We had a local yard remove the installed head after a year of use and put in an airhead. The pictures knotflying provided were very helpful (thanks again, Mike). One of the major reasons to use the yard to do the work was the necessity to remove the used black water tank. On our R25SC this required the removal and replacement of the muffler. Using the removed tank as a pattern, we had an aluminum tank fabricated and fit to hold fuel. We can get an extra 20 gallons of fuel out of that tank by pumping it into the main tank with a small Jabsco pump.
We are very pleased with this arrangement, but do have a couple comments about the use of the airhead:
It is much taller than conventional marine commodes and a foot rest is required for comfortable seating.
The small exhaust fan installed just before the vent overboard must run constantly, so the boat must be in the sunlight (if you have solar panels) or on shore power. The electrical draw is very small, so a couple of cloudy days won’t hurt you, but dry stacking without power is problematic. When we were in dry stack, we used to remove fuses from alarms – after we drained the house battery one time. The boat has been in the water since the airhead was installed.
When we are not using the boat on a regular basis, we visit her every other week to make sure there is still moisture in the pot and turn the crank. We don’t want that stuff to harden up in there.
Watch the liquid waste jug. We know we are not the only ones to overlook that – once. We have not met anyone who admits to doing it twice.
Airhead customer service is extremely helpful and friendly. Our Ship’s Steward has contacted them a couple of times to purchase additional supplies, and once to obtain an additional cap for the liquid waste jug. They shipped it to a marina that we were going to visit so that it could catch up with us. (Tip for success: Get a spare cap at time of install and remember where you store it!)
For all that, we are very satisfied with the airhead. No smell, easy to clean, and it took about 200 engine hours to fill the honey bucket. If we ever get a new boat (why would anyone want to do that?) we will go with airhead again.