To keep the stern light I avoided storage aft, but I still wanted the option to add weight when running downwind in heavy weather. With little extra work I built a seawater ballast tank right in front of the transom, roughly 500 litres.
Water ballast tank
The aft part of the F39 must be kept as light as possible, so no storage in that area. However, when running downwind in big seas and strong winds, some extra weight in the stern can be desirable. In truth, I don’t know if I will ever need that extra ballast, but at this stage of the build—and with only a little extra effort—I had the opportunity to build a seawater ballast tank in an otherwise unusable space right in front of the transom. I estimate the maximum capacity at about 500 litres.
The tank was originally dimensioned for filling with the very powerful Jet Thruster, which required large ventilation channels, and those were built in. In the end I did not dare to fill the tank with the Jet Thruster and replaced that idea with a branch connection from the deck-wash system.
This photo gallery (31 images) shows the construction of the stern seawater ballast tank: surge plates, the watertight torque tube housing passing through the tank, the vent/overflow labyrinth with gooseneck, and the final bed base and tank cover installation.
