England Ireland Find Havens
England Ireland Find Routes


Tanking rainwater whilst underway

Be the first to comment

What is the issue?
If you do not have an osmotic watermaker, or choose to do without the cost and regular maintenance such equipment requires, you cannot acquire quantities of drinking water whilst on route. Likewise whilst cruising in remote areas fresh water may be limited and can be hard to come by in the tropics.

Why address this?
Fresh water is a necessity for life aboard a vessel. You cannot typically acquire drinking water in quantity deep ocean without a watermaker.

When cruising in remote parts and trying to replenish tanks you are often required to go to rivers or streams. This is far from ideal as animals are prevalent on most islands and their droppings wash into the streams and rivers causing unhealthy levels of bacteria.

Other typical areas where it is collected areas on remote islands is a large island cistern, typically beneath the roof of a church that offer the largest catchment roof for an island. But again this is often sitting open for long periods and is of doubtful purity.

Finally, and in some developing countries, and developed, municipal water may still be unsafe for drinking.

Where good water is available you may often be required to ferry it back and forth to the vessel via the tender. This means you must row the jerry cans ashore and carry them to the water source. Moving a large quantity of water to the vessel may take an entire morning of hard slog in, as often as not, you may be anchored a long way out from shore and operating in uncomfortably high temperatures.

Finding sources of easily accessible fresh water is highly beneficial.

How to address this?
You can use the mainsail to catch rain showers whilst making passage. When the rain comes, depending upon how heavy the shower is, allow an appropriate period to wash off all the salt and debris that has built up on the mainsail. Once the wash-off is completed, ease the halyards a tad and take up the topping lift until the sail complains. The boat will not sail as efficiently as the mainsail is starting to become bag-like but it will direct the water runoff to the gooseneck. Place an adapted bucket at the gooseneck as presented in figure 1 to funnel the rainwater directly into the main tank.

All that is required to achieve this is a plastic bucket modified into a funnel. Simply drill a hole into the bottom of a cheap plastic bucket and fit a nozzle for a hose pipe that can be fed to the main tank - don't be tempted to use it for diesel oil as this will taint the water. As the bucket is acting as a funnel it does not support much weight so a loop of shock cord can be enough to hold it in place depending on the weather conditions.

This appears far from elegant but it works surprisingly well as long as you don’t have to endure squalls with the rain. If you are sailing in an area where showers are frequent it is a dependable means of capturing freshwater. You can increase the efficiency of capture by modifying the bucket / funnel (with a little heating) so it fits into the gooseneck area more effectively.

Finally filling your tanks this way is daunting at first. It took me some time to get to grips with this as I was concerned that I would get my wash-off timing wrong and take some salt into the main tanks. What I would suggest is experiment with for a while with the process. You can use your test runs for bathing water or washing clothes – remember it is not washing but the rinsing, which takes a lot of water in this case.

Trap the water in buckets and jerry cans for a while tasting it as you go building up experience. Then when you are comfortable with the approach and quality of the drinking water, direct it into your main tanks.

With thanks to:
Michael Harpur, Yacht Obsession.

Add your review or comment:

Please log in to leave a review of this tip.

eOceanic makes no guarantee of the validity of this information, you must read our legal page. However, we ask you to help us increase accuracy. If you spot an inaccuracy or an omission on this page please contact us and we will be delighted to rectify it. Don't forget to help us by sharing your own experience.