Sunday, October 25, 2009

An Icebox Cometh

After about 3 weeks of interupted work, the new icebox is finished. I am currently testing its efficiency with a 10lb piece of block ice, it went into the icebox at 18:00 hrs on Saturday, 24 October, I am going to track it and see how long it lasts, and how cool it keeps the box. My original guess was it would last 7 days, a friend thinks 12 days, I was skeptical of her guesstimate earlier, but now I think that she might be more on the right track, we shall see. So far, 24 hrs later, the block has only melted slightly, there is 1/4 inch of water in the bottom of the icebox, and the block has not shrank noticeably.

To recap this project, and to bring everyone up to date:
Arden's original icebox was a thing of beauty - stainless steel icebox, fully watertight with soldered seams and a very nice top loading door. However, as nice as it seemed from the outside, it was close to being totally useless, as there was insufficient and missing insulation surrounding it. From everything I have read concerning the construction of iceboxes, you want at least 3 inches, preferably 4, of foam insulation around your icebox, with no voids or air pockets that can rob the cold from your box. From what inspection I could do, without removing the old box, I thought I had about 2 inches of insulation surrounding the original icebox, boy was I wrong.

I had to first remove the old countertop, which I had hoped to salvage, but, due to the way it was constructed, it had to come apart in pieces, thus totally destroying it and requiring the construction of a new counter at the end of the project. Once the counter top was off, I could see why the old box was so inefficient, there were only 2 pieces of white styrofoam around the box, some places there was no foam at all, and in some places the glue they had used to contruct the counter top had completely chemically melted the foam.

Once the old box was removed, and the space it occupied cleaned up, I began to build the new box. As I had mentioned in an earlier post, I had access to some 2 inch thick foam, and I bought a sheet of 1 inch thick foam. The new box would be constructed of a mix of 3 and 4 inch sections, giving me R values of 30 to 40. Now I have looked up R values on the net, and to be honest, the true explanation of how it is calculated is close to rocket science. A simple explanation works better for me, the higher the number the better the insulation value, consider that the standard layup of fiberglass insulation in new home construction has an R value of 15, and that my new box would be twice that.

After putting all the foam in place - 4 inches on the bottom, 4 inches against the engine compartment and hull, 3 inches fore and aft - it was time to layup the fiberglass. Now the polyester resin for fiberglass will melt the foam, so I used 4 mil plastic sheeting as a barrier to avoid this from happening. I stapled the plastic to the foam, and then cut woven roving to lay into the foam box. Here is where I would have changed how I built the box, instead of using the plastic, if I were to do this over again, I would have lined the box with 1/4 inch plywood and laminated the glass straight to the plywood. This would have eliminated the slight problem I had with the interior walls sagging. Lesson learned.

Once the first layer of woven roving was in, I wetted it out with polyester resin. I opted for polyester over epoxy for a variety of reasons, foremost was cost, and structural strength was really not an issue. Once the first layer cured, I added a second, being sure to overlap the seams so that no seam was doubled in the same spot. After this second layer had cured, I located the low spot in the box, and drilled a 3/4 inch hole through the fiberglass, the foam and the inner bulkead, this hole had to be so long that I had to use 2 drill bit extensions to get all the way through the layers. Through this hole I put a piece of 1/2 inch pvc pipe as my drain tube. 1/2 inch is relatively small, but I did not want the drain to be too big, as this can be a spot for cold to leak out of the box, so I made it as small as practically possible. At the end of the tube I attached a section of hose, and routed the drain out of the engine compartment and into the bilge.
At this point it was time to put a barrier coat and color coat over the fiberglass. For this I did use epoxy, and used a tinting agent to color it white. I put down 3 coats of this, to give me a tough, smooth inner surface, to brighten the interior of the box, and to glue the drain tube into place. This was the point were I could really see that the box was coming together and that the project had turned the corner towards completion.

Now I had to fit in the threshold for the top loading door. To dovetail this in, I used a router to notch the old threshold. This allowed the wood to overlap the foam and fiberglass, and then I notched out the foam and fiberglass to allow the threshold to sit down flush with the cabinet framing. Once this had been done, I cut and installed the foam that would make up the top of the box. This consisted of 1 layer of 2 inch foam, and 2 layers of 1 inch foam. The bottom layer, which was exposed inside the box, I covered with a layer of fiberglass cloth and wetted that out with colored epoxy. I left tabs of cloth hanging so that I could glue them to the the walls of the box later.
Time to clean up the top edge of the cabinet and prepare for the countertop installation. I used an old favorite to clean the cabinet frame of old glue and plywood remnants, a Stanley Surform plane. This handy tool is like a combination of a rasp and a block plane, it quickly removes material, leaves a good working surface and can be used on a multitude of materials. Once the cabinet was ready, I measured out and cut the counter top substrate out of a piece of 1/2 inch plywood. I had to relieve the surface of the plywood where the new countertop merged with the old, I suppose Asian boatbuilders use metric sized plywood, and the old countertop was made out of 11 or 12 millimeter material, not quite as thick as our 1/2 inch ply.

When this was done I layed out the laminate for the top, and used a laminate trimmer to precut the laminate to match the substrate. I mounted the substrate to the countertop and the threshold with 1 1/4 inch stainless steel drywall screws. These self drill and countersink, and can be sunk with a cordless drill with no effort at all. I cleaned up the trimmed edges of the laminate and made a few adjustments to the way the laminate was cut. Now it was time to make a countertop.

Having built kitchens and cabinets before really gave me some experience that came in handy here. I coated both the plywood and the laminate with contact cement. I put on two coats so that there would be a good glue bond. I used scrap pieces of laminate to keep the glued laminate top off of the glued plywood substrate as I moved the laminate into the correct position. I slid the scrap strips out and pressed and rolled the laminate top down. Once this was done, I set the door into the threshold, and trimmed the opening for a good fit. Screw the hinges down, and I had a finished countertop.

Two items left. One was to glue in the tabs I left hanging on the foam and fiberglass I used to make the inside top layer of the box. This I did with more color tinted epoxy, brushing it onto the inner walls of the box,a nd then wetting out the cloth. The last item left was then the trim around the edge of the countertop. this is being made by a friend of mine with a woodworking shop, it will be screwed into place with stainless screws, and then bungs put in and the completed trim varnished to match the inside of the boat.
So now Arden has a new icebox, and I can put my Galley back together. If you think remodeling a house is hard while you are living in it - and I grew up in a house that was constantly evolving and improving - it is nothing compared to doing a major interior project of your liveaboard boat. I learned alot doing this one, but I am glad it is over and I dont plan to do anything nearly as complex anytime in the near future. Famous last words, akin to "Hey somebody, hold my beer, lemme show ya'll something."
Arden still needs an auxilliary water tank installed...tune in next week...

1 comment:

Jerr Dunlap said...

Great article about a very practical and common project - Really solid construction techniques, too - Thanks! The only thing I'd do differently is use a small piece of 2"x4" (Maybe 6" with barely rounded corners and edges), pushing like crazy on the edge to bond the contact cement. I remember reading the can and it takes a lot of pressure to fully bond. I'm looking forward to following your blog - Thanks!
- Jerr