe this is a structural issue since it's only about three inches from the hull/deck joint. It could be glassed back in if necessary.
These are my pictures with comments. Some of these pics might be in separate posts.

3857:    Galley stanchion and vent tube removed. Teak trim removed. Shelf still in. AC & DC wiring still in. Downward 'lip' of the deck head liner still in tact.

3858:   All the above still in. Looking up through a mirror. Impossible to do the surgery we needed and bond in a plywood and a backing plate. We had already determined some plywood was bad. Not sure how far?

3864:   Close up from below

3866:   Now we're talking!  AC & DC out. Big cut out made in the deck liner 'lip'. Probably did not have to go quite so far aft but be sure to leave the ~3/4 inch piece at the forward end as backing for reinstalling the teak trim. Note the shelf is still in.

0281:   OK- Shelf finally out. Now using this multi tool/saw, we cut through the bottom layer (skin) of the deck sandwich to see how bad the plywood looked.  We cut out the same size chunk of plywood. Go easy, don't cut into the top layer of deck. Not difficult since it's much harder.

0282:   Mush a replacement square of plywood with thickened epoxy (with maybe some micro fibres and some anti sag), brace it firmly with a prop. I don't remember if we epoxy'd back in the the thin piece of bottom skin we had first cut out. Seems hardly necessary.

0283:   Looking down on the deck at the epoxy'd in plywood. Use the end of a match stick take out some of the epoxy from the bolt holes if necessary so you have a good guiding hole for re drilling.

0584:   Plate installed and drilled, holes potted a la Maine Sail, stanchion installed, bedded with Life Caulk. Some Life Caulk squeezed through around the vent tube.

0593:   Port side stanchion over nav station. No plywood was rotten here so access must have been tolerable, even though we did NOT remove the shelf or cut out a piece of the 'lip' of the head liner. Nor did we remove the wiring (much more on port side).This pic shows what working through a mirror is like (the wide bolt holes are outboard). If you are using a mirror, make up a thin spacer (cardboard or real thin ply) to hold mirror in place (white piece at bottom of pic) or else you'll be picking up the mirror repeatedly after it falls down.



My recollection of the exact order of the steps we took to carry out this project is a bit fuzzy (2012) but I think  it was something like this:
After bonding in the plywood and letting it cure, we lathered up the backing plate with epoxy (enough to fill the voids and seal around the outside edge of the plywood, then pushed it up into place ensuring all the deck holes were covered and that it extended out beyond all four edges of the plywood and would bond to some of the original bottom skin of the deck. We again propped up this plate tight in place, making sure it did not slip out of position while applying pressure with the prop. The plate had no holes drilled at this time. The exact size and shape of the plate was previously determined with lots of dry fitting.
After this cured, and with the prop still tightly in place and using the deck holes as guides, we carefully drilled the four bolt holes through the plywood and plate. Use a one inch (I think) hole saw for the vent tube. Pot  and bevel the holes following Maine Sail's excellent instructions:

http://www.pbase.com/mainecruising/sealing_the_deck

I bedded the stanchions with Boat Life Life Caulk. Two years later both stanchions had to be removed again. The port one was bent from a minor accident lifting our engine out and the starboard one leaked a few drops ever so slightly. I rebedded with Butyl  and no leaks so far.

[Roger Rathbun]

The second four pictures. Good luck

[Roger Rathbun]

Opps, forgot pic 0593.

[britinusa]

Thanks Roger,
now I'll have nightmares!

Will report back when I find out how bad it is.

Paul

[Rick Roberts]

I had the same issue, sometime the base of the stanchion get bended/arched from lateral pressure (my new slip neighbors hit the stanchion), broke the seal and water sipped in from the vent hole.

What I would also recommend;
1. Over drill the holes, tape the bottom of holes and refilled them with epoxy.
2. Wait 24h, redrill the holes and bevel the upper end of the hole (~45 degrees).
3. Cleanup with rubbing alcohol or Acetone
4. Generously applied butyl tape on the stanchion base. (make sure the bevel part of the hole get filled with the butyl tape)

Since you over drilled the hole, the epoxy will create a sleeve around the screw. Even if it leaks, it won't leak into your deck but simply inside the cabin and makes it easier to detect earlier. Also, *beveling* the holes will give you a greater amount of sealant around the screws and less opportunity to leak. If some of your core is damaged, just use a Dremel and clean it up. You can also use a drill with allen key as a drill bit, aim for the plywood core, not the fiberglass and while it spins it will take the rotten or wet core out. Clean up and now start with step #1. It will fill the void and give a solid and waterproof repair.

Let me know if you would like to see pictures.

Eric

[KWKloeber]

1. Over drill the holes, tape the bottom of holes and refilled them with epoxy.
2. Wait 24h, redrill the holes and bevel the upper end of the hole (~45 degrees).

Just a comment on above -- I have some time doing this and recently did this with 46 thru-deck fasteners (winches, clutches, organizers, etc.)   It's much stronger to create a captive epoxy plug than just overdrilling and creating a thru-deck plug.  In other words, the top and bottom holes in the fiberglass skins need to remain as small as possible, preferable as close to the fasteners diameter as possible.  Then remove the inside core to create the plug that surrounds the fastener.  You use the method RC shows (5/16" dremel -- which means you need to over drill the 1/4" hole to 5/16",) or keep the hole at 1/4" and use the '90-degree, bent finishing-nail" drill bit technique.

RC's method:  photo from mainesail's site--


versus a straight thru plug (again, RC's photos):



anything is better than just drilling the deck, but a captive plug is the best method. 

JTSO
-kk

[Rick Roberts]

1. Over drill the holes, tape the bottom of holes and refilled them with epoxy.
2. Wait 24h, redrill the holes and bevel the upper end of the hole (~45 degrees).

Just a comment on above -- I have some time doing this and recently did this with 46 thru-deck fasteners (winches, clutches, organizers, etc.)   It's much stronger to create a captive epoxy plug than just overdrilling and creating a thru-deck plug.  In other words, the top and bottom holes in the fiberglass skins need to remain as small as possible, preferable as close to the fasteners diameter as possible.  Then remove the inside core to create the plug that surrounds the fastener.  You use the method RC shows (5/16" dremel -- which means you need to over drill the 1/4" hole to 5/16",) or keep the hole at 1/4" and use the '90-degree, bent finishing-nail" drill bit technique.

RC's method:  photo from mainesail's site--


versus a straight thru plug (again, RC's photos):



anything is better than just drilling the deck, but a captive plug is the best method. 

JTSO
-kk

Well, there is technically less "strong bonding" surface if you do that. If you over drill and after use the "90-degree, bent finishing-nail" drill bit technique. It gives you the best of the 2 worlds, more "strong bonding" surface and bigger distance in between the screw and the core of your deck.

[KWKloeber]

1. Over drill the holes, tape the bottom of holes and refilled them with epoxy.
2. Wait 24h, redrill the holes and bevel the upper end of the hole (~45 degrees).

Just a comment on above -- I have some time doing this and recently did this with 46 thru-deck fasteners (winches, clutches, organizers, etc.)   It's much stronger to create a captive epoxy plug than just overdrilling and creating a thru-deck plug.  In other words, the top and bottom holes in the fiberglass skins need to remain as small as possible, preferable as close to the fasteners diameter as possible.  Then remove the inside core to create the plug that surrounds the fastener.  You use the method RC shows (5/16" dremel -- which means you need to over drill the 1/4" hole to 5/16",) or keep the hole at 1/4" and use the '90-degree, bent finishing-nail" drill bit technique.

anything is better than just drilling the deck, but a captive plug is the best method. 

JTSO
-kk

Well, there is technically less "strong bonding" surface if you do that. If you over drill and after use the "90-degree, bent finishing-nail" drill bit technique. It gives you the best of the 2 worlds, more "strong bonding" surface and bigger distance in between the screw and the core of your deck.

I'll disagree with that from 25-years practical experience doing this because, the "strong bonding surface" in pic #2, is actually replacing/overcoming the fact/needed because, the the skin was compromised in the first place, and are now relying on suspenders so that the plug doesn't pull thru the hole.  It's best to keep as much of the original skins (top/bottom) intact as possible and not rely on the adhesion in shear, and remove more of the core if possible (reasonable so.)  Removing 1/4" - 3/16" of (good) core all around it plenty.  The only reason for overdrilling is to fit the 5/16" dremel reamer bit into the hole (easier than doing the bent nail routine, which fits a 1/4" hole.) Overdrilling considerably further than 5/16" could mean the fastener, etc., no longer covers all the epoxy, or it's more likely to be exposed to UV (degrades the epoxy).  Plus, done correctly the balsa end grain becomes infused with epoxy and is waterproof (I use unthickened LOW-viscosity resin/slower hardener in all holes first, let infuse 10-15 minutes, then suck out remainder, and use it w/ microfibers to refill the holes.  I get a complete infusion into the core/voids, and any other "barrier" (like drilling/filling an 1/8" or 1/4"  larger hole or whatever,) adds no additional water transmission protection but has strength downsides.

That said, YBYC.

-ken

[britinusa]

The method Ken shows has been my norm for quite a while.

When i do this, I will leave top and bottom skin in tact, remove core and fill as shown.

I'm actually about to purchase my 2nd roll of Butyl tape ever.

Will take lots-o-pics.

Paul