Add shapes to your boat with PVC pipes

Dave Osmolski


One of the oldest and ubiquitous polymers, PVC, or polyvinyl chloride, is used for water toys, rafts, boat curtains and many other marine applications. I have used it to hold propane cylinders on deck, make flagstaffs and hold trailer light fixtures. The list of things you can make from PVC piping is endless.

Readily available at most hardware stores, PVC pipe comes in two grades, or schedules. Schedule 40 has a thinner wall and is probably the easiest to work with. Schedule 80 has thicker walls but the same outside diameter. I suggest using schedule 40 for your projects, as it’s tough enough to withstand almost any abuse.

In addition to pipe, hardware stores carry an almost endless variety of threaded and socket (glued) fittings. Sometimes the fittings can make a PVC-fabricated project look sort of crude. This is particularly true when using glued fittings. Most glues have a purple color that’s nearly impossible to remove.

Although fittings such as floor flanges and caps can be difficult to make, couplings, complex bends or unusual angles can be made easily.

PVC is thermoplastic, which means that it softens when heated and can be formed into all sorts of shapes. You can stretch it and compress it, and it retains its shape when cooled.

PVC softens to a working consistency at around 325 degrees Fahrenheit. If you check the literature, you’ll find the melting point listed at considerably below 212 degrees. That’s for pure PVC with no additives to give it particular, desirable properties. The stuff we’re working with is different.

PVC is thermoplastic, which means that it softens when heated and can be formed into all sorts of shapes. You can stretch it and compress it, and it retains its shape when cooled.

To make PVC soft enough to shape and work with, you need a heat gun, available at discount tool stores for less than $10, and for smaller items, a kitchen oven. If you have one or don’t mind spending a few more bucks, a variable temperature heat gun can help prevent overheating.

Non-flammable PVC won’t sustain a flame, but it will release hydrogen chloride gas when overheated. For this reason, uncontrolled heating using a heat gun or propane torch should only be done outdoors.

That said, try to restrict your heating to controlled means. An oven set to 300 to 350 degrees Fahrenheit will stay there, providing controlled heating. If you are using uncontrolled heating, be aware that smoke or the PVC changing colors means that it’s too hot. To avoid scorching and releasing undesirable gases, keep the heat source moving, be patient and work slowly.

PVC piping heated to 350 degrees Fahrenheit is too hot to handle with bare hands. A good pair of leather-palmed gardening gloves can keep you from burning yourself while handling softened PVC piping. Keep 1- to 1.5-inch wooden dowels on hand to insert into the ends of the softened pipe to prevent distorting the parts that must remain round.

Use something flexible to establish the shape and angles you want. Trace this shape on a piece of paper, and use it as a pattern to shape your softened PVC pipe. Allow the pipe to cool, and you’ll have a custom-shaped piece for your project.

You can stretch softened PVC tubing around shapes other than round. To do so, use a piece of pipe close to the size of the other shape. Be aware that softened PVC can kink, tear and stretch unevenly, so try to stretch the softened plastic evenly around your shape. If you want to form an acute bend, filling the PVC pipe with dry sand can help prevent a kink in the inside of the bend.

Pushing an unheated piece of PVC pipe into a heated and softened PVC pipe will form a coupling with a smoother transition than ready-made couplings. If you need a coupling in the middle of a project and don’t want to travel 20 miles to the hardware store, a homemade coupling works just fine.

I hope these ideas will help speed along your next project.

David H. Osmolski of Charlotte Power Squadron/27 has been repairing boats since high school when his first boat, a canvas-covered canoe with cedar ribs, leaked in gallons per minute and required constant repair.

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