I have never gotten it confirmed but I think I got an pretty good idea of how the Blade F16 downhaul works. It is actually a very smart setup. I still like my internal system because it gives such a clean look and I never have to take it off but commericially the VectorWorks system is the best. The internal systems are a little labour intensive to build while the Blade system isn't. Also the system used there can easily be put on all other catamarans out there. So if you are having trouble with you downhaul. Not powerful enough or too much internal friction than you may want to give this a try.




The two systems shown use the same basic idea but the one above is a 1:8 and the one below is a 1:12 . I seem to remember that the Blade F16 comes with a 1:16 even.

It will be easiest to explain the system by the 1:8 model; the other are exactly the same apart from having more loops in the blue line.

The red line is the line that you'll hold in your hand. probably 5 mm or 6 mm diameter with nice grib properties and as flexible as possible. The blue line is a thin high tension line that is strong but still flexible. A good combination good by 6 mm swiftcord for red and 3 mm D12 for the blue line.

On either side of the lines you'll see to schematics representing the swivel cleats that are riveted to the mast near the mast foot. Black lines are drawn to indicated that the swivelcleats and the lower 2 blocks are fixed to the mast and can't move relative to one another.

Then we follow the blue line. This starts and ends at two free hanging blocks than move along side the mast. The blue line first passes through two blocks that are fixed to either side of the mainsail (or a double block that hangs underneath the mainsail). The black lines here indicate that these upper blocks are fixed to one-another and to the mainsail; they move up and down together with the mainsail and so the movement here is equal to the downhaul travell length.

How does it work.

Well the sailor pulls on the red line (which can be continious by the way ! THAT is VERY handy). This induces a tension in the red line of say i unit of force. By virtue of the two vertical loops in the red line the force on each of the free hanging blocks is 2 units. Therefor in the blue line there is now 2 units of force. The sail is linked to 4 segments of blue line therefor the pull on the sail will be

4 times the force in the blue line = 4 times 2 time the force in the red line = 8 times the force in the red line => 1:8

By the same reasoning you get 1:12 in the bottom system.

Why this system ?

Well It allows to optimize the line diameters for low friction and smooth operation. Because of the cascaded nature the total friction is alot less than a standard 1:8 system using 8 loops. You can therefor excert the same downhaul force for less red line tension = easier control.

And this system fits entirely on the outside of the mast between the foot of the mainsail and the mast step. Nothing is internal in the mast (easier to build yourself) and you don't have downhaul lines running up along side the mast for some 5 to 7 feet and disturbing the flow there. See the attached pictures.









Wouter