My boat is on the trailer now and going to the winterstorage so this season 2004 is over for me.

But there wasone last thing I tried and that is a shockcord system to take the 2.4 mtr slack that comes out of the downhaul system.

See the attached picture. Please bear with the spagetti looks as most of it is going to be removed later. I am afterall in a test situation here.

The white line running from the mainbeam to the rearbeam will be replaced by a hiking strap running over the trampoline. I need one afterall hence the quick fix that you see right now. Also the little white loops at the back were a succesful modification to the trampoline and I'm going to reinforce the grommets there and run a dark coloured line through it so that the trampoline look tidy. One loop has been remove already because we ripped the grommet out. These loops are very comfortable for the skipper to put his/her foot in and the ladder setup allows the skipper to sit anyway near the rearbeam without being in danger of sliding down when the boat heels.

Eventually I going to run the jib sheet through the mainbeam as shown but then with the shockcord fitted inside the mainbeam.

The white line running from the sidestay to the mastrotation arm is there to prevent the mast from vibrating when parked. This line is removed before sailing.

Than you see a light grey line, this is the downhaul, and it is this line I want to talk about.

I found that I like my downhaul line to be near the sidestay. Especially in strong winds you're trapping way back on the boat and the mainbeam is to far away. I also found that running it to the sidestay and then to the mainbeam is both unwanted, cumbersome and creates alot of drag in the system.

Unwanted because : This runs the line over the gunwhale between beam and sidestay chainplate and sometimes your want to place a foot there. Standing on a line is uncomfortable, slippery and a PITA when trying to adjust the downhaul tension. The current setup doesn't have this problem anymore.

Cumbersome because : It is diffult to hook on or unhook the system when it is inside the mainbeam and you wnat to drop the mast. The current system can be unhooked from the sidestay and bungee cords and be tied to the mast within a minute. Bungee cords stay on the trampoline and hooking it back up is a job of 30 seconds.

Draggy because : The friction between end plate and the line is quite high when the system is inside the mainbeam. The way you grap and pull the downhaul line in the mainbeam system wraps the line 360 degrees around the ring or shackle at the sidestay creating even more drag. The current system you see doesn't have both problems at all. When you grap the line between the mast and sidestay and pull it outward than the line comes totally free of teh ring/shackle and has no friction there. In addition there are no further corners or friction surfaces in the system that can created drag. When ou are sitting in board and pull on the downhaul than the excess line will make the curve around the ring go slack and thsi drop in tension will reduce the friction of the line on the ring to almost zero. Thus making it very easy for the bungee to pull the slack to the middle of the trampoline.


How does the new system look ?

It is hard to see all components but look at the picture and read the comments I give now.

-1- Line comes out of mast
-2- goes through cam cleat on the mast base plate. These are non swiveling and honestly I see no need to make them swiveling. It workds well as it is.
-3- line crossed the trampoline to the sidestay
-4- line runs through a ring or shackle
-5- Line crosses back over the trampoline to a simple block that in turn is fitted to a bungee cord (more on this later)
-6- Line than crosses back over the trampoline to another simple block on a bungee line.
-7- Line than crossed the trampoline a 4th time towards the ring/shackle on the other sidestay
-8- Line than crosses back over to the mast and cleats.

Bungee cords.

I have two grommets in oen either side of the trampoline just inside the hulls. Through these a bungee cord comes up and its end is tied to a simple block as described earlier. I use a quick knot here; just a figure 8 knot in the bungee line end and I loop this throught the block and use a simple hitch to secure it. Just like quick knot systems used on the spinnaker pole. As this bungeer is always under tension the knot will never become undone. So the bungee passed throught the grommet to the underside of the trampoline. Here I lead it back along the hull (only a 90 degree angle over the grommet this reduces friction) to another simple block and then I lead it back forward were I tie it off near the mainbeam. This gives me about 3 mtr bungee length on each side.

Because of these long bungee cord lengths the increase in force when stretched further is rather limited. So it feels like the shockcord pull on the line is pretty much constant at a mild level.


How does the new system work ?

When the downhaul is fully released than the two blocks on the trampoline are almost back to back with little slack in the system. Both bungees are stretched by about 0.60+0.5 = 1.1 mtr mtr on a overal untensioned length of about 2.5 mtr. (range = 20 % to 45 % stretch on a bungee that has a typical range of 0 % to 70 % stretch so force is rather constant). Now there are two ways in which it works.

-1- Crew from trapeze. Crew leans over and graps the line between mast and sidestay right in front of the ring. Crew pulls thus lifting the line of the ring and taken line both out the the internal system inside the mast and from the system of the trampoline. The simple blocks are pulled further together and the bungee stretches. When finished the crew can just drop the line from his hand and the trampoline system will immediately take out the slack. Of course the line is not wrapped around the ring as long as the long is not taught so there is hardly any friction in the whole system. The bungees with have an easy time pulling the two simple blocks apart and thus take up the slack in the line. The only serious friction in the system is where the bungee cord runs through the grommit but here a phenomenon is at work that will make the system work just the same.

Pretty much this phenomenon works here at the grommets but also at the rings. When there is no tension in the lines than friction at these rings/gromment must be very low as a result. Therefor it is easy to pull the lines through. As soon as tension is put on the lines than the friction increases rapidly and stops further pulling however by this time the lines are already pulled tight and there is no need to pull it more tight still. This is the beauty of it. The system stops pulling when the lines becomes mildly tensioned. And it only need low tensions to work.

When releasing the downhaul than the crew from the trapeze reaches for the line between mast and sidestay and pulls the some slack out of the system on the trampoline. He then flicks the line out of the cleat and feeds it some line. At high loads the sail will pull the line through your hands at lower loads you have to feed it manually. But the latter is quite doable even with one hand.

When sitting on the trampoline.

It works the same as from the trampoline only the way the the line behaved around the ring is a little different. Now the line is never pulled of the ring as it is from the trapeze. However when you pull on the downhaul to excess line drops the tension in the line wrapped around the ring making reducing the friction there to almost zero. The system on the trampoline can do pull the excess line in. When feeding the downhaul you just pull the line through the ring with a little force and feed it to the downhaul system. Line loads are still relatively low and this is easy enough.

I didn't put this system underneath the trampoline as I want all the clearence to the water surface that I got there. However it seems to me that it could be fitted there just the same. Epecially when using Ronstan microblocks (very lighttweigth) and swiftcord (extremely ligtweight line of still some 6 - 8 mm diameter.

In the picture you see the grey go into the daggerbaord well and see a large knot there as well. Ignore these. The picture was made when I was still testing the setup and finding the right line length.

next season I will try to splice the grey line together in oen continious loop and have no grommet put into my trampoline a little further to the front so the system on the trampoline is spread out less. I may even stitch a tunnel on top of trampoline where this system moves through. But that is future stuff. First I want to test it thoroughly during several months of sailing. Initial trails have proven that is works but there is always some improvement to be made after getting to know it fully.

Wouter