Running Rigging Selection Guide

Sailboats RacingWhen you need to replace running rigging, be it the mainsail halyard or your jib sheets, figuring out what size and type of line you need among all of the options can be intimidating for the average sailor. Below, we help you navigate to the best line for your application by showing you how to calculate working loads for sheets and control lines, by describing the characteristics of the different fibers used in today’s line, and by explaining the unique aspects of each Samson line.

Working Load for Sheets and Control Lines

The first consideration for selecting a new line is to determine the working load that your new line will be under. For sheets or control lines, the anticipated load should be considered the working load. To figure out working load on sheets for genoas, jibs, end of boom mainsheets, spinnaker guys and sheets, the following formula can be used (not applicable to multi-hull vessels):

(windspeed)2 × .004 × (sail area in square feet) = sheet load at clew in pounds

According to Samson, “The standard working load for any Samson rope is 20% of the rated breaking strength.” What does that mean? It means that whatever line you choose needs to have a breaking strength that is five times (5X) greater than the working load you’ve come up with!  

Working Load for Halyards

If you need to replace a halyard, we recommend that you consult with a professional rigger as there are many factors, and no single formula, that must be taken into account to determine the working load.


Quality LineNylon was the first synthetic fiber used in rope construction and while strong, it is too elastic for most purposes other than dock or anchor lines. Next came polyester – which was just as strong as nylon, but with less stretch and better flexibility for working with winches. While polyester double braids are still regarded as suitable for many applications, Samson and other rope makers have begun offering a new generation of lines using synthetic fibers with significant advancements in strength, performance and reliability:

  • Dyneema® is super lightweight, low stretch and is at least as strong as steel wire of the same size. It also has UV and abrasion resistance.
  • Technora® blends many of those same characteristics of Dyneema with extreme heat resistance.
  • Vectran® is known for very high strength and excellent heat resistance.
  • Zylon® is the highest strength of them all, but offers no UV protection.

Line makers will often blend these fibers together to achieve the kind of rope needed for the specific purpose at hand.

Samson Lines

Armed with your new knowledge on fibers and construction – what is the right line for you? Are you a high-tech racer where every ounce of weight counts and who’s putting their rig through super tough loads to win the race? Or are you a cruiser – out to sail pleasantly from point A to point B just for the simple joy of sailing? Or maybe you are ready to set out on a great voyage across the ocean and want something in between? The beauty of Samson is that they have something for everyone. Take a look at the following table from Samson, as well as the product descriptions that follow, to help determine the right line for your needs.

Samson Product Locator

Samson AmSteel


AmSteel – A class II, 12-strand line constructed of Samthane-coated Dyneema fiber. This line is super lightweight, has high strength and low stretch, is easy to splice and it floats! It’s great for halyards, control or reefing lines and lifelines.


Samson AmSteel Blue

AmSteel Blue – A class II, 12-strand single braid constructed of 100% Dyneema fiber. It has the maximum strength-to-weight ratio of any single braid line that Samson makes. Along with having superior wear and flex fatigue, it is UV stabilized, has very low stretch and it also floats. Samson recommends this line for areas controlled by winch or rope clutches, along with all the other uses mentioned above for AmSteel.


    Samson Control-DPX

    Control-DPX – A class II, 12-strand line that combines Dyneema with Samson’s DPX technology for a strong, lightweight line that is easier on the hands. It’s low stretch, easy to splice and works great on winch drums, but should not be used with a self-tailing winch. This line is good for sheets, spinnaker guys and control lines.


    GPX Line

    GPX – A class II, lightweight, core-dependent line (the core carries the load) with high strength and extremely low stretch. The GPX core is a custom blend of High Modulus Polyethylene (HMPE) Dyneema® SK99 for incredible strength and DM20 for no creep.  The rope's cover is a special blend of Technora® aramid and polyester fibers providing maximum performance with superior grip, excellent durability, as well as resistance to heat. This line is good for sheets, spinnaker guys and control lines.



    MLX3 LineMLX3 - A class II double braid line, MLX3 is a lightweight, core-dependent line (the core carries the load) that has excellent strength with very low stretch.
    The core is Samthane™ coated to match the color of the cover, making the line strippable for greater weight savings without impacting its strength. It adds firmness, greatly improves wear life, and also reduces cutting and snagging, and resists contamination.
    Although MLX3 is designed for the club racer, it is also an excellent line for the performance-oriented cruiser. Great for sheets, control lines and halyards.


    Samson Trophy Braid

    Trophy Braid – A class I double braid constructed with a polyester cover and core – offering a soft cover that is very easy on the hands. Great for use on sheets and control lines.



    Ultra-Lite Line

    Ultra-Lite - A class II double braid which is great for spinnaker sheets/guys, jib sheets and dinghy control lines. This lightweight, floating double braid has a 24-strand MFP cover and a blended core of MFP and Dyneema® fiber, which gives it low stretch and an excellent strength per weight ratio.




    Samson Validator-12

    Validator-12 – A class II 12-strand line constructed from 100% Vectran fiber with a Samthane coating. This line is easy to splice, has low creep and is extremely strong and lightweight. It can be used for halyards, running backs or davits.


    Samson WarpSpeed White

    WarpSpeed White – A class II double braid line constructed with a 100% Dyneema SK78 fiber core and a flexible 24-strand polyester cover. This line is the high-performance racers choice, combining high strength with low stretch and very low weight. Great for use as a halyard, sheets, spinnaker guys or control lines.


    Samson Warpspeed II

    WarpSpeed II - A class II double braid line constructed with 100% Dyneema SK78 fiber core with a flexible 24-strand polyester cover that provides good handling, excellent performance in stoppers and clutches and enhanced abrasion resistance.  The cover can be stripped for less weight onboard - great for halyards, control lines and spinnaker sheets.

    Samson XLS Yacht Braid


    XLS3 A class I polyester/polyester double-braid rope which offers moderate stretch, high strength and easy handling. Samson made XLS3 stronger and more responsive than the original XLS, resulting in a better performing line. Use for halyards, control or reefing lines, sheets and spinnaker guys.


    Class I vs. Class II

    Quality Samson ProductsIf you’ve done any splicing, you’ll have heard of ropes being referred to as Class I or II. What this indicates is where the strength of the line lays – equally with the core and cover – or just with the core.  

    • Class I lines incorporate a braided core within a braided cover – with both the core and cover carrying an equal amount of the load. Class I lines are usually constructed from traditional fibers such as polyester and nylon.

    • Class II lines are usually for applications that need higher strength – normally a core-dependent double braid. This means that the core is where most of the strength of the line is coming from. If the line has a cover, it’s usually made with Class I fibers and is meant to protect the core against abrasion, UV degradation and friction-generated heat – not to add to the strength.  Class II lines may also include single braids designed without a separate core – usually a 12-strand line like AmSteel®. Covers can be added to these lines as needed.

    It’s extremely important to understand the difference if you plan to do any splicing as Class I and Class II lines are spliced completely differently and it’s absolutely CRITICAL to use the correct splicing technique to maintain the line specifications!

    For more information on breaking strengths and sizes – just click on the product links for each type of line. If you still have questions, or would like to learn more about the full range of splicing services we offer, please give our product experts a call at (800) 426-6930.

    Want to learn a little about Dock Lines?  Click HERE.


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