nacra 5.2 hull spidering

That is probably superficial gelcoat cracks due to some approximate tightening of the beam straps. The strap we see seems to be overtightened (the bold twisted the strap on the left side). If the inside strap is not as tight the hull would move against the beam and generate this kind of failure.

Sand the cracked gelcoat over and if there is no crack in the polyester below simply cover with a new layer of gel coat. When you mount the beam after that add a small amount of silicone between the beam and the hull to help distribute the load better, and use a torque wrench to tighten everything equally.

To spread load:
Silicone - No
Thickened epoxy or polyester resin - Yes

Wax or tape beam before bedding in resin and only lightly tighten beam until resin has cured. A washer at the sides of each hull under the beam will allow a good 'bed' of resin.

Cheshirecatman

[Put on flame suit]
I always thought the NACRA beam straps was a goofy way to do things. To my way of thinking, it allows movement of the hull with respect to the crosstube about the axis of the crosstube, and also allows movement parallel to the axis. Apparently it (usually) does the job though.

DHO
TheMightyHobie18 1067

You do not need a flame suit. It's a ridiculous way of mounting beams. Bolting the beam through is so much easier and prevents the problem of rotating beams.