[bobmcgov]

We've added 31 gallons of water storage under the port settee, to bolster the standard 17gal tank waaaay far up in the forepeak. We intend to cruise our Albin Ballad in places where fresh water can be hard to come by. The tanks will connect to a Whale foot pump under the galley sink, stbd side. The V berth tank was originally plumbed down stbd, but it doesn't have to be. We'll also be carrying a couple jerry cans, usually full, in a lazarette.

The Ballad has a v.fine entry, so carrying 140# of water in the bow tank isn't ideal. The forward tank is quite a bit higher than the midships water tank. The big tank midships will be getting its own deck fill, possibly its own vent.

Should we:

1) Plumb the tanks independently, joining them at a T fitting (with shutoff valves?) just before the foot pump. That way, the water supplies are isolated from each other & we have control over which tank we use in what order.

2) Plumb the upper tank so it cascades right into the lower tank, ensuring we always & automatically take weight out of the bows first. Also, then the forepeak tank can have the sole air vent, which would spill into the anchor locker (low chance for damage.)

We'd like to able to fill both tanks at once, from a hose or possibly rain catchment on the side deck. Tho I guess that could be done with a mixing valve at the foot pump. No plans for pressure fresh water, dockside. Opinions?

 

[christian.hess]

Im a fan of separate simply from the point of view of contamination and or fouling from other sources

if one tank goes the other doesnt necessarily

fwiw

my current boat has t'd tanks and aI hate it..in fact the po singled out a bad tank in order to use the other...however the lines are still in and out of the bilges making for a mess of hoses and pumps etc...

 

[bobmcgov]

Should have included visual aids. Here:



Christian: I hear what you are saying, & that's a common argument for isolating tanks. But if we are in a place we can fill up, we're gonna fill both tanks from the same source anyhow. I guess rain catchment could be hit or miss re:contamination, and keeping the feeds apart might help with that -- IF we remember to turn the right valves when it starts raining.... But there again, we'd want to fill both tanks up with rain if possible. (BTW, we've lived off rainwater at our house for ten years, so we're pretty good at managing that game, taste- & safety-wise.)

 

[christian.hess]

ah that makes a difference my only point was that if for some reason 1 tank fails try to make it where the other wont be affected

if your comfortable with maintaining and observing rainfall and all Ill think youll be fine

a td filler hose is fine in my book...my issue in any system after the tank and before the outlets...

so in your case id go with oprion #1

cheers

 

[bobmcgov]

I do worry a bit about leaks, tho. If a hose or fitting in the lower tank failed, we could lose all of our tank water to the bilge before noticing it. (If the big tank itself leaks, it means we have been cut in half by a large freighter, so we won't be needing the water.:laugher)

 

[newhaul]

Separate the tanks using the tank in the bow last there is a reason the designer placed it there for balance that's 141 pounds in the bow helps the bow cut instead of ride over for a better ride and potentially better point of sail

 

[bobmcgov]

Separate the tanks using the tank in the bow last there is a reason the designer placed it there for balance that's 141 pounds in the bow helps the bow cut instead of ride over for a better ride and potentially better point of sail

Maybe in 1972, when weight in the bows helped your IOR rating. Hell, the Ballad's sibling the Scampi had its engine in the forepeak, to give it a bow-down trim for measurement purposes. But that's not a thing that concerns us. Weight in the ends is rarely good for sailing performance, full stop. The finer the ends, the longer the overhangs, the bigger the waves, the more destructive it is. We will be upsizing our ground tackle for cruising, so that bow tank becomes rather an issue on this boat.

 

[mitiempo]

I would plumb the tanks separately, for isolation in case it is necessary, for fore and aft balance when desired, and so you know when one tank is empty you have one tank left.

You will need a vent for each tank in any case as otherwise, filling from the bow first, the midships tank will take ages to fill and you may think it is full when it is not. The air the water displaces has to go somewhere.

Re balance with a water tank (or engine) forward, it evens out when the crew is in the cockpit.

 

[celenoglu]

Do both of them. All you need is some more valves. In case onemethod fails you can shift to the other method.

 

[Minnewaska]

We have two tanks that are completely isolated at a brass manifold, with ball valves for each. I like the isolation, so that there is no chance I lose all my water, due to a plumbing leak or tank failure. It could happen when ashore or asleep.

I always run the first tank to half empty, then switch to the second and run it dry, then back to the first. I do this, in small part, for weight distribution. However, it's more for supply management. When I get to that last half tank, I no longer have backup and have to be in a position to replenish in the near future. Up to that point, I'm pretty independent.

 

[Kencigler]

I know virtually nothing about sailboats (yet!), but here's what I do know:
Fresh water is a matter of life and death.
Ships always have multiple, isolable tanks to prevent cross contamination.
Carrying Jerry cans may be a sufficient safety margin.
If there is an unlimited budget, then the best of both is sufficient plumbing to have both.
Otherwise series is simplest. (I would put a ball valve on the outlet of the bow tank and the inlet to the salon tank for possible leak isolation.
As has previously been stated, you will need to vent the midship tank. And remember, the vent will need to be ABOVE the height of water in the (higher) bow tank when full.

Good luck!

 

[pdqaltair]

That nice fresh air in the anchor locker is now the air supply for your water tank. Many spiders in there? Consider a filter or strainer.

 

[bobmcgov]

I would plumb the tanks separately, for isolation in case it is necessary, for fore and aft balance when desired, and so you know when one tank is empty you have one tank left.

You will need a vent for each tank in any case as otherwise, filling from the bow first, the midships tank will take ages to fill and you may think it is full when it is not. The air the water displaces has to go somewhere.

Re balance with a water tank (or engine) forward, it evens out when the crew is in the cockpit.

Helpful points. We may be moving (if isolating tanks) or removing (if combining tanks) the deck fill for the forward tank. It's close to the forestay fitting, and roller furler/anchoring stuff is going to make it awkward to get to. Either way, when the forward tank is empty, it will vent the aft tank; when filling both tanks from the front fill, opening the lower tank's deck fill would create a vent.

Knowing when your tanks are approaching empty is a strong argument for isolating them. In a series/cascade setup, first indication comes when the foot pump starts blowing air -- and that means all 48 gallons is gone. Yeah, we might have another 10gal in jerries, but that would be an 'uh oh' moment. No dipstick or sight glass on either tank, so running them dry would be pretty easy. I like Minne's idea of working back and forth between tanks. We used to do something like that with water bottles, hiking in dry regions. When you are down to 4-5oz in the Nalgene on your hip; swap it for a full one out of the pack. Keeps you aware of how many full bottles are left, & if you run out of those before reaching a refill point, at least you've got 10-15oz reserve in partial bottles.

 

[eherlihy]

Isolate.

If you plumb them together, the green tank will be overfilled and water will enter the vent hose, when the pink tank is just full. You may find a leak at the access port (if you have one).

I am also a fan of isolation in case there is a leak in either the tank or the plumbing for the tank. If you loose one tank from a leak, and they are isolated, that's as far as it goes. If they're connected, you loose them both.

I also believe that it IS possible/probable that you may have have one tank contaminated, while the other is fine.

The final argument for isolating the tanks is (mentioned above) weight distribution.

In essence, if you plumb them together, you are creating one tank with a weird shape.

 

[christian.hess]

I agree on all points...think of them as water ballast too...

weve always had separate fill and empty tanks on well now 6 boats and for a all reasons mentioned

this is my first boat with td tanks and I hate it...mostly because if the mess of valves and hoses in the bilge from side to side

I am going the isolate way and using a separate filler and vent and outlet on each...

 

[bobmcgov]

Okay, y'all have talked me into isolating the tanks. I'd hoped to get off easy, but nooooo. The aft tank probably needs to vent in the former wet locker fwd, unless we put some kind of ball float check valve on it. This look about right?

 

[MarkSF]

Here's how my Bristol works :

The bow tank has the filler. It is isolatable from the tank in the keel. The keel tank has the vent, and all the connections to the pump etc. The vent has a loop, placed above the highest level in the forward tank.

In normal use (day sailing, overnight stays, etc.), I leave the forward tank isolation valve open.

If I were to do a longer passage, I would isolate the forward tank until the keel tank is empty. That way it functions as a reserve.

I'm in the process of running the keel tank vent to a faucet in the galley. That way any overflow when filling the tanks will pour harmlessly into the sink.

 

[GeorgeB]

Bob,
Can you give me a little of the backstory on your Ballard and your plans for her? Your signature indicates Wyoming, is that your cruising grounds? When I looked up the Ballard on the internet, most of the “hits” were for European boats so I am really interested in learning more about the boat (especially in installing an engine in front of the keel.)

In regards to the plumbing, I wouldn’t be surprised that separate tanks is a AYBC standard. Your main point of contamination is sea water going down the vent tube(s). The main source of leaking is loose hose connections. Is your plan to move both the fill and vent tubes to inside the cabin? (I have seen this on a couple of boats.) The problem of doing the cascading refill is the half inch hose connecting the two tanks. That would mean the bottom tank would fill only as fast as gravity feeds the water through the half inch line. The “city pressure” from the hose would constantly burble back the water in the fill tube. This set up would take multiple hours to fill and everyone waiting in line behind will hate you.

Without a sight glass or monitoring system, the only practical way of knowing when to refill is letting the main tank run dry and switching to the reserve and then proceeding to a fill-up. I’m not sure of your experience is for the boat or cruising but I think you are over thinking the fore-and-aft weight trim. Yes, when I race my “fatty Catalina”, my bow tank is empty (my stern tank too). The boat races better empty and light and has a better time in ocean swells. But when we cruise, a majority of the gear (and crew) are aft of the CB which gives us the stern-down, bow-up attitude. Because of that, I use my stern tank first.

I know from reading your other posts that you will most likely follow your own consul, which is fine. I am much more interested in knowing your back story and plans as we will most likely cross paths in the next couple of years and I’d love to meet up with you and say “hi”.

 

[svHyLyte]

I suggest you plumb each tank to a single T connector with a valves on each feed line so that you can choose which tank to draw from or both if you cared to do so. If you must have only a single deck fill, it would necessarily have to be led to the uppermost tank. Opening both valves in the feed lines will allow water to flow to the lowermost tank until its full at which point you'd close it's valve and continue filling the higher tank. To let you know when the lower tank is full, simply add a vent line whistle a short distance above the tank. When it stops whistling, that tank will be full and you can close it's feed line to allow the higher tank to fill.

I do not recommend fully depleting one tank before switching to the other. If one has been emptied, and the second develops a leak, you could be out of luck. Alternating between tanks every day or two ensures that there will be at least some water in one of them if one or the other leaks. (Note also, that, with a single fill, if the forward most tank does develop a leak, filling the lower tank could be problematic.)

Also, if you have not done so, it would be wise to plumb a small canister filter between the foot pump and the fixture on your counter top. Likewise, it is wise to carry a canister filter that source water is run through before being introduced to your deck fill. The amount of gunk they collect from dock-side water sources can be pretty astonishing. The canister can also be used to filter rain water or water that has to be jerry jugged to the boat by using a small submersible bulge pump in the bottom of a bucket to which rain water is directed or into which jugged water is decanted. (That pump should, of course, be dedicated to only pumping water into your tanks.)

FWIW,,,

 

[eherlihy]

Okay, y'all have talked me into isolating the tanks. I'd hoped to get off easy, but nooooo. The aft tank probably needs to vent in the former wet locker fwd, unless we put some kind of ball float check valve on it. This look about right?

Why make life difficult with hoses running all over the place?

Have the vent hose follow the fill hose (zip-tie them together) to just under the deck, and cap the vent with either a screen, or a wad of cotton pushed into the end of the hose.