Hanging Locker & Under-Berth Fans

All boats tend to have their own unique smell, it is the nature of the beast. Boat smells can run the gamut from imperceptible to overpowering, depending on one's olfactory perspectives, but its a rare vessel (in our price bracket) that has no odour at all below decks! When we got Circe she had a low grade 'cessy' smell which went away after we replaced the head, holding tank and associated plumbing, but we were left with a faint but persistent sort of sour smell in some of the closed spaces under the Pullman berth and dinette seats. It wasn't bad enough to be problematic but it was an irritation.

One of the really nice features of the Freeport B Plan design is the abundance of useful storage capacity. The downside of all that space is that the many compartments and lockers, particularly in the mid-section of the boat, hold a lot of stale air and all that dead air doesn't help with odour problems. We knew that good ventilation below decks is critical to the overall air quality in the boat so we took a look at what we could do to improve things.

In a previous life we had some good luck ventilating hot audio cabinets using the pancake style case-fans that are widely used in computer and electronics applications, so we decided to try them in the boat.

The 92mm x 25mm design is a case-fan standard and they are available almost anywhere that electronics are sold. We got four of these on-line for around $4.50 each. They only draw 0.13 amp but move air at approximately 40 CFM.

Our first target was the two big spaces under the Pullman berth, where the holding tank and water heater are mounted. Our plan for the ventilating air flow started by pushing air into the top of both spaces with a fan located centrally at the side of the berth. The air then would move between the two under-berth compartments through a new vent hole in the bottom of the dividing bulkhead. To remove the air a second fan would be positioned in another new vent hole in the main, mid-ship bulkhead, drawing the air into the storage areas under the dinette seats. That same fan would also push the air through those lockers under both sides of the dinette seats, before finally exiting through new vent grilles under the seats. 

Air goes into the under-berth area through this grille over the input fan. The control switch above is a flush mount to reduce the risk of unintended operation as we climb in or out of bed!

The next two shots are views of the rear of the input fan between the drawers. By positioning it centrally, air is fed down both sides of the dividing bulkhead.

This photo is taken from the forward side of the bulkhead with airflow going into the hot water heater area.

This shot is taken from the aft side of the bulkhead with airflow going into the holding tank area.

This new vent hole in the bottom of the dividing bulkhead encourages air to move between the two spaces under the berth. The holding tank visible through the hole is much further away from the bulkhead than it appears, about a foot, so there is plenty of space for free airflow.

This second fan draws the air out of the under-berth spaces, through the mid-ship bulkhead and into the space under the dinette seats.

Here is the other side of the mid-ship bulkhead. This fan does two jobs, pulling air from the under-berth area and pushing it on through the spaces under the dinette seats.

Because we had installed a new fused sub panel to feed a 12 volt outlet in the Pullman, we used it to power the two fans under the Pullman.

Here are some of the new vent holes that allow free air movement between the spaces under the dinette seats.

Finally the air exits through grilles under the dinette seats on the port side..........

..........and midships.

The exit and entry grilles were also cheap, $3.99 at West Marine.We went with black ones as we thought they blended better with the woodwork.

As soon as we wired everything up and switched the fans on we could actually feel the air moving around through all the previously closed storage areas and within 24 hours the overall air quality improved significantly. With the new fans added to the recently installed Nicro solar vents the boat is noticeably fresher, even after being closed up for hours while we are ashore. The case-fans are very quiet but they do generate a low humming sound that can be a bit distracting when we are trying to get to sleep so we got into a routine of turning them off when we hit the hay. The next step might be a timer of some sort? In any event we were so impressed with the results we started wondering where else we could benefit from positive ventilation. The obvious next area to look at was the hanging lockers.

The hanging lockers have louvred doors but without some way of moving air through the louvres they aren't very effective at providing ventilation.  This can be a problem if things ever get damp.

So....we designed another airflow plan for the lockers. This time we would put a fan in the back of each locker to draw air in through the louvre doors, through the lockers and the clothes, and then force it out through the bottom of the central dresser drawer area. That way there would be active airflow through both lockers and all the drawers.



A fan at the back of each locker draws air in through the louvred locker doors and forces it through the central drawer area. Because the current draw on the fans is so low, and all the cabin lights are now LED's, we felt safe tapping into the lighting circuit to power the fans.

Inlet grille at back of forward hanging locker. 

Inlet grille at back of aft hanging locker.

Outlet grille at base of the central drawer stack between the hanging lockers.

Control switch located over the AC outlet above the dresser drawers.

The locker fans work extremely well and are almost totally quiet. Being behind all the clothes and the dresser drawers the sound is almost completely masked. Another item struck off 'The List'!