How to build a roller furler for under $40

Ellie's home-made sub-$40 roller furler

Important Notes:

There are many different types of roller furling systems. This furler is a "wire luff" type which requires a jib that has a stainless steel wire sewn into the luff, or has a "jib set flying" (a jib that does not attach to a stay).  If your jib hanks onto a fixed forestay or needs to wind around a forestay this furler won't work for you. The furler you need would be more like this one., or perhaps this adaptation.

This furler, as illustrated below, is a small light duty unit sized for my 15' dinghy. It is somewhat similar to a Ronstan RF76 or a Harken 434, but not as strong.  It can be scaled up in size if desired, and can be made stronger by substituting a stronger eye-bolt, stronger u-bolt, upper swivel, and ball bearing thrust bearing.

Here is a test run of the furler

Origin

In issue #58 of Small Craft Advisor magazine, Kirk Gresham wrote an excellent article on how he designed and built two roller furlers for his 17' cutter Eider for a mere $40 each using bits of scrap and a few bits and pieces of hardware from a local hardware store.  This saved Kirk a whopping $670 off the $750 price tag he was quoted for two furler units from a local Port Townsend chandlery.  I knew from the moment I read Kirk's article over a year ago that I wanted to build one of his furlers too.  I love building things. I'd much rather build something than buy it, even if it ends up costing me more. But in this case building it saved me hundreds of dollars too.  That's a two-fer for me!

I had a couple questions after reading the article, but I knew Kirk attends the Port Townsend Wooden Boat Festival every year, so I met up with Captain Kirk at the festival last fall. He answered all of my questions and allowed me to take some close up photos of his furlers.

Being a designer, I couldn't resist making some improvements to the design.  I used bronze thrust washers in place of the steel radial bearings Kirk used, and I made the spool from a solid piece of hardwood instead of using a section of PVC pipe.  These two changes significantly increase the strength of the furler, make it operate more smoothly and increase corrosion resistance. I also used an ABS end cap instead of the bent aluminum strap used to contain the furling line. It looks better and does a better job of containing the line.

So, here I present my improved version of Kirk's $40 roller furler.

Making the Drum Assembly


The drum is made from an inexpensive 3" ABS sewer pipe end cap available at any store that sells sewer pipe, like Home Depot or Lowes. You will also need a stainless steel eye-bolt.  I used a 1/4" x 4" Stanley V2161, but welded eye bolts are a better choice as they are much stronger.

To make the drum assembly, drill a 1/4" hole in the center of the end cap for the eye-bolt. Drill 7/8" diameter holes every 45 degrees around the outside for access to the furling line. Locate these holes so they are 1/4" below the open end of the cap.

I also drilled a series of small drain holes in the bottom of the drum.

Use locktite to secure the two nuts on the eyebolt.


Making the Spool Assembly:


To make the spool assembly, first I cut two plywood disks from scrap 1/4" plywood. The outer diameter of the disks should be just slightly less than the inner diameter of the ABS cap, which is 3.5" diameter. We don't want the furling line to slip through the gap. Sandwiched between the disks is a piece of oak (or equiv) that is 2" in diameter and 7/8" thick.  Glue these three pieces together taking care to align them accurately.  Drill a 1/4" hole through the center for the eye-bolt.  Drill two more holes to match the stainless steel U-bolt legs.  The U-bolt I used is a 1/4" x 1-1/8 x 3-1/2 Stanley V2193.  Drill one extra hole in the upper disk for the stop knot of the furling line. Paint the spool with several coats of enamel paint.  Cut and file the legs of the U-bolt flush with the nuts. Use locktite to secure all 4 nuts.

Assembling the unit

To assemble the unit, place the spool onto the eyebolt of the drum assembly.  Then add a 1/4" stainless steel washer, your thrust bearing, and a locknut.  The thrust bearing is simply two 1/4" I.D. sintered bronze thrust washers. These strong, inexpensive corrosion resistant self-lubricating washers should be readily available at any good hardware store, or you can order them here.  Once in a great while, apply a drop of motor oil to the thrust washers. It will soak into the porous metal and lubricate them for a long time.  A ball bearing can be used instead of the thrust washers if you prefer.  They are more expensive but will operate more smoothly, especially when under high tension.  Here is a source.
The exact size you need will depend on your eyebolt and u-bolt.

Tie a stop knot in the end of your furling line, feed it through the hole in the upper disk and out through one of the holes in the drum. Spin the spool to wind up the line.

Upper Swivel

A swivel is required between the end of your jib halyard and jib. This anchor swivel available from Duckworks, is a good choice.  It is extremely strong, inexpensive, and although it's not a ball bearing swivel, it spins remarkably easy even when under tension.

A ball bearing swivel is better suited for larger boats with higher-tensions, while a jumbo sized ball bearing fishing swivel works well for light duty applications.

Conclusion

This furler works perfectly on my Navigator Ellie and I couldn't be more pleased with it.  If you have any feedback or if you build one of these furlers for yourself, I'd love to hear about it.  Please leave a comment below.