Water reserves during passages; emergency desalinators.

[Jammer]

In another thread, there is extensive discussion of an emergency during a crossing brought about by engine failure on a smaller cruising catamaran equipped with a watermaker that could only be powered by the engine. While the boat was capable of sailing, low water reserves led to a decision to seek assistance in an unfriendly port.


It is my understanding that weight is limiting for many smaller cruising cats. The performance, handling, and safety effects of carrying extra water must be balanced against the risk of failure of the RO system or its power source. I note that backup and emergency RO and desalination systems are cost prohibitive for many low budget cruisers. I further note that rainwater catchment systems usually require modifications to the boat as well as practice to use, and that they have fallen out of favor.


I would be interested in understanding the emergency freshwater strategy used by sailors who are planning for or have completed long crossings, particularly those on smaller catamarans where a large freshwater reserve is impracticable to carry.

[laika]

A small handheld manual WM isn't necessarily cost prohibitive. Used Katadyn 06s and 35s can be bought used for a fraction of the price of new. You will likely just need a new membrane for it. All in, maybe a couple hundred dollars then for an 06.

On our 27' with limited tankage we have a Spectra Cape Horn X as well as a Katadyn 06 in our ditch bag. We test, flush and re pickle the Katadyn annually. The Cape Horn has redundancy built in, with dual feed pumps, plenty of spares, and can provide us with enough water off just solar alone.

We think this setup is nearly bulletproof. If we were contemplating an ocean crossing however, we would likely develop a solid rain catching system in addition to the above, and possibly consider upgrading the Katadyn 06 to a 35.

Others will surely have differing levels of risk tolerance.

[BillKny]

I think too many people cut the reserves too fine.

On our current boat we have a watermaker, AND a 1000 liter tank. We keep the tank nearly full all the time. Being just a LITTLE careful we can stretch 1000 liters out for nearly 90 days. Being REALLY careful would bring us to 120 days. The extra backup is 10 gallons in jerry jugs, just in case...

On the old boat we carried about 280 liters divided between two identical tanks. We sailed from San Diego to Hawaii and were within site of the islands after 17 days when we switched to the second tank.

Anybody who has a "water emergency" is guilty of bad decision making, bad planning, or something similar.

I don't see it as being a question of risk "tolerance" but rather just normal good seamanship to have a backup plan to something so critical.

[Dsanduril]

Our cat has a water tank in each hull. The watermaker feeds the port tank, we generally sail with the starboard tank empty. Before embarking on a long passage we make sure the starboard tank is clean and fill it with clean, good water. That is our reserve. Yes, it is extra weight, but well worth it. If we ever have to switch to reserve (we never have - knock on wood) there is enough there to last a couple of weeks or more at drinking/cooking only rations.

We also have other liquid aboard suitable for hydration (and some that does dehydration ) and we have a water catching system that cost almost nothing (the hardtop over the cockpit) and can be quite productive in even a gentle rain (if/when it rains). We also have emergency stores of water with the ditch bag, and more in the raft and raft packages.

Then we have a little copper coil that can attach to the vent on the pressure cooker, it can actually be quite productive of distilled water so long as we have stove heat available. Tried it once or twice just for fun, have never had to use it in earnest (and hope we never have to - it is one of those mystery boat bits that you sometimes find aboard, wonder what it is for and whether or not you should keep it).

I can't really imagine starting out on a passage without enough water on board to make it to the other end, albeit at minimum rations.

[BillKny]

Originally Posted by Dsanduril

I can't really imagine starting out on a passage without enough water on board to make it to the other end, albeit at minimum rations.

I SOOOO agree! I get if you are racing and risking your life to beat the other guy, fine pare down the water, but setting out on a 3 week passage with 5 days worth of water, for a cruiser, just seems irresponsible, and unnecessary.

Our watermaker is a very important lifestyle improvement tool when we are at a destination, not at all as a way of surviving a passage.

[wingssail]

Originally Posted by Jammer

In another thread, there is extensive discussion of an emergency during a crossing brought about by engine failure on a smaller cruising catamaran equipped with a watermaker that could only be powered by the engine. While the boat was capable of sailing, low water reserves led to a decision to seek assistance in an unfriendly port.


It is my understanding that weight is limiting for many smaller cruising cats. The performance, handling, and safety effects of carrying extra water must be balanced against the risk of failure of the RO system or its power source. I note that backup and emergency RO and desalination systems are cost prohibitive for many low budget cruisers. I further note that rainwater catchment systems usually require modifications to the boat as well as practice to use, and that they have fallen out of favor.


I would be interested in understanding the emergency freshwater strategy used by sailors who are planning for or have completed long crossings, particularly those on smaller catamarans where a large freshwater reserve is impracticable to carry.

In my view a vessel which cannot carry enough fresh water for the crossing is unsuitable for ocean passages. Depending on the RO is foolish because they do fail.

If you calculate the minimum quantity of water needed for a conservative passage duration and you can carry that, preferably in two or more tanks, then with a working RO system you can use water that you make freely knowing that the tankage will be there if the RO fails.

For example taking 3lt per day per person for a 30 day passage with two persons, (1.6 gallons per day) you need 50 gallons of fresh water on departure. If you can make 2-3 gallons a day, or even 5 gallons, then you have plenty of water that can be used freely and still keep your tankage in case the RO fails.

We use approx 5 gallons per day (cooking, washing, drinking water and showers) and we carry 145 gallons of fresh water in four tanks. We supplement that with 1.5 gallons per day from our PUR 35 which is only running when the engine is running. This gives us capacity for over 30 days. Our longest passage was 25 days. If we found outself facing a longer period at sea we could reduce our consumption to under 2 gallons per day.

[Dsanduril]

Originally Posted by BillKny

...
Our watermaker is a very important lifestyle improvement tool when we are at a destination, not at all as a way of surviving a passage.

exactly

It improves our lifestyle on a passage as well as we bathe more often than we used to, but that is not strictly a requirement for getting to the other end (although the officials when we check-in may appreciate it).

[PirateGuy]

[=Dsanduril;3329128]
Then we have a little copper coil that can attach to the vent on the pressure cooker, it can actually be quite productive of distilled water so long as we have stove heat available. Tried it once or twice just for fun, have never had to use it in earnest (and hope we never have to - it is one of those mystery boat bits that you sometimes find aboard, wonder what it is for and whether or not you should keep it).

I can't really imagine starting out on a passage without enough water on board to make it to the other end, albeit at minimum rations.[/QUOTE]

That’s a nifty little device to have onboard. You could even make your own distilled spirits from spoiled fruit.

[stormalong]

On very long passages I have both full tanks and dozens of 2 liter pop bottles filled with water. The 2 liter are small enough to be stored in the unused nooks all over the boat, including in the bilge.

[DMCantor]

I met a crazy French sailor in the Caribbean, who had an enormous ketch. I think the bow must have been nearly 20 feet above the water line. Anyway, he single-handed it across the Atlantic. Took him, he said, 120 days. But he never worried about water with his 5000 liter water tank.


We carry a Katadyn 06 in our ditch bag, have never had to use it, thank God. We are religious about pickling it at least annually.

[zstine]

Makes you wonder about the Vendee Globe going on now... 80 days+. Do they have stores for that time or do they rely on multiple RO backups?


I tend to agree for recreational boats, if you don't carry enough water stores when you leave to make your destination, then the boat is not properly equipped for that passage. Of course "tanks" can be bottles of juice, shelf-stable milk, jerry cans, etc. It doesn't all have to be (actually should not be) water in the boat's tank.


That said, I would accept an RO system in lieu of 'full tankage' provided water stores for ~60% of the trip where on-board. In that case, if the RO fails at any time you can turn back or make the destination.

[roland stockham]

You can very easily make a rainwater collector from a tarp. Just cut a hole in the center and use a one of the snap together hose fittings. The ones designed to connect to a tap come with adapter rings for different tap thread sizes and you simply use this ring to to sandwich the tarp. Works better if you can add a couple of large fibre washers as well. Then you simply hang the tarp in the rigging and clip a hose to the filling leading to some 5gal jugs. Easy to take into a life-raft as well!

[meirriba]

We crossed the Atlantic on a boat without a watermaker.
At start from the Canaries, we had full tanks and filled almost every free space on board with 5liter bottles.
Calculation was water for daily cooking & drinking, weekly shower. Estimated time for crossing was 19 days (actually took 20) and water onboard was calculated to suffice for 30 days at the calculated use rate.
It worked, and we have arrived at St. Lucia with the calculated spare.

[Scubaseas]

Don't forget your water heater is full of water even when the pump runs out.

[meirriba]

Following on the above.
If you do have WM onboard, I think, that you should always keep enough water in your tanks/water bottles that will bring you to your destination on emergency rations.
I.e. you should use mainly water produced by the WM and deplete the tankage keeping it at the emergency level described above.
Of course handheld WM is nice to have in your ditch bag. Nothing better to do in a liferaft than making water to drink...