Index

Cabin Ventilation - Nicro Solar Vent.
INDEX - Summer comfort, Transom Vents, Winter comfort, More Air, Dual Vents, Replace Solar Panel, Replace Solar Motor.

• An open cabin interior ventilates better than a sectionalized one.
  - This is one of the reasons why Panache's port bulkhead is open to the ceiling.
• Do not let clutter build up, it blocks air flow.
  - Pick up your socks from the floor!
• Ensure that no water absorbing material like leaves, clothing or cushions are in contact with the hull or woodwork.  This is especially true along the edge of the ceiling under the toe rail.  It pays to be able to scan this area for water droplets.
  - I know of people who flip their cushions on edge when away from the boat.
• Remove dust.
  - It has a huge potential to trap moisture that accelerates rot.
• Wipe up fuel, oil and chemical spills from the inside the locker or cabin.
  - This shouldn't need a comment.
• Only fresh water causes wood rot!  Salt water pickles and preserves wood.
  - I didn't know that. Did you?

The cabin of an unattended closed boat accumulates humidity because the hull surface temperatures and water & air around it are never identical.  They are in constant change with day time heating and night time cooling.  You can feel humidity build up on a large scale when a warm and cold air mass meet, converting the atmospheric humidity to rain.  The changing air and water temperature is due to the rotation of the earth relative to the sun and the tilt of the planet relative to its orbital plane, but lets not go further than this.  While the process is accelerated inside your floating boat, it can also happen when a closed boat is stored on a trailer, especially if there is water in the bilge.  The sun can easily heat a light coloured deck to 120F (49C) and a dark coloured deck to 170F (77C).  These high temperatures then heat the cabin which is usually not a problem unless water is in the bilge which quickly creates 100% humidity.  There are few bone dry boats out there.

It's the condensation in the cabin that does the most damage.  When you close off a boat's cabin to “protect” it, you actually cause the cabin humidity to rise.  Water vapour is a potent gas that can permeate most materials with surprising speed, including fibreglass.  Expose it long enough and you have water droplets that drip from the ceiling or run down the wall to be absorbed by wall fabric, cushions or articles stowed against the wall.  Over just a few days or weeks, the moist air inside the cabin creates an ideal climate for mould to grow.  That smell of musty air is created when the mould attacks your boat's interior; wood, fabric, electrical connections and metal components.  Rot stinks, is miserable to remove and is expensive to repair.  This damage will quickly age your boat.

Cabin ventilation, the simple act of blowing fresh dry air into the cabin and/or stale humid air out of the cabin, solves the problem.  The temperature must be equalized between the inside AND the outside of the boat to prevent moisture build up.  Constant air movement is always advantageous to the cabin and its content, but even more so if your boat is in inclement weather.

The 3" Nicro day & night 2000 SS ventilator can blow air for ~(24-36) hours from its charged Ni-Cad 2.8 amp hour C cell battery.  All Nicro ventilators are equipped with an intake and an exhaust fan blade.  You simply push on the appropriate blade for the direction of air flow you want.  Look for the coloured dot on the fan.  The fan operates very quiet when the bushings are snug and lubricated.  But I have a sneaking suspicion that an intake fan lifts the motor off the thrust bearing, making it turn quieter. 

I installed a ventilator through Panache's forward hatch to retain deck space, precious as it is on an SJ23.  Others will say that cutting a hole through the acrylic weakens it and install their ventilator through the forward deck.  The hatch of an SJ23 is large enough to leave lots of light shining through around the ventilator.  The hatch doesn't have aluminum cross bracing or a reinforcing ring so for that reason I consider it too weak to support a person.  Therefore, I tell my crew that it is a NO STEP zone since I also don't want the acrylic scratched.  For those reasons it seems logical to have two delicate things in the same place; hatch and ventilator.  This way you have only one place to keep away from and leave a clear deck to tramp around on when the boat is rocking and rolling.  So far it has worked as nobody has had to walk the plank, yet! 

See Tech Tip B08 for important instructions about cutting and machining acrylic.  The wood ring around the ventilator hole shown above is fastened with silicon sealant to the acrylic.  It totally flattened and stiffened the acrylic.  This ring was installed several years after I installed the ventilator.  The ventilator now looks good from the bottom because I can't see the dust that settles in the ring over summer.  It is an essential part of the installation that I forgot to install way back then.  I have not seen it necessary to set the two screws through the side of the white ring to secure the ventilator from lifting.

SUMMER COMFORT - For the first two years I owned Panache, I struggled to dry the cabin.  Every weekend when I returned to the boat I had to wipe up the moisture.  I never could find a leak.  Food didn't last long and paper wrappers became soggy.  It was difficult to sleep in the sauna like atmosphere and I was tired of storing gear away from water dripping off the ceiling and condensation running down the walls.  I kept the hatch cracked open at night but I couldn't leave it that way while unattended.  I finally solved the problem by installing a Nicro Marine solar powered day ventilator on the forward hatch as shown above.  See Tech Tip B08 for installation techniques.  This fan blows 750 ft³/hr under full illumination.  An SJ23 cabin contains ~600 ft³ of air so this fan is adequate when the sun shines.  The ventilator dried the cabin in about two weeks, ending my humidity and stale air problem.  As good as that ventilator is, it was replaced with a day/night ventilator that proved even better.  The day ventilator has since been relegated to backup and winter storage use.  My next version may see me using dual ventilators.
 

TRANSOM VENTS (2024) - While the Nicro solar ventilator on the forward hatch works great, Panache is also equipped with two passive fibreglass air scoops on the transom to vent the space under the cockpit.  One scoop is pointed forward and the other aft.  The forward pointing intake scoop is installed in front of the engine (shown at right) so outboard fumes are not drawn in when idling or with a following breeze.  The aft pointing exhaust scoop is installed on the port side.  There are bug screens inside each vent that do a nice job of keeping them out and keeping things fresh and dry below. 

NOTE - These "scoops" are actually the handles from a Tanzer 26 companionway drop board where they double as vents.  Rather clever actually.  "Sure beats having a board slip out of your wet hands to land on your foot."  For original Tanzer "drop board handles," phone Yachting Services at 1-800-618-6748 (Eric Spencer). 

To install these vents on an SJ23 transom, be prepared to trim the edge of the vent to fit the narrow top.  Cut the hole with round corners as shown below.  Round equates to strength.  Panache's vents were installed by the previous owner using pop rivets.  My idea in working on these vents is to make both vents serviceable by mounting them with screws.

A DIFFERENT STYLE of TRANSOM VENT.  Chad Murchison.
Note that the vents are installed above the bottom of the tiller notch.  A good safety feature.  Lower would be dangerous. The cowl is removable to clean the screen.  Each vent is installed at an angle to shed water.  This reduces the chance of rain water find its way below.  These vents can likely pass more air than Panache's design.       The all important bug screen to keep wasps and other insects from flying into the locker.  I think we can all agree that nobody wants a wasp or hornet nest inside their boat!

WINTER COMFORT - A boat left floating for winter storage (an unheard of concept on the prairies or a mountain lake!) has an entirely different set of ventilation requirements.  These owners have the luxury of using the vessel as a weekend getaway with the ability to do some midwinter maintenance.  However, the cabin requires heating and active ventilation to offset the additional moisture of occupation.  If shore power is available then a small ceramic 1.5KW electric cube heater works well to heat the cabin air and to keep the dampness out of the cushions.  Use the low setting while you are away and the high setting while you are aboard.  This works OK down to around freezing.  Below freezing, two heaters may be required to make it liveable.  It's amazing how much heat (5000 BTU) comes out of one of these small ceramic heaters.

If the ventilation is inadequate while the boat is unoccupied, you may have to use a sponge to soak up the condensation under the v-berth and in the storage areas under and behind the settees.  In the Spring you may see a significant amount of water or ice in those areas to make you think the hull has sprung a deck leak.  In actuality, the water came from condensation dripping from the ceiling and flowing into the bilge through any holes.  If this is your situation, use an active dehumidifier resting over the sink to drain off the moisture.  It will keep the boat dry and fresh smelling so you won't have to clean anything when you step on board.  On and SJ23 it is wise to store articles in plastic tubs stowed under the settees.  The tubs also help to keep things orderly as it is quite easy to slide them sideways to find your stuff.  Leave an empty space between the tubs so you can slide them. 

NOTE:  If you sleep on board without a ventilator and the air temperature will drop below the dew point, then crack the hatch open (install a full hatch bug screen) and open the companionway (with another full bug screen) to keep the cabin dry.  It is amazing how much humidity a person can expel at overnight.  For most southern U.S. boats the air temperature seldom drops below the dew point and it is therefore irrelevant if the fresh air is blown in or the stale air is sucked out of the cabin.  Although fresh air blown in smells better!  For a northern latitude boat, especially in the shoulder seasons, the most effective ventilation is better determined by how low the air temperature drops below the dew point and to a lesser extent, what the drying index is during the day.  A high drying index almost always relates to a drier boat.  If the air temperature drops below the dew point you have to deal with condensation.  For a boat floating in an exposed anchorage consider which of the following to choose:

• A Day Ventilator (solar driven fan) - With the intake blades installed to blow dry air in at 700ft³/hr. during the day and relying on wind driven venturi suction at night it dried the cabin and freshened it a bit. 
  (For one season I tried to exhaust the humid air but the cabin started taking on that stale smell so I switched the blades back to blow fresh air in.  This freshened the air in a couple of days). 
• A Day/Night Ventilator (solar/battery driven fan) - With the exhaust blades installed to blow moist air out at 700ft³/hr. it dried Panache's cabin but didn't freshen it.
• A Day/Night Ventilator (solar/battery driven fan) - With the intake blades installed to blow fresh air in at 700ft³/hr. it dried Panache's cabin and freshened it.
  (This past Fall the cabin temperature dropped to 1C when I slept on the boat.  With all hatches closed and the fan running I had only a slight bit of condensation on the windows). 

SAFETY - Cooking fumes and humidity aside, if your cabin air is filled with dust particles, glue fumes or is low in oxygen due to a heater consuming air then you definitely need to get outside to breathe fresh air NOW.  While you are out there, blow fresh air into the cabin to push out the bad stuff as quick as possible.  After all, people need oxygen and clean air to survive.  Your nose can smell clean, fresh air very quickly, so follow it!

INCREASE THE AIR FLOW - Panache's ventilator shown installed above is a 1993 Nicro Day ventilator.  The air flows under the edge, through a narrow 1/8" wide gap.  If you do the math, the cross sectional area of this gap is much smaller than the 3" diameter fan hole.  A later version of this fan is equipped with long air slots along the bottom edge of the hood to improve the air flow.  If you stick a wet finger in front of a slot you can actually feel the wind chill.  This is the main reason why I switched to a Nicro Day/Night ventilator.  When I discovered that my day ventilator had such poor air flow I added 1/8" thick acrylic spacers under the perimeter of the stainless hood, glued with silicon sealant so they can be removed later.  In terms of water shedding ability, the spacers shed water better than Nicro holes drilled around the perimeter.  While I have never experienced problems with this installation, about 10 years later discovered the acrylic hatch was bowed downwards, like a shallow dish pan.  This was due to the lack of support around the ventilator hole.  The pan shape effectively closed the gap under the perimeter of the hood, restricting the air flow.  All this because I forgot to install a wood reinforcing ring under the ventilator hole.  The ring straightened the acrylic and added phenomenal strength and stiffness.  See Tech Tip B08, Reseal the Forward Hatch.  I retained the spacers to maintain the higher air flow.

DUAL VENTILATORS - If you really want to improve the cabin air flow, install a second ventilator as recommended by Nicro.  "Any time an air tight boat is kept in a confined area that has little wind, like a marina with tall power boats, a well protected anchorage or with buildings close by, the boat needs forced ventilation.  Usually more than a single ventilator can provide." 

"DON'T INSTALL A SECOND VENTILATOR TO OFFSET A DECK LEAK".

When I moved Panache to a sheltered mooring the push pull effect of two ventilators seemed like the best way to remove the occasional, faint musty smell.  The top of the sliding hatch is one place to install a second ventilator on an SJ23, there being no free deck space on the aft end of the boat.  With the forward ventilator blowing air in (intake) and the aft ventilator blowing air out (exhaust), the push pull effect of the two should dry and freshen the cabin very quickly.  Although it might vent better the other way around.  For example, an aft ventilator like a 3" Nicro day vent, could work in concert with hot air rising out of the cabin and the venturi effect of wind over the deck. 
- Install the aft ventilator on the center line of the sliding hatch so it doesn't block the line of sight over the cabin for steering.  As usual the wood core of the sliding hatch must be sealed with epoxy.  See Tech Tip G08.
- The 1" gap between the hatch and the top of the hull ridge at the forward end of the companionway is sufficient to clear the bottom of the ventilator.
- While the camber (curvature) of the hatch falls just within limits for the installation of a 3" vent, (1/2" gap over 12" of the hatch surface), I'd build up the top of the hatch with epoxy and gel coat to make it flat for the vent.
- For the hatch ventilator it is probably a good idea to install the Nicro air shut off valve to keep the heat in during cool weather.  Although there are many times when more ventilation is needed in cool weather.
- Prudence suggests the vent be replaced with a Nicro plug when stepping the mast so it's a good idea to store a second plug in the spares kit.

- An alternate location for a second vent might be on the cockpit bulkhead behind the depth sounder or other flat, low profile instrument as shown at left.  This is my rendition of an air intake that shouldn't be obstructed while sitting against the bulkhead.  This installation requires a 1/2" thick 12V PC fan installed on the inside and an appropriate sized solar panel installed outside.  You have to get creative for this.  I have not shown the side of the instrument spacer in order to reveal the air passage.
- Another idea would be to add a fan to one of the transom vents shown above.  Quiet and totally unobtrusive.

________________ REPAIRS ____________________

REPLACE THE SOLAR PANEL of a DAY VENT (600ft³/hr) - In 2003 Panache's Nicro solar day vent took a direct hit (left photo) from a golf ball sized hail stone during a tornado.  To say that it obliterated the solar panel is the understatement of the year!  However, the metal hood stood up well to the impact as the plastic frame under it survived, so I wasn't totally ticked off.  Rather than buy a new vent, I replaced the "punched in" solar panel with one scavenged from a garden light (right photo).  Sometimes it pays to keep old stuff around! 

Repair work of this nature requires surgical skills and precision cutting tools to separate the components without further damage.  This one was no different and it pays to have patience.  I cut a 1/8" thick acrylic disk to fit the hood, just inside the lip where the old acrylic was mounted.  This replaced the damaged backing panel that the solar panel was mounted on.  Silicon sealant was used to fasten the replacement solar panel on top of the acrylic disk and to seal the disk to the plastic frame.  The SS hood rests on top of the frame.  I'm very pleased with the results because the repair looks good and the fan now blows more air than with the original solar panel.

2023 - The repaired solar panel shown above turned opaque with 20 years of UV exposure.  I replaced it with an aftermarket panel available from my local electronics wholesaler at $10 Ca.  The new 2 1/2" square solar panel has a superior coating to withstand UV light.

An aftermarket panel can usually generate lots of power so be careful to pick one that can't overdrive your fan motor.  Also one that can charge two AA batteries (>3VDC) so it has sufficient power to start and run the solar motor while charging.  A little bit of extra power is OK since the motor can spin faster & run quieter.  I like the extra air flow that comes with it. 

The panel I bought has a 1/8" thick junction box on the back which necessitated a 1/4" thick spacer to fit it to the top.  I used some scrap G10 fibreglass board at the perimeter, sealed with Marine Goop underneath.  I also applied a fillet of Sikaflex at the outside perimeter to keep the weather out.  Its not the prettiest installation but given that this is my backup vent used for emergencies or winter layover, I'm happy with the results and performance.  Now that this panel works as well as it does, I may replace the one in my day/night vent shown below because it has difficulty starting in the morning with the marginal light.

REPLACE THE SOLAR MOTOR in a DAY/NIGHT 2000 VENT (700ft³/hr) - If you discover that the cabin is taking on a musty smell, it is very likely the solar motor has slowed down, stops intermittently, or has stopped altogether.  You can confirm this by watching the fan blades with the sun shining on the panel.  If the air flow of a fully illuminated panel doesn't chill your dampened finger, your motor has a problem.  For a day/night solar vent clean the battery terminals inside the battery compartment.  Don't touch the battery contacts with your greasy fingers.  It takes very little grease from your fingers to start a "culture" of green corrosion.  Coat each terminal with a dab of water proof grease.  A NiCad C cell should last about three years in this ventilator, which is about all you can expect in this installation.  In other applications a C cell NiCad will last about 5 years.  However, the minor cost of a C battery is pittance compared to the huge maintenance savings by preventing mildew rot in the cabin.  A charged battery can keep the fan running for about 36 hours. The solar panel can recharge the battery and run the fan during one day of bright light. 

Here are some tests you can perform on the motor to determine what is wrong, assuming the panel is illuminated by the sun.

1. Give the stalled blades a nudge with your finger.  If you can feel a magnetic force from the motor and it starts to turn, then you have a marginal winding in the motor.  It may continue to run as long as long as the solar panel remains illuminated.  If the motor has to be restarted with a nudge from your finger after the panel goes dark, replace the motor.
2. If you can feel the magnetic force from the motor and the fan holds still, you have a shorted out winding that is drawing a current from the battery.  Replace the motor.
3. There are many degrees between the above two situations.  I have seen motors with a bad winding that will restart when lots of sun is applied quickly.  This will be short lived.  Replace the motor.
4. If the motor turns but is very noisy, the bushing is dry or worn.  Oil the bushing with a drop of ATF and if the motor goes quiet go back to sleep.  Oil again in a week to saturate the bushing.  Repeat as required.  If the motor stays noisy replace it.
5. If the motor does not turn then the bushing is seized or the brushes are welded to the commutator.  Lubricate the bushing with a drop of ATF.  If that doesn't free the motor, replace it.

REPAIR - Around 2009 Nicro Marine was bought by Marinco and they discontinued the original 3" and 4" round solar ventilators.  Parts are no longer available.  The replacement square 4" vents don't fit the original universal deck holes.  However, the solar motor of a 3" solar vent can be replaced if you can find a suitable .5V solar motor.  The "toy" motor I found works quite well and costs far less than replacing the vent.  However, it has a slightly smaller diameter which requires you to modify the mounting arrangement with a stepped mount using some concentric plumbing tubes (ABS/PVC) to fit around the motor case.  Panache's motor is secured with silicon sealant inside the white PVC tube you can see in the photo.  It is nice to have a fresh smelling boat again!
PS: Only a partial cut away view of the case is shown in the diagram. 

Nicro Solar Motor Specifications.
CASE - 36MM OD x 25MM top to bottom.   SHAFT - 2MM x 11MM.
VOLTS - 1.5V.  Select a motor that can operate from the 1.5V battery.

Solar World (Now Solaris) Motor Specifications.
- Part # MC-05-07
- Good torque with 300 RPM @ .5VDC.
- .5-3V, 100 MA start up current and runs at 15MA (no load).
- 2MM shaft (1CM long), body size (1.25x1.25)"
 

There are three components to this successful repair; a PVC plumbing fitting (approx 1 5/8" ID x 3" deep), a short length of 2" ABS pipe and a solar motor.  Reconstruction is a fairly simple process if you have basic cutting tools and soldering skills.

1. Remove the SS cowling from the vent.  (4 screws)
2. Cut off the plastic motor housing at its base, leaving a 1/4" flange protruding from the base plate.  A hack saw through the side will do the trick.  Cut straight and smooth.  Sand the edge smooth and blow away cuttings.
3. Slip the motor inside the plumbing fitting till it rests on the inner ring.  Cut the protruding PVC off so the motor fits flush with the top.
4. Cut the bottom off the plumbing fitting so the fan blade sits at the correct height within the housing.  Center of fan blade fits midway to the ring in the venturi.  See diagram above.
5. Slice a 1/2" wide section of 2" ABS pipe.  Split the ring so it can expand to fit around the base plate flange.  Orient the split towards the battery compartment.  The split ring will receive the fitting to center the motor within the venturi and create a passage for the battery wires.
6. Solder 10" of 24 ga stranded wire and the solar panel wires to the solar motor terminals.  Observe correct polarity so it rotates in the correct direction.  Add a toggle switch S1 in series with the battery if you want to shut the motor off at night.  It will then operate like a day ventilator, spinning only when the sun shines.
7. Add resistor R1 if the solar panel voltage is too high.
8. Slip the motor into the plumbing fitting, feed the wires through the bottom and lower the assembly into the ABS ring.  Fit the wires through the ABS split.
9. Feed the battery wires into the battery compartment and solder them to the battery terminals.  Observe correct polarity when you push the terminals into their receivers.  Apply some silicon sealant to the holes where the wires go through.  This seals the hole and creates a strain relief for the wires.
10. Push the excess wire into the motor base cavity.
11. Glue and seal all components with silicone sealant.
12. Hold the solar panel in front of a 60W incandescent light bulb (if you can still find one) and watch it spin again for way less cost than buying a new ventilator.
13. Expose to full sunlight for 36 hours to fully charge the battery.

The best part of this technique is that if the replacement motor dies, simply cut the silicone sealant, break free the dead motor, glue in a new one, solder the wires to the motor and screw it back on.  So far I have replaced one worn out motor.

SWITCH - When I replaced the solar motor in my day/night vent I included a switch S1 to shut the fan off.  There are times when it is annoying to sleep with the noise above my head.  Although, when it is colder in Spring or Fall, I like to shut it off to keep the warm air in the cabin.  I see little point in heating the Arctic! 
 

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