Tabbing Material

[JetStream]

Tim, you've probably discussed this somewhere but I don't remember reading it. I notice that in all of your current tabbing work, you have been using 15 ounce biax. This stuff used to be more difficult to get but seems to be everywhere currently. Jamestown Distributors even sells 17 ounce biax tape (with 3/4 ounce mat attached) in 4" and 6" widths for about the same price as US Composites. Is it reasonable to think that any bulkhead (other than the main bulkheads) could be tabbed with just one layer of the 6" x 17 ounce biax on either side? If so, that sure saves a lot of work from previous methods with mat followed by layers of 10 ounce tape. Your thoughts will enlighten me.

[Tim]

Bruce,

For secondary bulkheads, dividers, and less important semi-structural members, one layer of the 15 or 17 oz. biax on each side is plenty. This stuff is really strong.

The 4" tape I have been using most recently is actually West System Episize, 15 oz. biaxial tape. It was suprisingly inexpensive when purchased wholesale. It is a pleasure to work with: easy to wet out, and very compliant when trying to roll it over corners or curves. Nice.

For my three main bulkheads, I used two layers of 24 oz. biaxial tape on each side, plus a layer of 10 oz. cloth over that. The 24 oz. stuff almost requires a layer of lightweight cloth or Peel-Ply over the top to help roll it out.

Forget about mat and light cloth. Go with the biax.

[Catalina0029]

Tim, when you filled the seams in you deck panels, did you also use Biax?
Is that the prefered material to fill seams in the fiberglass skins?
I will be recoring the cabin sides and deck on my Catalina. The fiberglass skins are about .100 - .125" thick. I can get a 1 1/2" wide taper per side for a total width of 3" taper. What do you recommend that I fill the gap with? 15oz Biax or should I use more layers of thinner material?

[Tim]

I think it would be best to plan on at least two layers of material for your seams, whichever material you choose. 2 layers of the 15 oz. biax would be excellent, if you can taper the seams out enough to hold the thickness (which shouldn't be a problem).

Hope this helps!

[Rick]

I'm confused after reading the posts on tabbing material. I'm going to tab the bulkheads, some knees and other interior wood in my A21. The recommended fiberglass here is either 15 or 17 oz. biax tape. It is sold with or without 3/4 ounce mat attached. I've also read about some concerns about epoxy and the glue that holds the mat to the biax. So the simple question is should I use the biax with or without the mat?

[Tim]

I'm confused after reading the posts on tabbing material. I'm going to tab the bulkheads, some knees and other interior wood in my A21. The recommended fiberglass here is either 15 or 17 oz. biax tape. It is sold with or without 3/4 ounce mat attached. I've also read about some concerns about epoxy and the glue that holds the mat to the biax. So the simple question is should I use the biax with or without the mat?

The mat on the back of 1708 biax (17 oz. biax) is lightly stitched to the fibers; it is not held together with binders the way chopped strand mat (CSM) is. The biax material with mat holds its shape better, and is typically the choice for most tabbing. There are no binder dissolution concerns with this product.

I have on occasion used the 15 oz. material without mat for lightweight tabbing, particularly when the extra flexibility it affords (during installation) is handy. But the "stock" material is 1708 (17 oz. biax with 3/4 oz. mat backing). This is strong stuff when combined with epoxy resin, and 1 to 3 layers will satisfy almost any structural need on the sorts of boats we're discussing here.

It's the CSM material, sold on its own, that may not work properly with epoxy resin, since in many of the CSMs out there the binder is styrene-soluable and won't necessarily dissolve properly in epoxy (which lacks styrene). That's OK, since there's no reason to use CSM anyway, unless you're using woven roving as a laminating material. And there's no need to do that, with improved and stronger products available now, so this particular issue isn't a worry.

And on top of all that, you can get CSM to work with epoxy. However, since there's no need to use this non-structural material in most of the repairs that one tends to undertake, one need not concern themselves with whether or not it works.

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[Rick]

Thanks for the quick response.

Looks like a great weekend for tabbing - well maybe not so much on Sunday - I need to earn some mother's day credits to offset the "minimal" time it takes to renovate this baby.

[Rachel]

I'm going to be tabbing a smallish (~6" x 7") frp board "dam" in place in my bilge, and am planning to use some sort of biax product. The current surface is the original woven roving of the hull. So, I'm thinking biax/mat to start with, so that the mat helps to "squooge" into the roving, but after that perhaps something like the "Episize" biax tape that has no mat? Or maybe only that tape and no mat at all? There are plenty of 90? corners to deal with (although I will fillet them first). I'm planning to use epoxy.

45/45 used for areas where tight bends are needed.
0/90 used in hull construction or any part where uninterrupted continuos fibers are needed. All bulkheads should be 0/90.
The knee is wrapped 45/45.... the dam is anchored with 0/90 as I ran out of 45/45....both were 1808.

Tynaje, I'm interested in what you're saying, but I'm a bit confused on a couple of the details. Could you clarify for me? When you say above that 0/90 should be used for bulkheads, I think I get the concept. But then you show a photo of a "dam" that kind of looks like a bulkhead to me, and say you used 0/90 because you ran out of 45/45. But wouldn't the dam want to be 0/90? Or is it not what you would consider a bulkhead.

all brands both ultra performers as well as prepregs in my own oven, high cost and low end such as WEST and MAS,dont like mat for the most part

I'm curious what you're saying there about WEST and MAS. Do your comments apply only to vacuum-bagging or to hand layups as well?

Rachel

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