Best thimble for an anchor rode

[Jerry Wegman]

Greetings,

When making up an anchor rode, the common practice is to use a length of chain and then nylon line. When not using a windlass, the conventional connection between the two consists of a thimble at the end of the nylon, connected by a shackle to the chain.

My question is what is the best type of thimble to use? There are three choices: nylon, galvanized, and stainless. Nylon has been disparaged on this forum as light duty. Regarding the stainless, is there a concern about dissimilar metals (the zinc galvanized chain and the SS thimble)? Are there other issues that would favor either a SS or a galvanized thimble?

The whole thimble issue might be avoided in some cases by a splice or a knot. A splice might work better for three strand than for the double braid that I prefer.

Many thanks for the very generous sharing of information on this site.

Jerry

[Brion Toss]

Hi,
The best thimble for an anchor rode is ... no thimble. splice directly to the chain. This works best for single-braid and three-strand rope. Double-braid has lesser energy-absorbing ability, and doesn't stow well, particularly as it ages.
Fair leads,
Brion Toss

[Jerry Wegman]

Brion,

Thanks to you for your response, and also thanks to another member who responded earlier but whose response does not now appear.

I am puzzled by your statement that "double-braid has lesser energy-absorbing ability" than single-braid and three strand. I assume that "energy absorbing ability" is a function of elongation; the rope manufacturers all cite the elongation of their ropes under load. If I am not correct, then please set me straight.

When comparing stretch (elongation) characteristics I see substantial differences among manufacturers, so that the nylon DB of one company can have more elongation (at the same load) than the three strand of another company. I base this on the published data on manufacturers' web sites.

For example, Novabraid Novagold, DB nylon, has about 10% elongation at a load of 15% of breaking strength, whereas New England Rope Premium 3 strand nylon has elongation of about 8% at the same load. The breaking strength of the DB is somewhat greater than the 3 strand, so the NER 3 strand elongation might be closer to the Novagold DB at the same amount of load.

On the other hand, New England Ropes nylon DB states its elongation is about 6.5% at a load of 15% of break strength, so within the NER family, it is certainly true that the nylon 3 strand has more stretch than the DB. Yale Cordage quotes its 8 strand braid elongation at about 10% at a load of 15%; NER Megabraid 2 quotes about 12% at the same load.

I appreciate that the selection of the rope component of a rode depends in part on whether a windlass is to be used. With a windlass, a direct rope to chain splice must be used, and this would seem to favor 3 strand or braid.

I plan to use DB Nylon Novagold, which has about the same elongation as Yale 8 strand and actually has more elongation than NER premium 3 strand nylon.

Which brings me back to my original question, what is the best connection of the chain to the nylon DB? I considered an anchor bend knot, but was dissuaded by some authors who urged use of a thimble. But perhaps you disagree, and would prefer to use a knot or a splice. If so, which one? If you agree that a thimble is the right choice, then is there a preference between SS and galvanized, or is bronze the best choice? I have not seen bronze offered in any of the major catalogs.

Regarding stowage and handling, my experience has been that DB is superior to 3 strand.

The matter of an anchor rode may seem quite mundane, but the survival of the boat, and her crew, could depend on its integrity. Thank you again for considering this question, and for sharing your expertise on this very useful site.

Best regards,

Jerry

[Brion Toss]

Hi again,
First, you are correct in that different manufacturers' ropes have different elasticity characteristics. This is a big variable, making it difficult to compare between brands. New England and Yale, in my experience, are much, much better at engineering ropes than NovaBraid, regardless of construction.
Next, energy absorption is not the same thing as potential elasticity. It might be better to think of absorption over time here. Like a shock absorber vs. a spring. Rope material provides the springiness, buy construction can change how the load accelerates and decelerates, and at what levels. You might want to wander around Yale's site for further details.
As for the thimbles, if you must use one, consider a Newco "keeper" thimble. This is bronze, with loops that keep the thimble from getting sideways and sawing through the rope that it is supposed to protect. But again, I would urge you to abandon that double braid, and splice either single-braid or three-strand to your chain.
Fair leads,
Brion Toss

[Ian McColgin]

People setting up their boat's anchor systems sometimes think that there is some advantage to a shackle and thimbled eye connection.

Some think that since the thimble prevents chafe - on the inside of the eye - it must be stronger and more long lasting than the thimbleless rope to chain splice. They don't seem to understand how the thimble also puts the outside of the eye in the way of getting chafed.

The other rationalization for resisting the rope/chain splice is flexability. Some think that they may want to disconnect the leader chain from the rope sometime. In point of fact, I've not talked to a single boater who ever actually disconnects and reconnects the two. All that happens is the shackle ages to the point where it cannot usefully be unscrewed anyway.

So to all doubters, think carefully and hard before you insist on a shackle and thimble connection. There are very very few instances where it actually makes sense.

G'luck

[Jerry Wegman]

Thank you, Brion and Ian, for your useful advice.

Best,

Jerry