Downhaul Ratio with Mylar Sails

I run 8:1, a cascade system, 4:1 driving a 2:1. Most importantly it must release fully so the system friction cannot restrict the sail from bagging up. Using good blocks and small diameter rope will make the rope run better through the blocks. Makes a lot of difference on my current sail with kevlar tapes holding it together and worked to a lesser extent on my old mylar sail though it would stay a little bit stretched after the first downhaul application. Dacron would be like stretching a piece of spaghetti.

Adjustability while trapezing at full stretch saves leaning in and guesstimating downhaul settings and allows the downhaul to be tweaked rather then dropping mainsheet in gusts.

Darryn
1704

Darryn,

Thanks for he feedback. Do you have any images or diagrams of the setup ? I'm a little confused imagining how it all goes together. <img src=

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/> Also what diameter rope do you use; 5mm or 6mm or something smaller ?

Regards,

Peter <img src=

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I will get a picture for you Peter, ropes sizes are 3mm dyneema for 2:1 and 5mm for 4:1.
Darryn

Peter

Have a look at this page on the F16 forum:

Blade F16 cascaded downhaul

There are drawings and explanation of how the 8:1 and 12:1 cascaded systems are set up on the blade.

I used to have an 8:1 internal system which I could also make 12:1 but these days I've just gone back to a simple 6:1 setup which gives me all the purchase I need with a lot less rope lying around the place. It may be that I only need 6:1 because I'm using a very flexible mast.

I am using very similar setup to 8:1 referred to but have replaced centre pulley on 2:1 with a hook which I can detach from mast. I only need a small amount of downhaul travel to go from Max to Nil so my 2:1 ropes are short, I would not be able to attach pulley to sail if 2:1 rope was captive. A picture will explain it better.
Darryn

Darryn/Tim,

Thanks heaps for the info. It all makes sense.
I'll jury rig something together and try it out this weekend. <img src=

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Regards,

Peter

Tim,

I tried the 8:1 jury rig set up but found that the pulleys on the rope ends got caught on things like the spanner mounting or got too close to the diamond wires. <img src=

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Once I go the downhaul working the rope could be shortened significantly. Maybe I had the upper rope section too long.
I reverted to my normal setup (non cascade) with a bit of concentration in putting the ropes through the right pulleys and found a marked improvement in performance. I even had the leaders in sight for the whole race. <img src=

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Will try it again next week.

Regards,

Peter

Hi Peter, it takes a bit of stuffing round to get the 2:1 ropes lengths correct, you need to measure how much downhaul travel required then double it and find a spot on your mast that has that much clear space for the pulleys on the tail of the 2:1 to travel. Sounds confusing doesn't it?
I have attached a photo I took in my shed, I was waiting for a rigged up pic but didn't sail on the weekend.

Darryn

Darryn,

I've given up on the cascading system and am finetuning the standard setup. <img src=

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/> My cleating blocks are at the front of the mast so the cascading blocks were just fouling on everything. Maybe if I use the front blocks for an outhaul system and put new cleating blocks at the rear then I might have a chance. <img src=

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In the interim I noticed that when I used the downhaul the double blocks at the top tended to slip (they are mounted on a loop through the eyelet). I've since made the loop as short as possible so that I don't loose any downhaul purchase. <img src=

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/> Maybe that will give me that little bit more. We'll see how it works at the state titles. <img src=

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Regards,

Peter

Peter,

This is what the arrangement we use for our masts looks like. This one was the protype and has now seen 3 seasons without being looked at, which I think is not a bad run from a downhaul system. The newer ones look the same externally but with small improvements internally....running 6 to 1 internally with an external doubler giving a total of 12:1 downhaul...and it works well.

trying to attach pic...

dkd,

Thanks for the image. 12:1 certainly would give heaps of downhaul purchase. How much stretch do you get with the 12:1 setup before you have to really fight with the downhaul sheet ? The only problem would be if you turtled the Mozzie and ended up with a mast full of salt water. How does the mast step attach to the base plate ? It certainly looks like a very clean setup.

Is that a mast rotation spanner at the bottom of the mast ?

Do you have any other images you can post with the complete setup ?

Regards,

Peter

Peter,

Stretch???....you referring to rope stretch, that depends on brand of rope used but we are getting nil from the stuff we use. It has enough purchase that my youngest's crew can haul it down to the black band with not too much problem.

Water getting into the mast...well if you have got it into a position where it can enter, I think you would have other problems too, it is only open at the very base where the exit blocks are.
Yes the mast sits on the bottom assembly, so the step and plate are one unit.
Yes again, that it the mast rotation spanner, located anywhere else it fouls the blocks and lines that are internal, and we like it low and running back off of the centre beam, not off of the boom like some other set ups.
I will get some other pics and email them directly to you unless there are others interested.....might do both.

Food for thought and another option.

David

David,

Sorry for my bad wording. <img src=

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As for running the downhaul inside the mast my personal preference is to run it on the outside and keep the mast sealed. I've seen a couple of instances where enthusiastic helpers have de-rigged a Mozzie and pulled the internal downhaul rope out of the mast resulting in removal and replacement of the mast base prior to the next race. <img src=

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Looks like another thread is about to start regarding base mounted mast spanners. <img src=

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How do you mount the spanner inside the mast ? Is it rigid or is it free to move vertically. ? Is it resting on the saddle in the image ? Where do you run the adjustment lines from the centre beam ? Do they run out to the sides or do you just use a swivel and cleat off the beam ? More images please.

Regards,

Peter

Peter,
Enthusiastic helpers,,,hmmm...we have not had a problem but guess that is always a chance of it happening. Guess that is an education thing, but not hard to stop....lots of rope to pull before it goes inside anyway.

The spanner is fixed...can't move in any direction and is sleeved into the mast base....we have found it works for us, and is probably a

throw back

to the A class, again.

Everything leads to the sides of the boat, mast rotation, down haul etc...and both crews are happy with it, after all it is their bits of string.

The saddle is the bottom of youngest's boom vang....still not convinced that it is needed but we have been moving it around to find a simple but easy fixing point.

Will get you pics when boats go back together, winter maintenance and all that, along with 2 new masts coming and other new bits for the other one.....bring on next season...it will be fun

David