bonding the big burly bow beam

Here's a look down the inside of the bow beam. For bonding, I used System three Gel-Magic which is a thixotropic structural epoxy adhesive. It's a pretty handy epoxy "glue" that mixes 2 to 1 like epoxy but it's formulated to turn itself into a gel that will stay put. I spread a decent amount along both bonding surfaces, placed the top chanel over the bottom, rolled them on their side and fixed the bow beam together with temporary screws. The photo confirms that I have 100% internal squeeze-out along the entire length of the seam.


poping the 2nd bow beam section out of the mold

Including building the mold, fabricating the two 19ft. bow beam sections has taken about 16 hours. Considering that I am paying myself 0 dollars / hr, that comes to a total labor cost of 0 dollars. Shown here, after popping it out of the mold, is the 2nd half of the bow beam section. Next step will be trimming it down to spec, bonding the two halves together and skimming the beam with a mixture of micro spheres and epoxy to smooth down the seams and minor imperfections. To eliminate bonding prep work I placed peel ply into the mold top and bottom. Peel ply is my friend.


Solar post-cure using the green house effect.

After bagging one section of the bow beam, I used pressurized air to blow the bag up and then set it out in the sun. Thanks to the green house effect, on a sunny day, the temperature inside the bag can easily reach upwards of 120F.


It's nice to have enthusiastic workers to keep the project moving along.


Composite bow beam mold

Here's my helper smoothing down the packing tape along the length of the bow beam mold. The two upper cap beams are in-set about the thickness of what I think the sides will be; thus forming an internal flange. After layup and vac bagging is compete, I'll remove the cap strips and lay up what will become the other half of the full 19 ft. length. Then the two channel sections should fit together and be bonded to form a composite beam that is 7 in. tall, 9 1/2in. wide and 19 ft long.