Dehumidifying Strategy for Trimaran Float Compartments

[DragonflyBob]

As we enter into the summer here in south Louisiana, my wife and I are looking at the best strategies to control the heat and humidity in the float compartments of our Dragonfly 32. Each float has two compartments with a separating watertight bulkhead. Access to each compartment is via a Moonlight Ocean Hatch (smoked gray color). The float hatches cannot be left open and the compartments are sealed by the hatches for obvious reasons when you are underway (i.e. we cannot circulate air in these compartments).

We are looking to do two things:

1. Reduce radiant heat from the sun into each compartment by covering the glass hatches internally with a removable reflective insulation barrier. We'll use some type of velcro attachment for this material.

2. Have some type of dehumidifier pack set up inside each float compartment. There are the tub types (MDR Damp Away) that sources like Defender sells and I'm interested in a product called SunPac Mildewcide that releases a chemical that bonds with the oxygen molecule that effectively robs the mold spores of oxygen, killing or not allowing them to form is my understanding.

As FYI for the main cabin, we are using a 5000 BTU Frigidaire window AC unit that we have mounted in a custom companionway hatch setup to keep the interior cool and dry. It works quite well and the condensate drains into the cockpit. We run it 24/7 if the boat is at the dock or if we are at a marina with shore power and it only draws about 4 amps so relatively economical. We'll turn the thermostat up to 80F when we leave the boat so that it is primarily cycling on/off from mid morning to early evening. We had a canvas bag made up for it so that when we use the boat, we put it in the bag and can store it either in our dock box or in a float compartment if we want to take it with us. I've used this same model window unit for cooling my office as well as my workshop and they have been quite reliable. If it dies, it's less than $200 to replace.

Would appreciate any feedback or advice on our float strategy based on similar experience.

[thinwater]

Why do people install dark, acrylic lenses in deck hatches on trimaran amas? Because they look cool or because they are available, not because it makes any sense. There is no reason to let in light or that that are see-through. They should be white solid fiberglass or similar material.


Why not cover the outside of the lens with white self-adhesive vinyl non-skid material? Or paint them white? Apply a reflective window film rated for plastic windows (not one for glass-it will bubble). Applying reflective material on the inside means the lens will see the UV twice. Also, acrylic absorbs most of the IR, so the acrylic will get hot and not that much will get reflected out (applying a reflective surface on the inside won't actually work).



I think you will also find that humidity in the amas really does not hurt anything.

[Bill O]

Agree, covering the lens covers from the outside makes more sense. Another type of material would be Phifertex (various products w/up to 97% blockage) if you can make/install a cover over the hatches. This would allow some light thru so it would not be a dark cave.

[DragonflyBob]

Originally Posted by thinwater

Why do people install dark, acrylic lenses in deck hatches on trimaran amas? Because they look cool or because they are available, not because it makes any sense. There is no reason to let in light or that that are see-through. They should be white solid fiberglass or similar material.


Why not cover the outside of the lens with white self-adhesive vinyl non-skid material? Or paint them white? Apply a reflective window film rated for plastic windows (not one for glass-it will bubble). Applying reflective material on the inside means the lens will see the UV twice. Also, acrylic absorbs most of the IR, so the acrylic will get hot and not that much will get reflected out (applying a reflective surface on the inside won't actually work).


I think you will also find that humidity in the amas really does not hurt anything.

Dragonfly’s are built in Denmark and probably 90+ percent of their boats are sold to customers in northern Europe. Compared to my home waters, much, much cooler and a shorter sailing season so the hatch choice in terms of how much heat is transmitted is probably a moot point.

Humidity in the floats causes mold and mildew, can affect any soft item such as sails, covers, bags, etc. It looks unsightly, stinks, and is not healthy if you have to spend time in the compartment. We are looking for solutions to keep it in check. We are considering several treatments to try to kill and stop the mold spores and hoping this thread would offer some real world experience.

My wife and I have discussed covering the hatch and we are considering adding Hydroturf since it will block the light/heat transmission and make the hatch safer to step on even though we limit going out to the floats if underway (if we do, we wear harness/tether/PFD).

[thinwater]

Originally Posted by DragonflyBob

Dragonfly’s are built in Denmark and probably 90+ percent of their boats are sold to customers in northern Europe. Compared to my home waters, much, much cooler and a shorter sailing season so the hatch choice in terms of how much heat is transmitted is probably a moot point.

Humidity in the floats causes mold and mildew, can affect any soft item such as sails, covers, bags, etc. It looks unsightly, stinks, and is not healthy if you have to spend time in the compartment. We are looking for solutions to keep it in check. We are considering several treatments to try to kill and stop the mold spores and hoping this thread would offer some real world experience.

My wife and I have discussed covering the hatch and we are considering adding Hydroturf since it will block the light/heat transmission and make the hatch safer to step on even though we limit going out to the floats if underway (if we do, we wear harness/tether/PFD).

I've had both cats and tris.


I would not store sails in the floats. They are notoriously hard to keep dry when driving through waves, since they pump and must be vented. You can try, but don't expect it to be reliable in the long term. It's hard enough to keep sails mildew-free in the main cabin. Spare rode and anchors (well secured) only.



Spraying with borax solution will kill the mold. About 2 tablespoons per liter of water. Do not rinse, the residue prevents return.

[Bill O]

Have zero experience w/tris and small cat floats, but seems like the main problem is the lack of air circulation. Anyway to circulate the air better into the dead zones? (fans, small dorade boxes?)

[DragonflyBob]

Originally Posted by thinwater

I've had both cats and tris.


I would not store sails in the floats. They are notoriously hard to keep dry when driving through waves, since they pump and must be vented. You can try, but don't expect it to be reliable in the long term. It's hard enough to keep sails mildew-free in the main cabin. Spare rode and anchors (well secured) only.

Spraying with borax solution will kill the mold. About 2 tablespoons per liter of water. Do not rinse, the residue prevents return.

We don't normally store sails in the float compartments. Our Code Zero and Gennaker normally live stored in sail bags secured on the floats if we are using them for a race or a cruise/daysail. If they have to go in the floats, it would only be temporary (2-3 days max). But we do keep cleaning supplies, fenders, dock lines, extra fuel tanks, spare anchor/rode, dinghy (uninflated), Torqeedo motor (for dinghy), and spare parts in the floats. Between the two floats and the compartments in the floats, we probably carry 300-400 lbs of equipment if we are cruising.

The hatches on the Dragonfly floats seem to keep the floats sealed quite well. Our forward float compartments seem to not leak at all and I've never seen more than a quart of water in the rear compartments. Dragonfly has a molded spray fairing on the deck for each hatch that I think is very effective at keeping water away from the hatch sealing surface.

Thanks for the suggestion on the Borax, another weapon.

[DragonflyBob]

Originally Posted by Bill O

Have zero experience w/tris and small cat floats, but seems like the main problem is the lack of air circulation. Anyway to circulate the air better into the dead zones? (fans, small dorade boxes?)

You are correct in no air circulation in those compartments.

[gonesail]

the only way to remove extreme humidity is with compressor driven dehumidifiers (which generate heat) or AC. other than that you need to ventilate .. which invites more humidity

[Training Wheels]

We keep 2 Spinnakers in our floats. We just keep the hatches propped open when we’re not sailing and have never had mold or mildew in our floats. 6 years cruising in the tropics and no issues. Our floats are very well sealed with no leaks into them, though.

[longjonsilver]

i have been using desiccant beads to dry out my floats and other compartments that are sealed.

https://www.amazon.ca/Premium-Indica...ps%2C95&sr=8-5

The jury is still out on how well they work in the long term. Heat them up and they dry out. They change color when they get wet.

[DragonflyBob]

Originally Posted by longjonsilver

i have been using desiccant beads to dry out my floats and other compartments that are sealed.

https://www.amazon.ca/Premium-Indica...ps%2C95&sr=8-5

The jury is still out on how well they work in the long term. Heat them up and they dry out. They change color when they get wet.

Thanks for the link. Do you pour the beads into some type of breathable or mesh bag?

[longjonsilver]

Originally Posted by DragonflyBob

Thanks for the link. Do you pour the beads into some type of breathable or mesh bag?

Yes, i bot some little cotton bags off amazon and remove them when the beads turn pink. Today i bot a baking pan to heat the pink beads in the oven and dry them out to blue again.

It works. But i don't know yet how much water it removes and if it is sufficient for a boat to keep it dry.

[thinwater]

Originally Posted by Bill O

Have zero experience w/tris and small cat floats, but seems like the main problem is the lack of air circulation. Anyway to circulate the air better into the dead zones? (fans, small dorade boxes?)

The amas on Dragonflies and Farrier designs can go under water and do go through waves, making vents a tough problem. They all struggle with this. But you aren't wrong.

[thinwater]

Originally Posted by DragonflyBob

Thanks for the link. Do you pour the beads into some type of breathable or mesh bag?

Yup, I've studied this on boats.



https://www.practical-sailor.com/bel...winter-storage


Silica gel can hold about 0.2-0.3 pounds of water per pound of gel (more in theory, but it really stops pulling) and is regenerated in an oven. H2OUT sells it in perforated stainless canisters, which are very handy and last a long time. I've used them on boats and in industry, and they are very durable. I'm sure there are other possibilities but something like this is very handy. Just plop it in the oven, super simple. I have used them to mothball large computer cabinets for outdoor storage for up to 20 years (tightly sealed)!



https://h2out.com/space-dryers/


My F-24 amas leak. My PDQ cat was desert-dry. But it sounds like yours are just humid and have no free water, so this could work.