Waterproofing the Canopy

A little while ago I posted about waterproofing the trunk/hatch of the BatBerry.  Now it was time to tackle the canopy of the car.  This is one of the more challenging tasks considering the canopy is also the roof of the car 🙂

There’s lots of challenges that come along with this task.  Things like how do I make it so that water doesn’t pour into the cabin from the seam where the roof of the canopy meets flush with the body?  Where does the water run off?  How do I open the canopy after washing the car without a bunch of water running into the cabin?  Where does the water go that comes in along the front of where the canopy touches the body near the hood?  And the list goes on…

The first part I wanted to tackle was taking care of water run off.  I needed to channel this water to a point where I could remove it.  This process started by creating a rain channel that ran down the sides of the cabin opening.  Since this is where passengers get into the car I needed something that wouldn’t cut/scrape the passengers.

I decided to take some small round bar and weld it to a plate that I could fasten along the edge of the canopy.

This creates a nice smooth/friendly channel that will direct the water where I want it to go.  I also drilled some holes every 4″ so that I could pop rivet it to the body shell.

I then ran a bead of body filler down along the welds in order to give them a nice smooth finish and then sprayed the channels with a couple of coats of primer.

Once I’m done with the body work on the car I’ll run a smooth bead of paintable seam sealer down along the edge of where the bottom plate meets the body.  This will give me a flexible seal that won’t crack as the body bends/flexes that I can spray with paint to have the channel, rivet heads, and seam sealer all one color.

So that handles channelling the water from the back-lower corner of the cabin to the front of the cabin.  But the front corners of the cabin are the lowest points.  The middle of the cabin where the front of the canopy meets the body is higher and will have water running down from that location as well.

I decided to take some inspiration from sunroof drainage.  Have you ever wondered why you don’t get a shower every time you open your sunroof after you wash the car?  The answer is drainage tubes.  Your sunroof has water channels that move water to a low spot that has a drainage tube that then runs the water down and out of your car.  Typically they drain near your door jambs.

So I created myself some drainage tubes using a small plate of steel and some little tubes that I picked up in the electrical isle.

These were then inserted into some holes that I drilled into the low spots of the channel that surrounds the canopy.  They were then test fitted and drilled for two pop rivets.

Because they sat up higher it meant that I was still going to get puddling in that channel.  So busted out the chisels and counter sunk them into the fiberglass.

Now we have a drainage tube, but where the heck does it drain to? Currently it drains right into my lap, so that’s not a good place.  Instead I inserted a couple of 3/8″ bulkhead fittings into the walls of the car just lower than the drain tube.

I then trimmed the tube to the desired length and connected a hose between the tube and the bulkhead fitting.  This will allow all of the water to run right out of the side of the vehicle and the hose is tucked away where it won’t get bumped.

Both the side channel and the drainage tube work was repeated on the passenger side of the car.  However, that left another small issue.  When water comes in at the front of the canopy it’s going to run right up against my dash lid which is covered in vinyl.

Now vinyl handles water without any issues, but I don’t want water running down around the edges/seams and dripping into the cabin.  To solve that I created a channel that goes around the front of the dash lid.

I had one failed previous attempt at this where the dash lid wouldn’t fit back in, so I took another approach.  The second time around I installed the dashboard and pushed some of the Lexan material that I used for making the trunk water troughs down in front of the dash lid.  Then I lay down’ a couple layers of fiberglass.

After a bunch of sanding/filling I was able to get a nice little channel around the face of the dash.  There’s still some spot filling/sanding to do, but it turned out pretty nice.  There’s also a very small gap between the channel and the dash lid which should be just enough room for the thickness of the vinyl that will eventually wrap the lid.

OK… So we now have channels for the water on the sides and front of the canopy, and drain tubes to remove the water from the channels.  But what about the top and back of the canopy where it meets the body shell?

A lot of people would likely think, “why don’t you just do it like they did on the movie car?”.  Well the answer is that they didn’t do anything on the movie car for water proofing or drainage.  The movie car never sees any kind of water at all, and washing is done with spot spray and buffing cloths.

This part of the canopy has been an area that I’ve been thinking about for quite some time now and I believe I have a solution.  The idea is to create a water trough with weather stripping on it just like I did on the trunk.

The only difference is that the canopy will have a ledge which goes back over top of this trough.  This creates an overlap all around the rear of the canopy and a trough to remove the water.

To accomplish this I needed to create another set of forms using the strips of Lexan.  Once they were all setup it was just a matter of laying down some fiberglass strips.

I also marked the edge of the canopy for where I’ll need to trim the excess material to make a good fit.  But I’m going to wait until I have the weather stripping in the channel first before making the cut.  I want it to be a fairly snug fit to ensure a seal with the rubber.

This system “should” make it so that there isn’t any puddling water on the top of the canopy.  That way when the canopy opens after washing the car the water should be in the trough and not dripping down into the cabin.

Once I get things a little more smoothed out and the weather stripping installed I’ll post some more details on how everything is working out.

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