Caliber 38 - Converting Water Tank to Fuel

[flyboy350]

I have recently bought a 1992 Caliber 38. It has a 46 six gallon fuel tank and two 75 Gallon water tanks, all aluminum. I was thinking of making one of the water tanks into a fuel tank giving me a total of 121 gallons of fuel. I have a water maker and feel that I could keep the water level on the boat well within what I would need for most passages. Anyone ever thought about this or better yet,done it?

[capt_douglas]

It's always easier to convert a water tank to fuel than the other way round. If you can live with a 75 gallon water tank then I don't see a problem. 121 gallons of fuel would be very nice - until you have to fill it up.

[James S]

Be sure to check that there aren't any interconnections with the other water tank, and this may include the vents...just need to have a good look.

[Chief Engineer]

Is the water tank rated for fuel carriage?

Probably not.

Fuel tanks are for fuel....water tanks are for water...

[flyboy350]

The tanks look the same in construction. I think I would just have to change the plumbing and the type of hoses used. Have to figure out a transfer system which could be as easy as putting and in line fuel pump to pump from the 75 gallon into the 46. I need to work a system out for filling the 75 gal tank as well. Not sure an over flow system from the smaller tank would work.

[Laidback]

Do not forget the unused return diesel from the injectors, may give a strange taste to water.

[KestrelBuck]

The water tanks on my 1990 caliber 38 share a common deck fill. They are plumbed to a manifold that let's the user decide which tank to draw from. Removing one tank from that system wouldn't be hard.

The tank top schedule of holes for the fuel tank differs from a water tank. Guess you would have to drill or plug as need. I believe the newer LRC's fuel tanks are plumbed in a fashion that allows user choice or pump over from one to the other as in a fuel polishing system.

All of that said, why would you do this? Didn't you buy this boat to go sailing?
1) My boat, with a Yanmar 4JHBE, shows SOG of 5.5 - 6 knots at 2000 rpm. She consumes about .4 gals per hour at that speed. Meaning I can run the engine for 112 hours, or 610 nm.
2) Unless you are going to own this boat forever after, don't do this. I should think that to do so would seriously adversely affect the resale value of the boat.

[gonesail]

the water tank on my caliber 33 is made of stainless steel .. not aluminum as the fuel tank is.

[flyboy350]

Thanks for all the insights on this. I plan to go offshore and would like to have the flexibility of more fuel without the jugs on the deck system. I will look at the tank construction a little closer. I have Yanmar 4JH2E and I'm not sure on the burn rate or range as the boat is new to me.