Thursday, August 27, 2015

A Pain In The Glass

As every sailor knows, your life is dictated by mother nature. We rely on the wind for propulsion, the sun for power (or I will once I finally get the solar installed on this bimini), and the seas for a smooth highway or bumpy ride, and we try to hide from things like thunderstorms and hurricanes. Those further south than I are currently bracing for Erika (a storm that formed right behind Danny and looks like it will be heading to Florida). But even when sitting in a marina and working on projects far from the storms, the weather still dictates my life.

[Image of 5-day forecast and coastal areas under a warning or a watch]
Tropical Storm Erika, National Weather Service Hurricane Center Image.

If I had been smarter, I probably would have held off on this project for a month or two, but the timing just didn't work out that way. So instead, I continuously wait on weather windows in order to continue the fiberglass work. Water contamination is a concern, so it can't rain. Dew that collects on the shade canopy most mornings can drip down and make a mess of things. By using polyester resin I can adjust the speed of the cure by the amount of catalyst used...but only to a point. Using the minimum amount of catalyst, I can get about 25 to 30 minutes of working time out of a batch when it is 90 degrees Fahrenheit. The only weather problem I haven't encountered thus far is the minimum temperature of 60 degrees...they say you shouldn't try laying up fiberglass below that temperature either.

Like in many days past, we have been somewhat cool overnight, at least to the point that the temperature and dew point meet. About the time it dries, the temperature is shooting past 90 degrees in the yard. So that only leaves us with the evenings. And that is the time slot we have been using. Around 4 or 5 PM the temperature drops back below 90 F, and if there aren't any storms, we can finally start applying fiberglass to the big foam sheet that makes up the core of the hard top.

Front curve of the top now cut.

Unfortunately, as the light fades, it gets more difficult to see what we are doing. The 500 watt work light helps a lot, but it is no replacement for the ambient light during the day. Not wanting to spend the rest of our lives at the boatyard, we press on. Over the last couple days, we have managed to cover the remainder of the top side of the bimini foam with one layer of fiberglass and with two layers along the rear edge where it will mount to the arch.

On the first new panel we started, we wanted to do the whole section with a single 9 foot long by 52 inch wide piece of cloth after laying up the 18 inch wide strip at the back/mounting flange. Wetting and applying that much fiberglass at one time with two people simply cannot be done in the time it takes for the resin to cure (at least not for us novices). In order to put down a sheet of glass that long, we need to do it in stages.

Positioning the rear mount reinforcing strip.  Note the black alignment marks.

First we positioned the dry cloth on the top, rough trimmed it so there was only an inch or two of overhang, and made marks using a permanent marker to act as guides for placement. We rolled the fiberglass onto a section of 2 inch diameter PVC pipe. Then we applied a coat of resin to the foam and allowed it to begin to gel. For the rest of the process my wife would mix up 16 ounce (1 pint or approximately 473 ml) batches of resin. I would apply some to the resin to the pre-wetted foam, we would position the end of the cloth on the roll using the marks, and roll out a couple of feet of the cloth. Using more resin I would wet out the top of the cloth.  My wife would make more resin, and I would roll the cloth back up to the wet area, apply more to the foam, and then roll more of the cloth out and wet the top side of it.  Then whoever wasn't busy at the time would use the fiberglass roller and squeegee to embed the cloth in the resin, work out bubbles, and move any excess resin toward the dry roll of cloth. This process of mixing some resin, wetting the foam, rolling out some glass, wetting the top of the glass, and working the glass was repeated until the entire piece was done. By the time we completed the last section, the polyester was starting to gel in the first sections.

Initial dry-fit of the long piece of fabric. Note PVC "roll".

The key to this approach is to stay well ahead of the resin that is starting to gel. You also need to make sure that the section of cloth is well wet out and in its final position while the resin is still wet. This process is a bit nerve-racking the first time you try it...or at least it was for us. Making sure to stay ahead of the curing resin, getting the cloth to wet out well (particularly on more vertical surfaces) and making sure the resin isn't too thick means you have to move fairly fast. Oh, and remember we are doing this by the light of a single 500 watt bulb, outside, where the light is attracting every insect within 5 miles to our little oasis in the boatyard. I'm sure if anyone had been watching, they might have found the whole ordeal quite entertaining. It took us from around 6 PM to almost midnight to complete the mounting flange band of fiberglass and the 9 foot long sheet (and clean and pack up the work area for the night).

The second side panel was done the following night and went about like the first, except that we ran out of material on the roll before we reached the end of the panel. So, in this case we had to pre-cut another piece of cloth and during the layup process it had to be positioned and integrated into the first piece as we went along. Having done the process once, the second time it did go a bit faster, and I think we made it back to the boat just a little after 11 PM.

The morning after each layup, we were finally able to see our prior night's work in the light of day.  For the most part, it looked good. There were a couple small spots that had bubbles or were not wet out well and we will go back and repair them before the next layer, but overall I think it went well. At least we are making progress towards the goal.

The first layer of fiberglass on the top.
As a side note, a few bugs (mosquitoes or similar) did manage to make it into the wet resin. They actually look just like the fossilized "fly in amber" you might have seen in grade school. Maybe a 1000 years from now some grade school kid will get to see a 2015 mosquito perfectly preserved in glass fiber reinforced polyester resin...wonder how the teacher would explain that. But hey, at least those are a few mosquitoes that won't be biting us again.


  1. Hi Mike and Wife,
    Project is looking good. Great to see you worked out a method of rolling out and wetting the cloth that works with just the two of you. As far as the dew, would a small 500-800 watt electric heater with slow speed fan put in the enclosure at night and on a multi on/off setting timer, raise the temp in the enclosure above the dew point and prevent dew from forming on the inside of the blue tarps or on the hardtop? Don't know how tight your enclosure is but, might allow you to do work in AM before it gets too hot, and no bugs.
    Just a thought, There is a light at the end of this tunnel project
    Doug from VT

    1. Hey Doug,

      Well, don't know it if it is a method, still very ad-hoc...but it seems to be working. I thought about a heater, but the yard doesn't want things like that plugged in when unattended (I can't blame them and don't want to sleep out there). The "enclosure" is a portable canopy with tarps tied around it to make "walls" at night and additional top during the day. The interesting thing is that the top doesn't have dew on it, only the tent itself. I usually open it up and setup a fan in the morning, but the heat seems to come up in a hurry most mornings. Hopefully the weather will cooperate a little more going forward. In any case, things are progressing.