Like any boat plumbed with PVC or rubber hoses, eventually the hoses will become permeated with the waste that runs through them and cause unwanted odor in the boat. In most production boat construction, this plumbing is done before the cabin and deck assemblies are joined to the hull. Everything is completely accessible at that time and there is no consideration made for replacing a hose in the future. To make matters worse, boat builders don't always take the recommendations of subsystem manufacturers. In waste systems one such recommendation is to never have hoses run against gravity on the way to the tank or to have hoses that will stay full of waste when the system is idle. Any runs with standing sewage must be plumbed with rigid PVC (page 37 of installation guide,) not hoses. This will certainly accelerate the permeation of the hoses. In the Vacu-flush system used on the 400, both these rules were broken. The hose between the pump and waste tank rises up and over the top of the air conditioner from the pump, which causes that section of hose to always hold black water. The other is the pump out hose runs along the bottom of the bilge for about 5 feet before rising up and above waste tank level and out to the deck fitting, so it too is always full of black water in that section. The first problem is easily rectified by running the hose behind the AC unit rather than over the top of it. The second problem will be tackled next fall, which will be a separate article.
The waste tank in the 400 sits under the landing at the bottom of the stairs between the main stringers. The hoses run outboard of the starboard stringer from the forward side of the engine room bulkhead to the limber holes cut through the stringers adjacent to the waste tank fittings. They are attached to the stringer with heavy duty plastic ties that would make the hose impossible to be pulled through when it needs to be replaced. There is no access to the outboard side of the starboard stringer from the engine room bulkhead going forward. The view below is taken from the area under the stairs looking forward under the landing. My boat originally had carpeting in this area but I removed it, as this is no place to have carpeting. As you can see, I have already removed the hose clamps on the top waste tank fitting and cut the hose free. It was impossible to move the hose through the hole in the stringer to be pulled out by the other end.
I then decided to cut a hole in the floor under the space where the water heater sits. I figured this would allow me about arms length access to both ends of the hose on the board side of the stringer. Using a Fein Multimaster I was able to cut a neat rectangular hole, and my plan was to reinstall the water heater back over this opening to cover the cutout.
Once the hole was opened, several things became evident. First there was water laying in a low spot between the two limber holes with no way to drain. The water was filthy and the pump out hose is laying in the water keeping it wet. Also the tee fitting between the bathroom and shower drains drops right behind the top waste tank hose. That was what was causing the resistance to pushing the hose off the waste tank. The hose, though not collapsed, had a very sharp bend into that limber hole to the tank fitting. The compartment was loaded with black mold from the moisture and dirty water. It was really disgusting. The air conditioner water feed from the pump, and also some wires were all plastic tied to the waste hose and attached to the stringer, so it would be impossible to pull the waste hose if you tried.
After cutting the plastic ties, I still could not budge the hose because of the interference of the shower drain. I used a PVC racheting type pipe cutter to cut the stiff hose into sections that I could pull out.
After cleaning out the compartment, I decided not to run the hose back through the same way. It would be impossible to get around the corner into the limber hole with the new heavier hose that I was installing. I also decided I wanted "anytime access" to the compartment without having to move the hot water heater every time. The need to keep an eye on any water in that compartment was now important to me as well as making sure things stayed clean and mold free. The bottom hose will eventually be replaced with schedule 40 PVC, but that won't be until fall.
From this top view, you can see that the hose from the pump now runs behind the AC and is on a continuous downhill flow to the waste tank. The hose will be clear of waste water except for when the pump is actually pumping. The new hose is much heavier, and of better materials to prevent permeation. Hopefully it will never need to be changed again as long as I own the boat. But if it does, it will be an easy job with the new routing.
I decided to put in another hatch in the floor to make inspection and cleaning of that compartment possible. After a solid week of rain I checked for water in the compartment thinking possibly a deck to hull joint was the reason I had water in there before, but it was dry, and smelling sweet. I'll just have to keep an eye on it going forward.