snow mats for electric heat

[pnw2022]

Hi All,

Thought I would post this since I have never seen the topic come up. For reference, boat is a Hunter41DS live aboard in the Pacific Northwest (USA side).

A few years ago, my neighbors wife always complained about cold toes sitting at the salon so on a lark, he picked up a small one of those 'snow mats' that people use to keep their stairs/walkways clear of snow in the winter time.

They reported it worked great, so a couple years ago I ended up picking up a set for my boat as well. For me they run down the walking area in the main salon and I actually leave them in year round as they also double up as great anti-slip mats if/when the weather is rough.

Anyway - two years and they are both in excellent shape and I got to wondering why I have never seen anybody else mentioning something like this.

Bonuses I can see are:
1. Low wattage - the largish ones I have are 300w each and get 'warm' but not hot/fire-hazard.
2. I also have a caframo-type space heater that works great, meanwhile these guys do not have any red hot elements and definitely are less obtrusive than oil filled radiators.
3. Great for warming/drying gloves, socks, etc. just by setting them down there.

Cons:
1. My biggest fear was durability and of course electricity+water. Meanwhile they are designed to be tramped on by snow boots on top of concrete all winter long. My sailing boots, slippers or sock covered feet definitely cause less wear and tear than that?
2. I did find out the hard way, do not leave a heavy metal bin on top or they will get warmer there and I managed to 'steam' off a section of the laminate of cabin sole. Never a fire hazard, just warm enough to loosen up the glue like you would removing laminate anyway.
3. Because they are grippy, they are also a little bit difficult to clean.
4. Definitely spending some energy warming up the bilge, but overall that is okay. I considered putting some other kind of insulation layer below the snow mats to avoid that but having the rest but have never bothered.

https://heattrak.com

Does anybody have any thoughts on this?
See any risks I have not noticed the last couple of years?

[Muaddib1116]

Seems like a cool idea. How are you powering them?

[pnw2022]

Originally Posted by Muaddib1116

Seems like a cool idea. How are you powering them?

These are primarily for dockside use, along with the space heater. So off the regular A/C system (I have dual 30 amp, second was wired with the boat for air conditioning). We have used them underway off the inverter when motoring before though.

[Muaddib1116]

Very interesting, 300 watts is way lower than a space heater.

[leecea]

They look great. Do you think they raise the cabin temperature significantly by themselves or is it more about keeping feet warm?

[Adelie]

I would lay a rubber or neoprene mat under them. Protect the sole and no sense in heating the volume under the floor.

[thinwater]

Placing insulation under them will make them run hotter (heat cannot leave that way).



The ones I saw were 300W for 20" x 60" = 8.3 feet^2. That's about 1000 BTU or 120 BTU/ft^2. If the heat comes off only one side that's about 100F, or 85F if both sides (assuming 70F air). Lay something over it, and consider the insulating value of a wood floor, and yup, temperatures could get high enough to damamge something.


Certainly any underlying insulation would need to be fire proof. I'm not feeling it. I'd wear thick wool socks. I would also put down carpet mats; they will keep the whole cabin warmer. Bare floors make zero sense in the winter. Pitch the snow mats. I think they are only safe on concrete.

[Muaddib1116]

100F doesn't sound that high to me. Pretty sure the interior of my boat is going to be getting above 100F a lot in the tropics, even up in Maine during the summer if I leave everything closed up on a sunny day.

[JPA Cate]

It is a kindly thing to try to make warm for icy feet!

I, too, get icy feet (poor blood circulation). I've tried lots of solutions, ranging from kit-made polar fleece "slippers", that I added a leather sole to, to apres ski boots; down booties, Chinese made slipper socks. My next iteration will be adding a leather sole to some expedition weight polypropylene + wool socks I have which are machine washable, and put a neoprene insole to them. I think the insulation, plus the warmth will work well, and with the leather outersole, I should be able to wear them above decks as needed, except in rain or snow.

I also have some lightweight polypro sockies for bed socks. It means Jim no longer has to fear the icy feet approaching his nice warm body while he's asleep. He thinks that's a yucky way to wake up--and I agree!

Ann

[thinwater]

The issue is temperature rise if covered, which can happen by accident. The OP saw this.


Really, put down carpet. It makes a huge difference. It keeps the cold in the bilge. Bare floors make no sense in a boat, in the winter. Roll the carpet up in the summer if you are a wood fanatic.

[deblen]

Originally Posted by JPA Cate

It is a kindly thing to try to make warm for icy feet!

I, too, get icy feet (poor blood circulation). I've tried lots of solutions, ranging from kit-made polar fleece "slippers", that I added a leather sole to, to apres ski boots; down booties, Chinese made slipper socks. My next iteration will be adding a leather sole to some expedition weight polypropylene + wool socks I have which are machine washable, and put a neoprene insole to them. I think the insulation, plus the warmth will work well, and with the leather outersole, I should be able to wear them above decks as needed, except in rain or snow.

I also have some lightweight polypro sockies for bed socks. It means Jim no longer has to fear the icy feet approaching his nice warm body while he's asleep. He thinks that's a yucky way to wake up--and I agree!

Ann

Old Canadian saying: If your feet are cold,put your toque on. / Len

[deblen]

I suggest using thin foil backed insulation under the snow mats. / Len

[pnw2022]

Hi all, and thanks for the feedback.

Sorry for slow reply - been busy with other things.

I 100% agree that this solution is a bit odd, and perhaps a little bit risky for impact to the floor and subfloor plywood long term. I also would like to clarify a few things.

#1. No, this is not to 'keep my toes warm' - the idea of doing this came from a neighbor who tried a small section underneath their main salon table for his wife some years ago. They were a new couple (the gentleman and older and experienced sailor) and since then moved ashore in Kingston WA and are now relocating to Oregon to be closer to children and grand children. And yes, I am familiar with wool, both for underclothing and do have a good pair of fleece lined slippers with rubber soles that work both on the boat and for occasional quick jumps dockside.

#2. For sure on the carpets, I actually do that in both the forward and aft cabins still and it definitely makes a huge difference! Meanwhile, as second owner of the boat, the main salon cabin carpets she came with finally gave out and I also have that 'slippery fake teak' on the floor which turns the main salon area without something else into the equivalent of a hockey rink when it gets even slightly wet - even when warm outside. Yes - a newer model boat (~2009 'dockside condo'). And yes, I understand (been there) offshore for multiple weeks both solo and with crew. Meanwhile this boat is the right tool for the job for what I need right now. It always breaks my heart when I see solid offshore boats tied up in a marina like a 'condo' for years on end and going nowhere and slowly being neglected.


Anyway - this will be my third winter with this oddball experiment. I am going to stick with it for now, and for the following reasons:

0. Caveat, everybody's use case and goals are different. I also do appreciate the feedback from a variety of folks that have different use cases and goals. +1 +1 +1


Pros:

1A. It simply works and is low voltage and low risk. For better or worse I still have not found time or money to install either a forced-air or hydronic system for heating on the boat.

2A. Related to #1 above, I feel both safer and more comfortable ergonomically. I have dual 30-amp power and am able to run those two (600watt combined) snow pads low in the boat where heat rises and keep less use on the space heaters.

3A. For better or worse, with the 'plastic floor laminate' - things are slippery inside the boat so the mats stay in place year around, simply switched on/off with an independent breaker. Not having to change things around during winter/summer (yes, this is only the Pacific Northwest so please do not tease me about seasons - grew up when I was a little kid in SE Alaska).

4A. Even in spring/fall, they are useful for other oddball things, and the solar power installation supports the power for limited use when sunny - cold or warm. For small things like letting the non-curmudgeon guests have a modestly warm place to go, faster drying rain gear (rather than hanging in the aft/stbd locker/shower) as well as other things like drying out fresh spices on top of a towel to jar them up for the winter.

Cons:
1B. You need to make sure that pick up crew doesn't leave heavy/large-surface things on the mats or they will overheat and potentially cause decimation on the cabin sole (I image this would apply to both teak and 'plastic')? I have direct experience here.

2B. Similar to #1B above, keep in mind water ingress underneath the mats once they are turned on to avoid any 'steaming wood' type behavior which can creep in if plywood edges are/were not probably sealed? No direct experience here, but was mindful in advance.


I did check temps with the heat meter (a DeWalt, not a Fluke) and have not calibrated since I purchased it a few years ago so those of you that may be picky with equipment, please disregard

This is data from today (all from the heat gun except outside temp) as of 2022-12-22:

Outside temp (from website): 25F
Sugar scoop temp: 19-21F
Water surface temp: 30-33F
Snow Mat surface: 110-125F at different sections near center via the two
Snow Mat underneath: 100-115F at different sections near center via the two.
Cabin Sole top: same as snow mat underneath
Cabin sole underneath:

I also did a similar check with the heat meter a couple months ago and overall temps were about 5-10F higher. I think I will be more cautious this spring about turning off the mats and relying only on the space heaters this spring when the weather warms up, other than drying spices or similar. I tend to think that keeping plywood over 120F+ on a sustained basis, given the inevitable humidity on a sailboat, is probably not good.


Again - thanks for the all comments here from folks that obviously have different attitudes and expectations about boating, or their boating 'right now' - because life is a river, not a road, and we all change course over time!


P.S. - Lets not let this thread segue into a 'proper heating system' tangent? Of note, I also have little to no humidity problems dockside with electric heat, understand the value of bringing in outside air (crank up the heat and crack a hatch/dorade' seems to work. Again, newer model boat with lots of interior airflow. Thank you!

[pnw2022]

Originally Posted by deblen

I suggest using thin foil backed insulation under the snow mats. / Len

I agree, that would certainly help with extra heat into the plywood and causing any weakness or laminate delamination. It would also help with excess energy being put into heating the bilge areas.

I did spend an hour or so googling around about materials, probably going to be easier to ask some of the local boat building or Boeing neighbors about what to use?

Requirements would be (in order of priority):
#1. 'grippy' - i.e. nothing moves around when people need to walk (while holding onto rails) while the boat is heeled and getting slopped around up and down the waves?
#2.Wear resistant, pressure will go through the mats as people constantly tromp on it.
#3. Thinnish - say max 1/4", otherwise we introduce a potential trip factor?
#4. Heat resistant reflective and moisture resistant?

[pnw2022]

Also - my post two above, I did not mean 'soaking wet outside' foul weather gear. Rather the inside things like socks, gloves, etc . Just to clarify. Definitely the outside/drippy stuff goes into the aft/stbd shower!