Today I glassed the outside of the 2 port tanks and later in the day I gave them a coat of white epoxy. I also measured up and started cutting the panels for the 3 fresh water tanks. Polycore is a fantastic product but it is not as easy to work with as duflex. It is no different to any other honeycomb cored product though. The issue with a hollow cored product is the edges need to be back filled. With balsa you just run a router along the edge and you have a curved edge to glass around. With honeycomb cores you must back fill the edge to glass around. On the starboard black tank I tried back filling one day then shaping once it had set. This worked to a degree but because of the nature of honeycomb when you round the edge you open up new chambers that need to be filled. So this time I decided to try to shape the edge, which I did with a grinder (I seized another grinder today, my second so I will soon have my third hand held angle grinder). I then over filled the edges and laid wet tapes over them and shaped the curved edge by hand. It worked but is not uniform and as neat as could be. Fortunately practicing with this material on the tanks is going to help me find the most effective ways to get a great result so that when I build the highly visible furniture I am able to get the best finish I can. There is only one other method I will try and that is to shape first, overfill then wait for it to set before shaping. I think that will be the most attractive method.
Once I had all the honeycomb edges filled I wet out the tapes I had pre cut and applied them to the edges and using my hands as molds I pulled the overfilled edges into as nice a curved edge as I could by hand. I then applied peel ply to the tapes. I intend to paint the tanks inside and out with white epoxy whilst the tapes are still tacky so I dont really need the peel ply but I apply it just in case I run out of time or have to go before I do the white epoxy but I didn’t so I just removed the ply before painting on the white epoxy.
I had lunch and then started measuring and cutting the dividers for the water tanks. I have an area between the 2 forward bunks that is 600mm wide, 1200mm deep and 1300mm long. With dividers this will result in 3 400mm tanks so each will be 250 litres. As water weight is equivalent to its volume, 250 litres is 250 kilograms. So with all 3 tanks full that is 3/4 tonne or half the boats payload in one area. Of course the only time we would ever fill all three tanks is for a super long cruise or passage so it might be that we never ever carry this much water, especially if we get a decent water maker.