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'!

Nicro Solar Vents

In an earlier post we described fitting interior grilles to the dorade vents in an attempt to stop drafts and give us an alternative to going on deck and rotating the dorades when it was wet and the wind direction changes while we are at the slip. On the hook is much less of a problem as the boat almost always follows the wind shifts.

The interior grilles worked well enough but didn't solve the basic dorade problems with directional wind changes and gave no real control over air-flow. 

Bigger problems for us were that we thought the dorades were butt ugly and were a tripping hazard for the unwary crew member travelling between the side decks and the mast. The scoops had bad UV damage and we briefly considered fitting new low-profile scoops to address the appearance and tripping issues but soon realised we were putting off the inevitable......the dorades just had to go. We wanted active, not passive ventilation and going solar seemed the best way to achieve that goal.

We had good luck with solar vents on our last boat although they were always a bit pricey, so we were happy to see some Nicro Day & Night Plus units on sale at WM. As WM isn't usually a place for bargains it was a pleasant change to snag a pair for $99 each. We have seen them around $125 - $130 elsewhere.

Our first step in the conversion was to remove the dorade bodies, which went fairly quickly. Lifting the dorade bodies off the bases exposed several layers of sealant plastered all over everything. This shot shows the length of the screws used to hold them onto the bases, they were barely engaged!

Evidently there had been some leaks in the past because the goop had been layered all over the place. It took a lot of scraping and prying to get the bases off the cabin roof. There was so much sealant that we couldn't get the bases off in one piece. We had to split them to get them out.

From the 'battle scars' under the old caulk it seemed that the dorades had been off several times before. The old dorade base had a 3.5 inch mounting hole but the new Day/Night base needed a 3.75 inch hole. We didn't have a suitable hole saw, plus a plug is needed for the existing hole to use a hole saw, so we had to break out the old faithfull.....the Rotary Dremel.

It took quite a while with the small cutter but we were able to open up the hole in the cabin roof to the correct size. Gotta love the Dremels.....they are so versatile.

To minimise the mess in the Pullman berth we piled up the cushions and backrests from the sofa and put a pail under the hole in the cabin roof to catch the worst of the fall-out from the Dremeling....is that a word?.

Once the hole was opened up we made some test fits of the new Nicro bases and then caulked them in place.

After a couple of adjustments the inside trim rings and bug screens were fitted.

Finally the solar vent assemblies were installed.

The new Nicro Vents were supplied with two fans, one that makes the vent 'blow' and one that makes it 'suck'. We set the one over the hanging locker to suck air down into the cabin and the one over the Pullman berth to blow it back out, creating continuous circulation to ventilate the centre of the boat.

Next stop the dumpster...... best place for them!








This project was a major improvement in every way. We have complete control of airflow, the wind direction is irrelevant to performance, we have an integral bug screen, we have continuous active ventilation when the boat is closed up and there is minimal tripping risk, plus........the Nicro vents look good! 

Dorade Vent Grilles.

On early Freeports, pre-1980, there was flex hose running from the cabin-top dorade vents to deliver air down into the engine room area. In many cases, bilge blowers were also fitted, under the cockpit, for air extraction from the same area. The hose from the dorade to the engine room was hidden behind cabinetry over the berth area. It was a good system which kept the engine compartment and and bilge well ventilated but, around 1980 as Islander looked for ways to cut costs, the blowers, vent hoses and cabinetry were eliminated. The dorade vents were retained but were left open directly into the cabin! 

A teak trim ring was installed where the dorade comes through the head liner to address the cosmetic problem of holes in the cabin roof but there was no way to control airflow through it, other than rotating the dorade away from the apparent wind!

Even with the dorades rotated away from the obvious wind direction there was still a draft! Also, naturally, the wind clocks round when we are at the slip and so periodic adjustment of the dorade was an ongoing chore to avoid those unwanted drafts. While this direct airflow into the cabin was a nice feature in hot weather, it most definitely wasn't good when the temperature dropped and was particularly irritating with the vent over the Admiral's side of the Pullman berth!

What to do? The answer was very simple and inexpensive.....once we found a suitable adjustable vent grille. 

4 inch Sea Dog Butterfly Vent Grille

While mooching around the West Marine on-line store we saw an ideal solution. Made by Sea Dog, these chromed brass vent grilles were perfect. With one of our WM discount slips we got them for less than $3 each! What a deal.

Vent Grill open.

Vent Grille closed.

Who would have thought that  a couple of such small parts would have such an impact on cabin comfort? The grilles aren't completely airtight and with them closed and the dorade facing into the wind there was still a hint of air coming through, but with the dorade rotated away from the wind the grilles stop the drafts completely.