Aft berth, stowage, ventilation

[trswem]

Howdy folks. I just scored a pretty sweet deal on a brand new memory foam mattress that's coming out of an RV. I'm concerned about having enough airflow around the mattress to prevent mold. I think I have some good procedures for operation and storage that should work out, and I live in a low humidity area. One thing I'm considering, replacing the panels that cover the stowage in the aft berth with some fresh marine grade plywood, and drilling a series of holes. This would allow some air to circulate under the memory foam mattress at night while we're on it. Has anyone done this or have any concerns with that?

Thanks!

[C Buchs]

I stole this idea from Chinook.

If you look up "dry deck" on Amazon, you'll see a lot of these tiles. I haven't used this myself, but they were reported to work well.

Jeff

[Be Free]

I tried a memory foam mattress in the aft bunk. It got very moldy. I do not live in a low humidity area.

It will probably be fine for you if you give it a little air circulation. Good luck!

[OverEasy]

Hi Trswem!

Air circulation is a really good idea!
Memory foam is open cell so air “slowly” moves in and out of the foam when somebody/thing compresses or decompresses the foam.
So moisture definitively will get into the foam
The surface area of memory foam is HUGE so the entering moisture will wick to the interior surfaces of all those open cells.

The moisture will come from not only the ambient air but also from whoever lays or rests upon it.
Condensation under the mattress (the aft berth is at/below waterline and generally cooler than the ambient air even though the interior surface is separated from the actual hull) is another source of moisture. Note that the mattress will also cool down somewhat so ambient moisture will wick into the foam as well.

Moisture, once inside this type of memory ( or the firmer conformal) foam mattress, will be difficult to dislodge.

For our application when we made the conversion to 6” conformal foam pads, we don’t use the aft berth (too awkward) for sleeping preferring to use the fwd berth and dinette areas. We use the aft berth area for plastic boxed storage).
We used a multifaceted approach to mitgation of the moisture problem.
1st after spraying our pads with a good dose of Lysol spray (crisp linen scent) on all surfaces we wrapped and sealed our foam pieces in 4 mil black plastic (like one finds for heavy duty contractor or leaf bags. Sealing tape was also heavy duty quality packing tape over all the folded seams. Before wrapping we placed a 1/2 inch thick synthetic sheet quilting on the foam pads to provide a softer surface. (Remember we used conformal foam, not memory foam, which isn’t so squishy.)
2nd we wrapped all the pads with a nice smooth sunbrella type exterior fabric.
3rd we used 1/2 thick airflow pad pieces (Tochta 1/2” thick Air Gap Moisture Pads) that match the shape of each pad. This stuff provides a much more open air gap with much less thermal conduction than the multiple ‘dry deck’ type tiles we looked at. The airflow pads also have som give to them so they are easier to fit and don’t scuff the hard surfaces contacted.

The fwd berth and dinette are further above the waterline which minimizes the condensation.
We also use a dehumidifier when at a slip and when storing the boat in the off season.
The dehumidifier vents to the exterior to ensure good airflow within the cabin.
The dehumidifier condensate drain feeds to a mini bilge and pump to drain overboard.
This works really well for us during the temperate as well as the high humidity seasons.
During cold weather we also use a small heater to warm and aid in circulation of the interior air.

Overall this has worked out really well for us.
The Lysol provides a baseline mold/mildew repellent/kill factor (and yes we will annually/biannually check and reapply as needed).
The plastic wrap sealing (is somewhat UV resistant and will remain pliable for a very long time) keeps any spills /leaks / spatter from getting to the actual foam pads.
The airflow pad provides a very good air gap, thermal break and air circulation.
The sunbrella type fabric is stain and moisture resistant as well as very UV resistant.
The dehumidifier function of our A/C unit system is a low current draw and does an excellent job of drying out the interior and air circulation.

When using the fwd berth and dinette area for sleeping we use quality polyester flat sheets for comfort and the ease of cleaning/airing out. These fit and tuck nicely and fit in a small laundry bag to bring back to the house to launder after overnight trips.

For blankets we utilize polyester sleeping bags that we open up and spread out. Again easy to use, store and clean in a standard washing machine.

Polyester is nice as it doesn’t hold moisture or wick (like cotton or wool blends are apt to do) so they dry out readily.

So after a year plus with our cushion modifications we can unequivocally state that we are really happy in all aspects.
SO MUCH MORE COMFORTABLE! ! !
No mold or mildew! None on, in or under!
==> (Our operational areas are Coastal South Carolina and New England… so lots of humidity and temperature variations).
We posted our cushion pad replacement in the Mods section of the forum.
https://macgregorsailors.com/mods/index ... em&id=2200

One suggestion with having an air gap under an aft berth mattress is you might want to look into making provision to include some means to provide an active (forced) airflow through it rather than solely relying upon just a passive gap. Mold and mildew seem to love static conditions.

Best Regards,
Over Easy

[NiceAft]

In twenty years we have never had a mold problem. The Delaware alley can get rather humid in the summer. I have attributed the lack of mold to the two opening ports I had installed early on.

The ports are port and starboard, just in front of the large aft berth, which we use when cruising.






Now, we don’t use a mattress as you describe, but again, we have never had a mold problem.

The port side one is just over the galley. You can see the sun shining through the starboard port.

[pitchpolehobie]

In twenty years we have never had a mold problem. The Delaware alley can get rather humid in the summer. I have attributed the lack of mold to the two opening ports I had installed early on.

The ports are port and starboard, just in front of the large aft berth, which we use when cruising.

Those portholes are also opened in the event of scuttling the ship...intentionally.

[NiceAft]

You laugh

I make it a point to keep them closed while sailing. Once, I forgot.

We were intentionally heeling in in excess of forty-five degrees (much fun if one does not mind the cabin mess) when I remembered I forgot to close those ports. I excitedly told my wife to go below and close them. Afterwards, I told her there is a nautical term that could apply...................SINKING

[pitchpolehobie]

You laugh

I make it a point to keep them closed while sailing. Once, I forgot.

We were intentionally heeling in in excess of forty-five degrees (much fun if one does not mind the cabin mess) when I remembered I forgot to close those ports. I excitedly told my wife to go below and close them. Afterwards, I told her there is a nautical term that could apply...................SINKING

That was the event I was referencing - To be honest I was thinking about putting some in the same place and after reading that I figured.. Ill just get some more fans but I am envious - the 26X does not have any "low" portholes to look out.

[NiceAft]

Highlander has similar ports on his Mac. I don’t regret installing them, and encourage anyone interested to do it.

The open ports keep air flow while at a dock. The open ports keep air flowing while wrapped for the winter. They also allow a great view when dining below.

My grandson wanted to go below and “stare out the window” the gentle rocking under sail got to him.


P.S. if you notice that the port is open, I did it so the kid would have some air. There are exceptions to every rule.

[OverEasy]

Cute grandson!
Now…. So who’s gonna make the first glass bottomed Mac?

[Russ]

P.S. if you notice that the port is open, I did it so the kid would have some air. There are exceptions to every rule.

Also the location of the opening porthole is above the gunwale. A safer location to install an opening porthole yet should still be closed when underway.

Sad story of one installed below and accidentally left open and when heeled the boat filled quickly with water.

[NiceAft]

A boat owner while enjoying the boating lifestyle, should always be conscientious to common sense and safety.

In my case, I was totally aware of that little boy, that open port, and the water I was on (Lake George).

[OverEasy]

Hi NiceAft!

Just to be clear, We Like your portals and your good judgement of how you operate.
No criticism there at all.

Getting some cross ventilation in the cabin must be nice without having to open the fwd hatch.
We’ve seen soon portals with built-in bug screens too!
Kinda hard to have an effective bug screen with an open fwd hatch without a lot of fiddlin’about…. And there have been instances of waves breaking over the bow and water coming in an open fwd hatch. So nothing is perfect… so the good common sense operation which you so aptly demonstrate is always the key to a happy day on the water.

We’ve contemplated similar portals but have presently placed those thoughts on our future pending project ‘might wanna do’ list.

Meanwhile we have been contemplating a trip south to the Florida keys sometime in the future.
The water being so much clearer in the Florida keys (as are the waters in Lake Champlain) we’ve actually given some thought as to being able to casually look below our boat… for the sights and the wildlife.
What we’ve found are these neat small waterproof battery powered wireless cameras that I’ve been contemplating to either hang over the side or adhere to the hull that would let us do so on our iPad. These cameras often have a wireless remote light and it would be something fun to watch at night being much clearer than just looking over the edge or a view box. Even more so desirable if we were ever up to making a Bahama trip!

With our new stern transducer slide bracket it shouldn’t be hard to rig up on an auxiliary slide plate as another option instead of adhering to the hull….. Liking this idea the more we think about it!



A glass bottom boat without the hole!

Best Regards
Over Easy

[NiceAft]

Overeasy said:

Getting some cross ventilation in the cabin must be nice without having to open the fwd hatch.
We’ve seen soon portals with built-in bug screens too!
Kinda hard to have an effective bug screen with an open fwd hatch without a lot of fiddlin’about…

The ports I have, have bug screens. I never, never have the the front hatch open while underway. I do have a flexible, fine mess screen designed for front hatches. https://a.co/d/06g4ap6
I use it while docked. I also have a similar fine mess designed for the open companion way. These are used at a dock.

When high humidity is in the forecast, then all openings to the outdoors are sealed. It’s then time for the companion way air conditioner.