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Old 21-02-2017, 01:53   #76
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Re: Gravity tank for fresh water - any experience?

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Originally Posted by Boston Blackie View Post
You develop develop a foot dither
Great term .

Foot pumps are hard to beat. As you note, you can dispense just a teaspoon of water if that is all that is required.

Importantly, this can be done leaving both hands free. In some conditions it is nice to have a hand free to hang on. You cannot hold a glass and operate a tap or hard pump with just one hand.

However, I am not sure foot pumps or any manual pumps are more reliable than electric pumps. Living full time on board we get an average of about 24 months out of Whale foot pumps. We have both salt and freshwater foot pumps and the life seems the same.

They invariably fail because the main diaphragm develops a split. Annoyingly, this means at the end of their life they leak while still appearing to function normally. The pumps are quick and easy to replace (at least on my boat) or rebuild if you prefer. But keep a lookout for the diaphragm splitting. The pumps are down at floor level so leaks can be easily missed.

As a side issue has anyone used one of these self contained battery operated water alarms?





https://www.bunnings.com.au/family-f...alarm_p4211048
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Old 21-02-2017, 02:09   #77
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Re: Gravity tank for fresh water - any experience?

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(...)



They invariably fail because the main diaphragm develops a split. Annoyingly, this means at the end of their life they leak while still appearing to function normally. The pumps are quick and easy to replace (at least on my boat) or rebuild if you prefer. But keep a lookout for the diaphragm splitting. The pumps are down at floor level so leaks can be easily missed.

Exactly what happened with the pump I rebuilt twice in space of few weeks. Obviously replacement diaphragm was not good quality. One of the malfunctions of this particular pump costed us quite a lot of water (pump was actually lower than a tank - another thing I learnt not to do )
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Old 21-02-2017, 03:52   #78
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Re: Gravity tank for fresh water - any experience?

I think you have been unlucky.

On our current boat the pumps are located above the level of the top of the tank. This is not easy to achieve, especially if you include all valves, joints in piping etc that are also potential sources of leaks.

Another helpful feature of our current boat is that bilges are always completly dry so even a small amount of water is an indication that there is a problem. However, a slow drip from the foot pump wets the plywood flooring in the galley cupboards before it finds it way into the bilge.

Given the mission critical nature of your endeavour, these features might be worth incorporating.

One advantage of an electric water pump is any leak will be revealed as the pump will audibly cycle when water is not being used. The same is true of an automatic electric bilge pump providing the bilge is normally dry.
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Old 21-02-2017, 04:35   #79
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Re: Gravity tank for fresh water - any experience?

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I think you have been unlucky.



On our current boat the pumps are located above the level of the top of the tank. This is not easy to achieve, especially if you include all valves, joints in piping etc that are also potential sources of leaks.



Another helpful feature of our current boat is that bilges are always completly dry so even a small amount of water is an indication that there is a problem. However, a slow drip will wet the plywood flooring in the galley before it finds it way into the bilge.



Given the mission critical nature of your endeavour, these features might be worth incorporating.



One advantage of an electric water pump is any leak will be revealed as the pump will audibly cycle when water is not being used.


On the boat which I was sailing then tanks were placed under the bunks and their bottoms were above the foot pumps - hence a problem with loss of water due to leaks.

On my current boat there are no tanks at the moment (I took away damaged one when I bought her). I plan on placing four tanks in the bilges (having long keel on full-bodied boat means I have a lot of space there ) so those will stay well below any eventual plumbing if I decide to go this route. So such a catastrophic loss of water should not happen in this case. But electric pump is still no. I'm warming up to the idea of the foot pump, but still some of my water stores will be in shape of bottled (6-8l each) water and those may be easier to use with a gravity tank.

So the idea gets a bit reshaped- foot pump (or an existing hand pump on the tap - Whale as well) to draw water from tanks below the cabin sole (unlikely leak if plumbing damaged) AND space I was talking about prepared as an emergency gravity tank if something goes horribly wrong with pumps. I start to like it

As I said, preparing this space as a tank is not a large expense or something which takes a lot of effort and time so I still can prepare it for future use but use foot/hand pump instead.

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(My hand pump currently in use)
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Old 21-02-2017, 05:24   #80
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pirate Re: Gravity tank for fresh water - any experience?

Hi Monika.. nice looking boat.
Also like your idea of a separate FW tank and the thought of that small amount of weight above the W/L would not worry me in the slightest as I used to carry 8x25L drums strapped on my side decks back when I cruised as a full time liveaboard.. 6 water and 2 of diesel.. rode out gales and big sea's in the Biscay and Atlantic with no problems.
To be honest I've found the waffle about the weight above the W/L folks have ranted about hilarious considering many have 15hp OB's and heavy RIB's etc sitting above deck level.. but I guess they figure you'll have all that junk as well making weight that much more critical for them.
For a simple rain catcher may I suggest a strong bucket with a tap fitted to the bottom and a hose long enough to reach a safe filling point (where sea water cannot sweep to). When it rains cant your boom with the topping lift by 10-15degrees.. allow a few minutes for the rain to wash the sail then hang the bucket below the gooseneck.. worked a treat for me crossing the S Pacific.. sadly I did not have the hose so used 2 buckets and was running back and forth every 5 mins switching buckets..
Best wishes for your Prep and even more for the Adventure..
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Old 21-02-2017, 06:00   #81
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Re: Gravity tank for fresh water - any experience?

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(...)

For a simple rain catcher may I suggest a strong bucket with a tap fitted to the bottom and a hose long enough to reach a safe filling point (where sea water cannot sweep to). When it rains cant your boom with the topping lift by 10-15degrees.. allow a few minutes for the rain to wash the sail then hang the bucket below the gooseneck.. worked a treat for me crossing the S Pacific.. sadly I did not have the hose so used 2 buckets and was running back and forth every 5 mins switching buckets.. (...):

Thanks... You just gave me yet another idea to consider. If I have already this spare tank (using foot/hand pump) I may easily connect it to any rain catching system (perfectly safe from sea water entering). Which will be also easy to empty to some spare cans from inside if I'm lucky enough to collect more water than it can hold.

It all comes together slowly team work works
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Old 21-02-2017, 06:20   #82
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Re: Gravity tank for fresh water - any experience?

We have a gravity water tank system on our boat.
I installed it for two reasons, one to add a bit more tankage and two to be able to measure our consumption.
We only have a ninety litre tank in the keel (supplemented with jerry cans) so adding the ten litre gravity tank helped.
When we need to know our consumption (on crossings or when away from regular water supply) we just count the number of refills which tells us what we've used.

The ninety litre main tank is supplied to the foot pump which pumps to the gravity tank and the outlet tap in the same hose line. This way only one hose is needed to the gravity tank as it supplies the tank when using the foot pump and the tap is closed. Open the tap and the 10mm (ID) hose then supplies gravity fed water through the 6mm tap via about two foot of head (ie the tap is two foot lower than the tank).
It's a little slow but good enough for us, and if it bothered me enough I'd change the hose and tap ID's to around 15mm.

It's a good system, a bit manual but works well and the foot pumps I use (Whale galley Mk3's I think) have been very reliable.
After a while I installed an inline electric pump on a switch (to save the foot pumping when filling the gravity tank) and to use the foot pump less. The system worked fine without it but the electric pump was left over so I put it inline and it works well. Except if we forget to turn it off and then the water overflows out the tank breather

FYI our consumption when cruising is about five litres per person but when doing crossings we average three litres each, six litres for the two of us. On crossings we use salt water for washing dishes (then rinse a little in fresh) and use some seawater when cooking the pasta etc. So your minimum consumption predictions are doable.

Consider rain catching methods like canvas along the underside of the boom (like an inverted sail cover). Once the salt water is washed away its a great way to top up the water tankage.
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Old 21-02-2017, 06:30   #83
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Re: Gravity tank for fresh water - any experience?

Haha Boatman got the rain catch method posted before me..

Our boat is only three and three quarter tonne designed displacement and the ten litres just under the deck head two foot off the centreline didn't make much difference at all to performance though we are cruisers not racers..
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Old 21-02-2017, 06:55   #84
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Gravity tank for fresh water - any experience?

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(...) So your minimum consumption predictions are doable.



From some of your comments it sounds like you are going in the Golden Globe perhaps?(...)..

Close enough. I actually had a thought about going the same route since I bought my boat and learnt about the connection to Suhaili. When McIntyre was announcing the new Golden Globe I was already preparing to my private race, having thoughts about organising of such race myself (mind you, I've even registered "Golden Globe Race" trademark ). I knew I cannot (and I didn't want to) compete with McIntyre in terms of popularising such an event and decided to go on my own - some of the restrictions of McIntyre's race are not for me.

I always wanted to check if I can sail on the same (close enough - same lines) boat faster than Suhaili 50 years ago, using modern technology- mainly communications allowing for getting real time weather forecasts.
My race is with Suhaili from 50 years ago and sir Robin if I can sail faster I'll be very happy indeed. If I manage to be faster than McIntyre's racers it will be added bonus, but that is not a main goal.

Main is make it back in one piece, with no outside assistance and faster than 312 days. Taking into account that this is 4kn average speed on almost 30k route - that is hard enough
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(Btw, this note in Yachting World about my project is not very precise - Sea Witch is not a sloop, she is a cutter, and fundraising campaign was done on different site. But still - they've got main points right ).

About water consumption predictions- they should be right, they're based on my experience. I do not use fresh water for washing up, don't need a lot for washing myself (I actually don't mind salt water with a little rinse of fresh water - cup is usually enough).
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Old 21-02-2017, 07:05   #85
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Re: Gravity tank for fresh water - any experience?

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(...).

Consider rain catching methods like canvas along the underside of the boom (like an inverted sail cover). Once the salt water is washed away its a great way to top up the water tankage.

I'm thinking about similar solution. Maybe also some kind of gutter on the edge of my new coachroof - after all that is over 8 square meters. I'm not sure about using a deck for that purpose
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Old 21-02-2017, 07:44   #86
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Re: Gravity tank for fresh water - any experience?

I would definitely put some effort into developing and testing a water collection system. In heavy rain you can collect a lot of water very quickly.

It is very often windy during the heavy showers so try and have a system that is still usable in high wind. On our current boat we have a very simple system that just involves putting a small sandbag behind the fill point. The only hi tech addition is a string tied to the sandbag so when the tanks are full the sandbag can be pulled away without going outside.

It works well and we are duplicating the system on our new yacht.
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Old 21-02-2017, 08:23   #87
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Re: Gravity tank for fresh water - any experience?

I like the idea of a gravity tank as it is simple and totally reliable. It only quits when it is dry.

We have a dedicated drinking, cooking water tank (50 gallons) and another for general use, (90 gallons) showers, washing etc. The drinking tank, is piped into the electric pump as is the other tank and is valve controlled to choose. Both are filtered going in by an RV type garden hose filter.

We simply installed a T take off between the tank and the pump. The take off line goes to another inline filter (SAWYER)(this is a backpackers filter, and is said to allow drinking from a mud puddle if needed and will process 100,000, gallons) (It is not fast but fills one gallon in about two minutes.) with a shut off valve. The filter and valve are gravity fed, as they are just above cabin sole height, about one foot below the tank. We keep two one gallon containers full with this filtered water and use them as needed for drinking, cooking, and coffee. Should we lose the pump we are still fine for the majority of our needs.

Our whole boat, where possible, meets the KISS concept. We enjoy basic simplicity to the max. Not much beats homemade biscuits from a kerosene oven.
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Old 21-02-2017, 08:23   #88
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Re: Gravity tank for fresh water - any experience?

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I would definitely put some effort into developing and testing a water collection system. (...)

It is very often windy during the heavy showers so try and have a system that is still usable in high wind.(...).

There is a reason why I want to finish all work by the end of summer this year. I need some time to test all solutions before going.

And "high wind usability" is behind thoughts of using coachroof for that purpose. On the other hand, my main stays on quite long time, especially that I changed it to a smaller one but still with three reefs.
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Old 21-02-2017, 08:40   #89
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Re: Gravity tank for fresh water - any experience?

Hand pumps.
Your going to have to pump to fill the day tank anyway.
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Old 21-02-2017, 08:54   #90
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Re: Gravity tank for fresh water - any experience?

We use a 35 l olive oil barrel as a hot water maker in summer. It is an imitation plastic olive oil barrel, food quality. I found the solar showers to hot and unhygienic. The imitation wooden barrel stands in front of the mast and is connected to the boats water system. It has a large filling opening, can easely be cleaned inside. The water from the barrel is hot but not burning hot. The barrel can feed by gravitation or by electric pump ( Shower ) Feeds to the shower or the internal tanks.
The barrel with its big filling opening is also used as a decanting vessel for water before it goes into the tanks. I am often surprised of what comes out of water taps in the Med. The barrel takes sand and calcium out of the water. Take off is 1” above the bottom.
We sail a classic so the barrel looks original. It is lashed to the front of the cabin on which stands the mast. Has never parted but receives a good beating from time to time. Not only waves but also the weight of the tank plus water bangs it against the cabin front in big seas and that resulted in a a few leaks. Repaired from inside with Sikaflex. The plastic barrel is not made for such a hard life.
The 35 litre extra is a plus, the big filling opening also since I fill almost only by ( clear ) jerry cans.
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