PaulR
Well-Known Member
our boat has a stainless steel holding tank permanently plumbed into wc system - it has 3 connections - an inlet pipe from the wc , a breather pipe and an outlet pipe to the seacock - it does not have any deck pump out facility or access hatch and is a b to get to being high up inside a moulded heads locker.
over the years we have had our boat it has blocked perhaps 3 or 4 times (yuck) and has done so over past weeks on summer cruise - bit the bullet this weekend to tackle it and found blockage is caused by hard scale deposits that come to rest in outlet of tank and in conjuction with normal contents of a holding tank form a very effective plug preventing any waste from getting out via the outlet pipe/seacock,
managed to flush tank out this weekend (very yuck) leaving just these hard deposits which appear to be scale but some of the deposits are too big to come out through the holding tank outlet - ugh - with fingers I can feel the deposits at the top of the tank outlet pipe but cannot get a grip on them (is at end of my fingers reach having reached up the stub of stainless steel 1.5" pipe onto which the oulet flexible pipe fits) so my connundrum is how to get these out?
inevitably the tank is built into the boat and to remove it complete I suspect will be a major (and winter layup task) ,
my thoughts at the moment are :-
1. is there some sort of tool or gadget that I could use to reach up the outlet stub and grab - crush/break the deposits into small enough lumps that they can come out of the pipe? if so what ?
or
2. if I buy a length of flexible pipe and fit it to the stub and then bend it up so that it forms a u I could raise the end and then pour into it something (what?) to break down the scale lumps so that I could then lower the end into a bucket to empty the tank (bit concerned about pumping through the heads any aggressive chemical, any suggestions on what could be used to dissolve such deposits without damaging the stainless tank ?
or
3 last resort -have to either dismantle complete heads compartment to get tank out and then tackle it in relative comfort of home or did wonder if by removing backs of some lockers (grp moulded) I might be able to get access to the side of the tank and then cut and fit a waterproof access hatch so that either a solution could then be poured in through the hatch or a hand reached into (ugh again) grab and remove these scale lumps which seem to be settling on top of the outlet pipe - any thoughts on how difficult it might be to cut a hole in the side of a stainless tank in situ and what sort of waterproof hatch is viable to fit ?
or
4 any other ideas on how to solve this?
keen to tackle it asap as tank is now empty other than nice fresh seawater (definitely nothing ugh left in there)
over the years we have had our boat it has blocked perhaps 3 or 4 times (yuck) and has done so over past weeks on summer cruise - bit the bullet this weekend to tackle it and found blockage is caused by hard scale deposits that come to rest in outlet of tank and in conjuction with normal contents of a holding tank form a very effective plug preventing any waste from getting out via the outlet pipe/seacock,
managed to flush tank out this weekend (very yuck) leaving just these hard deposits which appear to be scale but some of the deposits are too big to come out through the holding tank outlet - ugh - with fingers I can feel the deposits at the top of the tank outlet pipe but cannot get a grip on them (is at end of my fingers reach having reached up the stub of stainless steel 1.5" pipe onto which the oulet flexible pipe fits) so my connundrum is how to get these out?
inevitably the tank is built into the boat and to remove it complete I suspect will be a major (and winter layup task) ,
my thoughts at the moment are :-
1. is there some sort of tool or gadget that I could use to reach up the outlet stub and grab - crush/break the deposits into small enough lumps that they can come out of the pipe? if so what ?
or
2. if I buy a length of flexible pipe and fit it to the stub and then bend it up so that it forms a u I could raise the end and then pour into it something (what?) to break down the scale lumps so that I could then lower the end into a bucket to empty the tank (bit concerned about pumping through the heads any aggressive chemical, any suggestions on what could be used to dissolve such deposits without damaging the stainless tank ?
or
3 last resort -have to either dismantle complete heads compartment to get tank out and then tackle it in relative comfort of home or did wonder if by removing backs of some lockers (grp moulded) I might be able to get access to the side of the tank and then cut and fit a waterproof access hatch so that either a solution could then be poured in through the hatch or a hand reached into (ugh again) grab and remove these scale lumps which seem to be settling on top of the outlet pipe - any thoughts on how difficult it might be to cut a hole in the side of a stainless tank in situ and what sort of waterproof hatch is viable to fit ?
or
4 any other ideas on how to solve this?
keen to tackle it asap as tank is now empty other than nice fresh seawater (definitely nothing ugh left in there)
