STEAM Fair 2020 Activity
Thanks to Chesapeake Bay Maritime Museum
Rope grommets served many uses on traditional sailing ships. A discerning eye would find a rope grommet as a handle of a chest, or being used as a soft oarlock on a row boat. What is a rope grommet? Basically, they are round, endless rings of rope. The “”knot”” used to make a rope grommet is unique because we must disassemble the rope to tie it properly.
To make a rope grommet we will be “unlaying” the 3-strand rope and re-assembling it in our preferred size. One section of rope will make three grommets, so don’t worry if your first one isn’t perfect! Follow the steps below to make your grommet:
What you need:
- -3-strand rope 3.5x-4x longer than desired circumference of finished grommet.
- Recommended diameter range is 3/8″ to 1″ –
- 55″ length is usually plenty
- Natural fiber rope is highly preferred due to its “memory” of the lay, making the project much easier. Hemp, Manila, Sisal, etc. Stiffer poly or nylon rope will also work.
- Roll of masking/painter’s tape
- Knife/scissors to cut rope
Please have parental supervision/assistance when cutting rope, especially thicker diameters.
How to make a rope grommet
- Unravel the three strands
Tape each end of the three strands (on each side) to prevent the strands from unraveling. Unwrap the three strands by carefully unwinding one at a time. Be careful to preserve the natural “twist” of the strands during this step!
- Wrap around tape roll
Lay your tape roll flat on your work surface. Find the middle of one strand of rope and put it on the bottom of the tape roll. Wrap each side of the rope up and around the tape roll until they meet and overlap at the top.
- Re-wrap the strand
Pinch the overlapping rope piece and remove the roll of tape. Begin to re-wrap the strand around the circle, aligning the natural twists of the strands so they are “seated” together.
- Re-wrap the other strands
When you reach the beginning spot, continue this process with the other loose strand. The strand should naturally tuck into the “gap” that the 2 strands leave.
- Add knot
When you reach the beginning point, tie an overhand knot with the two loose strands. But, be careful not to tie too tight or you can twist the grommet.
- Trim ends
These loose ends can be carefully cut close to the tightened knot, or for more security they can be tucked under the next lay of rope and then cut. Roll the knot area under your palm to flatten the knot.
- Try different sizes
Your rope grommet is complete! You can attempt another grommet with the other two strands that will be the same size, or you can shorten the rope and make a smaller grommet.
How does it work?
The rope’s twist helps to give it form and combine the strength of many small fibers into one larger rope. When loaded with weight, our grommets distribute force through all the strands and use the combined strength of the three strands to remain strong.
Great job! If your rope has a soft lay (it untwists easily) this will be a more difficult project, but not impossible. Keep the natural twist in the strands through all steps and you will have the most success.
A rope grommet can take longer to tie than most other loops in rope, but the strength it carries is hard to match. All knots will reduce the strength of rope, but when properly made, a rope grommet will only lose about 10% of its working strength. When you compare this to a 30%-50% reduction in strength found in other knots, a 10% reduction looks pretty good! Strength loss in rope is caused by the tight bending and compression that is found in most knots. While we make our rope grommets, think about how twisting, bending, stretching, and compressing can help or hurt a rope’s overall strength.
Your grommet will work great as a hot pad, a dog toy, a napkin ring, or a handle for a door or toy chest. What other uses can you think of for your grommet?