What is Adequate Tankage Capacity?

[hellosailor]

Maark-
Your best bet is to make some plans and take some notes, then come up with your own water, fuel, energy budgets. On a boat, I can make do with "Navy" showers, i.e. wash up with salt water and then just rinse down with thirty seconds of fresh. (And if you don't heat it, somehow the rinse always get faster.(G) At home? I'd like to skin someone alive for requiring "conservation" showerheads. I want gobs of water for five minutes, I'm not allowed to get that from one showerhead. But someone else who takes a half-hour long shower and uses twice as much water...somehow is allowed to do that?


Same with fuel. You may want to run 1500 rules like Dockhead, or, just to carry the "48 hours against headwinds" that some offshore racing rules would require. When you make dinner, do you boil water for pasta? And use the stove, plus another burner? Or just make a simple meal-in-one? How much you need is a fairly personal number, but if you start to take notes and work up your own numbers, there's no mystery for what will work for you.
Fuel, water, energy...Sure, but don't forget the toothpaste and toilet paper!(G)

[barnakiel]

We are in a sailing boat so diesel is not relevant here.

Water is another story. I think one can't have too much. Most cruisers opt for small tanks and big watermakers. This is good. I think one month of water independence is an absolute minimum for a long range adventure. Our water tankage is about 50 gallons, but I would love to have well in excess of 100 gallons water tankage and a watermaker on top of this.

Gas we do not have as we row our dinghy.

LPG is another major thing, unless you cook on diesel or on an electric stove /oven. We carry some 5 gallons of LPG. This is roughly 6 months of cooking in the tropics.

So, in short, max water and LPG, diesel only if you cook on diesel or else if your boat sails like a tub ... or else - when you have a genset. ;-)

We are two onboard. This is a small boat. Very small, by your standards.

Cheers,
b.

[TrentePieds]

Quote: "Did you make a solar still? It's not so simple, but I am trying to achieve 1 liter per hour per sq m which should be easily doable."

Of course it's simple. Baden-Powell taught us how. Plain ordinary "fieldcraft" in the old days, just like crossing streams using corracle and jack line :-)

You don't NEED a litre per hour. As I said, what you NEED is 1/4 litre = 250 cc per man per day, or 10 millilitres per man per day. What you WANT is a whole different story :-)

Here on the Wetcoast, I don't need a solar still, but would you accept a pot still for making screech? Your local hardware store has all the makings. It's the mash tun that's would be the tricky bit for making screech at sea, not the still.

TrentePieds

[DMCantor]

How much do you use, and how often are you willing to fill up? We cruise in the Caribbean for 5 months a year. Our diesel usage is just about 100 gallons a year. We carry 200 gallons of diesel, and I worry that the fuel gets too old before we use it. Fuel is easy to come by, so having to top up a couple times a year wouldn't be a hardship. If you are making long passages where you need to motor hundreds of miles, its a whole different story.

Propane: We carry 2 twenty-pound bottles, but have never used more than one in a season.

Water: We generally use about 10 gallons/day, more on the days we run our washing machine. This is very generous, we could get by on half that if we needed to. Our boat carries 200 gallons in two tanks, but we generally just use one for daily living, saving the other for "just in case." We have a 13 gal/hr watermaker, and run it every 4-5 days to refill the tank.

I think a lot depends on where you cruise. In the Eastern Caribbean, it is never far to a fuel dock, where you can also fill your water tanks. It becomes more an issue of convenience. In other parts of the world, tankage is a much bigger issue.

[Paul L]

Originally Posted by Dockhead

This is kind of a "how long is a piece of string" question, but for whatever it's worth, I have:

700 liters of diesel fuel
1000 liters of fresh water
20 liters of dinghy fuel
2x 4.5kg bottles of LPG for cooking

Of these:

1. The fuel is enough on our boat (54', 25 tons all up, 100hp diesel, plus 6.5kW generator and Eberspacher heating) to get us 1500 miles from the UK to Finland over a month, and still last for another month of cruising. Not motoring the whole way of course. I wouldn't want less, but I don't really need more. Autonomy with fuel is very important especially when you are generating electrical power and heating with it. We use fuel carefully -- so when motoring or motor sailing, usually under 2000 RPM. If you motor hard, against the wind, etc., the consumption goes up geometrically and 700 liters wouldn't be so much. Fuel capacity is also useful for taking advantage of differences in price in different countries -- like in Europe. Diesel fuel at some times has cost half in Guernsey, compared to what it costs just a few miles away in France, just to name one example. So with big tankage which lasts you for a month or two or three, you can take advantage by buying a big load where it's really cheap.
.....r.

Definitely agree, being able to fill in places where fuel prices are low saves a lot

[denverd0n]

Originally Posted by TrentePieds

You don't NEED a litre per hour. As I said, what you NEED is 1/4 litre = 250 cc per man per day...

This is a minimal amount. You can live on that for quite a while, if you want. As you said, what you WANT (what most people will WANT) may be very different.

Most experts suggest that to maintain good health, over the long term, an average human needs about a half a gallon (~2 liters) of liquids per day. That's just for consumption. You will probably want to do at least a little bit of washing and/or rinsing with fresh water.

My own conclusion, for my wife and I, is that we should have a minimum of a gallon per person, per day, for the longest time that we think we will have to go without replenishing. This amount would require being careful with our water usage, but nothing like extreme rationing.

A watermaker is a useful thing, of course, but remember that anything mechanical is liable to breakdown--usually at the worst possible time. If you are halfway into a 30-day passage when your watermaker stops working, will you have the tankage to comfortably make it to your destination? Or are you going to have to immediately go into extreme rationing mode? Something to consider.

Good luck.

[TrentePieds]

Re #21

Of course. I agree absolutely with everything you say. My stressing the difference twixt needs and wants stemmed merely from my bemusement that there is even a need to ask a question about "enough" tankage. Bei mir, the answer to such a question is self-evident.

TrentePieds carries a mere 120 litres (35 or so gallons) of water, about four days worth for the two of us if we are moderately parsimonious. But here in the Salish Sea you cannot turn around without bumping into a marina with, generally, excellent facilities, so pressing up in never an issue.

Diesel tankage is a modest 40 litres (10 gallons more or less), enough for about 20 hours of steaming. "Down this end", south of Johnstone Strait, the longest haul twixt fuel docks is about 6 hours.

So do I have "enough"? Yes, clearly. But only because TrentePieds will never be doing any blue water work. So it comes back to the ancient question: Is the vessel "fit for her trade". And that, when speaking of tankage (including electrical "tankage"), can only be answered through defining the vessel's "trade" — and then "doing the math"!

Bei mir, noone is ready for skipperhood until that is self-evident :-)

TrentePieds

[seandepagnier]

Originally Posted by barnakiel

LPG is another major thing, unless you cook on diesel or on an electric stove /oven. We carry some 5 gallons of LPG. This is roughly 6 months of cooking in the tropics.

I can cook a meal on 8 amp hours (12 amps for 40 minutes) with my homemade electric cooker.

So, in short, max water and LPG, diesel only if you cook on diesel or else if your boat sails like a tub ... or else - when you have a genset. ;-)

I don't understand why people use LPG. I guess the same reason they use engines?? For so many reasons it's a bad idea.

I have been cooking on wood for years it's great, even on passage.

One of my long term goals is to produce wood gas say once a week filling a bag, then using it for cooking. In theory you can do it from human waste which would eliminate gathering firewood (though I am still burning wood I got in the philippines)

I burn about 1 handful of small twigs to cook a meal. I use also a small 12 volt computer fan to increase combustion efficiency, and the cooker itself it insulated so that all the heat goes into the food, not escaping out the sides or top wasting it like most gas stoves do.

In fact I can simply use 1 or 2 candles instead of wood and it will cook fine because my cooking (for electric also) are more than 10x the efficiency of a gas burner.

Originally Posted by TrentePieds

Quote: "Did you make a solar still? It's not so simple, but I am trying to achieve 1 liter per hour per sq m which should be easily doable."

Of course it's simple. Baden-Powell taught us how. Plain ordinary "fieldcraft" in the old days, just like crossing streams using corracle and jack line :-)

You made this solar still and use it regularly on your boat? I did use a simple one on passage but it made 1 liter per day which isn't very good, but I don't like because the water tasted like the plastic it was made of.

The typical solar still design isn't efficient because the water droplets that form reflect the incoming light, and they are air cooled.

A still which uses a small fan to circulate humide hot air into a condenser which is water cooled will be both smaller and yield far more water. Multiple effect units are also possible to improve efficiency further.

I have read claims of 50 liters per square meter per day using these more complex designs.

You don't NEED a litre per hour. As I said, what you NEED is 1/4 litre = 250 cc per man per day, or 10 millilitres per man per day. What you WANT is a whole different story :-)

Is this some kind of "survival" ration?

You need to be able to bank and store the water on days with overcast. I have plants to water (right now my yam is about 6 meters long and running around the deck keeping it cooler by shading it), skin to wash etc. I am healthy with 2 liters a day, and healthier with 4 liters a day.

If I have 1/2 square meter still, I would get half a liter per hour, and lucky to achieve 3 liters per day. This is barely sufficient and doesn't leave much for banking water.

Here on the Wetcoast, I don't need a solar still, but would you accept a pot still for making screech? Your local hardware store has all the makings. It's the mash tun that's would be the tricky bit for making screech at sea, not the still.

TrentePieds

I don't know what you are talking about screech. Is that moonshine?

Originally Posted by denverd0n

This is a minimal amount. You can live on that for quite a while, if you want. As you said, what you WANT (what most people will WANT) may be very different.
...
A watermaker is a useful thing, of course, but remember that anything mechanical is liable to breakdown--usually at the worst possible time. If you are halfway into a 30-day passage when your watermaker stops working, will you have the tankage to comfortably make it to your destination? Or are you going to have to immediately go into extreme rationing mode? Something to consider.

Good luck.

I don't have a watermaker and have never relied on a solar still and I carry 40 liters of water. I never ran out. I left vanuatu with 20 liters and arrived 4500 miles later with 40 liters in the philippines. I didn't even try to catch most of the rain.

[TrentePieds]

Quote "I don't know what you are talking about screech. Is that moonshine?"

Yes, "screech" is, however, made on a molasses mash. I believe "moonshine" is made on the dreaded maize mash. Screech has, AFAIK, a somewhat limited range that doesn't reach south of 49ºN.

Quote: "You made this solar still and use it regularly on your boat?"

Whyever would I do that when, as I have carefully explained, where I sail, you can't turn around without by bumping into a marina with more wholesome potable water than you could possibly want? Free for the asking, too!

I think you missed my essential point that beyond the minimum requirement dictated by biology and environment, additional consumption is mere UNNECESSARY profligacy. So far, we have no laws against profligacy, though as a child of one "welfare state" and a proud and contended citizen of another, I've argued for such laws all my life.

So in the end, you and I are very likely, methinks, to be in accord ;-)!

And yes, I was talking survival, and as I pulled the lanyard on the message you quote, I noted as it left the barrel that I had "misspoken myself". Obviously the 10 millilitres is NOT "per day" but rather "per hour".

TrentePieds

[Scott Berg]

I'll play...
Our 60' ketch (45t) has significant tankage:

Fuel: 2200L in 3 keel tanks and a day tank
Water: 2000L in 3 keel tanks (plus a watermaker)
Propane: 2 20# bottles
Dinghy Gas: 2 20L Jerry Cans plus 1 20L and 1 10L outboard tank

We heat with diesel

Range under power@ 7kts: 2200km

We fuel when it's cheap, polish as needed with built in system, transfer between tanks for for and aft trim. Water use is moderate but we do everything with fresh water from flushing heads to washing dishes.

This is a very long way from my 30' yawl I started on in the mid 80's! She carried 100L of water and 50L of fuel (and an alcohol stove)

Every boat is different but we love the options this gives us and the winter heat in cooler latitudes is wonderful!

[DDabs]

40' monohull

180 gallons of fuel
200 gallons of water
100 gallon holding tank

All tanks are located in the floor and act as collision bulkheads.

I love the large tanks and there are good inspection ports in the floor as well for cleaning. I would love a water maker.

[S/V Reveille]

Thanks to everyone for replying. A wide range of answers, but as always, very helpful, and much appreciated.
Mark

[valhalla360]

Even at dockside, we run off the tanks and 60 gal of water is usually good for about a week with no real effort to conserve (2 people). If we made even a modest effort, we could easily double that time and not go thirsty. If we made a good effort 3-4weeks would be reasonable without going into desperation mode.


While you may be able to survive on 1/2 pint of water per day in an emergency, it's not healthy and would only be considered in desperation.


A simple way to increase water range would be to carry a some 5 gallon water jugs. They can be stored inside the cabin or in hatches as there is no risk of fumes like fuel. This has a side benefit that if your main tank fails and you lose that water, you have an independent backup source.

[JPA Cate]

Originally Posted by TrentePieds

It is traditional sea-going wisdom that the survival ration of fresh water is half a pint per man per day, i.e. 1/4 litre per man per day. Not nice, but Bligh and his loyal men went three and a half THOUSAND sea miles across the South Pacific on HALF of that!

Beyond that 1/4 pint per man per day, it's only a question of how profligate you want to be.

Jim and Ann have already said it: Use seawater for anything that you aren't gonna swallow. Cook your spuds in seawater, and you don't have to empty the salt cellar. Take a few hours to make and rig a "water sail", merely a big canvas funnel slung in the rigging with a tube leading to your water tank. Buy a water maker. Use a solar still, even a "rollyerown" version.

For fuel as for water, the question is never: "How much is enough?". It is always "How little am I comfortable with?". There was no propulsive fuel required AT ALL in many commercial sailing ships even into my time, and the fuel for cooking was often coal or coke. Only you can know what your "comfort level" is.

A "conservation fetish" goes a long way :-)

TrentePieds

Yup, couldn't agree more.

Nope, never wrote that. Our experience was that straight salt water was far too salty for us for cooking vegetables: about 1/3 salt to 2/3 salt water worked for us most places, except in the highly saline Sea of Cortez, where more fresh water was needed.

Ann

[denverd0n]

Originally Posted by boat_alexandra

I don't understand why people use LPG.

I have been cooking on wood for years it's great, even on passage.

Seriously? You can't understand why people would prefer a fuel source that delivers a constant 22,000 BTUs per pound, versus one that varies dramatically, maxing out at about 7,500 BTUs per pound and averaging closer to 5,500 BTUs per pound? Never mind the huge difference in the amount of space these two different fuel sources require.

You can't understand that? Okay, well then I probably can't explain it to you.

(Wait! I know. You're going to talk about how dangerous propane is. Heard it all before. Basically it boils down to this: Propane can be handled perfectly safely if you take a few basic, well-documented precautions. If you can't do that then, definitely, stick to wood.)