Condensation Control On Board in the Pacific North West
29 May 2016
John
This morning I answered an email inquiry from some Aussies who are planning to head to Alaska. They had been reading our blog and had questions about condensation control. My response ended up being so long and detailed that I thought it might be a good idea to post it here for others who might be headed that way.
Hi Kate and Paul,
Congratulations on your impending Alaskan adventure. It is the most spectacular place we visited in our 7 years cruising. We did not make it to Patagonia which is supposed to provide similar scenery but Im not sure it has the same wildlife.
Sometimes NZ tries to pitch itself as being like the Pacific NW, in terms of scenic beauty but it does not come close to the real thing. If you have been to Milford sound think about that on a scale that is ten to 100 times bigger, both in square miles and height.
If you have been through our blog you know how we lucked out and were given an excellent strategy for getting to AK through the eternal string of gales that cross the north pacific. We know people who left Kauai within days of when we did and turned for Seattle or Vancouver and were clobbered by riding in gales for days. One guy with a boat like ours used his Jordan drogue. We sold ours unused when we got to Seattle. That was one of the goals for our circumnavigation.
Condensation is a problem at those latitudes for un insulated boats and most of the fixes we know about work fine in port, where you have electric power, but are not usable on the hook. We ended up buying a dehumidifier here in Seattle that runs most of the time. It eliminates the sweating in the cabinets and most of the condensation on ports but using the propane stove generates water vapor that the dehumidifier does not eliminate before it condenses. I dont remember us having similar problems with condensation while we were in Tasie but even the southern tip of Tasmania is 20 degrees closer to the equator than Kodiak.
We have friends who have worked out other solutions for their boats. Some have used plumbing type heating tapes in troublesome areas or heat bars intended to keep closets dry on shore. We never needed to do that.
We had three very annoying places for condensation.
1. The overhead hatches in our main cabin and in our sleeping cabin get condensation on them that can drip on your head either at dinner or when you are sleeping. In the sleeping cabin, and for two small overhead hatches in our pilot house, I had stiff foam inserts made that insulate the hatches and cut off access of damp air to their cooler surfaces. The inserts are a 100% cure for that problem.
We have wood frame insect screens and I just took those to a foam shop and had them cut the inserts to match plus a couple of mm to make the fit snug. The inserts are made from a dark grey closed cell foam and are holding up quite well after two Seattle winters.
An insert like that would darken the main cabin too much so for that hatch I used a 3m product that is designed to weatherproof windows in homes in cold climates. I got it on Amazon http://www.amazon.com/3M-Indoor-Insulator-Kit-2-Window/dp/B000AXXCUC?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_search_detailpage
There are several different size packages so you just make your best guess as to which is appropriate for your application. It consists of a roll of double sided tape and a large sheet of clear plastic that looks like saran wrap. You put the tape around the window/port you want to protect then stick the saran wrap to the tape as wrinkle free as you can manage. Then warm the plastic with a hair dryer or heat gun and the remaining wrinkles disappear
This plastic film solves the problem of condensation on those surfaces. The disadvantage is that you cant open the port if you get some nice weather.
2. We have one troublesome port (stainless steel) in our sleeping cabin. I think it sweats because of the water vapor we exhale at night and that particular hatch is farthest from the dehumidifier so the exchange of air is not adequate to keep the air up there dry enough. I covered it with the 3m plastic wrap and that seems to do the trick while not an entirely ideal cosmetic solution.
All the rest of our ss ports are adequately kept dry by our dehumidifier.
3. We have a pilot house boat and there are lots of large windows. The 3m product works for those just fine. It takes me a few hours in the fall to put the plastic on and a few minutes in the spring to remove it. The special tape does no damage to the surfaces it is used on.
We also had problems with condensation on the bottom of our 6" latex mattress. None of the other cushions had the problem but the mattress had it big time. I could stick my hand under in an feel water. \\
At first we battled it by pulling the mattress halfway out of the bunk a couple of times a week and moving the dehumidifier up to that cabin for the day.
At last year's seattle boat show I found a better solution that works very well. The product is called "Hypervent".
Here is a link to it on Defender
http://www.defender.com/product3.jsp?path=-1%7C2276179%7C2276186&id=1818021
and a link that shows the detail a little better on Fisheries supply here in Seattle
http://www.fisheriessupply.com/hypervent-hypervent-mattress-pads
the photos on the fisheries supply page give you a better ide of what the stuff is like. Its a sheet of flexible plastic with a web of short bent pieces of what looks like monofilament fishing line on one side. When its under the mattress it provides an air space for ventilation and the movement of the bodies on the mattress seems to work to pump air through the space. It works very well. It makes it a little more difficult to get into the lockers under the bunk. I improved access by cutting it into three pieces that roughly correspond to the lids on our lockers. So I can pull out the hypervent that is covering the locker of interest and replace it when I am finished. Marking it so the correct orientation is obvious helps a lot. Sharpie works fine.
Its priced by the foot and it cost me about $130 (including sales tax) for our double bed sized mattress. Make a paper pattern next time you have your mattress out of the bunk.
When we first bought our boat we installed a small propane heater which was more than adequate for weekends in San Francisco. It also took the chill off the cabin on our passage to Alaska and while we were anchored in Alaska. It makes water vapor that is not all vented and it consumes a lot of propane so we have to be careful about how much we use it.
When we got to Kodiak we bought a 1500 watt 110 volt electrical heater that was more than enough to overheat the cabin in the Alaskan summer and it helped dry the cabin a lot. Within two days of being docked most of the condensation was gone but it returned promptly once we left the marina.
If your boat is set up for 220 volt shore power you might just buy an extension cord when you get to alaska and use that to run a heater. We had a breaker box made in NZ that was on the end of an extension cord and used that to run a smart charger when we were in 220v countries. We keep the batteries up and used all our US applicances off the inverter.
We have a big (100AMP) charger in our inverter but I added a Xantrex Tru charge 40A charger. It has a smart inlet circuit that figures out what AC power it is seeing and adjusts accordingly. So when plugged into 220 v power in other countries our charger just started making 12 DC. It also works here in the US where we used it to keep the batteries up while I took the inverter in for service.
The US is a lot more casual about the AC power systems on your boat and you will not be required to have your electrical system inspected by a licensed electrician before you can connect to 100v shore power. Of course the connectors you need are all different that what you already have but there is an excellent boat store in Kodiak where you can get that sort of stuff for reasonable prices.
Another very effective tool for keeping un insulated boats dry is a diesel heater. You can spend a fortune on those but a lot of people use the open flame type heaters and they are somewhere just north of $1000 US to install. We decided against the option for several reasons. One is that the installation requires cutting a 5 inch hole in the cabin top and I not emotionally prepared for that. Placement in the cabin is important to proper functioning and the things get really hot and are known to damage foul weather gear and human skin when the come in contact. Even the guys who sell the things here in Seattle tell you that your boat will always smell of diesel if you have one of these heaters in constant use. That seem to be true for the boats I have visited with a diesel heater.
The final nail in the diesel heater coffin was that it end up costing a lot more to operate than electrical heat here in Seattle where we settled. The diesel heaters are rated by how much fuel they burn, not how much heat they put into the cabin. The manufacturers wont tell you what percentage of the heat goes up the stack but Ill bet it is at least 50%. Electrical is less per BTU and all the heat stays in the cabin. Here in seattle we have a lot of hydroelectric power so our rates are cheaper than many places. As you pass through Alaska, Canada, and the Pacific NW of the US you will probably not be staying in any marina long enough to end up getting billed for electric power so electric heat would be essentially free.
Your ac unit may be enough to dehumidfy your cabin but if you need to buy one they are cheap here. appliances in general are really cheap in the US compared with Australia and NZ and even Canada is not too bad these days because of the exchange rate. here is the one we bought and it works fine
http://www.homedepot.com/p/GE-30-Pint-Dehumidifier-ADEL30LR/203661853
I have to empty the bucket once per day during most of the year and when we travel away from the boat for a week or more I put it on the cutting board over the galley sink and install a hose that leads the output into the drain. It will run indefinitely in that configuration and we always come home to a dry boat. In the Caribbean side of the Panama canal the marina (Shelter Bay) rents dehumidifiers for boaters that leave their boats for a while. Those you dont get that service frequently come back to boats that are almost totally destroyed by mildew.
Living on your boat in steamy places like Panama is not a problem since the boat is well ventilated and still hotter than hell.
One last bit of info that might be helpful.
The best place in Alaska we saw was Prince William Sound. Despite its association with the Exxon Valdez disaster it is incredible for its stunning natural beauty. There is only one cruising guide for the sound and it is full of excellent information and very poorly organized.
Its also expensive, even for old editions.
http://www.amazon.com/Cruising-Guide-Prince-William-Sound/dp/1877900176/ref=sr_1_1?ie=UTF8&qid=1464533322&sr=8-1&keywords=cruising+guide+to+prince+william+sound
Shop around if you want to buy one. I dont remember where I found ours but it was way cheaper than Amazon.
The primary problem with the book is that its not well organized with overview charts that help you find the pages you need. So one of the things I did during bad weather in PWS was enter the waypoints for the anchorages in the guide in open CPN and labeled them with the page numbers of the description in our edition of the guide. I can email the file with the waypoints but not sure it will align with other editions.
I have loaned our copy to some friends who are headed to AK this summer. Ill write to them and ask which edition it is and let you know. It looks like the one in the pic in the Amazon listing.
The primary author died and his wife has put out new editions so I dont think it will make much difference if you have an early one or a more resent one.. The only reason I know to be particular is if you want to use my waypoints. Even without my waypoints you can find your way around. there are hundreds of secure anchorages. We were in one anchorage toward the center of the sound waiting out bad weather when the buoy reports said it was blowing 45 kts out in the sound and our wind generator was not even rotating.
You need to be patient with the weather up there. You will have two or three days of absolutely shitty weather followed by two to three days of glorious weather. Its quite a bit easier to forecast in Alaska than at similar latitudes in NZ and Oz so you can plan your marina days a little better.
Once you leave PWS and head into the inside passage you will have left the best part of Alaska and the part that most cruise ship passengers never see. The parade of cruise ships moving up and down the inside passage is impressive and the thousands of people on these ships see scenery they will remember for the rest of their lives, but they miss the best part. Our trip down the inside passage was anticlimactic after PWS. There are more active glaciers in College Arm in PWS than the entire glacier bay national park at the northern end of the inside passage.
You have to have reservations to take your boat into Glacier National Park/. We blew off our reservations when we realized how much better PWS was.
Hope this helps. It turned out to be a lot longer than I planned so I think Ill post it on the blog, too.