Bulkhead tabbing repair - seeking advice

[preserved_killick]

The first bulkhead in the saloon in my Alberg 30 has separated tabbing.

Images can be seen here:
http://picasaweb.google.com/fongemie/BulkheadTabbing

I've been thinking about the best way to approach this.

One option, I may try is to go in with a knife and something to pry with and see if I can just cut & pry the old tape off, and use the resulting well to fill with new tape & epoxy. I have doubts about this, that I won't get much of a cavity to fill.

Second, I wonder if I could leave the existing tape there, drill some holes and inject some slightly thickened epoxy under it. From there, I'd need to drill clean through in a couple spots and through-bolt with washers to temporarily put some pressure on the tape. Later, remove the bolts and perhaps add one more layer of tape over the whole seam. I question whether I can close up any gaps after I add the epoxy. There's nothing nearby to push against to apply pressure. The through-bolting sounds questionable.

Lastly, I'm thinking the real answer is to cut-grind all the old tape off, get a clean surface and just re tape the whole thing.

I've got a pretty bit list of projects going on, so I don't want this to consume all my attention for too long, but then I won't be happy if it fails again real soon, or looks like crap.

For taping, with mat or without? I've seen opinions both ways on this. Is the technique of 3" then 4" then 6" tape the way to go, or I've read where 4" tape alone can be staggered.

Any suggestions or advice? I'm open for anything.


-Jeff

[bcooke]

I can't quite see in the photos but is the tabbing failing all over or just at the edges?

Maybe attach some nice wood trim along those edges and call it good.


If it is truly failing then grind off and replace is definitely the way to go.

I don't think injecting new epoxy underneath would not be nearly as strong a bond as real tabbing.



I love biax tape for this kind of stuff. And you can get it in 90 yard rolls too! (photo from jamestown distributors)

[kristian]

Just had the same problem on our Shields' hull/deck joint. Was faced with an extremely unattractive prospect of grinding it all off in a tight space. Instead I broke down and bought a fein multimaster, which made a long dirty job fast and easy (like 4 hours) The tool has a flat saw blade that seems made for liberating bad tabbing.

http://shields88.blogspot.com/2008/03/s ... ate-2.html

[David VanDenburgh]

I have this same thing happening in my Alberg 30. Although I haven't addressed the issue yet, my plan is to gently lift the loose edges, squeeze some epoxy in there, then, as Britton suggested, trim the areas with wood. If there were extensive lifting, then I suppose I'd remove the old, ineffective tabbing and replace with new material.

During removal of two other bulkheads, however, I discovered just how little material it takes to maintain a tenacious grip on the bulkhead.

David

[preserved_killick]

Thanks guys. I went and poked-pushed today, and I think the issue is just the edges, and the bulkhead seems to be attached still.

I'm about to sand and paint so I'm not sure what to do. Hide the lifting edges with wood trim? I'd need to see it done well..not sure I can picture it looking ok. Wouldn't it just look like you are hiding something?

We have lots of flaking paint in the cabin so since I'm going in to make a mess, I'm leaning towards grinding it off and doing it right.

-jeff

[David]

The first bulkhead in the saloon in my Alberg 30 has separated tabbing.

Images can be seen here:
http://picasaweb.google.com/fongemie/BulkheadTabbing

I've been thinking about the best way to approach this.

One option, I may try is to go in with a knife and something to pry with and see if I can just cut & pry the old tape off, and use the resulting well to fill with new tape & epoxy. I have doubts about this, that I won't get much of a cavity to fill.

Second, I wonder if I could leave the existing tape there, drill some holes and inject some slightly thickened epoxy under it. From there, I'd need to drill clean through in a couple spots and through-bolt with washers to temporarily put some pressure on the tape. Later, remove the bolts and perhaps add one more layer of tape over the whole seam. I question whether I can close up any gaps after I add the epoxy. There's nothing nearby to push against to apply pressure. The through-bolting sounds questionable.

Lastly, I'm thinking the real answer is to cut-grind all the old tape off, get a clean surface and just re tape the whole thing.

I've got a pretty bit list of projects going on, so I don't want this to consume all my attention for too long, but then I won't be happy if it fails again real soon, or looks like crap.

For taping, with mat or without? I've seen opinions both ways on this. Is the technique of 3" then 4" then 6" tape the way to go, or I've read where 4" tape alone can be staggered.

Any suggestions or advice? I'm open for anything.


-Jeff

When you reglue it, consider running some sheetmetal screws into the tabbing to reinfoce it.

[Rachel]

Actually, wooden trim at the bulkhead/coachroof joint is a classic look. I think it looks especially nice when it's varnished wood on a white bulkhead. These aren't the best photos, but they give you the idea:

Oh say Britton, I just noticed the cutout in this first one:







This one's "wood on wood," but it gives an overall view:

[Tim]

If the tabbing's truly loose, the only real way to address it is to remove and replace with new, particularly on a significant structural member. Not all bulkheads are structural, and the importance of tabbing varies from situation to situation.

But in many cases, it's only the edge that seems loose, with the bulk of the material still well-bonded. Sloppy original glasswork leads to this issue as often as not. Since epoxy, when thickened properly, is a strong gap-filling adhesive, you can resecure a partially loose edge with minimal effort. Assuming your tabbing is actually still really holding the bulkhead, then you're only relying on the epoxy to hold the "loose" area against any future movement or worsening. If you need more than that, probably you have tabbing that should be removed and retabbed properly.

Your Picasa site isn't loading for me this morning, so I haven't seen your pictures and can't comment specifically on your situation. There's "loose", and then there's loose. Debonded tabbing will be easy to pull away by hand, "loose" tabbing generally is well bonded except at the very edge, which looks worse than it is. It's usually quite straightforward to tell apart these conditions.

Little loose edges on tabbing often look worse, to the uninitiated, than the situation really is. If you doubt the bonding quality, then use a chisel or other prying device to gently pry away from the gap. If it's well-secured and solid, you'll know promptly; if it's loose, you'll also know promptly. Anything you can pry away by hand isn't strong enough. Don't waste your time grinding and cutting off good tabbing, but if the tabbing's not good, then by all means cut it away, properly prep the area, and install new tabbing.

[Quetzalsailor]

I'd for sure bet that tabbing is intended to be seriously structural. It's what holds the deck down, not just locating the bulkhead. By comparison with a Morgan 27, it's far less wide onto the plywood. By comparison with our NE 38, it's about the same width. Both these boats suffered failed tabbing to some extent, and only at the center-most bottom ends nearest the maststep. I opted to ignore the problem on the Morgan because I wired the shrouds down to the hull (reducing the flexure of the boat) and because there was no room to work to replace the tabbing. I have taken to rebonding the tabbing in the NE 38 with epoxy as a provisional repair; I want to see whether the bond was simply inadequate in a few places or whether wholesale repair is in order. Generally, I think the NE 38 is a little too lightly tabbed, so wholesale repair will be quite an undertaking!

Adding trim to conceal tabbing is all very nice and good looking. As in the previously submitted photos, they're also lovely in the NE 38 (and really trashy in the Morgan). Of course, it's better when the tabbing is capable of work.

[preserved_killick]

Thanks everyone.

We've got everything out and are about ready to begin some heavy sanding. It looks like some latex paint that didn't stick to super-gloss pink enamel. Tim I'll do as you advise, and try to pry some back to gauge if it is still bonded.

As much as I hate to add something else to do, I'll likely redo it all if I see anything suspicious. We're going to make a mess anyway.

The wood trim does look good. Thanks Rachel. I like the look, but I don't think it would save me any time or effort as I'm fussy with my trim work.

I'll post pictures once finished.

-Jeff

[preserved_killick]

Turns out tabbing is ok. Mostly just the edges had lifted with the rest ok. I snapped off a few small chunks that I expect will not have any effect on overall strength. I'll just fill in the gaps before I prime.

Thanks!

-Jeff

[preserved_killick]

Bringing this old subject back up because this spring I see some new cracks here and there in the tabbing. The bulkhead tabbing was fine last season, fine when I put the boat away in November, and now some small cracks/failures are apparent. I'm guessing that since it happened over the winter, different materials expanding & contracting at different rates is the issue? Certainly no outside stress on the joint. If this is the cause, then not much can be done? Is this common? Am I just noticing it since everything is exposed?

jeff

[Zach]

She may be wet inside.... Freezing water expands.

I'd do some exploratory drilling to see what the wood is like closest to the hull.

Zach

[preserved_killick]

She may be wet inside.... Freezing water expands.

I'd do some exploratory drilling to see what the wood is like closest to the hull.

Zach

Not the answer I'm looking for. Anyone else?

I've actually wondered that, and did drill some holes in the bulkhead a few inches from a broken tab (for running wires) and it comes up dry. There's no chainplate nearby, no deck openings. Could be soaking up cabin humidity I suppose. I should drill some little holes to see.

-jeff

[Case]

Check the jackstands and blocks... are they properly set up? Improperly arranged jackstands can kind of twist the boat somewhat... Its not overly uncommon for some sailboats to have doors not open or close properly when on jackstands. Its not really discussed very often in forums but it does happen. Boats are surprisingly flexible in many ways.

I have no other ideas. Sometimes polyester bonds to the bulkheads just fail. Redo with epoxy and it should be fine.

- Case

[Tim]

Seeing what you're seeing (i.e. pictures) would help determine if a problem exists.