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Anke and I live aboard WAYWARD, and wrote about it's design and construction at

Access to the net comes and goes, so I'll be writing in fits and spurts.Please feel free to browse the archives, leave comments where you will and write... I'll respond as I can.

Fair winds!

Dave and Anke
triloboats swirly gmail daughter com

Sunday, March 4, 2012

Spore Wars: Winner Takes All

On board, it's Us or Them!

Ya know, when mildew took in a Chinese ship, they'd burn 'em.
An unsympathetic Friend on hearing us whine.

The greatest challenge we face, living aboard, is not the Sea, the Weather, or even financing the Life.

Our greatest challenge is housekeeping.

Dirt, per se, isn't so much a problem. We have an easy relationship with it, and are on relatively good terms.

It's a good thing, too, since woods are full of duff and beaches full of grit. We brush off as best we can, but fleece and wool probably inspired Velcro for their tenacity. We slosh our boots at water's edge and bucket down the decks, sometimes several times a day, but the deep tread that gives good footing also carries a load of sand and gravel. The woodstove is a sloppy eater, and we're not such dainty creatures ourselves. Whole ground grains make crumbly goodies.

Not having storage ashore means that our holds and lockers are snugly packed. Even with adequate ventilation, such density impedes airflow. What air does make it into the cool, still corners is sea and rainforest humid. This creates perfect conditions for our arch enemy: mildew.

Mildew, aka mold aka fungus, is one of those category terms. Few efforts are made to distinguish between species. It has no place on board! I'm sure the feeling is mutual! And yet, it has made a place for itself on board since the first log put to sea. To the point that a 'boaty' smell is faintly musty... olofactorial evidence of minute, airborne spores out lookin' for a home. If you smell them (and sometimes when you don't) they're trying your airway and lungs on for size!

Fungi are a significant health hazard to mariners and our vessels. Black mold, in particular, can be crippling. Some forms eat wood in a misnomered condition called dry rot, which, untreated, can hole the hull.

As Bugs Bunny would say,.DIS MEANS WOWAH!

Know thine enemy... like all life forms, fungi need nutrient and moisture. Keeping surfaces sealed (to isolate that tasty wood) and wiped down removes nutrient. Ventilation (to some degree) evaporates moisture. Leaks and seeps - especially fresh water ones - are like smugglers supplying the enemy; they need to be stopped.

Fungi  propogate via spores, which are produced by fruiting bodies. The more fruiting bodies, the more spores, and, shortly down the road, the more fruiting bodies. Early intervention is the stitch in time that saves nine.

While wiping down, some mildewcidal chemical will often be used. Clorox is classic. Recently, less generally toxic and more environmentally friendly substances are available. We do use some Clorox, for very bad spots, but mostly use white vinegar (acid), which wears many other hats on board.

Thoroughness and carry-through seem to be the key. A cleaning project that is started today and finished next week has a low success rate. The first half is recontaminated (invisibly) by the second. A quick wipe down is mostly cosmetic.

Choose the ground... here's what we've learned to do at the design/construction level to tip the odds in our favor:
  • Divide and conquer - Water-tight compartments are a classic way to limit loss of buoyancy in a hull breach (another topic). As a bonus, they divide the interior into separate bioregions. Compartments can be unloaded, cleaned and restowed one by one, without fear that its neighbor will replenish its spore load.
  • Open bay architecture - Small, tight spaces break up air flow, and are extremely hard to clean thoroughly. Open spaces, all corners of which can be easily reached and inspected aid thorough cleaning.
  • Smooth, hard surfaces - Quick and Dirty hasn't made up its mind, on this one. For ply hulls, the best idea I've heard is formica coated surfaces. Stuff is spendy, though... sold by the square foot, it adds up fast. It's also hard to retro-fit... if it can't be done on the bench or on an open surface, it's a finicky process.

    We settle for filling voids, smoothing, and painting with a hard, glossy paint. Haven't added mildewcides to the paint, but are considering it for primer. Problem is, they're toxic to us, too. A last resort for us.
  • Smooth, filleted corners - Mildew loves the inside of a hard, right angle. It's very hard to get it clean - there's always a small, dense line of residue along the crack. Even if our mildewcide has killed it, the left-overs will provide food for the next round.

    Fillets round that corner and bridge between smooth surfaces on either side. They're a piece of cake to wipe down, with no sharp corner to hide in.
  • Solid, composite constructions - Where used, composites bonded uniformly (with no voids) and edge sealed exclude moisture, nutrient and spoor laden air. If voids are unavoidable (rimshot, please) consider making the components removable for periodic inspection and cleaning.
  • Seal porous surfaces - Spores are small and get into dinky little holes in everything from wood to foam. We get best results by sealing those pores to exclude fungus.
  • Containerized storage - Bins are cheap and easy to build, but to empty one, its pile of stuff has to go somewhere. A lidded container on an open shelf can be bodily transported elsewhere, while the shelf is cleaned. The lid allows transport and work during moderately wet weather... a boon in our rainforest.

    A further benefit is that, where the contents of open bins often require cleaning themselves, containerized contents seldom do. Just to be on the safe side, we'll air them occasionally in warm, dry weather.

These approaches add time and cost to a project, but, I believe pay for themselves over time.

On LUNA (from whom we learned a lot of these lessons), we figure that we were spending almost two months a year on cleaning, mostly during prime cruising weather. In twelve years aboard, we never once compled a contiguous, stem to stern sweep. SLACKTIDE, laid out on these principles, takes only a few days per year. No compartment cannot be cleaned in a single day.

We'll huff and we'll puff... A last round we've been contemplating is ozone generation shock treatment. This employs an ozone generator, which produces high levels of ozone in a confined space to sterilize it.

Ozone (O3) is an oxidizing agent that's extremely toxic (as is O2, incidentally). Being gaseous, it creeps into minute corners. If concentrations are high enough, it sterilizes all in its zone (it's essential to exclude the three Ps - People, Plants and Pets - from the area being sterilized).

Unlike most toxins, it breaks down into completely benign oxygen (O2) with no toxic residue.

Many things in it's wake will be partially and prematurely oxidized. Same process that ruins your rubber bands, but stepped up a bit. It can also attack wiring insulation, pressure cooker seals, window gaskets, open foods (promoting rancidity), etc.. So we'd use it sparingly (once a year) and protect what we can.


As a last word, the enemy is a master of survival, far and away older than ourselves. It's patient and persistent. It's everywhere outside the boat, so can always draw on reenforcements. It propogates exponentially whenever conditions are ripe. It has its own array of chemical weapons, with which it can sensitize or sicken the unwary and/or unprotected.

It is an adversary worthy of respect!

PS. I should point out that much of our cleaning takes place dried out near a freshwater creek, which complicates things, procedurally, but simplifies them socially. At the dock, our efforts are too often broken up by visitors who stop to discuss the mountain of gear we've piled next to the boat.

And of course, we're all too willing to take a break!  8)


  1. Mold.. Yucky.

    I once had a nasty experience with mold, delivering a 28 footer from Brisbane to Wellington across the Tasman. When I arrived the boat had been sitting in the tropics fully closed up and half sunk for the best part of a year. With every surface black with mold I hit it with a water blaster, threw out any fabrics on-board, binned all the books and then started scrubbing, one week later the boat seemed livable, so off we went, but the mold had other ideas, and as soon as we got to sea it spread to all the new books, clothes and anything else that it could get it's nasty claws into. Absolutely horrible the way in two weeks the mold took over the boat, and it makes me wonder what it has done to my lungs. Since then I have been really careful of the stuff.

    My two favorite weapons are insulation and good ventilation. Both do not need much input on my part and have other benefits. But I do worry about what can happen inside/behind the insulation if it is not sealed like you recommend, though it is a pretty dead air space so hopefully the mold spores wont get in.

    I used some of that toxic anti mold paint on the headliners and inside the headliner where the foam insulation is. so far so good, no mold yet(6 years) but maybe poisoning from the toxins... The boat has pretty good ventilation and insulation and I almost always cook with the hatch open.

    One very experienced guy I sailed with preferred to use a scrubbing brush and detergents to deal with mold saying that after using bleach it would just come back? I use a combination of scrubbing first then bleaching, Followed by vinegar. That ozone shock treatment sounds good.

    You have written about a very important part of living aboard, one often forgotten about, until it's become a big problem.

  2. Hi Ben,

    You're right about the insulation being a major impediment to mold, reducing condensation, as it does.

    (I got side-tracked from including that, I see... thanks for pointing it out, and I'll update the post.)

    A relevant book is THE WARM, DRY BOAT by Roger McAfee... ventilation is a big part of his approach, and he's got a lot of great methods.

    RE coming back after bleach - I haven't noticed that it comes back any SOONER after bleach... it does tend to come back in the same spots, in my experience, regardless of cleaning method. My theory is that the conditions that are favorable to its growth stay favorable, unless something is done to change them.

    That trip sounds scary! I read a horror story when I was a kid, about a guy who rows ALMOST out of the fog to hail a becalmed ship, begging food. Tells a tale of shipwreck on an island covered with mold and weird growths. He and his wife have some provisions, but when they run through them, there's nothing left to eat but... the MOLD. He won't come alongside to take on the food, so they float it to him on a line... as he rows off, the fog clears a bit and the horrified crew sees a clump of indefinite green, bobbing over the oars.



    1. Ha.. that talking blob of mold sounds like us when we got to NZ. But at least the boat was lovely if somewhat mouldy, a Holman 28 called "Wild Chorus", one of the nicest sea boats I have sailed, and extremely well set up for offshore work.

      Found this interesting article:

      The gist of the article is that bleach doesn't kill mold well, just bleaches it. But vinegar and methylated spirits scrubbed in can actually explode the mold cells and work effectively, Though the black stain can still be visible.

      I didn't know that Meths worked as a mold killer, this is good to know because it drys so much quicker than anything else. I always thought bleach was the gold standard mold remover, but maybe it's not. Sounds like some essential oils work (eucalyptus,cloves etc) might have to give them a try on the shower grout.

      One thing I worry about is the mold gaining resistance to whatever chemicals I use, so I like to rotate them.

      As you can see you have touched on a subject dear to me, I can put up with lots of mess, but I absolutely hate mold, having seen the damage it can do to a boat and the difficulty of removing it.



    2. Hi Ben,

      Very interesting article!

      As I understood it, the recipe was 7 parts white vinegar to 3 parts water plus elbow grease.

      They didn't mention it, but since it works by crossing the spore membrane, a film of solution (delivered by a sloppy wipe) that was allowed to sit for a bit would afford more saturation, and more working time. We've done that with bleach, but not vinegar... sounds like we've been barking up the wrong tree.

      This spring, we'll give vinegar the... ahem... ACID test!