Fresh Water vs Fuel Capacity

Dear Steve, Just finished your Offshore Cruising Encyclopedia. Great ideas and information. My wife and I just bought a Stevens 47 and hope to start applying your theories soon on our planned circumnavigation. Its 500 nm fuel range has me concerned though. Would you advise converting 50 gal. of its water tankage to fuel, leaving 75 gal. of water and a 20 gph genset powered watermaker? – Jim

Hi Jim: No easy answer to your question. Seventy-five gallons of water would be considered a lot by most of the boats cruising 25 years ago. But if you were to lose the watermaker early on a long passage, you would want to be well versed in living frugally – and have the ability to wash with salt water and/or catch water off your awnings and decks. Another question is the reliability of the water maker and genset.

Then there is the definition of your 500 mile range – at what speed and wind/sea state? Can you extend this by slowing down a bit?

Another factor is the boat’s sailing ability, especially in lighter winds. The better the sailing qualities, the less diesel you require.

Finally, have you looked into a fuel (or water) soft type of tank – assuming you can secure it well? Might be that the best trade-off is to switch over a water tank to fuel as you’ve asked about, and then carry a bladder tank in case extra fresh water is required.

Note: Make sure you keep the fuel and water tanks physically separated. Having a water tank with an internal divider will not work with diesel and water! – Steve


Posted by Steve Dashew  (November 30, 1999)



Comments are closed.