Dehler 34 Holding Tank

Sep 4, 2021
2
Dehler Dehler 34 Southampton
We have recently bought Peggy's book and have found it really useful.
We have a 1992 Dehler 34 which has a mysterious holding tank configuration that seems to be slightly out of the ordinary. It does not have a pump-out facility, it only has an inlet, outlet and air vent. The odd thing is that the air vent’s outlet is on or just below the waterline when moored up (seems to be sometimes on the waterline but mostly it seems to be below). We are not sure how the holding tank (which is above the waterline) is meant to be emptied if the air vent is under water, so not allowing any air into the tank. Do we go sailing and make sure that the air vent is above the water level by sailing with the boat heeled over? Or, will it only empty if we pump the toilet? To complicate matters we do not have a level gauge to tell us whether the tank is empty or not – so we have no idea if, after sailing with all seacocks open, the holding tank has in fact emptied or whether things are building up inside – a worrying thought! Dehler seem to have thought everything else through so well that we feel there must be something we are doing wrong here- can anyone advise? Please!!
 
Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
The owner's manual attached indicates you have a deck pumpout fitting (1) / (13). It appears the vent line (6) vents to the side oif the hull above the waterline?

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Attachments

Sep 4, 2021
2
Dehler Dehler 34 Southampton
The owner's manual attached indicates you have a deck pumpout fitting (1) / (13). It appears the vent line (6) vents to the side oif the hull above the waterline?
Thanks for the reply....
Our boat is older than the one described in the manual that you've uploaded. Our owners' manual is on the boat, so I've done a hand sketch of the piping. We definitely don't have a pump-out fitting on the deck, and the air vent is definitely below the water line, unless the boat is heeling to starboard. Not sure what Dehler was thinking when they designed this, but it looks like they fixed it in in the more recent boats.
 

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Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
I would install a deck pump out fitting with a hose into the bottom of the holding tank and reroute the vent line to vent above the waterline.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
It seems to be a rather small holding tank. The notes say it can be used 8 times before emptying. In todays world with no discharge zones this is going to severely limit its use. Also, the SS tank may become an issue.