Every spring when I open the boat I find some mold/mildew (not sure what it is) on the cabin top and on the interiour teak. This year I found a mold/mildew cleaner left behind by the previous owner of our other boat. You spay it on and wipe it off. Then you spray it again and let it dry. This is supposed to retard the growth. The product did a fantastic job removing the spots on our white boat bumbers. I tried bleach, then Oxiclean and they didn't work. The product is Rammo Power Ultimate R.V. Mold-Mildew Eliminator. I thought I found a miracle cure, until my neighbor showed me RMR-86 Pro Instant Mold Stain and Mildew Stain Remover. I hadn't finished cleaning all the bumbers so he took one and sprayed it. Without wiping it, the stain disappeared. I tried it on the black stained deck railing at the marina and it fizzed up and afterwards looked as though it had been scrubbed clean with bleach. He bought it from Amazon and U'm supplying a link for those who want to try it.
https://www.amazon.com/dp/B071V6RLWT/?coliid=IUYE0QZV46AQI&colid=1B3RBCCKP39JO&psc=1&ref_=gv_ov_lig_pi_dp (https://www.amazon.com/dp/B071V6RLWT/?coliid=IUYE0QZV46AQI&colid=1B3RBCCKP39JO&psc=1&ref_=gv_ov_lig_pi_dp)
This is Tim's world. He helped me greatly in the process of mold remediation at a hurricane damaged house. I will defer to his judgement in matters such as this. Of course that was a macro job, a whole house fog, so spot cleaning may be a different animal.
Tim lent me a book about mold abatement. I took notes that I promptly misplaced.
Regarding the RMR86, it is just a concentrated sodium hypochlorite bleach around 5% by wt. Clorox outdoor cleanup is essentially the same product. If one has more than just surface mildew, it will not kill the Hyphae (roots) of the mold and the mold will return in a few weeks. DO NOT use it on fabrics or vinyl cushions. It will bleach the color out of the fabrics and harden the vinyl making it crack.
We don't have a problem with either - I leave two ports open, one to port and one to starboard, with a bucket hanging underneath. My ports are round with the lock down on the bottom so its easy to hang a quart size plastic bucket from the fastener bolt. The ports open about a half inch. I also prop up the cushions with the access covers from the storage bins below. The ports are locked down when a tropical storm threatens. Other than the main bulkhead and open storage under the sink, the HideAway has no factory installed cabinetry. There is no liner for the ceiling. Yes, there is a video -"Cabin Ventilation Com Pac23" https://youtu.be/71dnH-e3c-A
I used to get it primarily on the bead board cover on the top of the main cabin and only during the winter. Two things helped eliminate it. I installed a solar powered vent on the foredeck and the normal open area between the sliding hatch and the drop boards provide plenty of area for supply air. But the biggest help was just putting a Davis air dry on the cabin sole during the winter months. Not a spot since those two things done. Lot's of warm dry air circulating through the boat did the trick.
Baking soda and water. About 1/2 small box per landscape (Agway, Home Depot, etc) style sprayer which I think is 5 gal. Or buy a 4 lb box. Kills moss and bad for plants that like acidity so be careful of nearby plants if spraying on your lawn or driveway or it you want a moss lawn. Adjust amounts for smaller sprayer. I spray the roof and house (unfinished cedar siding and tree shaded) and hit the boat with any extra. Rain mostly washes away any exterior mold or lichen and to a lesser extent mildew.