portable boot dryer

For overnighters I think we all accept wet boots. Even a dry track would see boots soaked in sweat.

Hi @jonah. That sounds interesting, but would you expect it to survive being dunked in a river and/or mud? Exactly what people do could vary by a large margin, but in NZ it's not uncommon for people to spend hours wading up rivers. How does the fan work when there's a foot in it? Or is that meant to be for drying out more rapidly overnight? I do think some people wouldn't be interested given you'll often pull boots on in the morning and go straight back into a creek bed or pile of mud, and sometimes people are just used to that, but that's not going to be everyone and not all the time.

Hi @jonah, not to question your motives, but I'm uncertain whether you're genuinely, privately pursuing this endeavour to engineer/design such a device or whether this is a sales pitch with ulterior undertones, noting that you joined the forum the same day you posted. Regardless, my frank opinion is that such a concept/product would have no market in NZ, echoing sentiments expressed above by @geeves and @izogi: Tramping in NZ = wet boots. Regardless of the thoroughness in which you dry boots overnight, within 5 minutes of leaving the hut/campsite yer gunna have wet boots. However, it could fly off the shelves in someplace like the western US, where your boots don't get soaked every day.

Hey @Gregor, no not at all lol I'm just trying to get some expert advice before fully diving into the engineering and crux of the design. I joined this as it's hard to get multiple opinions through email. I agree with the market being limited as most New Zealanders just put up with it but my thoughts were more towards people going on longer multi day or week long trips with one day in the river and maybe the next on the tops where stuff like trench foot and material wear comes into play. This could also be for hunters that often bring in a lot more gear. cheers Jonah

I for one think there could be a demand: how nice to put dry boots on in the morning. Look - your biggest challenge here is that wet boots present two problems: 1) they are cold to put on in the morning, and 2) they are heavier. Problem 1) isn't that big a deal. Suck it up for 10 minutes and your feet warm the boot up. So, really 2) is the area you are aspiring to make a difference. For me to actually purchase a product like this it would have to satisfy a few design requirements. It can't weigh much - ideally it makes it's case to have a spot in the pack by offsetting the additional weight of wet boots. It needs to be robust and able to take a beating. It needs to make a material difference to the dryness of the boot in say a 10 hour window. And it can't be too hot - most of us are aware of the damage heat can do to a boots life span. Honestly - I can't see the chemical option working. The last thing I want to do is extract the moisture content from my boots, just so that I can carry that additional weight in my pack. Challenging myself on the subject - I would say that you need to beat a battery powered bbq fan. And I don't take something like that tramping because the battery ones are too heavy. And they tend to be gimmicks, that are not that robust. Good luck.

Something tells me that the amount of energy needed in terms of heat and air movement to get a boot from saturated to dry when the surroundings are pretty cold and damp is quite high, more than can be provided by a small portable rechargable battery. I just looked at my wife's hairdryer, it's 1000 W. If I poked it in a saturated boot and turned it on, it would still take quite a long time to dry out the boot. Even dropping the power back to 100W and running all night, would it get a boot dry? 100 W x 10 hours is 1000 Wh. 1000Wh is 3600 kJ, so yes it would as it takes about 2260 kJ to evaporate a litre/kg of water. I also looked at the portable battery pack she uses to charge her phone, it's 10000mAh or 10AH at 3.7V so only 37 W hours, I can't see that amount of energy removing much water from a boot. Maybe if the air is already warm and dry from a woodstove in the hut, and you're just blowing it at/into your boots? You'd want to make a quick and dirty prototype/ do some proper calculations and see if the concept was even feasible before proceeding.

There is a market in contractors, bushworkers etc. Which is to say I've worked with 1 person in the last 20 years who carried such a device (with a ciggy lughter plug or croc clips for direct truck battery connection) to dry his boots at camp. 1 person in the 50+ I've worked with. And that product already exists

Hey @Ian_H. thanks for the insightful info. Yes I agree that's definitely something I'm looking into. I looked at the amount of moisture a boot absorbs which is around 150-200 ml. also I'm pretty sure it's 2260kj for water to evaporate through boiling whereas with drying it's about breaking the molecular bond between the moisture and the boot fabric then using the fan to push dry air in getting rid of the damp air in the boot. I'm currently making a prototype then I'll do some actual testing to get a gauge of the drying speed and whether it's technically feasible like you said. I also have a design using a really absorbent material and fabric similar to what's been made just with better chemicals and more portable for hiking. thanks for the help :)

cheers @PualEvans for the advice those points you talked about are some great specifications that I'm currently using in my design. I agree that leather boots should never be subjected to heat in order to dry them as it wrecks them but my design is using a low heat just to dry the air going into the boots so it's not moist or damp air getting blown into the shoe. For the chemical one I'm waiting for the chemical to arrive so I really won't know whether it's going to work till it arrives and I can test it. The main problem for that is drying time so your not lugging around the absorbed moisture. thanks :)