Preparing hulls for glassing

Sanding The Filled Hull Joins

Posted by Paul

I started sanding the filled hull joins today. I found the going slow and hard with the orbital sander. I had applied way too much filler and only had to remove it all again. In the end I used a 80 grit sanding disk on the angle grinder which removed it very fast but will a lot of dust. I stopped half way through the first join to go out and buy some cheap tarps to cover the stock so that dust doesn’t settle on it. In the end with the experimenting with the grinder and going for the tarps I only managed to do the one join today. I also assembled the Wombat wet out machine as a distraction from sanding. It looks like it should work really well and as I wont be glassing for a month or so the heat should have subsided meaning I should have a little more time as the heat causes the resin to go off fast.

After grinding away the excess filler I used the orbital to smooth out the join and round it off. I ground a little too far in just one spot about 5cm long by about 5mm wide and about 1mm too deep, removing the pre glassed layer. It is only small and wont affect the hull strength, it will be under another layer of glass, is tiny and is well above the waterline. A tip here to find if you have a smooth round join is to run your hand along the join but not to look at it as you walk along the hull. You will feel any irregularities. I had about 3 highs or lows that will need either more sanding or some filling but they are so small that I will wait until I have the glass on to fair them as I think that the glass will cover them anyway. This method of feeling for irregularities may only work where you can move along the join uninterrupted which may be harder on the ones up high. You certainly cant see these high or low spots.

I figure I have made about 4 mistakes so far and none have cost me anything but more work. I made a cutting mistake with the jigsaw when removing the panels from the sheets, that needed filling and will need to be glassed over, I put way too much filler on the joins and this grinding error and I put the last temp bulkhead up in the wrong position which needed me to re position it. All up they have cost me about 5 hours work and a small amount of resin/filler wasted. I am sure there will be more mistakes like this, as there would be on any new thing but lets hope they are all minor like they have been so far.



I have an explanation of what the wombat junior wet out machine does if you click on the picture above or this link.

I have 2 days to sand 5 more joins (6 including the keel join). I think I can achieve this. I also still have spot filling to do. I will then go on my business trip and will be ready to tape the outside of the hull on my return. One more thing, I rang Hans today, who is building the same boat, he started after me but has now caught and passed me. He has used the same amount of resin and hardener that I have so we have either both used the wrong amount or both got it right. I think the boat is so easy to make to this point that we must have got it right.

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