Downhaul Systems – Ordering Guide

The following is designed to help you choose the optimum downhaul (cunningham) system by looking at what is important, the types of system available, and then the blocks, rope, and lower block attachment options.

What’s important

In comparison with the outhaul system, the downhaul is conceptually a lot simpler. However, the downhaul system has to really work well – it’s hard pulling the luff down – and the last thing we need is a poor system that makes it harder than it needs to be. After the kicker this is where money is best spent getting the best system that you can afford, so that you can effectively control your sail shape.
Unlike the outhaul where every turning point can have a block, the downhaul system primary must pass through the sail cringle and that means friction. We need to minimise the friction in the system by using the largest sheave blocks we are allowed to use under the Laser class rules (30mm) and by minimising the friction through the sail cringle by using slippery rope for the primary line.

Types of System

There are two types of downhaul system and it is important to select what is right for you. The decision should be based on the rig you are using, and your weight and strength.

  • 6:1 Downhaul System – This is what the overwhelming majority of Laser sailors use. It gives sufficient purchase for the 4.7/Radial and Standard Mk1 rigs, and minimises excess rope in the cockpit when pulled on hard.
  • 8:1 Downhaul System – This is ideal for lighter sailors who are struggling to pull their downhaul on really tight. The 8:1 system is also really required if you are using the new MKII standard sail where the additional purchase is really needed due to the stiffer sail material used. For more detail as to why you should use an 8:1 for the MkII sail there a few links at the bottom of this page.

6:1 and 8:1 Downhaul Systems

Optimised for Rig Type

Because the tack cringle on the new MkII standard sail is positioned higher than all the other rigs, our systems are optimised (4.7/Radial/Standard MkI or Standard MkII) to ensure that the rope lengths/block positions are ideal.  If you want to be able to sail either the 4.7/Radial/Standard MkI and the MkII standard rig with the same downhaul system there are ways of rigging the system to compensate that are described later.

Block Types

With the much higher loads involved, and the desire to reduce friction, you should use the largest blocks allowed. We recommend Harken’s T2 Soft-Attach 29mm block for the downhaul (which is what you get with a new Laser), or the more economic Allen 30mm Tii blocks. If you are not racing then you could consider the smaller sheave blocks from Harken or Ronstan. Two blocks are required to put together a 6:1 purchase system – one at the base of the mast by the kicker attachment and one that is floating just below the sail cringle. For an 8:1 system three blocks are used.

From left to right Ronstan 20mm Orbit block, Allen 20mm and 30mm Dynamic Tii blocks and Harken T2 Soft-Attach 18mm and 29mm blocks

Rope Types

For the primary line a thicker D12 Dyneema line than is normal is best to reduce the chance of it getting trapped between the gooseneck and boom, Standard on our systems is 5mm SK78 D12 Dyneema for Harken 29mm systems, and 4mm SK78 D12 Dyneema for the other block types.
For the secondary line (the one that you pull on) we use two main rope types – the popular FSE Robline Dinghy Control which has a Dyneema core, and Gottifredi Maffioli Compact Braid which is a more ‘extreme’ uncovered 4mm D12 Dyneema rope that is used by some top sailors.
 
Both of these rope types work perfectly with the Harken T2 Soft-Attach, Ronstan Orbit and Allen Dynamic Tii blocks. The method of splicing the ropes types on our ready to fit systems is different – the FSE Robline Dinghy Control’s strength is in the Dyneema core – so it’s the core that is lock spliced and the outer cover stitched. The Gottifredi Maffioli Compact Braid is a 12 strand rope so the entire rope is lock spliced.
 
All our secondary line ends are epoxied/heatshrink sleeved to help keep them nice and tidy, and we offer a wide range of primary/secondary colour combinations.

 

Rope Length (Handle Type)

The secondary control line length can be selected for either a simple loop handle or a braided handle.

Lower Block Attachment

Finally, you need an appropriate method of attaching the free end of the primary line. A good way of doing this is to use the lower block strop around the mast as the anchor point for the end of the primary line. It has a number of advantages – it doesn’t put additional load on the kicker assembly; there are no pins or shackles or knots to mess about with; and the primary line and block are symmetrically positioned.

Lower block strop and primary line termination


The simplicity of rigging depends on the type of system that you are using (6:1 or 8:1), and the handle type (simple or braided chain). For the least simple to rig (8:1 system with a braided chain handle) to avoid having to thread the secondary line and re-do the chain handle, some customers have opted to terminate the primary line at the top of the kicker/vang assembly (either using a pin or caribiner). If you want to rig your primary that way, select ‘Top Of Kicker’ under the Systems Option section, and we will shorten the primary line by 10cm/4 inches.

Using a Caribiner

 

Using the Same System with Multiple Rigs

As mentioned, as the tack cringle on the new MkII standard sail is positioned higher than the other rigs, our systems are optimised to the rig that you are using. If you want to be able to sail either the 4.7/Radial/MkI and the MkII standard rig with the same downhaul system it needs to be adapted in some way as the primary line length for the MkII is 10cm/4 inches longer. We feel that the best way of compensating for the above is to order a Standard MkII optimised system, and add the ‘Top Of Kicker’ under the Systems Option section. When using the system with a Standard MkII sail, terminate the primary at the top of the kicker assembly using a caribiner. When using a 4.7/Radial/Standard MkI sail, terminate the primary via the lower block strop which will effectively shorten the primary line length by approximately 10cm.

Rigging Instructions

All our systems are supplied with detailed rigging instructions which can be seen here:
6:1 downhaul installation instructions
8:1 downhaul installation instructions.

Links etc:

For more detail as to why you should use an 8:1 for the MkII sail there is a good article from International Sailing Academy that covers this in more detail.
 
Building an 8:1 downhaul video
 
A detailed write up from Southeast Sailboats sponsored GBR Team sailor Michael Beckett from November 2016.
The new 8:1 downhaul is complete game changer (not a phrase we often hear when talking about Laser kit). Not just for smaller sailors but for any sailor trying to get to grips with the new MkII sail. The new and stiffer Dacron cloth requires greater tension to be applied to achieve the same depowering of the sail in hiking conditions (10+ knots). It is an inevitable conclusion that the old 6:1 systems used on the MkI aren’t going to be sufficient, no matter how hard you think you can pull. The issue one would expect from a greater number of purchases is all the additional rope in the cockpit. However, the MkII the sail stretches over a far smaller range so there is still less rope in the cockpit, making this the ideal system (even after the sail has seen many months of use).

The system provided Southeast Sailboats is immaculate, all of the splicing is done to millimetre perfection and the block arrangement leaves no room for improvement, providing a very smooth running system. The downhaul is very quick to set-up and the difference is instantly noticeable; instead of ‘pull as hard as you can until you can pull no more’, the system allows you to fine tune the adjustment giving complete control over the rig.”

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