Sea Ray

the problem is that unlike your dancer the waste outlet is horizontal just above the swim platform so it has to have a right angle elbow to get it to go down to the tank. So this leaves about 3" for the waste to drain out. I believe the only solution would be to relocate outlet to the above deck so it would be the same as your dancer.

Sorry I wasn't clear.

Why is the pump out being disconnected prior to all of the waste being evacuated?

Mine would also leak if disconnected mid stream during pump out.

Instead, I disconnect after the holding tank is empty and the waste flow is almost nothing.

For the rubber cone, it is tipped sideways to permit remaining to either go down or up. For the cam and groove, I do a slow disconnect for the same purpose.

It is leaking after the tank is empty and the hose suction is stopped. it is hard to explain unless you have the same boat. If you look online at ones for sale and look at where it is located as you enter the boat from the swim platform just before the transom door.

Still leaks if disconnecting while suction running, as described above?

That is correct

Would this fitting that I use help to eliminate the problem?

https://newcontent.westmarine.com/content/images/catalog/large/150636.jpg

No I would just have more poo coming out. I like your tenacity, I’m sure if you got your eyeballs on it you would figure something.

"after the the holding tank is pumped out and the hose removed poo comes out and drains onto the swim platform'

This should NEVER happen!

When the dockside pump out is connected to the deck plate fitting, either using hand held operator force with the rubber cone tip or with the screwed in adapter and the cam lever connector, the pump out vacuum will rapidly evacuate the entire contents of the holding tank.

The tank volume will remain "constant" with air drawn in through the hull side vent fitting and the charcoal odor filter (for normal rate pump out stations), or replacement air will also be drawn in through the integrated pop off tank valve (for VERY HIGH rate pump out stations).

When the holding tank is pumped out, vacuum is applied to the deck plate, drawing waste through the hose and the holding tank dip tube, to evacuate from the bottom of the tank.

When the tank is being evacuated the pump out nozzle and hose connected to the deck plate are all filled with waste. If the nozzle is disconnected at that time, then there will be a very big mess.

On the other hand, if the nozzle with vacuum running remains attached to the deck plate until after the tank is evacuated, then disconnecting at that point should have at most a few drops.

It sounds like the tank has not been evacuated prior to disconnecting the nozzle.

Most of the pump out stations I've used have a clear pipe section near the nozzle to permit visual inspection of the flow.

The air vent to the tank is clogged. Replace the carbon filter that is part of the ventvsystrm

Also check the vent on your hull to make sure it’s clear. Mud wasps like to make nests in the little holes.