Help locating all the thru hull valves.

Hello to everyone. I have a 1986 300 Sundancer. I'd like to locate all the
seacock valves. I've only had this boat for two years and still getting to know it. When I arrive at the boat I open two valves under the aft cabin prior to running the AC. Not sure why I open two valves there. Can someone explain the two and also where are any others are, particularly for the manual head raw water intake.
Im going to replace the head and decided I should take this time to understand all thru hull valve locations.
Thanks,
D Frank

Unfamiliar with the 300, especially 1986. How many ac units do you have? Would guess only be 1 on a 300. The two valves may be 1 for the ac (only requires 1) and the other for the head. Are they identified? Good idea to keep them closed when away from the boat and/or not in use. Prevents any leaks downstream that may arise while unattended. Close them both and try your head to see if it still works. If not, open one at a time and see if does. I close all my sea cocks when boat unattended unless I leave the ac running. (keys hang on a hook in bilge labeled (OPEN SEA COCKS) to prevent engines from being started w/o sea cocks opened).

Perhaps I'm in the minority but I only close my seacocks when I'm cleaning my strainers. Otherwise they are always open...

Stee6043 said:

Perhaps I'm in the minority but I only close my seacocks when I'm cleaning my strainers. Otherwise they are always open...

Click to expand...

Ditto

I started closing ours when I watched a boat sink when the ac hose came off the strainer fue to a hose clamp breaking. We could not get to it because the boat was all locked up and access was in the cabin floor. The boat was already a foot n a half sunk when we came up on it. Bilge pump failed. Guess I am just overly cautious. With them closed, no worries.

Thanks for the replies. I will try and isolate the AC valve as mentioned. One Ac, I guess that makes sense that the head intake would be the other. This weekend I'm going to remove all cushions and empty the cabinets and try to identify and tag everything I see. I've searched thru manuals but I have not found a plumbing diagram. I'll post what I find.
Thanks again for the replies.