Hose in stern of boat - Can anyone identify?

Apr 6, 2013
Catalina 310 Annapolis
Happy Holidays. I could have posted this at the end of the recent thread on bilge blower hoses. However, I am not sure that is what this is. I was putting my boat to bed the other week and saw this hose down by the steering gear, forward of the fuel tank. Does anyone know what this could be? My best guess is it is the exhaust for my air conditioner but does anyone think it could be something else that, somehow, got disconnected? The problem is I can't figure out what else it should be connected too.


Aug 19, 2021
Hunter 280 Chesapeake Bay - Fort Monroe
I think that your are correct. HVAC duct or Exhaust duct. From the dirt inside I am leaning to exhaust duct.
Jan 7, 2011
Oday 322 East Chicago, IN
Do ya have a washer & dryer aboard?

if not, then I agree with @Crusty Ol Salt…either air conditioning duct (unlikely as it should be insulated) or some sort of ventilation for the engine compartment or bilge. I assume you have a diesel engine, so bilge ventilation to get rid of flammable vapors out of the bilge is not needed. That leaves us with ventilation for the engine compartment often to cool the alternator or to cool the engine room down after motoring.

Merry Christmas,

Jan 1, 2006
Slickcraft 26 Greenport, NY

Tom J

Sep 30, 2008
Catalina 310 Quincy, MA
There are three of those hoses in that compartment. One is the exhaust for the bilge blower, and the other provides fresh air to the bilge area. They should be connected to the vents on the transom. I believe there is a third hose that provides fresh air to the fridge condenser.
Last edited:
Mar 6, 2008
Catalina 310 Scott Creek, VA
That appears to be starboard side. It is likely fresh air intake from stern vent. The other intake (hull 218) is for the fridge compressor further outboard, much shorter, and up in the top of the locker.
Apr 6, 2013
Catalina 310 Annapolis
Thanks for all the comments. I crawled into the stern from the back berth far enough to see that it is, in fact, the house that should connect to the starboard aft fresh air vent. The hose itself split about a foot and a half from the vent. I am looking into ways to reconnect it cheaply without having to replace the whole house run.
  • Like
Likes: Tom J


Apr 2, 2013
Catalina 310 Niagara-on-the-Lake
Duct tape, good for 200 mph…..
Seriously, I agree with the post above , replace with the correct duct.
  • Like
Likes: Alansails