For years I had an idea to build a boat out of HDPE.  I had learned how to fuse HDPE plastic and worked around it all the time.  I also worked in the marine industry and was always around boats.  I imagined that it would be realatively simple to build a ZODIAC shaped boat using pipe and then adding the hull. 

 

The problem was that the appropriate sized pipe that had thin walls was not readily available.  HDPE pipe has come a long way over the years and is used heavily in industry. And as such has become much thicker walled.  Years ago one could find Sclair pipe pretty easy.  It was used alot in irigation. But most of the pipe out there nowadays is heavy wall.

 

Finally after years of constantly being on the look out, I found some 12" and 14" DR32.5 pipe.  The DR is the measure of wall thickness.  The bigger the number the thinner the pipe wall.  Basically, the DR is the number of times the wall thickness fits into the diameter of the pipe.  Most pipe in the industry is DR11. For this first build I decided to make a small boat out of the 12" pipe as I had less 12".  This small boat will be the one where I make and learn from all my mistakes.  R and D if you will.

 

The size and shape will be about a 13' ZODIAC shaped boat.  I hope to install an inboard jet from a Kawasaki PWC that I got pretty cheap.  But I have to build the boat first.  So we made some plans and began down the path of this fun little project.  

 

The first part of the build and one of the most challenging parts was cutting the pipe at a miter.  The pipe was too lagre for the chop saw and HDPE is a bit hard to cut.  After some though and trial and error, we ended up building a sort of miter box to be used with a chainsaw.  Ideally the cuts need to be clean and square.  The chainsaw is not the best for clean cuts nut it was pretty good.  we were using pretty thin wall pipe so I knew the heated plastic would flatten on the heat plate. 

 

The next challenge was the fusing.  I had a few options.  Use an extrusion welder to weld the seams, which I did not have.  Hand weld with HDPE rods and a heat gun, or use a heat plate.  Luckily I had also recently acquired a heat plate from an old busted up Butt Fusion machine.  So for this first boat we had to develop a way to both heat and press the two pieces being fused evenly.  This became one of those, I will do it different next time moments.  

 

The prototype system we used was a pair of clamps made of thick plywood.  It worked okay.  But it was not perfect.  The plywood would slide on the pipe. It was a race against time when it came to fusing. And the pipe was not held perfectly and some of the fuses slid when pressure was added.  But I have plans for the next time.  In the end it worked okay and we only had one fuse fail.  That was due to contamination from saw dust and rushing during the fusing process.  

 

Once we had the pipe all fused the next step was to build and weld the ribs.  All the ribs were designed on the computer and then cut from 1/4" HDPE sheet on a large CNC table the my dad built.  The ribs had to be fused by hand.  I've been told that an extrusion welder is ideal for this.  But I don't have one and I wasn't about to drop $2000 for this silly fun project.  After some practice doing some hand welding I decided I would try my hand at installing the transom. I found out very quickly that hand welding works pretty good.  

 

The ribs were next and i did find that the thinner 1/4" material bends and warps dramatically when heated.  It makes it challenging to weld long seams as I would find out on the hull.  It is tedious work, but once all the ribs were welded to the pontoons we moved onto the hull.

 

The aft part of the boat was easy, as the pieces lined up with the squared lines.  The bow however was the next big challenge.  Afetr hours on the computer the appropriate shapes were entered into the CNC and cut out.  As I mentioned earlier, the long seams became a challenge when fusing.  The plastic warps so much that I had to make a whole bunch of tack welds down the seam, let them cool then go back over with a full bead of weld.

 

So now that is were I am at now.  Winter set in and it is too cold to continue work.  But spring will come soon and I will continue to get this boat to working condition.