I'm currently fitting a holding tank and I'm generally happy about the plumbing except location of the 38mm open vent. Looking at the diag in PBO this month it seems this should be in the hull as high up as possible. (Presumably this dumps bad air over the side rather than rolling down the decks!) Even if I fit this just below the toe rail I'm worried what will happen when heeled over as my vent will be fwd of the beam. Any advice ?