5 golden rules to follow with dyneema on a boat

Dyneema has an infinite number of uses on a boat. It’s high strength, low stretch, and slippery characteristics are all pretty unique to this type of rope and can be great advantages. However, with different materials comes different rules to follow and dyneema is no exception. Follow these 5 golden rules of dyneema for long term success on your boat.

1 No sharp edges

Dyneema is pretty tough stuff when it comes to line on a sailboat. It is relatively cut and chafe resistant which you learn quickly if have ever try to cut it with a pair of household scissors. With that being said chafe will eventually wear through even a dyneema line. The easiest way to avoid chafe is to make sure it doesn’t touch any sharp edges or corners. There are a lot of edges where you might want to attach dyneema on a boat including a luggage tag or soft shackle around a metal toe-rail or through an eye on or through a stanchion. Try to avoid these edges or corners and if you can’t the best way to eliminate the edges in these areas is to use a piece of emory cloth to round and smooth them. Start with a low grit and work your way up to a higher grit for a nice smooth radius. Ideally you want the radius to be at least the same radius as the piece of dyneema wrapping around it.

2 Cover for cleats and clutches

Dyneema is great for running rigging and control lines and its slippery property makes it work really well with simple and cheap low friction rings as leads. However, this same slippery property works as a disadvantage through cams, clutches, cleats, and even handling it by hand. To address this just make sure you have a cover over the line for all the areas that will be used through the hardware above. The cover should be a different material than dyneema, usually polyester or a polyester blend and sometimes technora where it still needs to be extra tough. The simplest way to use single braid dyneema but have a cover where needed is to just buy double braid dyneema core line such as warpspeed ii our ______   then strip the cover from the line where it is not needed or wanted and keep the cover where it is. The disadvantage here is that it is usually more expensive because you are paying for all this double braid line when you only need cheaper single braid for most of it. The cheapest way to add a cover is to just get some polyester cover maybe from some old lines or even a rope or rigging shop that does a lot of splicing and has remnants and add that over your single braid dyneema. Don’t forget to terminate the cover into the core and stitch/whip it so it doesn’t slip. With all that being said I have used single braid dyneema uncovered around cleats but only where loads are very low such as lazy jack tails and topping lift and I cleat hitch it like 5-10 times to make sure it won’t slip.

3 Always Splice, Never Knot

As mentioned above dyneema is very slippery which means knots slip very easily. In addition, in general knots weaken the line significantly from its original strength. For those two reasons dyneema should almost always be spliced. The only exception that comes to mind is in soft shackles where a complex diamond knot or button knot is used. Luckily single braid dyneema is extremely easy to splice. The most common space for a dyneema eye is the locking brummel splice and an end-to-end splice can be used to join two dyneema lines together. With any splice in dyneema the main strength of the splice comes from burying the tail into the core. The conservative amount to bury the tail is 72x the diameter of the line you are working with although I have seen people using as low as 50x the diameter when in conjunction with a locking brummel.

4 Bend Radius and Throat length

The bend radius of a dyneema loop or eye can be as low as 1:1 to the diameter of the line you are working with and still be within a few percentage points of the total breaking strength of the line. A 3:1 bend ratio is virtually at 100% of the breaking strength of the line. The other thing to consider is the throat ratio. You may have a bend radius of 3:1 but if you close up the throat very tight then you can significantly reduce strength. ELABORATE ON THIS

5 Watch for the fuzz

As mentioned above, sharp edges and corners will eventually cause chafe in dyneema. The good news is that if you inspect the lines and components on your boat regularly you will spot the fuzz that forms on dyneema line when it begins to chafe. It is super easy to spot on the slick line and if you spot it early you can address the issue before any significant strength is lost in the line. Just keep your eyes peeled.

I hope this article helps in your journey to using dyneema on your boat. If you found this article interesting or valuable please let others know by giving it a share. Thanks so much!