KA Koncept RDM cam rigging help.

I'm having trouble rigging a brand new 2016 5.4 Koncept on the 100% KA 400cm RDM mast with RDM cams that have been fitted to the sail. Specifically, the top cam seems too long as pushing down on the luff doesn't get the cam to a position where it can pop onto the mast. The bottom two cams are easy. I have not used cam spacers.

My rig method is like the other cam sails I have used in the past:
Insert the mast over the cams, downhaul ~90%, attach boom and apply lots of outhaul, then release some downhaul and pop the cams on. The bottom 2 cams go on easy, the top feels like its just too tight and I'm afraid the top cam is going to damage the sail. I have played with different downhaul settings and outhaul, but no luck.

All the RDM cams are the same size and are longer than the SDM cams that came in the sail.

For those that have RDM cams in their smaller KA sails, can you offer any advice?

Try and give it almost all recommended downhaul, then pull the outhaul as tight as possible, then release at least half the downhaul. The cams should be easy to pop in then. I found that with recent models I also need to release the outhaul to pop the cam near the boom

The second pic clearly shows *far* too much downhaul... if you can see the cam protruding through the mast pocket, you are just damaging the material. On cammed sails you need only enough downhaul so that you get the boom on -> some of us dont even put any downhaul on at this stage.

Then put on a lot of outhaul, ie: close to whatever max outhaul setting that would be appropriate for that size sail.

Then try fitting the cams - if they pop off, then add just a tiny bit of downhaul.

Once all cams are located, put the recommended downhaul and minimum outhaul.

As someone who has been rigging KA Koncepts since they were invented, on SDM's and RDM's.

A. Top Cam: While the RDM can will work in the top position (4th batten), and I have used it in some speed sail sizes for maximum draught, the normal and best all round solution is to use the standard SDM top cam (which is slightly different on the later sails from the lower SDM cams).
The reason for this is that the mast diameter difference between SDM and RDM at the top cam point is quite minimal. Usually, I don't even find the need for a spacer.

B. Rigging:

1. Thread mast on top of cams and make sure the head is fully seated.

2. Put mast extension in and apply very little downhaul. Just enough to complete threading the pulleys and cleat the rope. Sometimes even less!!!

3. Put the boom on the mast at the bottom of the cut out. This should be easy to do with the luff quite loose. If it is not easy, use even less downhaul!!!

4. Outhaul the sail fully until almost flat.

5. With the cam zips open, while supporting the mast on your thigh, Pop the cams on by pressing down with one hand just behind the Luff pocket and giving a gentle thump with the heel of the other hand on the cam under the mast. It should pop on very easily. I do it from the top cam down, but that is just personal. It really does not matter which way you do it.

6. Downhaul the sail until it looks about right. Don't rely on the measured settings. They are about 3cm too high for max conditions on most sail and mast combo's if measured by the industry standard. (Applies to Koncept model only - long story...) If in doubt, start with less and add more only if needed, not the other way around. These sails are not designed to look as loose and floppy in the leech as many other brands, but they still have adequate twist.

7. Let outhaul off to get nice depth in the sail. As a guide, the cross boom batten should be just touching the boom unless overpowered. Use a lot less outhaul for broad speed runs.

8. Zip up cams and boom cutout. Tighten up the tack strap. Tuck excess downhaul rope into the velcro pocket in the mast foot padding.

My settings for 5.4m Koncept on RDM mast (2014 - 2017):
Downhaul measured to bottom of the pulleys - 405 to 407cm. Usually 406. (will vary slightly between individual sails and masts up to 5mm)
Outhaul measured from front edge of mast above the boom (middle of cutout) to the clew edge of the sail next to the clew eye - 169 to 172 max.

Steve, the downhaul settings vary a lot depending on which brand and carbon % of mast you are using. Sailquik sent me his rigging chart for the 2016 KA's and his numbers vary by a few cm from what I use, because we have different masts. It is best to tune by the crease which forms in the white panel in the third panel down from the top. You want the crease to go about one third (light wind) to one half (strong wind) of the way across. SAilquik has some photos of how it should look if you need them.

Good news! The SDM cam works and so does the RDM cam . Once I used the SDM cam, I could see it would need multiple spacers to get it snug on the mast and there was definitely room there for the RDM cam.

The trick to getting it on was to have virtually no downhaul on the sail when popping the top cam on, then apply downhaul so the bottom two cams could be popped on (with out popping back off when applying more downhaul).

Below is what I believe to be approx (I have not measured mast length) max downhaul at 4065mm, outhaul 170cm (neutral).
As per Windxtasy suggestion, the crease is half way across the white panel (in the third panel down from the top). This was about as much downhaul as could put on with my harness hook, but I was using old line on my wave sail's rdm extension and the two pulleys were coming to their end of travel. I will swap to formula-line to make this much easier

The cams rotate well on land, so I know they will be sweet on the water.

Hope we get some wind here soon!

Looking good!

I would rarely use as much downhaul as you have in the top photo. Perhaps in epic speed sailing conditions with gusts to 40Kts on a very broad course.

My typical setting would be more like your second photo, and I have been experimenting with even less lately with very good results in 20-30 knots winds like last Monday here.- (Crease just crossing the colour divide in the second top panel between the 2nd and 3rd battens.)

Also beware of getting carried away with adding spacers to get the luff pocket tighter. Doing so tends to knuckle the sail more and make cam rotation stiffer. The more Knuckled shape can 'feel' good, but I eventually came to the conclusion it was slower in most conditions.

Hopefully, more 5.4m testing tomorrow, with a nice 25-30 knot WSW front forecast to come through mid morning.

I will try to remember to take some more measurements!

Select to expand quote

sailquik said..
Looking good!

I would rarely use as much downhaul as you have in the top photo.

My typical setting would be more like your second photo

I agree with Sailquik. (He is the expert after all). Top photo only if way overpowered and maybe not that much DH even then.
I usually use a bit less DH than the second photo also.
But you get the idea of judging downhaul by the crease in the white panel.

I just wish we had enough wind for me to use that sail again...