Rain Water Collector

Wisdom has its fresh water tanks set up in an ideal way for ocean sailing. While this is the safest way to store your water, it is not to say the easiest way.

There are eight tanks with no plumbing to the outside of the boat. To fill the tanks, a hose needs to be taken to each tank and filled through the inspection port. The vent to the tanks are also inside the hull. Internal vents prevent the risk of saltwater working its way into the tank during heavy seas. Safe fresh water is nice, but if you overfill your water tank, water will begin to pour out of the vent into your storage lockers or out the top of the tank. Either way, the inside of the boat is soaked and you now have a large mess to clean up. 

Safe and secure segmented water storage is nice while ocean cruising, but it makes it rather hard to fill up the tanks when water presents itself. Most people picture water presenting itself in the form of a hose at a fuel dock, but it can also present itself in other forms. My favorite is when it comes in the form of rain which pours down on the deck in bountiful quantities.

Since the deck is the largest area of the boat that is always available to collect rain water, I figured it would be a great place to start our rain collections. I first identified the lowest place on the deck and began working. On our boat, the lowest point is right between the primary winch and mainsheet winch.

This area of the deck pools water after every rain storm, causing the paint to deteriorate faster in the form of a spiderweb of flaking paint. The small chips are the result of us storing hard and heavy items on the side decks such as chains and anchors. Over the years, they have taken their toll on the deck paint in this area as it lived neglected under a layer of city dirt that builds on the boat from the polluted air. The constant standing water and chemicals in the air have quickly damaged the paint in this part of the deck, offering further evidence that this is the lowest point on the deck and the ideal location for the rain water collectors.

There is a slight lip in the deck as it approaches the toe rail, and water collects equally in both of these points. I decided that the best way to make use of the deck topography would be to place the deck fill plate over the ridge of the deck so that water from either area will flow into it and into the rain water tank.

To allow the deck fill plate to collect water from both regions, it would need to be recessed lower than the deck, this way water would flow into it during a rain storm. To get everything lined up properly, the deck fill was placed over the region of interest upside down and used as a guide for the hole saw. Just like when placing a dental implant into the jaw bone, angulation is crucial! The holesaw was drilled down into the thick deck until the shallowest part of the saw was buried to the depth of the deck fill plate.


With the perimeter hole cut, there was a constant depth available to the hole that simply needed to be trimmed away. For this, I used a reamer and slowly but surely expanded the central hole to outer perimeter.

After a while, the perimeter was reamed out to the appropriate depth so that the deck fill plate would lay flat. The central hole was left in place so that all the dust would remain on the deck where I could easily vacuum it up instead of falling down into the underlying locker. After all the reaming was finished, I then took a smaller hole saw and removed the central portion.

At this point, the deck fill plate could be test fitted to make sure that it laid flat and below the level of the deck so that water would flow into it.

Once the fit was established, I sanded all the edges of the hole so that it would be easier on our feet if we ended up standing in there. Copious amounts of 3M 4200 was used as bedding compound and the deck fill plate was screwed into place. The excess bedding compound was wiped off and cleaned up using acetone. 

Yes, there is way too much bedding compound in use on this deck fitting, but this is my boat and it will spend the majority of its working life under a small layer of water and I don't want my deck to leak! I made sure that 4200 oozed out of the screw holes and all around the deck plate flange. I then smoothed the bedding compound to be flush with the surrounding deck so that water will flow better and dirt won't get trapped on it as easily. When I repaint the deck, the exposed fiberglass will be properly covered and protected from UV radiation. In the meantime, these exposed areas of fiberglass live under the protection of the cockpit shrink wrap.

The other side of the deck was much easier to do since I had the hang of it by then and the resulting hole was much smoother and cleaner.

With the deck fill plates on both sides of the deck, we can collect rain water from passing storms. As we see the rain approaching, we can quickly scrub the deck to clean it of any dirt or debris that may be present. Then allow the first few minutes of rain to wash away any residual scuzz that needs to be swept overboard. Then we can open the fill plates and let the rain water rush down the hole and into a bladder tank that will be located down in the keel. 

The plan is simple: collect the rain water in the bladder tank and test if out to make sure we like the quality of the water. If it is good, we can pump it into our water tanks. If we don't like it, we can either pump it out or use it for washing clothes and bathing. If the water is not up to snuff, we don't have to worry about it contaminating the rest of our water supply, and it will only be relocated if it is up to our standards. As we add it to the regular tanks, we will be treating the rain water with chemicals to kill anything that might be present in the water.

Having two deck fills will allow us to favor which side we wish to collect rain water from. If we are sailing, the leeward side is going to be devoid of rain water since it will slide right off the deck and will also be closer to sea level making it riskier to open that deck fill. The windward side of the deck will be relatively flat, so water will be sent to this low spot. As long as the seas are not splashing up on deck, we will be able to collect our water as it falls from the sky!