Welcome to the Dribble
I have a similar problem on my 1978 H27.Last year some water was left in the cocpit drain lines over the winter. The water cracked the brass T that connects starbord floor drain to the rear lazarette and the stern drain. This reduced the water in the bilge by 90%. I noticed that the hoses were pretty brittle and they could also leak a bit.I solved the ice box drain by using a portable chest. I have 2 leaks in the non opening ports (I think) , port and starbord drip a small amount. Short of removing the portlights I can't seem to stop the leak. Next years project is to remove them and rebed the units. I'm afraid that once I pull them out they will need to be totally replaced. Since the cabin liner is molded you can't relly tell where the leak is.I noticed a small leak in the cockpit wall where my depth sounded, Knot meter and compass were mounted through the wall. I re-beded them and solved that problem. There is a small amount of dripping from the shaft seal- normal- but it only drips when the shaft turns.I'm going to try the to tighten the rail bolts (from the inside to see if this helps, I hadn't thought of that.)Here's to Dry sailing.............If I can't find the leaks, I'll justremember to "wisper" vermouth over the gin. but only while in port. Not that's dry.Hope it helps.