Agggh - flexing side decks

[BritAbroad]

I recently had the standing rigging replaced on my 1977 Catalina 27. The rigging survey suggested that it was original and in need of replacement.

After the replacement, I noticed that the side decks were flexing upwards where the aft lower shroud chain plates attach. This evening I noticed that the deformation has caused the coachtop sides to buckle slightly between the windows.

After seeing this I unwound the tension on the aft lower stays - they are now completely loose.

I also walked around the side decks around the chain plates and noticed several things. The deck creaks when I walk on it. There is very slight movement around the aft lower shroud chain plates. When tapping the area with the handle of a screwdriver, it sounds sharp around the chainplates - but a slightly lower noise from an area further away.

So - with this vague description, am I looking at a disaster?

Is this clear signs of core rot and delamination? Or is it simply an indication of the shrouds being too tight, and that retensioning at a lower tension will cause all to be fine?

If this is delamination, could it be delamination without water intrusion?

Is it fixable without recoring? Can I do the "drill some holes and inject epoxy trick?"

[BritAbroad]

Thinking back, the boat used to creak alarmingly while sailing before we replaced the standing rigging (one of the reasons why we did so). This creaking seemed to start after battling through a nasty force 5-7 headwind for 8 hours in short 3-4foot choppy seas in the Chesapeake back at Easter this year.

[Sailormann]

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I recently had the standing rigging replaced on my 1977 Catalina 27. The rigging survey suggested that it was original and in need of replacement.

After the replacement, I noticed that the side decks were flexing upwards where the aft lower shroud chain plates attach. This evening I noticed that the deformation has caused the coachtop sides to buckle slightly between the windows.

After seeing this I unwound the tension on the aft lower stays - they are now completely loose.

I also walked around the side decks around the chain plates and noticed several things. The deck creaks when I walk on it. There is very slight movement around the aft lower shroud chain plates. When tapping the area with the handle of a screwdriver, it sounds sharp around the chainplates - but a slightly lower noise from an area further away.

So - with this vague description, am I looking at a disaster?

Is this clear signs of core rot and delamination? Or is it simply an indication of the shrouds being too tight, and that retensioning at a lower tension will cause all to be fine?

Changing the tension is not likely to solve the problem. If the sides of the deckhouse (coachtop/cabin/whatever...) are buckling then there is some weakening that has occured.

If this is delamination, could it be delamination without water intrusion?

Certainly, the core and fibreglass may have seperated under the stress without rot having set in.

Is it fixable without recoring? Can I do the "drill some holes and inject epoxy trick?"

The best thing to do is to loosen the chainplate and use a very small screwdriver or some such to dig around in the core. If it's soft, then you'll probably need to recore. If not, then you might be able to drill and fill.

If you do end up drilling and filling, you need to remove the chainplates and anything else that is exerting any kind of force on the deck for quite a wide radius. Allow the boat to return to as near its original shape as it can.

Before you proceed, you'll need to get some very substantial backing plates/brackets. Ideally they will be 15 to 18" long, and shaped so that you are able to attach them to the main bulkhead (inside the boat)as well as the underside of the deck.

You'll need some for the top of the deck, however these can be a bit smaller, just flat plates, ideally about 1/4" or so thick. The holes on the top plates should correspond to the holes in the underplates, as you are going to sandwich the deck between them.

Your deck has been weakened a bit here, so you want to simultaneously strengthen it, and attempt to transfer as much of the stress load to the rest of the boat as possible.

Once you have these (probably custom items) you can proceed to drill and fill with low viscosity epoxy, and then put the plates on top and bottom but DON'T tighten them anymore than is required to get the deck flat and even between them. (Cover the nuts and through bolts with something to prevent the epoxy from adhering to them before you put them through the holes.)

Leave them until the epoxy has cured. Then remove the top plate and drill the hole out a bit bigger than the bolt ONLY in the top layer of fibreglass and the core - not the bottom layer. Close off the bottom of the hole with tape and fill the hole with epoxy. Let it set, and then drill a hole that is sized for the bolt through again. You now have an epoxy seal protecting your core.

If your deckhouse is still warped, try taking out a port and seeing if the core is wet or if it is just loose. If it's wet - you MIGHT be able to dig it out from the existing port hole, but if it's extensive, then you'll probably have to recore. It could also just have separated without rotting, in which case you can pump gobs of epoxy in there and then clamp it into shape while it sets.

NOTE: Cover the inside of your boat while you are working on it. The epoxy can be very messy stuff.

NOTE: If you are going to be using a lot of epoxy, remember that it gets hot as it cures, so you want to avoid filing a large void all at once. Do it in stages. It can get hot enough to damage the fibreglass if you try to do too much too quickly.

Good Luck - let us know what happens...

[BritAbroad]

Great info, thanks. For the drilling and filling, what's best to use for the injecting? Standard small syringe, or something that's able to push epoxy for large distances under pressure?

Should I be using any high density filler in the eopxy, or just use raw stuff?

[Rickm505]

I use a large 4cc syringe. Get them at any Feed store (horses). You need the epoxy to be very thin, almost like water... so it penetrates and saturates your core. I've used the low viscosity epoxy from these guys

http://www.shopmaninc.com/epoxy.html

get the pumps and some paper cups and mixing is a breeze. Remember to buy enough rubbing alcohol at the supermarket to clean up with. In 90 degree temps, you have about 40 minutes of working time. Needs a couple of days to harden completely.

[Rockter]

I may ned to do that one too there Rickm.

The tealk decks have got to be torn up.

I wonder what I will find?

[Rickm505]

I had a cabin leak that seemed too small to be bothersome. Well, in time it got worse until I finally couldn't justify putting off locating and stopping the leak any longer. Of course, by that time the core damage had been done. So... now I'm proficient at epoxy injection.

If I had this to do over again, I would have stopped that leak immediately.

[sailingdog]

Brit-

If the chainplates attach to the bulkhead inside the boat, you'll probably also want to check the bulkhead for any signs of rot.

Sailormann's instructions are pretty good, but when you drill the holes oversized, fill them with THICKENED EPOXY, not the thin, watery stuff you were using initially. This will help them bear the compressive loads of the fasteners, as well as protect the core from water intrusion. I also like to countersink the top of each hole slightly, since it gives the sealant a space to form an o-ring like seal.

[deniseO30]

by the way.. this is a secret.. uncured epoxy can be removed with vineigar.

[NOLAsailing]

If you are merely rebonding the fiberglass skin to good core, then you should be able to drill a few small holes and inject thickened epoxy as described above. However, if you're dealing with an area of saturated core that is greater than 1'x1', removing either the outer or inner skin and properly recoring is the only way to effect a proper repair.

I've tried it both ways - the drill and fill is more of a band-aid than a repair and will make an inevitable repair more difficult. Also be sure to find out where the water is coming from and isolate that area from the core with thickened epoxy.

If it is not the core, then it is some other structural deficiency. I would suspect the bulkheads, particularly if they secure the chainplates. Check the tabbing where the bulkhead is secured to the hull. If there is any damage or deflection, run a fillet of epoxy along the bulkhead/ hull interior joint after grinding away paint, old glass, etc. (get the West System instruction booklet for directions). Overlap several layers of fiberglass along the length of the joint, increasing the width of each layer starting from about four inches and going to perhaps 8 or 10 inches.