This thru-hull 90° fitting cannot be cleaned or cleared with a snake. Yet this is where I suspected my obstruction was.A charged garden hose nozzle with integral shut-off valve *may* help clear the clogged vent hose.
When my “non-invasive” water pressure strategy stopped working, (after months or years), I determined the more aggressive project was necessary. Pictures of the larger project follow:
A 4-1/2” round inspection/access port was cut through the inside of the starboard midship bulwark. Once cut, I could remove the thru-hull fitting and hose.
Another view of the fitting at top end of the 5/8” vent hose. This vents to atmosphere and allows oxygen into the TOP of the holding tank. This is essential for the natural aerobic digestion to occur inside the tank. Methane is a key by-product of the process, and it exits through this same hose...It appears that this fitting minimizes the possible flow of wastewater “out”. But it also prevents a snake to be inserted to clear any clogs in the vent hose.
“Why is this vent hose important?”
A clogged vent hose inhibits the aerobic digestion process AND it forces methane “sewer gas” to bubble up through the sanitary hose to head itself… inside our living space. Not a good thing.
A new thru-hull fitting was purchased; it is shown here on the OUTside of the bulwark. This is about 11” below the gunwale near the midship cleat. See the orientation pic below.
A street fitting enables a smooth maintainable 90° turn so a snake can be used to clear this vent hose.
A 1/2” bronze Street fitting, with adapters connect to the 5/8” hose which goes about 10 feet to the top of the holding tank. There is an elevation difference of several feet from this fitting down to the tank. So the probability of waste making it up to this level is nearly zero percent, even in a tossing sea.This pic gives a good orientation of where all this happens on the Mainship 390. Near the sliding door by the lower helm, and the midship cleat on the starboard gunwale. The nylon cord prevents me from making the project worse if I drop the hose down below. This inspection/maintenance port and cover gives me future access if needed.
