After battling the foul currents and light night winds throughout Nantucket Sound, we finally scooted through Pollock Rip Channel and found ourselves about 10 miles east of Cape Cod. Alison and I were doublehanding to Vinalhaven, Maine, aiming to drop anchor in Long Cove, a cozy anchorage on the west side of the island, where we’d hide for a day from some predicted wild weather.
On board, the breeze was softly coming over our port transom and the ocean was relaxed. Jack, the windvane autopilot, was holding course and I was keeping myself entertained with a rigging project.
When I first bought Ben-Varrey, our Luders 33, there wasn’t any sort of preventer. Up to this point, I’d secure a line to the end of the boom and then make the other end fast to a bow cleat. It worked but wasn’t quick to adjust and was far from ideal for a shorthanded boat. The new system components were now spread out across the cockpit amid my splicing tools and a pile of freshly cut short rope fibers.
The new preventer routing could have been solved with the latest roller-bearing blocks, but there was a simpler and more cost-effective option. I spliced a series of HMPE (e.g. Dyneema) loops and lashed them onto Harken low friction rings. Then I luggage-tagged the low friction ring loops onto port and starboard hard points, leading from the bow to each of Ben-Varrey’s secondary winches and ready to accept a new preventer.
This was a project that I tackled entirely underway. I wouldn’t willingly attempt it in a gale, but it could be done. The point is, this low friction ring system can be repaired at sea, and in a short amount of time. I now also have a great preventer system.
Low friction rings, if you’re not already familiar, are a small aluminum doughnut with convex surfaces surrounding the inner hole to allow a line to pass through smoothly; around the perimeter is a concave trough, making it possible to secure another line around it. To reduce friction, the smooth aluminum surface is hard-anodized. The premium products also introduce a lubricant, commonly PTFE (for example, Teflon), into the anodizing process.
The concept isn’t new. Wooden versions, whether deadeyes or grommets, have existed for hundreds, if not thousands of years. But today’s products benefit from a leap in materials technology. Not only is there less friction, but modern low friction rings are incredibly lightweight and so is the cordage material that we commonly pair with them: HMPE.
The aluminum design was first commercialized in our industry around 2007. I encountered an Antal low friction ring a year or so after that. It was sleek, and on an I-14 racing dinghy it would have been easy to lose in the mess of rigging, but the concept stuck with me as an elegant solution for an unforgiving environment. It nailed the concept of simplicity.
Ronstan, Tylaska, Wichard, Barton, Schaefer, Antal, and Harken, among other manufacturers, now all produce their own version. The lack of moving parts streamlines maintenance and creates an affordable boat part.
When preparing Wildcat for the 2024 Race to Alaska, I worked with Lanex Yachting USA to create a low friction ring solution for my reefing system—six of them, secured to HMPE loops, formed the turning blocks at base of the mast for my 18-foot Marshall Sanderling. Not only were these helpful in keeping my budget on track, but with hundreds of miles of Canadian wilderness ahead, they ticked the self-sufficiency box. Keeping hardware lightweight, especially on a small boat, didn’t hurt either.
Despite my praise, low friction rings aren’t a replacement for blocks, but rather an alternative in the right running rigging applications. Where do they excel? Static loads or low dynamic loads. Let’s break that down.
Static loads are present in running rigging such as reefing lines, preventers, and cunninghams. These lines are infrequently adjusted (static), but still experience considerable loads. Low static load applications are also a wonderful fit—lazyjacks, for example.
Low dynamic loads are seen in control lines like spinnaker sheet twings and jib inhaulers. The lines passing through the rings will be regularly adjusted (dynamic), but because the deflection angle is small, the load on the rings is low.
Friction is the driving factor behind where low friction rings should be used. They are fundamentally less efficient than a conventional block. Ball, roller, and virtually all plain bearings are simply much smoother in their operation; they have less friction. Despite their name, anywhere low friction rings are placed, there’s a tradeoff. We’re just willing to accept higher friction in those applications in exchange for simplicity, cost, and less weight.
A mainsheet, for example, is a challenging place for low friction rings. The added friction reduces sensitivity and may become unbearable in the last few inches of trim. That same friction also produces heat, potentially damaging a loaded mainsheet when it is quickly trimmed or eased (at a macro level, the cover fibers may even melt together).
Purchase systems (think boom vang, outhauls, or backstay controls) are another area to be cautious with low friction rings. There is added resistance from 180-degree bends, and the friction of additional rings is cumulative. The best approach with low friction rings is to use a cascade style purchase, which has a multiplying effect on power while providing only a fraction of the overall friction (e.g. instead of a traditional 8:1 purchase, stack three 2:1 systems to achieve the same 8:1 ratio).
The compact design of a low friction ring adds flexibility to its use—they can fit where you may not be able to place a block. However, that benefit is exchanged for a tighter bend radius than the equivalent block. And, the tighter the bend, the less the fibers of a line are able to work together to share the load, shortening the life of the line. Lighter loads present less of a concern. Fortunately, low friction rings come in a range of sizes and stepping up a size or two may solve the issue.
In the end, appropriate applications vary with each boat and depend on the load, level of line movement, and deflection angle. Low friction rings are used as floating jib leads on Class40s and even larger racing machines. They can serve as replacements for mast base blocks, especially for halyards that aren’t frequently adjusted, and can make great leads for a furling line. Low friction rings can even be used to create 2:1 jib sheets.
With a few spare low friction rings and length of HMPE, any boat would be well-equipped to handle a running rigging hardware failure. Perhaps one step better, Harken recently launched a line of Open Ring Shackles. These are the low friction ring version of a snatch block. The low friction ring has an opening in its circumference (like a doughnut with a bite missing) and a soft shackle that surrounds it. Antal offers a similar product (Hook), but with the addition of a wire gate to ensure the line stays in the partial ring, and Wichard offers the MXLEvo which modifies the horseshoe to integrate a locking point for the HMPE loop.
Refitting a boat or installing a new system can be expensive and challenging. Low friction rings and HMPE might just offer flexibility and simplicity you need for your next rigging project. Sometimes they work best in harmony with traditional blocks. Consider them one more tool in your box of rigging options.
April 2025
