Converting Bilge section into black water tank

[BartW]

sequel on my thread about black water disposal,
Conclusion is that our black tank is too small,

Approx. 7y ago we have replaced the original SS black tank with a new custom made Plastic tank.
The space where that tank sits, the bilge under the utility room, is accessible and would be possible to convert in a closed tank.
With plywood panels, glassmat and epoxy
I could increase the capacity of our tank with at least / roughly 25% (>300l to >400l)

Some pictures of the tank replacement / available space in post nr 556 and 592:
http://www.ybw.com/forums/showthrea...ld-thread/page56&highlight=blue+angel+rebuild

Question is ofcause if the compartment can be made tight enough close to avoid leaks, and odeurs,
Or even liquids penetrating in the tank / boat walls.

Is plywood and epoxy good enough,
The main adjacent frame is fiberglass, with foam inside
The main adjacent bulckhead wall is plywood.

Advice ?


Its about time I can post some additions in my old rebuild thread ;-)

 

[nortada]

sequel on my thread about black water disposal,
Conclusion is that our black tank is too small,

Approx. 7y ago we have replaced the original SS black tank with a new custom made Plastic tank.
The space where that tank sits, the bilge under the utility room, is accessible and would be possible to convert in a closed tank.
With plywood panels, glassmat and epoxy
I could increase the capacity of our tank with at least / roughly 25% (>300l to >400l)

Some pictures of the tank replacement / available space in post nr 556 and 592:
http://www.ybw.com/forums/showthrea...ld-thread/page56&highlight=blue+angel+rebuild

Question is ofcause if the compartment can be made tight enough close to avoid leaks, and odeurs,
Or even liquids penetrating in the tank / boat walls.

Is plywood and epoxy good enough,
The main adjacent frame is fiberglass, with foam inside
The main adjacent bulckhead wall is plywood.

Advice ?


Its about time I can post some additions in my old rebuild thread ;-)

By default, many peoples already is!

 

[vas]

NO don't do it Bart, you'll regret it!

I bought a proper nice blue rotomoulded (iirc) tank with its own proper fittings, had it nicely rest in the bilge sitting on the frames under the one bed in the port cabin.
There was an annoying hint of smell (and often a not so minor stink) and only this summer managed to sort out odour leaks completely.
Culprit: ALL THE BLEEDING connections even the inspection lid ffs!

Starting with mat epoxy and plywood I can see things not going as planned and tiny leaks ruining your hols
With crappy el.jabsco style toilets and 6-7 onboard I can make two days on anchor before moving to the next anchorage giving me space to empty the tank in the open sea. Tank is 108lt only.

V

 

[petem]

Can you get flexible tanks big enough to do the job?

 

[vas]

Can you get flexible tanks big enough to do the job?

not sure, but then you'd need a big bugger hole (around 2inch!) at the bottom to empty the thing, that, I'd not like at all!
prefer a top outlet with a tube going down the tank.
Further, how would the sucking empty from the dock work in this case, I doubt it...

V.

 

[BartW]

NO don't do it Bart, you'll regret it!

Hi Vas, you know I take your advice very serious on this,
a slightly bigger custom made tank, like the one we have , probably is a better solution
lets see what other opinions come up

 

[BartW]

Can you get flexible tanks big enough to do the job?

Pete, you know we have experience with bladder tanks in the bilges for fuel,
I'm sure they are capable of holding toilet water, (I briefly considered them)
but its a bit of faffing, making it filling up the bilge completely (the bladder is fairly stiff)
and emptying it completely,
OK for occasional use as we do for fuel,
but not ok for daily use as a toilet tank
and then you also have issues with fitting the level and full sensors,
and multiple in and outlets...
no go

 

[longjohnsilver]

Hi Vas, you know I take your advice very serious on this,
a slightly bigger custom made tank, like the one we have , probably is a better solution
lets see what other opinions come up

Bart, to increase the capacity by only 100l is not worth it, imho,

I recall you saying that only allowed 3 days use. Surely you’d be better looking at way soon of at least doubling the tank size. And I certainly wouldn’t want to build such a tank myself, far better to get a proper pre made tank.

 

[vas]

Bart, to increase the capacity by only 100l is not worth it, imho,

I recall you saying that only allowed 3 days use. Surely you’d be better looking at way soon of at least doubling the tank size. And I certainly wouldn’t want to build such a tank myself, far better to get a proper pre made tank.

true LJS, but what needs to be demolished to get a nice new big tank in the bilges of BA???

Bart, I don't know recall the exact setup with all the toilets on BA, but would it make sense to use the existing tank for say 2 or 3 of them, and fit a new similar sized one for the other 2 or 3 or whatever?
Extra positive point that if something happens to tank or pump 1 you ask ppl to use the other toilets sending to tank2 until you fix it. Could also have diverter valves as well but probably a bit complicated...

V

 

[BartW]

its nearly impossible to find another decent space for a extra tank in the bilges,
tubes and hoses everywhere,
and the available space is needed for servicing many under the cabin floor junctions, etc..

keep in mind in that section of the bilge, right above the keel,
we have along the length of the boat, ao
50mm tube for collecting all the grey water, tank is in the engine room
50mm tube for black water,
quite a few 1" metal tubes coming from all bilge compartments,
and going to the bilge pump manifold in the utility room,

I did some further investigation:
the orriginal SS tank was 0.7 x 0.45 x 1.3m = 400l (outside volume)
the current tank is 0.7 x 0.3 x 1.7m = 350l

this tank
-sits on a 35mm wooden support that I could take out
-has a 35mm U/R space / floor above it,
I could make a new tank with a strong topplate that could serve as a U/R floor
-I can stretch out some more length,

so I could get in roughly 0.7 x 0.37 x 2m = 518l
I think that would be a big improvement.

I found the adress from Detlev, who made the current tank in spring 2013.
www.dlkunststofftechnik.de

one concern is that such a big tank can't get in that compartment in one piece,
so must be from 2 separate pieces, with a simple and leak free junction, ..
Have to talk and meet with Detlev about this..

 

[Bilgediver]

I would suggest you repost this on https://www.cruisersforum.com/forums/ and you never know who might come out of the woodwork with a detailed answer. Might even be The Headmistress. Peggie will no doubt come up with many answers including how to ensure that the tank is sufficiently vented or treated so that every flush does not send a foul smelling cloud of gas over the Poop Deck. Who knows you might finally be flushed with success

 

[longjohnsilver]

I would suggest you repost this on https://www.cruisersforum.com/forums/ and you never know who might come out of the woodwork with a detailed answer. Might even be The Headmistress. Peggie will no doubt come up with many answers including how to ensure that the tank is sufficiently vented or treated so that every flush does not send a foul smelling cloud of gas over the Poop Deck. Who knows you might finally be flushed with success

Does Peggie still post there? If so, that’s good news. She is THE expert!

 

[Bilgediver]

I think it is the only forum she monitors and would think she might respond to something like this. She is still in good form.

You are best putting question in the correct subsection.