Tank Capacities

[Gary Wyngarden]

In one sense tank capacities are very straightforward. You can read in the specs for my boat for example that my fuel tank holds 35 gallons; my water tank holds 75 gallons; and my holding tank holds 20 gallons. Of more relevance is how long do these tanks last under normal use? For the kind of cruising we do, our fuel tank has never been a constraint. Fuel consumption ranges from half to three quarters of a gallon per hour depending on rpms and conditions. I figure I can get at least 300 miles under power on a tank. Sailing as often as I can, it's just never been an issue.Water on the other hand has been. My wife and I will go through our water tank in five days. I don't think of us as wasteful, but that's how much we use. I just read an article in Blue Water Cruising that suggested for planning purposes two gallons a day per person if you're not taking showers, and five gallons per person per day if you are. Makes me feel wasteful. With plans for extended cruising in Alaska where safe water fillups can be few and far between, it's a concern.Then there's the holding tank. Even being judicious in our use of the holding tank, the two of us will fill ours in about two and a half days of normal use. Most of our cruising has been done in Canada where pumpouts in open water with good tidal flushing are still legal and where pumpout stations are by and large nonexistent. (That's all about to change however.) Based on proposed new regulations and lack of adequate pumpout facilities, our holding tank "capacity" becomes a real constraint on cruising in Canada.How do you and your crew do with your boat's tank capacities? Do your tank capacities meet your cruising needs? How do you supplement those capacities?Gary WyngardenS/V Wanderlust h37.5

 

[Ross]

I use a five gallon mannually filled water tank

for a day tank. I pressurize it by hand so that we have pressure water in the galley and the sink in the head. We wash with a wash cloth and a bowl of water. Hot water is perpared each morning in two quart coffee dispenser thermos bottles. You are using too much water to flush the head. limit yourself to just enough to clean the bowl and then pump dry several strokes. My eleven gallon holding tank serves two of us for six days. 35 Gallons of fuel should last for a month if you are sailing and anchoring. you can sail into your anchorage and sail off the anchor with no need for the engine.

 

[larry w]

tankage

On my OC400, the 40 gal fuel tank is fine for local stuff, but for cruising Mexico, 80 gals would be better since it takes about 70 gals for the run up Baja from Cabo to Turtle Bay. I used a bladder and several jerry jugs and am considering building or having built extra fuel tanks. Water is not much of an issue so far. 120 gals in two tanks does fine. The holding tank on the forward head is only 12 gals, but we, the two of us, can get four days use before we have to pump out. The aft head is another 12 gals, but that head is being used as a storage locker more than anything else.

 

[Terry Cox]

Our P42 has 150 gallons of water, 70 fuel...

and 26 holding. Each year we cruise the PNW waters for about two months and during that time have adequate tankage all around. We prefer anchoring but have been known to slip up at a local marina. I alternate water tanks, so when one becomes empty I look for a refill spot. There are a few places up north with poor quality water and we avoid stopping there. One of the best watering holes is Blind Channel Resort. Having a Genset on board makes life on the hook very pleasant with plenty of hot water for bathing and cooking. That five gallons per day sounds about right for us, too. I can usually take a three gallon navy shower; a bit more for the admiral.Terry

 

[Warren Milberg]

Peggy's math

Peggy recently opined that the "average" person would use the head five times per day. Assuming an "average flush" uses a minimum of 1 gal of water, a boat with 3 on board would present a holding tank with 15 gal of "material" per day. At that rate, you'd never get very far in coastal/bay cruising. This thread sort of adds some real world facts and figures which seem quite different than Peggy's math.

 

[Malcolm Young]

Tank capacity adjustments

Gary,As we sail in the Great Lakes our needs and response are different than yours. However, some of our experience may be of interest to you and as well to those that sail the lakes. I have made adjustments to our C-36 standard tank capacities to suit the Great Lakes. There were 3 fresh water tanks which totalled about 72 gallons (including the hot water heater). There was one holding tank of 17 gallons and is one fuel tank of 25 gallons.Holding Tank(s)On the Great Lakes you are not allowed overboard discharge from the head//holding tank. My wife and I like to cruise away from civilization and anchor 95% of the time. A 17 gallon holding tank is just not enough. When we ordered the boat we had the 24 gallon bow water tank replaced with a properly molded holding tank to fit the space. It was supplied to our dealer through Catalina. We now have 2 holding tanks with a total capacity of 41 gallons. We have been away from civilization for 17 days and have not run out of capacity. I expect the two of us could last for 20 days without a pumpout (about 1 gallons a day of usage per person). We use the holding tanks frugally. As has been previous suggested, we do not use water from outside the boat to flush urine. We dry bowl it. The other stuff is flushed with a minimum of water.WaterWe have 2 remaining 21 gallon water tanks. As we sail in fresh water, and anchor almost every night, we swim and wash in the lake. We do not use the shower. In addition, as the water is clean where we sail (away from civilization) we use a seawater pump that I installed for rinsing etc and that reduces tank water usage. In 2 weeks we use a little more than one 21 gallon tank.How good is salt water at doing dishes? FuelOur fuel usage at about 70% of full rpm on a Universal M35B is about 2 litres per hour (slightly more than 1/2 US Gallon per hour). We could probably go close to 300 miles on a tank but I wouldn't bet on it especially if there was hard slogging (wind/waves). At 80% of full rpm we are climbing towards 3/4 US Gallon per hour. I have been thinking of getting a jerry can for diesel as a back-up.

 

[Terry Cox]

Whether I'm backpacking or sailing...

I carry a pee bottle that I use at night in the tent or on board while sailing. It gets emptied when full, which reduces the amount of head flushes. KMart carries a similar device designed for female use, FWIW.Terry