Rainwater Plumbing: Deck to Tank

Getting the tank in the bilge was pretty straight forward. Getting the water to the tank is a little more complicated. 

To accomplish this task, a small aqueduct needed to be constructed. Nowhere near the level of grandeur of the ancient Romans, but the same principles still apply. In general: the starting point needs to be higher than the ending point, there should be no inclines, and tight bends should be reduced.

Having the deck as our starting point and the bottom of the bilge as our ending point makes the first point easy to accomplish. Now we just need to make sure the flow rate stays adequate during the entire journey.

Water flows downhill. If there is any incline, the speed of the water will decrease and flow problems will ensue. To keep the speed of flow adequate, water needs to drop rapidly to gain speed that will shuttle it along the less declined sections. With this speed, the water will then flow quickly to the water tank down in the bilge.

Tight bends are another problem, simply because of the added resistance they impart on the passing water as the fluid attempts to make twists and turns.

With these concepts in mind, it is fair to say that plumbing the water tank is rather straight forward. This pleasant state of mind will take you all the way to the starting point of the project where you soon realize that sailboats are a collection of compromises.

The low spot on the deck is next to the cockpit, so the hose will begin at deck level and drop down quickly as it makes its way to the bilge. This will give the water a quick burst of speed that will help make everything else flow nicely. From the cockpit lazarettes, it then needs to work its way past the steering mechanism and into the bilge where it reaches the flexible water tank. This is where the problems begin!


The starboard side was easy. The old diesel exhaust hose used to run through the hole visible at the top of the area. The port side is rather packed full of hoses. The three hoses visible are the cockpit scupper drain, cockpit manual bilge pump and electric bilge pump hoses. Adding an extra hose on this side will prove challenging.

The hoses all need to run over the top of the metal frame to the steering quadrant to avoid interfering with our steering, and this makes the available hose space even more limited.

The final decision was to drill a new hole below all the other three holes on the port side and then have the hose ride up over the metal frame and then quickly back down again. Hopefully, the water will have enough speed that it will be able to flow up and over the little hump and into the tank without much issue.

Once past this point, the hoses are joined in a Y where they follow along as a single hose to the tank. From this point forward, everything is a steady decline with no upsets on its way to the water tank.

The next step will be getting the water out of the tank so we can use it!