My boat has these aftermarket air scuppers with associated tubing. This is on the port side at the stern near the motor mount.
Air vent/scuppers at port stern - what are they for?
- Thread starter hudson_rogue
- Start date
-
- Tags
- catalina 22
They look like a PO's attempt at ventilating that compartment.
What would be preferable are incoming cowls somewhere more forward. Exits on the transom are fine but a clam shell would probably be adequate and less intrusive.
Boats should breathe to help prevent mildew, control humidity and freshen the air to control odors. You've probably that most boats smell musty when you first enter the cabin but smell fine while underway or at anchor. I read a very good article years ago on the subject. It inspired me to increase ventilation on my formerly dank Ranger 29. It became like a new boat.
I put a solar vent in the vee berth area. I put a vent in the companionway sliders. I also disconnected the hoses from the fan system retroactively installed by a PO by re-purposing the vent hoses. While the fan system ventilated the engine compartment when the fan was running but did nothing the rest of the time. In fact it hindered ventilation. Once freed from the fan the hoses resumed their roll in the natural movement of air through the boat. The dankness went away. That natural circulation would also sweep out any gas vapors. I never had a problem but didn't want to explain that to any USCG personal doing an inspection.
Why the hose on the vent? I don't know. Maybe that's a way to vent the lower areas of that compartment.
What would be preferable are incoming cowls somewhere more forward. Exits on the transom are fine but a clam shell would probably be adequate and less intrusive.
Boats should breathe to help prevent mildew, control humidity and freshen the air to control odors. You've probably that most boats smell musty when you first enter the cabin but smell fine while underway or at anchor. I read a very good article years ago on the subject. It inspired me to increase ventilation on my formerly dank Ranger 29. It became like a new boat.
I put a solar vent in the vee berth area. I put a vent in the companionway sliders. I also disconnected the hoses from the fan system retroactively installed by a PO by re-purposing the vent hoses. While the fan system ventilated the engine compartment when the fan was running but did nothing the rest of the time. In fact it hindered ventilation. Once freed from the fan the hoses resumed their roll in the natural movement of air through the boat. The dankness went away. That natural circulation would also sweep out any gas vapors. I never had a problem but didn't want to explain that to any USCG personal doing an inspection.
Why the hose on the vent? I don't know. Maybe that's a way to vent the lower areas of that compartment.
My bet is unpowered fuel tank storage ventilation. That hose is intended to be the exhaust with the cowl facing backward. The cowl facing forward forces air in.
Here are some links that describe passive ventilation. I am NOT recommending passive ventilation alone. Get a blower too. But it is an accepted thing. This is the essence (bolding mine, this explains the hose):
The Natural Ventilation System must be made up of, at least:
1. A supply opening or duct from the atmosphere or from a ventilated compartment that is ventilated to the atmosphere, and :
2. An exhaust opening located on the exterior of the boat
What does all that mean? You must have a means to bring in air from the outside and a means to take air out of the compartment, to the outside of the boat. Air in from the outside, air out to the outside.
Each exhaust opening must originate in the lower third of the compartment. This is because the fuel vapors collect in the bottom of the boat. So the duct that takes the air out has to begin in the lower part of the compartment.
www.ecfr.gov
The Natural Ventilation System must be made up of, at least:
1. A supply opening or duct from the atmosphere or from a ventilated compartment that is ventilated to the atmosphere, and :
2. An exhaust opening located on the exterior of the boat
What does all that mean? You must have a means to bring in air from the outside and a means to take air out of the compartment, to the outside of the boat. Air in from the outside, air out to the outside.
Each exhaust opening must originate in the lower third of the compartment. This is because the fuel vapors collect in the bottom of the boat. So the duct that takes the air out has to begin in the lower part of the compartment.
Federal Register :: Request Access
www.ecfr.gov
Yes to fuel storage ventilation. Note that there's a level shelf molded into the liner below that space (and accessible through the cockpit locker lid). Intended for a ~2-3 gallon tank. I didn't like the idea of storing gasoline in a space open to the rest of the cabin, so we always kept our tank in the cockpit under the tiller.
I replaced one of the vents with a Vetus, and the other with a deck-fill plate to pass through electrical cables when needed.
We found that locker / shelf space worked perfectly for a cockpit cooler (see model and modifications in that post). And a bungee cargo net behind the cooler to hold foam PFDs for paddling, stadium chairs, and other light items that would otherwise disappear into the corners of the coffin. YMMV.
I replaced one of the vents with a Vetus, and the other with a deck-fill plate to pass through electrical cables when needed.
We found that locker / shelf space worked perfectly for a cockpit cooler (see model and modifications in that post). And a bungee cargo net behind the cooler to hold foam PFDs for paddling, stadium chairs, and other light items that would otherwise disappear into the corners of the coffin. YMMV.
Looks like an aftermarket passive bilge ventilation system. If the intended purpose is to store a gas tank in the locker and have the vent passively remove any gas vapors, it is a poor solution. An ignition protected powered exhaust fan is the preferred solution. An even better solution is to keep the fuel tank in the cockpit and not below deck.