Down-haul, cunningham or halyard to tighten luff?

[RussC]

We took Tweety (Victoria 18) to a small local lake yesterday for some AM (calm) fishing and PM sailing. in between, I had a bit too much time to contemplate, and discovered all sorts of things that I didn't know I didn't understand. For one, I must be missing something in the translation when it comes to tightening the luff of the main, to attain a nice smooth sail. to me, the halyard, downhaul and cunningham all do pretty much the same thing, except that the halyard tightens from the top and the other two from the bottom. 6 of one = 1/2 dozen of the other, but they all tighten the luff. when would one be used over the other and why?



TIA

 

[markwbird]

I am not sure what you are calling the downhaul but tightening the halyard and tightening the Cunningham do the same thing. The cunningham is there because it is more easily adjusted while underway.

 

[BlowMeAway]

Hi Russ, can you attach a photo or two of how your boom is attached to the mast. It might help us determine downhaul or Cunningham. If the boom has a single fixed point, than a Cunningham would be better for lower tightening. If the boom slides in a track, than a downhaul might be preferred. Halyard is not really a variable here for luff tightening if you haul it up tight when raising. Down force on the luff is a lot easier than Halyard adjustment when the sail is loaded underway, as Mark has stated. With the Cunningham you'll really only need a reinforced grommet in the sail and an a available cleat on the mast.

 

[RussC]

I am not sure what you are calling the downhaul

The boom floats in the mast sail track, therefore needs to be held down and cleated with a downhaul cord.

 

[dzl]

Well I'm pretty inexperienced, but my boom floats in the mast also, so I haul the sail up with the halyard then tighten the luff with a downhaul attached to the bottom of the gooseneck fitting. I have my downhaul led aft to the cockpit since I was always forgetting it and it makes sail adjustments way easier while under way

 

[BlowMeAway]

The boom floats in the mast sail track, therefore needs to be held down and cleated with a downhaul cord.

Got it! So what is the real question, considering an 18 footer? Sounds like you have it all under control. I looked at a few online images of the Victoria 18 and assume you also have a stern mounted traveler. If so, it doesn't get much better than that for smallish boat trim rigging. If the boom is lifting during downwind runs, than perhaps a boom vang is next on the list?

 

[markwbird]

Ah. I see. The boom is adjustable up and down on the mast. So, yes. the downhaul tightens the luff as well. All do the same thing.

 

[Charlie Jones s/v Tehani]

Use the down haul.

The Cunningham was named for Briggs Cunningham, who invented it as a "rule beater" while racing. Race boat sails have black bands top and bottom on the mast, based on the admeasurement for the class and the sail has to fit within those. The Cunningham tightens the luff without lowering the tack.

On a boom with a fixed gooseneck the Cunningham must be used. On one with a floating gooseneck, simpler to use a downhaul.

Has been some massive discussions (arguments??) on other boards about this

 

[RussC]

Got it! So what is the real question, considering an 18 footer? Sounds like you have it all under control. I looked at a few online images of the Victoria 18 and assume you also have a stern mounted traveler. If so, it doesn't get much better than that for smallish boat trim rigging. If the boom is lifting during downwind runs, than perhaps a boom vang is next on the list?

Yes, for a small boat it is set up really well. no problems. I was just curious why there was seemingly three different ways to do (what seemed to me) the same thing . Perhaps a better mechanical advantage would be advantageous on the down haul. even a 2:1, but other than that.......

 

[dzl]

Perhaps a better mechanical advantage would be advantageous on the down haul. even a 2:1, but other than that.......

I did just that. My line starts at the mast base and goes through a block on the gooseneck fitting. It's very easy to use, even on my 22 footer, so your 18 would be easy for sure.

 

[Charlie Jones s/v Tehani]

Three to one purchase on my 25 footer. Simple

 

[Joe]

The down haul is there but remember, besides the luff, it is also pulling on the boom which makes it very inefficient for the task, especially with an attached foot mainsail. The Cunningham is a much cleaner and specific adjustment. It only affects the sail luff. The boom downhaul is rarely used anymore for sail trim... everyone I know uses the Cunningham.

Another interesting point, on small boats with flexible masts and no backstay, a high powered Cunningham can be used to help bend the mast. My Nacra's Cunningham is 6:1. I have seen many high performance cats with 16:1 devices that can be controlled from either side of the boat.

I think of the halyard as being used to get the proper tension on the sail. The Cunningham functions as a quick de powering device that can be easily applied or removed without going to a winch.

 

[LeeandRick]

Every basic sailing book I've ever read says the cunningham is used to adjust the draft position of the sail. On a dacron sail that's exactly what it does at least on my boat. It changes the relationship of the warp and fill strands and moves the draft fore and aft. With a downhaul or halyard winch you can make small changes to draft but you are pulling on the luff rope which doesn't stretch much. The cunningham cringle is away from the luff rope so it will pull on the cloth more readily.

 

[Jackdaw]

Because the Cunningham operates in a much smaller range than the halyard has to (all the way up the mast), it can be connected to a 2:1, 4:1, or 8:1 block, making it an easy-to-adjust hand load. Halyard has to always to go the winch.