We get some strange requests, but turning a Transit van into a mobile sauna is definitely one of the most unusual. We weren’t even sure if it was possible.

But in Ford Pro Special Vehicles we love using our engineering ability to come up with solutions for customers and got together to figure out how we might do it and if it was even feasible.

Then I remembered something from being a kid growing up in Germany. My dad bought a sauna, which was actually a flatpack kit, and I helped him put it all together. That was powered just with a regular plug in a domestic socket.

This was the green light moment for us because the electric E-Transit has a system that allows you to power things in the back, which is normally used for powering tools. In this case it would be used to power an infrared sauna unit from a normal 3-pin plug.

Knowing it was feasible we then had to figure out whether it was actually possible to make it all function to an acceptable level. And we also wanted to make it look good too.

The wood part of the project really interested me. Many of us in the team do some kind of tinkering outside of work, quite a few of the guys build kit cars. For me it’s woodworking, something I’ve got even more into while restoring and living in a 450-year old house that needs constant work or one-off solutions.

For example, my wife wanted a cabinet in the bathroom under the window, but the window came so low to the floor that off-the-shelf units would end up obscuring it. I ended up building her one, with dovetail joins on all the drawers and everything which I am quite proud of.

Anyway, we wanted it to look like a real sauna inside and one of the team created a computer drawing of the interior which we sent over to a wood supplier we’d found. I think that made their job easier than the usual scribbles on napkins they get.

They were able to supply the right amount of special Canadian pine for the project; wood that doesn’t warp or leak sap... as sap could really hurt if you sat on it hot.

Although I didn’t get to be hands-on with the actual fabrication of the interior I did offer as much support as I could, and the end result is really great. Not only does it look good, the guys did a great job on that, but it performed even better than we hoped.

"Not only does it look good, the guys did a great job on that, but it performed even better than we hoped."

A major concern was insulating the van to make sure the heat from the infrared sauna we planned to install wouldn’t escape and make the whole thing inefficient. The team ran numerous tests on this to see how long it would be until the system needed a boost from the battery until we were happy.

Our calculations show that for every one hour the sauna is in use, the E-Transit only loses about four miles of range, so you could run it for eight hours and still be able to drive for 180 miles. I believe in the UK you’re only ever about 70 miles from the coast, so you could drive to the coast use the sauna while wild swimming and get home after a full day without any problems.

We’ve not actually tried it ourselves, I don’t think anybody wants to see a bunch of Ford engineers half naked in there, but we can’t wait to hear feedback from the wild swimmers.

Simon Robinson is chief engineer in the Special Vehicles team, based in the UK.