Holding Tank Location - Advice please

[5teve]

HI All

Looking for some collective wisdom.

Our new boat has no holding tank (as was common in Aus in the late 90's) I want to get one in asap as most places we will end up are zero discharge and no point having the head if your not going to use it (this is of course me saying this prior to any kind of future maintenance!

I'm planning on disconnecting the existing outlet and having the system as a seawater > head > holding tank > electric discharge or pump out only and doing away with direct discharge as the chances of us ever using that are going to be slim - I may add a point where I can add a temporary fresh water input (from a separate temp tank) to aid with flushing tanks and lines when required.

Now my issue is that most Aussie boats are build with a mezzanine galley stepping down from the saloon and then down from there into the cabins. This leaves not a great deal of room under the floors near the head and inlet / outlet thru hull fittings., however toward the rear of the hull, aft of the engines / fuel tanks there is literally acres of room - ready positioned glassed in platforms just begging for stuff to loaded up on them - however this would require pipe runs to the tank and back again of around 8-9 meters each way (including through a watertight bulkhead). As the boat has just been lifted - I dont really want to be lifting again just to put holes at the rear of the boat (unless I can find a 1.5" thru hull already there - but sure there isnt! - other advantage of this would be the pump out thru hull isnt directly in front of the port engine intake - genius!)

What is the general consensus or remote tanks for this purpose? My gut feeling (scuse the reference) is that its a lot of water to be pumping to fully flush the pipes which would lead to needing a larger holding tank to cope with this and the possibilities of leaks will increase. Advantage is over this distance I could probably use rigid piping..

Thought please!

Steve

 

[mcanderson]

5teve,

Before we moved our old Beneteau sail boat from Edinburgh to the South of France I installed a holding tank. It was required by the port in France. Luckily our boat had had a holding tank installed when new (we were the second owners), but the removed. So I had deck fittings and a space where the tank was supposed to go. For the installation I used marine sanitation pipe as it will need to flex and having a leak wasn't a pleasant idea. I also diverted all black water to the tank as our port in France has a dockside pump out. However I also fitted a pump so the tank could be emptied at sea if required.

It took me two weekends to do, mainly because it was January in Edinburgh when I did it and the weather was bloody awful. I wrote an article for the Beneteau Owners magazine so I will try to find it and send you a copy.

I would rate the job 3/5 for difficulty, but once you get the pipe run and tank fitting location sorted out, it just a matter of getting all the bits and then getting stuck in.

My top tip would be measure pipe runs twice and cut once. It's very annoying to find a pipe that takes your 2 hours to run via almost inaccessible points is then 50mm to short.

 

[benchmark]

have you considered one of these?



http://www.nauticexpo.com/prod/raske-van-der-meyde/product-23391-130741.html

it is very easy to install and the waste tank wraps around the bowl, with the option of flushing to tank or flushing overboard if far enough out at sea. it is not suitable if 25 liters of waste is too small for you. I have the exact thing in my boat.

 

[Portofino]

Steve .
Do it properly .
You can have the tank in the ER and you should ,to get to it for sender maintenance etc .
You should fit a diverter seacock in the bathroom under a cabinet ( sink .?) for Sea and tank .manual pref for simplicity or electric depending on how much cash you want to throw @ this project .

Two issues spring to mind -depending on tank location relative to the bog height.
1- tank lower ie gravity will drain the piping ( long in your case ) from bowl to tank ,after macerator pump has flushed it
2- tank higher than bowl needing a sronger macerator pump and one way valve to stop seepage backfilling the bowl .

When I was scouting around boats a few years ago I did get inside a Riviera 42 ER and the tank was higher than the bathroom .So I know it can be done seen it .Ask contact them for the name of the kit they install .

Your tank needs 3 in /out 38 mm white sanitation flexible hose connections 1 air vent hose and a sender access .
One in from the bog -it should have has its own macerator cum pump .
One out to a deck fitting -for pump out
One out to a Jabsco back water pump (another macerator ) then I,am afraid seacock under water fitting @ the transom -for sea discharge .
Although you say you will never use it ,you really need that option and going fwds a buyers surveyor may pick up on its absence , and you never know if there will be a prob with pump out -two ways out better than one .
Vent pipe taken to the ER air inlet grills .
Tank guage wiring and Jabsco Tank to sea wiring taken to the control pannal in the saloon ?
You will also need power to the bowl for the macerator and the water solinoid (s) if fresh .

presume a sea water pump if using sea ?-but I would go for fresh every time .

As I said it all depends on the relative heights of bog n tank .

We have fresh water only flush and a bidet tap feature on the same bowl .TBH as a " hairy arsed bloke " if you know what I mean wearing mostly gauze linned Villebrequins -that's a useful feature .--sorry too much info

500 L fresh tank for two toilets ---seems ok for 4 pax living on board .
For hygiene it's possible to fit none return 12 mm normal plumbing valve s in the bog fresh plumbing if you are concerned about possible contamination of the fresh from bog ,but Remenber there is a air gap the inlet nozzles are higher than the bowl contents .Also you should dose the tank anyhow in the normal way .

Not a very good pic ours is between the engines in the depth of the V it's lower than the bowls -easy to do in my boat .

You can just see 4 x38 mm two bowls in ,one pump out to deck ,one going to the jabsco sea pump out .
Small one vent and just out of shot masked by the x section of wood the sender access .

Speak to Riviera 1st and get the name of there off the self kit .
I realise there are cost issues etc ,but comfort wise that ONE bog has to work for you .
No stuck unable to find a vac out dock discharge
No back flow of tank into bowl -at certain tight turns ,sea conditions etc
No potentially smelly and staining sea /river water in the bowl
As bigger tank as you can fit ---no worrying about how -when discharge -our is 500 L

Tecma do a nice range of E bog

 

[vas]

1- tank lower ie gravity will drain the piping ( long in your case ) from bowl to tank ,after macerator pump has flushed it

I'm on this and have the problem of smell on the heads due to pipes draining clean and letting the bowls work as vents
having the input to the tank on the top rather than the suggested (wrongly imho!) spot on the bottom doesn't help either.

Yes, I know shouldn't happen but I stupidly DIDN'T add a loop just at the back of the bowl so no water remains in the bowl after flushing. Got to rectify it this week, and will probably take me half a day to do as I have to lift all heads floors, dismantle a bed and generally move and remove various bits about.
So make sure you have a decent loop at the exit of the bowl just like normal household bowls do...

cheers

V.

 

[Portofino]

Yup good point find a place for a loop if poss .
We have fortunately no bad odours ,for what ever reason thus no need to comment much more .
I,am keen on plenty of marine toilet cleaners too .Currently "starbrite " as well more as a preventive measure .
Never really not used some type of stuff ,put it in 1st after tank discharge .
while I,am in goodie two shoes mode -unrelated to the post

Also put tabs in the fresh water
Anti diesel bug stuff in the fuel tank evey refill
Spend may be in season on those three discretionary additives €1-200 -- but my "man thinking "says they are worth it .
Never had any probs with any of the three fliuds ,fresh , black and importantly fuel .

 

[5teve]

HI Guys

Thanks for the responses will digest and reply back shortly - you are all very helpful of course - Mcanderson Thanks for the document - will read it shortly.

to give you an idea of the system i'll be installing - this is what I was envisaging

Toilet is there already and electric saltwater flush - cant put the wrap around tank in as its in a recess already - great idea so thanks Benchmark - but 25l wouldnt be enough (thats only a carton or 2 of beer!)

Portofino Thanks for the extensive post -

I have some room at the front of the engines - but it may block off easy access to the engine seacocks - Thats where I was originally looking as the pipe runs would be small (2-3m each) but relooking at it the easily available black water tanks here are over 1100 long but only 400 high and 360 wide - not a small tank. Custom jobbies are not easy to get either. I specifically want a dip tube tank with top access everything waste in and out at the top - breathers at the top. The standard tank i'm looking at has a large access port too should things get messy..

I'm not sure how much room is in the V but will check it out as its covered by board I'm fairly sure not much room but will see.

I want to minimise the number of valves hence I was going to scrap the direct discharge - the ocean is rarely calm enough to use the loo while underway - so i'd say the chances of using direct discharge would be maybe 1-2 times in a year.

The only Y valve I was planning on having (if I dont get 2 outlets) was the discharge pipe being split between pump out (even though there are no pump out facilities here i dont think) and macerator to sea... (via a vented loop? - not sure if it required as there isnt one currently - Guess it depends on the height of the tank vs waterline)

How long are your pipes Porto? I reckon that at 10m there is 8l of fluid in the pipes to clear them you would only get 10 flushes (in simplistic terms)

If I mount at the rear - routing the pipes will be pretty simple as there is heaps of room between and at the sides of the engines (even under) but its the length that has me worried. Its basically take the hard - squeeze the tank in job or the easy but far less sensible option of mounting toward rear.

Regarding flushing.. I'd love to go fresh water and probably could by just altering the plumbing and adding a fresh water tank specifically for the flush again it would have to be under the rear deck with extensive pipework.

I'll have a word with riviera and also take pics and draw something up of what I propose - we only handed over the money and bought the boat back on Sunday.

Steve

 

[Tranona]

Couple of observations.

Agree the inlet, pumpout and vent should be on the top with a dip tube for the pumpout. Would not have the pumpout connected to the main outlet as shown in your schematic. The outlet should be on the bottom immediately below the inspection hatch and a ball valve to shut it off before the macerator. If you have space underneath you might be able to do away with the macerator and just have a secock to empty by gravity. You can leave this shut except if you want to discharge at sea. Being immediately below the inspection hatch you can access it to clear if it gets blocked.

My last boat had a remote tank across the other side of the boat in the original design, but the though of 4m length of sewage running under the saloon plus the complexity of pumping was not a good idea so we ordered the boat without it and fitted a gravity tank. This type is very common on production boats now, but not easy to retrofit. However the way you describe your boat a simple system should be possible and should work quite well if you put a loop in the hose after the toilet and run the hose/pipe downhill to the tank. don't forget to use proper sanitation hose.

 

[5teve]

Couple of observations.

Agree the inlet, pumpout and vent should be on the top with a dip tube for the pumpout. Would not have the pumpout connected to the main outlet as shown in your schematic. The outlet should be on the bottom immediately below the inspection hatch and a ball valve to shut it off before the macerator. If you have space underneath you might be able to do away with the macerator and just have a secock to empty by gravity. You can leave this shut except if you want to discharge at sea. Being immediately below the inspection hatch you can access it to clear if it gets blocked.

My last boat had a remote tank across the other side of the boat in the original design, but the though of 4m length of sewage running under the saloon plus the complexity of pumping was not a good idea so we ordered the boat without it and fitted a gravity tank. This type is very common on production boats now, but not easy to retrofit. However the way you describe your boat a simple system should be possible and should work quite well if you put a loop in the hose after the toilet and run the hose/pipe downhill to the tank. don't forget to use proper sanitation hose.

I believe the pumpout on the same outlet is pretty common hence the Y valve - but if the tank has the outlets then I'll keep them separate as it saves a Y valve.

The outlet on the top with a dip tube for the macerator is also something I see recommended as you can change the pump without having the tank empty - unless of course the macerator is placed above the tank level - this is why i'm thinking along these lines plus you dont need the valve then. As i'm using existing thru hulls - gravity wont be an option unfortunately!

The more I think about it the closer I think I have to get the tank to the head i'm with you and dont like the idea of m's of pipe full of nasties..

Steve

 

[Portofino]

About 5 M the main bowl .Pipe runs under gally cabinetry through a water tight bulkhead in the ER .
ER is in an old school position in the centre of the boat cog wise .
As I said its gravity fed -cos the tank is set low. There must be some sort of u bend near the bowls .
1-2 flushes or maybe a 3rd for a no two is all thats needed
I don,t think L is an issue if there is a gentle gradient down from the bowl u bends if there is one ?

I would avoid a Sealand Vacuflush ---- if you can --others hopefully will be along soon to 2nd that comment.

 

[Forty_Two]

HI Guys

Thanks for the responses will digest and reply back shortly - you are all very helpful of course - Mcanderson Thanks for the document - will read it shortly.

to give you an idea of the system i'll be installing - this is what I was envisaging

Toilet is there already and electric saltwater flush - cant put the wrap around tank in as its in a recess already - great idea so thanks Benchmark - but 25l wouldnt be enough (thats only a carton or 2 of beer!)

Portofino Thanks for the extensive post -

I have some room at the front of the engines - but it may block off easy access to the engine seacocks - Thats where I was originally looking as the pipe runs would be small (2-3m each) but relooking at it the easily available black water tanks here are over 1100 long but only 400 high and 360 wide - not a small tank. Custom jobbies are not easy to get either. I specifically want a dip tube tank with top access everything waste in and out at the top - breathers at the top. The standard tank i'm looking at has a large access port too should things get messy..

I'm not sure how much room is in the V but will check it out as its covered by board I'm fairly sure not much room but will see.

I want to minimise the number of valves hence I was going to scrap the direct discharge - the ocean is rarely calm enough to use the loo while underway - so i'd say the chances of using direct discharge would be maybe 1-2 times in a year.

The only Y valve I was planning on having (if I dont get 2 outlets) was the discharge pipe being split between pump out (even though there are no pump out facilities here i dont think) and macerator to sea... (via a vented loop? - not sure if it required as there isnt one currently - Guess it depends on the height of the tank vs waterline)

How long are your pipes Porto? I reckon that at 10m there is 8l of fluid in the pipes to clear them you would only get 10 flushes (in simplistic terms)

If I mount at the rear - routing the pipes will be pretty simple as there is heaps of room between and at the sides of the engines (even under) but its the length that has me worried. Its basically take the hard - squeeze the tank in job or the easy but far less sensible option of mounting toward rear.

Regarding flushing.. I'd love to go fresh water and probably could by just altering the plumbing and adding a fresh water tank specifically for the flush again it would have to be under the rear deck with extensive pipework.

I'll have a word with riviera and also take pics and draw something up of what I propose - we only handed over the money and bought the boat back on Sunday.

Steve

Two things. You want to make your vent no5 the same size as the pump out otherwise there is a risk of collapsing the tank, pumpouts can be fierce & also consider a rinse deck inlet, only needs to be a thin line to the tank top at the opposite end to the pumpout fittings.