I am building a stitch and glue dinghy and the plans call for 4" or 6"
glass tape for the inside and outside seams. The inside is specified to
be taped with 2 layers of this tape offset by a couple of inches giving
a 6" or 8" total tape width. The whole underside and most of the inside
is also sheathed with glass cloth as well.

The instructions do indicate that the boat is very very strong and is
possibly over engineered.

I have a big roll of 2" tape and am interested to know if using two
staggered layers of 2" tape giving a total 3" width would be considered
sufficient by those who have experience in these things. I still intend
to sheath the whole thing with 3 oz cloth as well as the tape.

Any input gratefully received.

Brian

Brian wrote:
Well given that (surprisingly) there was no response I did a test. I
joined some bits of scrap by filleting and taping with a single layer of
my 2" tape. See the first two pics.

Once cured for a day I tried to break it. See next pic. The wood
delaminated and broke away from the join. With some considerable force I
managed to break the join (see 4th pic). The join broke but a lot of
wood was still attached to the tape (5th pic).

I have no doubt that a second layer of tape on the outer seam would have
made it stronger still since the tape ripping was obviously a major
reason for the failure. It doesn't look like the width of the tape was
an issue because the tape was still well attached away from the break.

So its 2" tape with a staggered double layer on the outer seam. It looks
like the seams are not be the weakest parts anyway. That is unless the
test with torque stresses around the join is not representative of those
experienced by the boat. However I would imaging that if first
millimeter of tape pulls away from the join it is seriously stuffed as
it would probably let water in.

Hope someone finds this interesting or useful,

Brian

Another option you might want to explore it using bias cut tape that you
make yourself. Bias cutting results in twice as many fibers crossing the
joint.

BTW, some "newsgroup Nazi" is bound to scream at you for posting pics
here. Just ignore them.

On Sat, 07 May 2005 10:41:00 GMT, Brian Nystrom
wrote:

[another] Brian wrote:
Well given that (surprisingly) there was no response I did a test. I
joined some bits of scrap by filleting and taping with a single layer of
my 2" tape. See the first two pics.///
Hope someone finds this interesting or useful,

Brian

Another option you might want to explore it using bias cut tape that you
make yourself. Bias cutting results in twice as many fibers crossing the
joint.


Until Brian came right out and said it, I was ignoring this salient X2
fact.

Thanks!

Brian W

On thing that I like about biax tape, or woven tape cut so that the yarn is
+- 45 degrees, is that it follows curves much better. Consider something
like a chine seam where it makes the turn to the bow. With biax (or the
woven cut as stated), you generally don't have to cut darts in the glass to
make it lay flat around the corners. AND you get more yarn across the seam.

Brian D



"Brian Whatcott" wrote in message
...
On Sat, 07 May 2005 10:41:00 GMT, Brian Nystrom
wrote:

[another] Brian wrote:
Well given that (surprisingly) there was no response I did a test. I
joined some bits of scrap by filleting and taping with a single layer of
my 2" tape. See the first two pics.///
Hope someone finds this interesting or useful,

Brian

Another option you might want to explore it using bias cut tape that you
make yourself. Bias cutting results in twice as many fibers crossing the
joint.


Until Brian came right out and said it, I was ignoring this salient X2
fact.

Thanks!

Brian W

I hadn't realised that one of the prerequisites to do stitch and glue
was to be called Brian.

Thanks for the tips on bias cut tape. However the whole point was to see
if the 2" stuff I already have would be sufficient for the job.

I hadn't realised that it was taboo to post pictures. I am still not
sure why but I will avoid it in future. In the meantime I will try and
live with any national socialist flack. Surely "newsgroup fascist" would
be a better description but we quibble over terms.

Brian Nystrom wrote:
BTW, some "newsgroup Nazi" is bound to scream at you for posting pics
here. Just ignore them.

Brian wrote:
I hadn't realised that one of the prerequisites to do stitch and glue
was to be called Brian.

Scary, ain't it? ;-)

Thanks for the tips on bias cut tape. However the whole point was to see
if the 2" stuff I already have would be sufficient for the job.

The point of bringing up bias cut tape was that it would probably
prevent or at least reduce the tape failures you had in your test panels.

I hadn't realised that it was taboo to post pictures. I am still not
sure why but I will avoid it in future.

This is technically a text-only newsgroup, but there are times where
pics are worth the proverbial thousand words and you shouldn't have to
take any flack for posting an occasional photo when it's appropriate.

A link to a picture always works too, and there's plenty of places where you
can upload galleries of pictures for free.

Brian D


"Brian Nystrom" wrote in message
...
Brian wrote:
I hadn't realised that one of the prerequisites to do stitch and glue was
to be called Brian.

Scary, ain't it? ;-)

Thanks for the tips on bias cut tape. However the whole point was to see
if the 2" stuff I already have would be sufficient for the job.

The point of bringing up bias cut tape was that it would probably prevent
or at least reduce the tape failures you had in your test panels.

I hadn't realised that it was taboo to post pictures. I am still not sure
why but I will avoid it in future.

This is technically a text-only newsgroup, but there are times where pics
are worth the proverbial thousand words and you shouldn't have to take any
flack for posting an occasional photo when it's appropriate.

Brian D wrote:
A link to a picture always works too, and there's plenty of places where you
can upload galleries of pictures for free.

Yeah, I forgot to mention that. Thanks for pointing it out.