As I wrote
here we decided for mushroom instead of dorade vents.
But how to do this? On the hand hand we want the drainage of the foredeck sealed from inside the cabin, but on the other hand we'd like to keep the 'dorade' boxes to accommodate the mushroom vents, to stiffen bulkhead 2, as a small storage space and for the look of the boat of course
Our solution is to guide the water through the 'dorade' boxes via short tubes. We looked at some options but finally decided for PVC tubes that are intended for plumbing installations and to glue them with epoxy. We know its not optimal, but we found some guidance
here. Moreover the famous 3M 5200 sealant does not seem to be available to the end-user in Germany (only from obscure sources). Our tubes have 16(13)mm outside(inside) diameter.
To get well aligned hole at both sides of the dorade boxes, I used a cheap 16mm HSS spiral drill of 40cm length (intended for formwork and installation, its basically a 10cm long drill on a long steel rod). Starting with 2mm diameter pilot hole(s), this finally worked out pretty well. Uff!
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Drilling through the starboard dorade box. The two chunks of wood prevented the drill from slipping off the fillet when drilling through the 2nd wall.
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A look through the boat. The holes in the side panels received a countersink shape at the outside. The idea is to have some sort of thickened epoxy ring around the outside end of the tube. If I was more courageous, I could have drilled the holes even 1 mm more towards the fillet between deck and BH2.
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The portside dorade box with tube installed.
Of course, all surfaces of the tube outside and holes inside were sanded, treated with alcohol and then received unthickened epoxy and finally thickened epoxy.
Will it finally work out? We will know next year maybe. At least the holes are above the waterline, all wood is sealed with epoxy and in the worst case we'll need to figure out plan B.