Places to check for stagnate standing water in a C26 or C28 or things to do to prevent boat odors in a C26 or C28.
(1)The limber tube ( bilge drain tube from forward bilge to engine compartment bilge pump) can be easily plugged or plugged from the factory build. This tube drain can be found just aft of the shower sump in the forward cabin under the floor. Use a stiff cable, or electrical fish wire to confirm it is clear to the engine compartment. This allows for proper draining Fore to aft.
There are also drain tubes that drain the voids on the port and starboard sides of the fuel tank. If water is trapped in these areas the water will become stagnate.
This is a photo showing were drains are located C26 C28
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Next has Jim stated is the Air unit condensate pan. This is located behind a monkey hair bulkhead in the mid 1/4 berth area (Cave) Port side forward bulkhead where the teak air grill is located. Remove the full panel and you will have access to check the pan for standing water and to check that the drain hose is hooked up properly and the drain is not plugged. I know of several C26 and C28 that the factory failed to attach the drain hose properly and the pan would fill and spill water in the cave area.
Shower sump easy check pour water in the shower drain you should hear the pump kick on. If the pump doesn't kick on get ready to swear for a bit because the removal of the sump to repair the pump and clean the pan is a PIA the first time around because of the poor installation location.
The head and waste system has a couple of installation issues this added with a raw water flush can present some odor issues. First confirm the heads joker valve is not leaking. The head in the C26 and C28 is the lowest point of the waste system. There is a 1 1/2" waste hose that goes from the head to the waste tank and has a few high and low points were waste and raw water with sea "Cridders" can lay in between flushes. If the joker valve is bad than this stinky stuff can back up back at the head. (I change the joker valve every year to prevent this) When we do a pump out we fill the head bowl 3 times and pump fresh water through the line every time !!!! If we are leaving the boat for a few days, or weeks we fill the bowl 3 times with fresh water and flush it through to the waste tank so nothing but clean fresh water is in the hose. ( We also do not use raw water flush. I installed fresh water flush when we bought the boat.
Waste tank vent hose and vent. This gets plugged up and when it gets plugged and when it does the tank builds pressure ,this will eventually bleed off but it bleeds off to the path of least resistance which is through the joker valve. I yearly remove the vent hose from the hull vent attach a garden hose fitting to the hose and then run city hose pressure thru it back to the tank to confirm it is clean and clear.
There is an access port on the top of the waste tank 3" Remove this and clean and flush the tank. I do this once a year to keep the tank from getting to much stinky sediment on the bottom of the tank.
Hull drains, air unit drain and head and waste system components are the things I would inspect for the odor. Clean all limber holes there are several.
A dead rodent could be your issue too. It may be behind a bulkhead. There are many removable bulkheads in the C26 and C28 that will give you access to every area of the boat. I have removed all of them at one time or other while doing installations or repairs to my C26. I use a small pick to find the screws and a screw gun to remove them ( square head ) and the panel easily come out. There are no supportive bulkheads in the boat so you can get to just about every where when removing panels.
Good luck for your search for the odor.
