Loop vents

[shorty]

20 year old boat, new to me. Today removed holding tank that had been installed w/diverter to seacock & no vented loop. Removing panels to access a place to mount a new vented loop, found the original one still in place. Loop was clear, vent of course clogged. Vent loop was tee'd into tank vent line w/1/4" hose, then out thru hull. The hose barb at the loop top only has a 1/16" hole. (This is a Wilcox Crittenden fitting.) Assuming I can adapt the right fittings could I, should I, have a bigger hole in the loop vent? I can't imagine a 1/16" hole staying unclogged for more than a month or two.Also, there was never a supply vented loop. I can fit one between the pump & the bowl but only get the top of the loop ~12" above waterline. It seems to me this would be preferrable to nothing because greatest danger is when the boat is on the mooring.Thanks in advance.

 

[Peggie Hall HeadMistress]

Vented loop shouldn't need a vent line

If you look carefully at that 1/16" hole in the nipple at the top of the loop, you'll see that it's threaded. There should be an air valve--a one-way valve that only allows air IN to break a siphon, nothing out--threaded into it. Air valves are sold separately because they have to be replaced every few years...you can order one from W-C. As for a vented loop on your intake, it should be at least 8-12" above the waterline at any angle of heel, not just when the boat is at rest. One that's only above the waterline when the boat is at rest will do to keep water from flooding the bowl while you're aboard in the slip or at anchor, but no vented loop should ever be relied on to protect your boat on a mooring, 'cuz vented loops cannot prevent the boat from sinking in the event of a hose connection failure. ALL seacocks should be always be kept closed when no one is aboard...seacocks left open are the #1 cause of boats sinking in their slips.