I am looking to improve my jib setup on my Nacra 6.0. I currently have the older Harken “Ratchmatic” blocks at the jibs with camcleats on each hull to hold the sheets. The cam cleats are a pain to use and aren’t reliable since they’re susceptible to a foot dislodging it (which is real interesting in a stiff breeze!!!).

I was thinking that I should go with Oxen blocks. Or, in lieu of the Oxen blocks, I was also thinking that a self-tacking jib would make sense.

Does anyone have thoughts on the Oxen blocks and has anyone heard of converting the 6.0 to self-tacking – and if so who does it?

I understand that the conversion would likely result in a smaller jib. However, since I have a Hooter I didn’t think the loss of sail area would matter in light winds, and in heavier winds, I wouldn’t miss the now smaller jib anyway.

Thoughts?

Bill Nieuwkerk

Skip the Oxens. They are overall less "reliable" in use without serious maintenance. Also, when they fail, they tend to fail cleated. Talk about real interesting in a stiff breeze...

The original 6.0 did have a smaller self-tacking jib. Was a really nice boat. Too bad it didn't catch on.

Take a look at any one of the modern self-tacking jib boats and see what you would have to add in addition to the new jib to go to a self tacking setup. Looking at a couple of F18s and Nacra 20s will show you what you need. Take time to look at the relationship between the clew of the jib and the sheeting angle (up and down, not side to side) to understand how your new jib will have to be cut.

I would not:
1) Go to oxen blocks. There are many reasons.
2) Go to a self tacking just to solve jib sheeting. If you want a self tacking jib, that is anouther story. By the way, the 6.0 points a lot better with a non-overlapping jib. Borrow a H16 jib and try it.

The easiest way to solve the problem is to mount additional cleats on the shroud chainplates. It is easy to cleat and uncleat from the wire. Adjust the block cleats up as high as they will go and take the fairlead strap off. This is for when the crew is on the tramp. I would also get rid of the six-way wire across the tramp and replace it with rope loops in the tramp.

If you decide to go to a self tacking jib, the original 6.0's system is not great by today's standards. Look at the Tornado and F18.

Ok, take a look at my freinds 6.0NA here. The trick to convertingot self tacking, without loosing sail area isto move the forestay out to the front of the bows. Any old traveler car and track will work on the cross beam to get you there. If your interested in thisI will diagram for you how the sheets are run. Oh you really can't do this without a VTM bow foil, I believe it woulkd cause too much sideways force on the bows. If your 6.0 came with one your god to go. I have seen this boat pass almost every other type of boat on this forum until the downwind leg when the inters and T's pop their shoots.

Do you have any close ups of this boat?

Nice, but is the longer forestay class legal?
Maybe NACRA 6.0NA is more liberal in their class rules?

Ummm...no. There's not much on that rig that would be class legal. For starters, the bridle foil is attached at the tips of the bows instead of the factory points, the jib is folded over on the leach (and thereby not a "factory unmodified sail")...not to mention that it has an aftermarket square top on it.

Oxen blocks are a pain. Had them on a TheMightyHobie18. Those new Harken Ratchematics are the way to go.

On a side note... more people need to do performance mods as shown on the N6.0. Class rules are B.S... Nice work!

Looks like the set up on my Arc21, straight track.

I can get you close ups of the ARC set up as soon as you say "givem to me" ! I'll have to put my sandals on to go outside, get the camera, and crack abrew. Then, you will have a close up.

maybe sooner

2

Cool thanks!

Hey Eric,

Could you get a pic of how it comes back up through the trampoline. We are putting the same thing on our SC20.

I sent you an e-mail in response to your pm. It would not let me reply to it.

Thanks

Eric,
Be sure and tell the person that the 4:1 mechanical advantage pulley system that goes between the jib car and jib clew is a necessary part of the self tacking jib system when a straight jib traveller track is used. Also a jib batten low in the jib sail spanning the luff to the jib clew position is necessary.
The higher the mechanical advantage of jib clew pulley system is, the more outboard the car will position itself. The lower this mechanical advantage, the more inboard the car will position itself along the track. No jib clew pulley system and the jib car will position itself right in front of the mast.
The stiffer the jib bottom batten, the more outboard the jib car will position itself. The softer the bottom batten, the more inboard the jib car will position itself.
These are the tuning levers for the self tacking jib system with the straight track. Once selected, the jib car in/out position and jib leech twist are automatically set and coordinated for a given jib sheet tension/wind strength. Only one control line is necessary; one jib sheet and one cleat.
Also with this system, sailing to windward for example, when a puff is encountered, the increased sail pressure does two things: 1. It pushes the jib car outboard opening the slot slightly. (The relative wind angle on both sails has increased in the puff.) 2. The jib is sheeted down harder by the outward movement of the jib car and this increases jib leech tension which keeps the jib leech from blowing open and wasting the extra energy in the puff.
The perfect circle jib tracks where the track radius equals the foot of the jib radius does not do these things. The jib car is free to run out along this ideal radius and therefore another control line, pulleys and cleat are necessary to position the jib car and this position fixed, no modulation during the puffs and lulls. This is a slower boat speed arrangement of the self tacking jib system during wind speed transients.
One other comment based on experience: The self tacking jib system and jib sail plan form on ARC products resulted in no boat speed loss even though the jib sail area went down. The jib luff length went up approximately 2.5ft with the addition of the "pelican stricker" tube also 2.5ft long.
The forward part of the jib, the luff, is where the forward push comes from in a jib sail. The aft part of a sail pushes sideways and makes the daggerboard have to generate lift equal and opposite to the sail side force. In doing so the daggerboard makes induced drag. The aft part of a sail is necessary to support the front part of the sail, but in the front 1/3rd of a sail is where the majority of the sail forward driving force comes from. Long luff sails are faster; long luffs lead to higher sail aspect ratios. Higher sail aspect ratios, jibs in this case, are faster. On the ARC boats we found this to be the case because we made such a large increase in jib luff length, 2.5ft even though the total jib sail area went down relative to the old style jib with the tack at the top of the forestay bridle and some mast overlapp in the jib leech area.
Bill

Excellent info. If I was to put a smaller jib on my 6.0 with the straight track system, does anyone know what size the jib should be? Are there any jibs from other boats that would work? Or, if a custom jib is required, what are the mearurements?
Thanks,
Dave

Craig,
I'll photo the whole thing. Because of the forwardtramp, the jibsheet runs forward to near midpole and then returns to the beam internally.

Tradewinds? I'd love to hook up, check out yer boat and such......

3. Taken from the tramp, facing forward behind the fore beam. The blue sheet is the jib sheet. It emerges from the spi pole and enters the block then exits for the crew to handle.

from the car to the turning sheave mid pole. I'll get a better pic in the day time.

Eric, Thanks for the pics. I am not going to be bringing my boat to the Tradewinds but I might be able to come to help out.

Bill, thanks for the detailed description and all of the help you have been supplying us. We are almost finished with the new self tacker set-up and the other things you have been helping us with.