New biaxial tape.

We introduced the concept of structural taped seams more than 10 years ago and from the start, we recommended the use of biaxial tape for those seams.
There are two advantages to the use of biaxial tape: stronger easier to apply.

The superior strength is easy to understand. If one uses plain woven glass tape with fibers running at 0 and 90 degrees, half of the fibers run parallel to the seam and don't do much while the fibers perpendicular to the seam are at the worse angle to resist shear loads.

Biaxial tape does a much better job: all fibers are put to work and resistance to shear is optimum:

There are other advantages:

1. At equal weight, biaxial fabric is stronger than woven tape. In biaxial, all the fibers run straight but woven fibers are intertwined. This produces a difference of around 20% in tensile strength along the fibers.
2. The radius taken by the fibers is much larger. This means easier application, no air bubbles, no fighting to get the tape down in the resin
3. Woven tape is sold with stitched edges. Those edges create a ridge and this means more fairing work. Biaxial tape has loose edges that blend smoothly in to the adjacent surface.

In all our designs, wherever possible, we specify biaxial tape for structural seams but this was a problem for small boats.
Ideally, we need a biaxial tape of around 6 oz.
Until now, the lightest biaxial tape easily available was 12 oz. This was unnecessarily heavy and we specified woven tape 9 oz. instead.
While not perfect, the 9 oz. woven tape was the closest in performance to our requirements and that is what we show in our BOM's for small boats.

Stitch and glue is not a big market for fiberglass mills and for years, they did not offer this tape but after some research and negotiations, we found a supplier that accepted to produce our ideal biaxial tape for small boats.

Biaxial tape 6 oz. is now available in our small boat kits and online store (www.boatbuildercentral.com)

6 oz. Biaxial tape is stronger than the 9 oz. woven tape, easier to apply, and solves the problem of the protruding edges.

The first shipment arrived yesterday and starting next week, we will update all BOM's and kits in which we specified the 9 oz. tape.

For those who can't order their supplies from us, we recommend to keep using the 9 oz. woven tape.
Our specs will show the biaxial tape 6 oz. as the specified material with the 9 oz. woven listed as an acceptable substitute.