Hello all,
First, I want to thank everyone here for their help - it really gave me a jump 
start on fixing my water tank.  

Here's what I found:
   - The tank is definitely made of LDPE (low density polyethelene).  HDPE does 
NOT stick to it, so don't even begin to think that all polyethelene is the 
same.  You can weld LDPE to HDPE, but not HDPE to LDPE.     

   - Welding is the preferred method for fixing by comparison to epoxies 
designed to fix polyethelene.
   - I used a hot air blower welder from Harbor Freight Tools - it cost about 
$50.  In hindsight, I probably could have done a better job with one of their 
soldering iron type that heats a hot disk end.  Getting smooth melting of the 
rod into the tank plastic is very important, and I kept having issues with the 
plastic from the rods bubbling.  In the end, I took a torch, heated up an old 
putty knife, and using that to smooth the edges.  I'm sure this is partly 
because I don't get along particularly well with welding and soldering.  It's 
the one task I have to teach myself to do better.  Ideally, I think I would 
have used the type of welder that feeds strips/rods through the tip of the 
welder, but that one was not immediately available.     

   - You want to weld the plastic with strips, not rods.  Strips are easier to 
work with.  If you can't find LDPE strips online, keep looking around the house 
for #4 recycleable plastic.  The only place I found it around our house was the 
snap-on tops to Tupperware type containers.  If you are buying strips, buy more 
than you think you'll need.  I bought 5' of strips, and I could easily have 
used 10 to lay on the thickness I wanted.
   - Practice welding HDPE, say with a cracked old paint bucket or something.  
HDPE is much easier to find around the house, as laundry detergent bottles, and 
just about every other piece of recyclable plastic (except clear bottles) is 
made from it.  Once you learn how to weld with HDPE, the process with LDPE is 
the same, and it will go much more smoothly.
   - Clean the tank with MEK.   I did it both before and after the 
   - Using a dremel, grind out a groove (this is actually pretty important, so 
don't skip this step).  Even if you go through the tank, don't worry, you can 
build it up again with the strips.
   - Find a YouTube video or two to watch the process.
   - Sand the area with 80 grit sandpaper.
   - Drill a small hole at the ends of the cracks to keep the cracks from 
   - At the suggestion of another poster, I layed in a layer of stainless mesh 
over the crack thinking that if it cracked once, it might do so again, so 
reinforcing the area would be a good idea.  Time will tell.
   - Be sure to water test it before putting it back in the boat.     

Hoping this set of step-by-step instruction helps, Bruce Whitmore1994 C&C 37/40+
(847) 404-5092 (mobile)

This list is supported by the generous donations of our members. If you wish to 
make a contribution to offset our costs, please go to:  

All Contributions are greatly appreciated!

Reply via email to