Friday, 28 August 2015

Why you should always listen to your own advice...

It's been a while since a spent any time using Jim, or doing any work on him but with two trips planned I decided to tick a couple of items off of the list of repairs and modifications I'd accumulated whilst travelling around America and Mexico. Almost all of the items on the list are either permanent fixes to small field repairs, or modifications which would make things work better, but one of the items needed proper attention before it caused further damage.

I mentioned in this blog whilst converting Jim into a motorhome, that I was trying as far as possible to avoid using fixtures and fittings from caravan and motorhome suppliers, partly because they tend to be fugly (technical term), and partly because they have the resilience of a chocolate tea pot. In general I managed to stick to this ambition, and I largely used parts from marine and industrial suppliers. In the bathroom however, I broke my pledge, and bought a series of matching plastic pieces that combine to make a reasonably attractive moulded bathroom suite. To replicate the appearance and functionality of these items in something tougher like fibreglass would have taken me a significant chunk of time, and so I took the lazy option. Below is a photo taken whilst I was installing the items in May 2012.

Thetford C400 toilet and matching bathroom fittings in Jim the overland motorhome

As soon as I picked up the shower tray component of this suite, I knew the decision would bite me on the arse, but I thought that a hefty amount of plywood and sikaflex reinforcement would be enough to prevent it from falling apart. I bonded a sheet of plywood across the bottom of the tray, and supported all four edges with a plywood upstand. In hindsight I completely underestimated the utter uselessness of the original product. I hate calling anyone out without giving them a chance to defend themselves but in this case the shower tray that I bought from CAK Tanks to match the C400 type Thetford cassette toilet was so appallingly low quality that I feel compelled to advise others to either not waste their time, or to simply use it as a mould to make a better version out of fibreglass.

Crack in CAK Tanks Thetford C400 type shower tray

Even supported completely by a sheet of plywood, the base of the shower tray developed a series of cracks all over within a few months of use. It’s difficult to comprehend how this is even possible but I suppose that the tiny amount of flexibility in the adhesive used to bond the plywood to the shower tray was enough to allow the tray to flex and crack. The cracks started off as ugly, but not intrinsically problematic, but after a year of full-time living in the truck, I could see beads of dirty water squeezing out of the cracks as I stepped on the tray. In addition, the radiused corners of the tray, which I had presumed would be safe as one doesn’t stand on them, also started to crack. Without intervention, I would have had water ending up in places where it shouldn’t, potentially rusting the floor, rotting the plywood furniture and causing corrosion in wiring.

Crack in CAK Tanks Thetford C400 type shower tray

Crack in CAK Tanks Thetford C400 type shower tray

I must acknowledge the awesome abilities of the CT1 adhesive that I used as a temporary repair to the tray whilst we were travelling. It is described as a hybrid polymer adhesive sealant, and it worked remarkably well to seal all of the damage and prevent water leaking into the area under the tray. When I first used it, I expected it peel off, as the cracks flexed. But it stuck the tray far better than the Sikaflex I used to bond the reinforcement pieces, and remained flexible enough to absorb the significant movement in the cracks around the edge of the tray. Unfortunately as well as it worked to prevent leaks, it made the shower tray look shabby, and ultimately I couldn’t live with the shame of such a visible bodge.

Cracks in CAK Tanks Thetford C400 type shower tray repaired using CT1

The way in which I constructed the bathroom in Jim would make it a massive ball ache to remove and replace the shower tray, and whilst I acknowledge that this may be in my future, I decided to first try and repair/rebuild the shower tray in-situ. The easiest way that I could think to repair the damage, was to fibreglass over the existing shower, effectively building a new tray inside the old one. The only snag in this plan was finding a way to get the new tray to bond effectively to the old one. Having a fair amount of epoxy resin left in the shed, I decided to use this for the fibrglassing, but I knew from experience that there are many plastics that epoxy does not effectively adhere to. My first step was to try to find out which plastic the tray was made from.