tabbing in a new main bulkhead

[falcon]

I recently discovered that the plywood forming the companion way bulkhead on my cheoy lee frisco flyer was delaminating down in the bilge by the engine mounts. There was a little rot, but it appeared that the idividual laminations had simply come unglued. I couldn't think of a way to "fix" the problem with a patch so have sucked it up, taken a giant step backward, and removed the galley furniture on both sides to expose the bulkhead. My intention is to completly replace the original 3/4 inch chinese plywood with 5/8 inch meranti aquateck (marine plywood). I have replaced and tabbed in several of the smaller bulkheads but wanted to get your advise before tackling the big one. My plan is to tab it in with West Systems and several courses of the 6 inch biaxial tape with the 0.75 oz mat backing. Will this be adequate? I find the tape a lot easier to manage than wider spans of cloth.

[CharlieJ]

Sounds like a reasonable fix to me. I've used the Bi ax to create chine filets in tack and tape boats. It's really nice to work with.

[Quetzalsailor]

Tape is nice; beats cutting your own. I've been known to bottom feed but the 12" roving tape I bought on eBay was over age and crinkled as I unrolled it. (Used it anyway, it's the pads on a cradle)

Be sure to coat out, with epoxy, the end grain of the new bulkhead and whatever you leave of the old.

[Tim]

Use a few layers of tape, starting with something like 4", then 6". I often use a wide layer of smooth cloth as a final layer over the coarser biax material, since it makes for a smoother and cleaner appearance when cured; plus, it adds one additional layer and overlap.

If you're using 15 oz. or 17 oz. tape, such as the commonly available biaxial tape with mat (1708), I believe two layers is adequate thickness on a boat your size. You can do more if you want, but it's not really necessary. Old tabbing on these boats might seem really thick and heavy, but it's often mostly mat and large amounts of resin, so it isn't that st rong. Modern materials and epoxy are much stronger.

Good luck. Sorry to hear of the setback, but you'll be glad you did the job right.

[falcon]

Good sugestions all. I really appreciate the input!

[Rachel]

I know this must have been addressed somewhere here in the past, but since it's on-topic here, I'll ask it again and hope no-one minds terribly.

For things like tabbing in bulkheads, less-structural dividers, and/or things like fuel tank supports -- and if one is going to use biax tape or fabric, how does one choose whether or not it should be "just" biax or biax-mat?

I ordered some WEST "Episize 727" (mat-less) biax tape - it's 4" wide and comes on a nice, tidy roll - and some of the boaty folks here questioned why I wasn't using some form of biax-mat. There was some biax-mat tape lying around, but it looked all stringy at the edges and like it would be thick and uncomforming (not that I tried it). I can't actually say what I used it for, because that would force me to make excuses for why I haven't updated certain other threads...

Anyway, how does one choose whether there should be mat stitched to the back of biax fabric or tape - or not - when doing a project or repair?

Thanks,

Rachel

[Ceasar Choppy]

Anyway, how does one choose whether there should be mat stitched to the back of biax fabric or tape - or not - when doing a project or repair?

Thickness.

There is some strength in thickness depending on what you are doing, and there are those jobs where you need mass. But for most run-of the mill jobs, I like the Episize stuff. For tabbing in serious structural supports like bulkheads or where you will end up using a lot of layers of the thin stuff, the thick will save you time and money.

IMHO, the thin works for stiffeners and minor repairs.
The thick for load bearing stringers or floors, major bulkheads, filling throughulls.

[Idon84]

Thought I would search for this topic before reposting one of my own.

Looks like I got the original question answered by Tim above whom mentions only really needing 2 layers of tabbing and maybe a lighter layer for the top for fairing purposes etc.

I believe two layers is adequate thickness on a boat your size.

The boat being talked about is a Frisco Flyer.

I just started roughing in the settees in my BCC and I can't help but to ask my self if the strong fillet, 4" then a final 6" layer of 1708 Biax is enough. I can get and 8" layer of Biax from NOAH's but I wondering if that is necessary. Of course that means waiting to finish the final layer before building the Settees.

This boat will eventually take me to the Caroline Islands (PALAU) in the Philippine sea via either the South Pacific or Hawaii and Guam. So getting thrashed and bashed around is going to be normal for me.

THOUGHTS PLEASE?

And as always, thanks for the input!

Bryon
www.picasaweb.com/idon84

[Idon84]

PS. I'm using EPOXY only on this whole job.

Bryon
www.picasaweb.com/idon84