Moisture and Mold Issues

When Kosmos was brand new, we were paranoid about developing a mold problem. After all, mold was a common issue on boats and we were traveling in the tropics, where the warm, moist air was a mold haven. But we made it all the way around the world without ever finding mold. (Well, there is one exception, when some sheets got wet and moldy after water got into a storage compartment located under a window).

Our first “real” experience with mold came in early 2010. In October of 2009, the weather turned especially cold and damp (by San Diego standards) and stayed that way through the spring. Around Thanksgiving, we started to notice occasional drops of water on the forward stateroom floor. Our immediate assumption was that the hatch was leaking. The next time we washed the boat we ran lots of water over the hatch, but it was water tight.

We paid more attention to where the water was coming from and noticed the drops were forming on the headliner. Oh no! Did we have a hull leak? Soon after, a storm blew in that brought heavy rain for a few days. We watched like a hawk, but there were no more drops of water during the rain as there were on days when there was no rain at all, so clearly it wasn’t a hull leak. We were baffled. If there was no leak, where were the drops of water coming from?

Eventually we realized that it was condensation. Cold air was coming into the dorade vents and hitting the warm air inside the boat and condensing on the headliner. We started to run a dehumidifier in that room and the problem seemed to be solved.

Meanwhile, as soon as the weather turned damp, Christi’s asthma started to flare up. This was odd, as Christi’s asthma rarely bothered her. As time went on, the flare ups were getting more frequent and more severe. In February 2010, she ran out of medicine and made a trip to the doctor. The doctor told her he thought she was exposed to mold and to go home and look for mold.

We thoroughly searched the boat and found small amounts of mold in all three hatches, on several window sills, and on several port holes. We knew it was from condensation — we’d seen moisture forming in those places several times, particularly on days when Christi was cooking foods with boiling liquids, like pasta or soups. Christi started running the exhaust fan when cooking (she was already in the habit of keeping the kitchen porthole open during cooking) and wiped down condensation whenever she saw it.

We also found some mold in the forward stateroom closet (on the mold resistant cedar) and in the cabinet above the desk in the forward stateroom. We needed to get into that cabinet frequently, and since the door was out of the way, we often left the cabinet door open. The closet was vented. We weren’t sure the mold in these two places was residual from the condensation issue we’d solved earlier or if it was a different problem. We kept an eye on it, and the mold never returned, so clearly it was tied to the condensation.

We cleaned all the mold with a special mold killing cleaner and treated each area with a mold preventing solution. We also treated other areas onboard that were susceptible to mold with the mold preventer. And, last but not least, we started running an air filter onboard to remove airborne spores and help keep air circulating throughout the boat.

Last summer (2011), shortly after finding out Christi was pregnant, we did a major spring cleaning onboard and never found any mold. We put the mold preventer spray on just about every surface anyway, just to prevent a mold problem from ever starting again.

Right after cleaning was completed, we changed almost all the lights onboard to LED, so we pulled down most of the headliners in the boat. Much to our surprise, we found a little bit of mold on the hull above the kitchen, probably also a result of boiling items on the stove. In the past, when we’d cleaned and looked for mold, it never occurred to us to check the headliners. We were pretty certain the mold up there was residual from the year prior, before we started running the dehumidifier and the exhaust fan when cooking. We cleaned it with the special mold killer and sprayed mold preventer all along the hull up there.

This summer (2012), Christi’s asthma flare ups started again. As we mentioned in another post, mid-June to mid-September were especially difficult months for us. We half-heartedly looked for mold in the places we’d found it before, but all those places were clear. A serious mold hunt was a labor intensive process and we were just too tired and spread too thin to deal with it at that point in time. Christi stayed away from the boat as much as possible.

In October, we finally hired someone to search for mold and do another serious spring cleaning. We found mold in several places in the master stateroom bathroom: in one of the mirrored cabinets, in one of the lockers inside the shower, in the area under the shower seat that houses the stabilizers, and under the floor between the shower and toilet. In addition, we found some mold under the floor in the forward bathroom, as well. Since we purchased Kosmos, we’ve always wiped down the shower after each use to prevent moisture issues. But, Christi likes hot, steamy showers and we think the moisture from the steam was probably the primary culprit, especially because 1. the bathroom exhaust fan was broken for several months (one day maybe we’ll get around to writing a post about replacing that exhaust fan) and 2. this year we had an especially hot and humid summer (by San Diego standards).

Our cleaning person also pulled down every headliner to check for mold, but all was clear except for a very small spot in the pilot house. He used the mold killer everywhere he found mold and treated virtually every surface on the entire boat with the mold preventer.

This time we also checked a couple places we hadn’t previously thought to check: the dorade vents and master stateroom blower intake. Both dorade vents had some mold inside them. The intake for the master stateroom blower was mold city–by far the most mold we’ve found anywhere. Our primary sources of fresh air were contaminated with mold! This explained why Christi often felt her worst when we were laying in bed. We usually kept the blower on, thinking the fresh air would make her feel better, but it was actually blowing mold spores in her face and making her asthma worse!

We are pleased to report that Christi now feels great while aboard, so the problem seems to be solved now. Our opinion as to why we never had issues with mold while we were cruising was two-fold. One, we ran the engine regularly, usually for several days at a time. The engine room got very hot, and the hot, dry air circulated through the boat and killed the spores. Two, we ran the air conditioning at least a couple times a week to dry out the interior.

Now that we mostly do short bay trips, the engine room doesn’t get hot enough to kill spores. And since San Diego’s weather is so temperate, we rarely run the air conditioning. While the dehumidifier definitely works, the air conditioning probably works better.

4 thoughts on “Moisture and Mold Issues”

  1. HI Guys!
    Just wanted to comment about your mold problem. We have a trawler and have 2 16,000 BTU units that both have a setting called “Moisture Control”. The unit turns on (automatically) every 4 hours and samples the air for 1 hour. The unit then determines if the air needs cooling or heating to keep moisture out. Then it will run for 1 hour with the correct setting or not run if it determines it is not needed. This keeps our boat really moisture free and keeps the electric bill down when we are not there. I just thought this may help if you ever wanted to change out your a/c units.

    John Winner

  2. Hi Eric and Christi
    Can you tell me what product you used as a mold killer and mold preventer? Thanks very much!
    Larry Crass

  3. Both times we went on the mold attack, we used a pair of products that were meant to work together. One was a mold killer and the the a mold preventer. After you applied the mold killer and wiped the mold away, you then applied the mold preventer to keep it from coming back. The first time, in 2009, we used products made by National Allergy Co. The preventer was called No More Mildew and we can’t remember the name of the killer. We were happy with those products, but we couldn’t seem to find the killer, so the second time around (in 2012) we used products made by Mold Armor called Mold & Mildew Stain Remover and Mold Blocker. We were also happy with those, though they were way more toxic to humans than those made by National Allergy Company.

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