Downhaul Systems 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.
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 majority of Laser sailors use for the 4.7, Radial and the old Standard MKI sails. It gives sufficient purchase for those rigs, and minimises excess rope in the cockpit when pulled on hard.
8:1 Downhaul System – The 8:1 system is essential if you are using the newer MKII standard sail where the additional purchase is really needed due to the stiffer sail material used. The 8:1 system is also ideal for lighter sailors in 4.7 and Radial rigs who are struggling to pull their downhaul on really tight. For more detail as to why you should use an 8:1 for the MkII sail read this short write up by 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).
Optimised for Rig Type
Because the tack cringle on the 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.
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. One of the other benefits of the larger 29/30mm sheave blocks is that when the secondary line wear out it is easier to fit a new one through the larger central 'axle' of the block. 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.
More expensive, high load blocks run better under load, reducing friction in the systems and hence improving system efficiency and effectiveness. We have made (and will if requested) systems using the amazing Harken 29mm FLY block for customers who want the ultimate downhaul irrespective of price, but we don't list these solutions due to the very high price. However, we how listed solutions using the Allen 30mm High Load block which provides 'high load' benefits at a more affordable price - this is now our premium solution available in both 6:1 and 8:1 configurations.
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 Robline Dinghy Control as the standard line and Marlow Excel Racing GP78 as the premium line. The Marlow Excel Racing GP78 has Technora in the cover which makes it more durable. Gottifredi Maffioli EVO Race 78, which is similar in performance to Dinghy Control is available as a no-cost option - If you want that line just add a note at checkout. All our secondary line ends are epoxied/heatshrink sleeved to help keep them nice and tidy. We offer a wide range of primary/secondary colour combinations. If you want more information on our secondary lines and how to select which is best for you read our article on selecting secondary lines.
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.
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 the Same System with Multiple Rigs
As mentioned, as the tack cringle on the 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.
All our systems are supplied with detailed rigging instructions which can be seen here:
6:1 downhaul installation instructions
6:1 downhaul 'top of kicker' installation instructions
8:1 downhaul installation instructions
8:1 downhaul 'top of kicker' installation instructions
- You sell both 6:1 and 8:1 downhaul systems – which is best for me? The 6:1 system is best for the 4.7, radial and standard Mk1 rigs. The 8:1 is best for the standard Mk2 sail which uses a heavier cloth. If you are a lightweight sailor you may want to use the 8:1 for the radial or 4.7 rigs, accepting the tradeoff of ease of use versus more rope in the cockpit.
- I sail both radial and the new standard Mk2 rigs – is it possible to have a downhaul system that works for both? Yes. The tack cringle/grommet on the new Mk2 sail is about 5-6 cm higher than on all the other sails, and whilst this doesn’t sound much, when it is combined with a 6:1 or 8:1 system this distance is multiplied. Our usual downhaul system fixed the primary line at the level of the kicker tang on the lower mast. One option is to use that fixing position for the radial/Mk1, and to move the fixing position up to the top of the kicker assembly for the Mk2. This reduces the impact of the difference. It can be reduced further by using a snap type caribiner on the kicker assembly such that the primary attachment point for the Mk2 is even higher.
- Why is the downhaul primary line so thick? From a strength perspective Dyneema is so strong that we could probably use a very thin 1.5mm line, but it would probably saw into the tack cringle and would certainly get snagged in the gooseneck. Over the years the line has got thicker, as the type of blocks – such as the Harken 29mm block – can accept larger lines, and reducing the chance of it getting caught in the gooseneck.
- Can I see the instructions as to how the systems are rigged? Yes, follow the following links:
- I am unsure of what is best for me – do you offer free advice? Yes, we offer free advice on what we feel is best for you, based on years of sailing the Laser at championship level. Just contact us at firstname.lastname@example.org
- You list Harken and Allen based systems – which is best? From a weight perspective, the Harken block are much lighter. From a strength and functional perspective both are very similar. The Harken blocks are by far the most popular, and are the block type supplied with new UK supplied Lasers. The Allen blocks are an excellent economical solution.
- I like to rig my Laser differently. Do you offer custom systems? Yes. A quick walk around the Laser boat park at even a world championship will show that there is no ‘right way’ to a rig a Laser – a lot is down to personal preference, and we are happy to build up exactly what you want.
- Do I have to have everything spliced together? The answer is no, but there are a number of reasons why we splice our systems together. For the primary lines, the fixing to the new ‘soft attach’ blocks is important that it is done correctly, as an incorrectly fixed primary line can pull apart the head of the block. For the secondary lines, particularly the smaller Harken 18mm and Allen 20mm blocks, the size of the sheave makes it difficult to thread a 4mm control line through when a 3mm primary line has already been threaded through.
- Having a spliced system is great, but what happens when the ropes inevitably wear out? If you liked the original spliced system that we supplied we can rebuild the system using your original blocks. Just send the blocks back to us and we will replace and re-splice the lines for the listed price/metre of the ropes on our website – we can’t say fairer than that!
- I have just bought a new Laser and I have the bag of blocks and ropes that comes with it. Can you put it all together for me? Yes, we have done this for a number of customers. The bag of ropes that comes with a new Laser can be daunting. We can turn all those ropes and blocks into a ready to fit system from just £75.
- Can you fit your systems with other types of control line? Yes. Our standard secondary control line rope is FSE Robline Dinghy Control (which is standard on new Lasers) but we can supply most ropes that you may want. Other popular choices are English Braids continuous control line, naked 4mm Dyneema. We can also fit ropes from Gottifredi Maffioli. Some other rope types are not amenable to splicing and would be tied.