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I have an inspection port/light mounted in the cockpit sole just aft of the helm. Over the last few months I've noticed that the cockpit sole in that area has become spongy. I've looked on the Internet for articles advising how to repair this area, but I can only find instructions on replacing the entire cockpit sole (not required, thank you).

I seem to remember from past readings a procedure as outlined below:

1 - Remove light, mine is about 4 inches in diameter.

2 - Using a nail bent at a 90° angle and placed in an electric drill, run it along the outside diameter of the hole to remove what I suspect to be rotting balsa core.

3 - Construct a floor from underneath probably made of heavy cardboard larger than the existing hole.

4 - Fill the void between the two layers of existing fiberglass that was created by removing the rotted wood.

5 - Allow the filler to set up, and replace the light.

Does this sound like the proper procedure? If not, what would you recommend? What is a good way to fill the void so as to assure all the open spaces are filled? What product would you recommend to use as filler? Do you think Bondo which is locally available would be suitable for this purpose?

Thanks in advance.
 

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Sailor
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That sounds about right except I wouldn't use Bondo. Particularly because it is the sole in the cockpit which would be susceptible to stresses and water, I would use a marine grade epoxy filler. Marine-tex would be suitable.

Tod
 

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How large an area are you dealing with? I had about a square foot to repair and replaced the rotted core with Marine ply for strength. Other products are available but the plywood is what I had on hand. Coat everything with epoxy and then glass over the patch.
 

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Barquito
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One small additional step: Try to wet-out the void with unthickened epoxy before filling with the thickened epoxy. That will prevent the core material from wicking the epoxy out of the thickener. Not sure how you would do this with a big hole. Maybe form a dam with tape, pour the epoxy in, then let it drain.
 

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If you want to know the extent of the rotted core, you can drill holes into the core, at various distances from the edge of the hole. Doing it from underneath would be neater if you can. I just did this around a cleat that had been leaking. The transition from soft, dark, core to light, dry, sound core is obvious.

The next step is to remove rotted core. There might also be damp, but not yet rotted core, which your pilot holes will help to dry out.

I have the cleat re-installed with new bedding, but the pilot holes are still there and will not be filled for a year, to make sure the core around the cleat is dry.

The proper way to repair is to replace the rotted core with new. To do this you have to cut away either the inside, or outside, layer of fibreglass.

The slightly less proper way is to remove the rotted core from the edge with a knife or improvised tool, then fill the void with epoxy.

Either way, you need to get the damp but not rotted core dry before you go further.

You can get a fairly good idea of the extent of rotted core, by the sponginess you have noticed. The part that feels spongy has rotted and needs repair. I suspect this extends quite far, just from the fact you've noticed sponginess.

MarineTex is NOT suitable. It doesn't flow. It is best for small repairs of drill holes etc. What you need is quality marine epoxy like West System.
 

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Broad Reachin'
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Sounds like you're on the right track. In any case, here's an excerpt from Don Casey about installing a new deck hatch, but with a similar procedure which might be helpful:

Seal
When you make a cutout in the deck, you nearly always expose the core material--either wood or foam. Because water finding its way into the core has such disastrous consequences, it is imperative to properly seal this raw edge. The bedding under the flange of the hatch is not adequate.

Dig out a half inch or more of the core material all around the cutout, then sand the interior surface of both skins. Saturate the exposed core with unthickened epoxy. Thicken the remaining epoxy to peanut butter consistency with fibers or silica and fill the gap all around the cutout. When the epoxy cures, the core edge is permanently protected.

Fair
Lay a straightedge across the deck just beyond the cutout to assess curvature. If the deck is not perfectly flat, you will need to fabricate a spacer that matches the deck curvature on the bottom and is flat on the top, or you will need to build up the deck around the cutout with epoxy paste or fiberglass laminates. Grinding down the crown is almost never an option because it further weakens a deck already insulted by the cutout.

Normally a hatch's metal frame provides adequate reinforcement to compensate for the weakening effect of the cutout, but in the case of large hatch, especially one mounted in close proximity to other holes through the deck, some additional reinforcement may be advisable. This usually involves structurally framing the hole, either with wood or with additional laminates of fiberglass.

Bed
Dry-fit the hatch in the cutout and drill the pilot holes for the screws. Mask the deck all around the perimeter of the hatch with Long Mask--the blue masking tape. Mask also the flange. You can let the tape stand vertical; its purpose is to keep sealant squeeze-out off the frame. Remove the hatch and completely coat the deck between the tape and the cutout with sealant. Use polysulfide if the hatch frame is metal. For plastic hatch and deck plate frames, you will need to use silicone, or a silicone/polyurethane blend (Life Seal).

Install
Put the hatch back over the cutout and wiggle it gently to distribute the sealant. Insert the screws and snug them all. Now tighten them, following a pattern of the next screw in sequence being as opposite as possible, i.e. right side, left side, front right, rear left, etc. Do not overtighten the screws or you will squeeze out all the sealant and the resulting metal to fiberglass joint will soon leak.

Finish
Let the sealant cure for two or three days, then trace a razor knife around the perimeter of the hatch frame to separate the squeeze-out from the sealant under the frame. Peel up the tape from the deck and the excess sealant will come with it. Remove the tape
 

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Freedom isn't free
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I have a much larger area I am working on presently than that which you describe. Of note, the port seat was only "spongy" for the last 4 inches or so near the traveler... larger inspection showed much more extensive water penetration than that... If you look at this picture the right 8-10 inches has dry core...

I'm slowly rebuilding this whole section from the bottom up... I cut out the square, removed the bad core... washed it with acetone... laid down laminating resin, put in wetted end grain balsa coring... then started to lay up chopped strand mat....

I've not been back to work on it in a few weeks... I figure I have about 4 more layers to do, making a total of 6 layers of CSM... then I'll be fairing and gelcoating. Not sure if this is the "right" way or not... but so far it's stronger than all heck.

This is how it looks right now... I've not had any "warmer" days to work on it... I figure I'll layup the next 3-4 layers all at once... as the laminating resin dries to a tacky level pretty quick... I'll know I am where I need to be when the level of the build-up is nearly up to the existing gelcoat.


Good luck with your repair... take your time, plan on repairing more than you can "see."
 

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I worry for you. Although the inspection port is only 4 inches in diameter, if you can feel the sole being soft it indicates the rot - as it almost certainly is - has spread wider. Maybe far wider. The bent nail trick works on a fresh-drilled hole, but think how far in you will excavate- maybe 1/2? I bet the "spongy" feel spreads wider than that.

MarkSF has it right. You may also be able to get a feel of the size by tapping, and listening for a tonal difference ("hollow" tap vs. solid)

What to do next will depend on a complete repair of a quick fix (which will last a few years). Temporary fix: Firstly, the core needs to be dry, or epoxy won't adhere. When totally dry, pull out rot until you reach solid wood. Saturate the entire area with epoxy - let it soak up as much as possible, so the remaining wood/rot is fully saturated - perhaps close the hole from below, fill with slow-cure epoxy, wait for it to soak in, then remove what is left, thicken, and use to fill the voids. Penetrate then fill. It should set up solid, and if you are lucky it may stabilise the rot.

The correct way is to follow MarkSFs instructions. Shnool's pics will give you some idea of the work.

Rot spreads - water (as I am sure you know) creeps in everywhere. Good luck - I hope the rot has not spread as much as I fear.
 

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Old enough to know better
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Yes, the instructions to use the nail is what should have been done when it was first installed the port, not now. You can try to pick out what is rotted, but I agree that if you can feel the "sponginess" then it is going to be deeper than you can reach with a knife or chisel. Do you know what the material of the core is? If it is balsa you may be able to get away with either drilling and filling holes but it is likely plywood as this is a high stress area as it is constantly walked on. If it is plywood you are in trouble as it wicks the moisture between the layers and likely the whole thing is at least wet if not rotted. The other thing to keep in mind is that any hacks like the drill and fill methods are very hard to undo once the time comes to do the repair correctly. Lots of people recommend drilling lots of holes and even go so far as to fill a grease gun with resin/filler mix and inject it under pressure till it comes out the surrounding holes. Every time I read this I cringe, as I think wow that is going to be a mess to clean up and fix properly some day.
 
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