Surprised that no-one answered this. I wondered if you were an fcs stooge or had asked questions before that put people off answering. Anyway check out http://www.lokboxfins.com/installation.cfm
which tells you that the boxes should have been covered with cloth when laminated.
I’ve only had 1 fin box bust with Lokbox, but quite a few with FCS. I believe the Lokbox problem was with the installer. I had glass-ons taken off a favorite board and replaced with Lokbox by my FORMER ding repair guy.
Yeah lokbox are supposed to be capped with glass. Try topping this post in a week “Lokbox” who answers all the questions is way south of the boarder getting mile long lefts while were sitting here.
One other note on Lokbox’s; a kid came into my shop and wanted me to replace all his Lokbox boxes with FCS plugs because he said his fins would just fall out. I took a look and discovered he had removed all of the little O rings under the screws that held the fins in. I ask him why he did that, and he said “I DIDN’T THINK THEY WERE NECESSARY!” I told him to quit thinking and just follow the instructions.
I thought the rings were designed to hold the tab in place while installing rather than have it get lost in the sand. Lokboxesfins are also designed to be cranked down hard and tight. The tabs bend; if bend enought to bother you turn them over.
Other than the obvious that you have stated, the O-ring is to prevent the innerbox part of the box to become water-logged and possibly leak into the foam. If you notice the Lokbox is a two piece construction and the inner part of the box that is face down into the foam has a seam where the water could leak through.
I can’t see how once installed water sipping through the box could be a problem given that resin used in the installation process would most likely seal the box and/or create a barrier that would keep water from reaching the foam. Personally, I’ve had no problems with lokbox in the 2 years or so I’ve used it. Try to bounce this to the top next week when lokbox is back in town and I’m sure he will be able to address all your questions.