This isn't the most eloquent description of a process but the best I could do for now.
I replaced the three main head hoses (toilet to tank, tank to thru hull
discharge, breather to thru hull
discharge) today. It took a total of about three hours. Parts
: breather hose, 1 inch dia ($3.50/ft). Tank outlet to thru hull
& toilet to tank inlet: 1.5 inch dia ($4.25/ft). 20 1.5 inch hose clamps, 10 1 inch hose clamps. I measured and overbought 28 ft of the 1.5 inch hose and 12 ft of the 1 inch from a local marine
hdwr store so I could do both heads. Tools: large long shank standard and phillips screw drivers, socket wrench, utility knife, WD-40, hair dryer. Here's how:
Remove everything from the head room. Remove the tank cover and sink door. Fill and pump out the tank 3-4 times with the dockside pumpout. Put a plastic bucket underneath the discharge thru hull to catch any effluent upon hose removal
In order, I removed and replaced the breather hose, tank to thru hull discharge, and toilet to tank inlet in this manner: Remove all hose clamps. Carefully cut into the hoses where they're on the various nipple fittings and squirt some WD-40 into where the hoses fit on the nipples to aid removal
. The FP 1.5 inch hoses are wire reinforced; don't try to cut thru the wire. Heat the hose to nipple junctions and use the standard screw driver to spread the hose to aid in slipping the hose off. Take care not to snap any of the fittings off during all of this. Discard the hoses.
Remove the head pump from its' base. FP silicones the seawater intake and toilet to tank hoses in place; remove the silicone so you can lift
the pump up and disconnect the toilet to tank hose. I didn't resilicone them.
To replace the toilet to tank hose, it was easiest to take the hose end and feed it down thru the hole next to the base of the toilet, pull it towards the sink, then up thru the counter hole to the top of the tank, attaching it to the tank inlet nipple. Cut the hose at the toilet end leaving enough to attach it to the joker valve fitting. Attach the pump to it and remount the pump to its base, it's easier that way. The tank outlet to thru hull can be measured, precut and installed BUT it's difficult to keep the tank base hose clamps from sliding down the hose and thru the counter holes so be aware. The breather hose can be precut as well. For the breather, it's easier to remove the right angle nipple on the threaded thru hull, install it on the hose, then reinstall it on the thru hull. Scrub the whole head room down with a Clorox solution and rinse well. NOTE: After all was done, the tank still wouldn't always drain properly. Further investigation proved that in addition to the clogged hoses, years of sludge (toilet paper, whatever) was blocking the tank drain. Further flush/fill sessions were required to remove all the blockage. I'm considering installing Y valves to provide an emergency
tank bypass to allow flushing directly overboard
should the tank ever block again. Pix are below.