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?
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.
(I'm not sure I really want to start this) - while I agree that the radiused self tacking jib does not self regulate in the gusts, there are other advantages; One of them is that you don't have to mess with different size / stiffness battens or purchase in the sheeting arrangement in order to get the traveler car to stay where you want it. Because of this you can change your jib position within seconds on the water to try different tunings, adjust to a changing breeze, or adjust to a different point of sail.
The self regulating aspect sounds inviting, but it also sounds like a lot of experimentation is required in order to get the setting and response to work properly - and then it's not widely tunable from the water. Perhaps I missed something or read too much into the explanation?
From the way Bill explained it to me, you adjust it using the jib sheet. The others are to just get it in the ball park. I can't wait to try it out.
Bill,
Going back to answer your original post, most folks seem to agree that Oxen blocks are not the way to go. Nothing more need be said.
The Ratchamatic IS the way to go. The problem you are having is having an easy way to cleat. So, the absolutely best answer is to use the Harken 2628 (a Ratchamatic, with cleat and becket.)
This gives a ratchet while sheeting and cleating. And the beauty is that when tacking or jibing, the sheet has no drag and will come across to the other side without fouling.
This system has kept many a bad tack from happening. I love the system.
We do carry the blocks on this site at http:/
No need for self-tacking and all the hassles you will encounter to set it up, not to mention the less sail area.
The reason the pre-Nacra6.0NA was not popular was because of the self-tacking jib -- not nearly the power, balance or control of the NA.
Good luck,
Rick
Since there really is no 6.0 class anywhere near us here in CA to speak of, that boat really went for speed, one poin ton the sail cut being modified, if the mast were not raked so far back this would not have to happen, the mast rake on the boat really is eye catching, but interestingly enough, the thing points upwind like no other. Umm, yeah, so its a rough sailplan, ehhh. hehehehehhehhe
Thanks everyone for your comments, although I think I’m leaning away from the self-tacking jib.
Rick – How well would the Ratchamatic work if it wasn’t attached to a firm base – or would you recommend that I install them on the chainplates and eliminate the wires across the tramp?
Bill
Jake,
I guess I told you too much. I explained how the system works and mechanically what effects what relative to sail trim. I did not say or mean to infer that the boat owner has to go through these same experiments to get the straight track self tacking jib system right. The SC and ARC boats with self tacking jib come "correctly tuned" from the factory. These things were worked out prior to 1992 when they became upgrades with spinnakers available on all SC and ARC products.
Some day the self tacking jib system will be common on all multihulls of all sizes, cruiseing and racing and on monohulls also. The system works too good and is too simple to operate to pass up.
I have noticed that boat owners on some Tormados and I20s with curved tracks have added the center pull control line with cleat to set the car postion off boat centerline. To change this line from the trapeze means the crew has to come in off the wire, make the change and get back out on the wire. The automatic self trimming characteristic of the straight track was not recognized by some boat manufacturers.
Bill
Bill: I still have not seen even one Tornado with a straight track here in europe (there might be some of course).
It sounds to me like there is a certain amount of 'unknowns' in the straight track system. How stiff does the lower batten need to be, and will the jib 'auto-trim' to the proper shape and position ( I assumed that the leech would tighten and the sail overtrim in the gusts)? Will the lower batten be flexible enough to give a good shape over the wind-range?
With the curved track, you know where the jib is, what shape it has, and what you need to do to correct it.
I would very much like to hear more about the system!
Plain and simple BS !
Selftacking fore sails have been on boats as long ago as several hundred years. Only after the introduction of the dominant mono hull rating rule that favour large overlapping foresail did the builders move away from selftackign systems. I have personally sailed on a 1887 pleasure yacht that had a selftacking rail and jib as good as identical in nature as modern systems. That is not an really old sail boat by Dutch standards. With the correction of the mono hull rating rule where the actuall area of the foresail is talking into account do we see the return of boom jibs and selftacking foresails.
In multihull land ; Yardstick initially favoured overlapping jibs as they are marginally faster because alot more sail area goes into the jib and this area is put to use on reaches and broad reaches. Now that the newer designs are much more dominated by measurement systems that look at actual area's and formula class rules that limit area, they selftackers are returning to multihulls. This because the they are about equal on upwind as the slightly bigger overlapping jibs and on the broad reaches the spi takes care of the rest. Of course we don't do much reaching in races anymore. This all has alot more to do with things like rating systems and temporary cultures than discovery of new technology.
With respect to I-20 and Tornado having issues with their jib traveller line. This is just plain BS. They use this line to find the optimal trim for the car for the conditions and before the start and then leave it there between start and finish. It is never adjusted while racing except on SOME distance races where they fine-tune it for a very long reaching leg. This control line must be compared to the line than sets the luff tension of a jib. There is absolutely no need to trim is continiously, let alone from the trapeze. But more strikingly Bill system can certainly not do all this automatically. In fact in some case it does the very opposite of what you actually want. For this very reason straight jib travellers are disgarded by the serious racing crews. This has nothing to do with lack of recognizing auto trimming potential.
To make this all more clear I refer to the example of a nascar car suspension and that of a baha 1000 vehicel. Bill wants us to believe that he can design an identical (and unpowered) system auto adjusts itself to the different
conditions found between the track and the dirt road. One size suits all, right ?
Yeah !
Try and implement a straight rail track, it'll work well enough. But don't kid yourself that is better than what the truly professional guys are using.
Wouter
Hi Wouter,
I would never publish BS on this forum or any other forum. That is not what these forums are for. Also in my little narrow window of sailing knowledge and experience, there must be millions of details about sailboats and rig designs that I do not know about. I do not claim to be "all knowledgeable" like some people. I do know that when I put a spinnaker on my first RC27 in 1983, I saw immediately that some kind of an automatic jib jibing system would be of great benefit. Prior to this I used a wire bridle across the tramp with a double jib sheeting system.
The first thing I tried was to route the jib sheet to the jib tack and then back to the jib car and up to the jib clew. When the jib sheet was trimmed to set the jib leech and overall shape to the proper form, the jib car was immediately in front of the mast on boat centerline. Well, this obvisously won't work. One could always bend the jib track to the radius of the foot of the jib and add a second control line to the car but that wasn't good enough for me. I wanted it to be automatic, jib car position and sail shape controlled by one line. For this objective to work, the tension in the jib sheet had to be reduced to let the car/sail run off center with sail pressure without losing control of sail and leech shape. When the sheet tension was eased and the jib car began to run off center, the sail became too full for sailing to windward and the luff had backwind in it. The question became, "how do we have a high level of tension in the jib sheet for proper sail trim/shape and a low level of tension in the sheet at the same time to allow wind pressure push the jib car and sail off center for sailing to windward and reaching?" This objective was acheived by adding mechanical advantage between the jib car and jib clew. Pulley systems from 2:1 to 6:1 were tried. On the RC27 sail plan that I was working with at the time, I found that a 4:1 mechanical advantage pulley system did the trick. I could set the sail shape/leech tension that I had in the first place with only 1/4th the sheet tension in my hand or with only 1/4th the sheet tension in the sheet leg from the jib car to the jib tack. Now the wind pressure in the sail allowed the jib car to find an equilibrium point off center at the proper angle for sailing to windward with the same tension in the sheet that properly trimmed the sail. The trick was that the sheet tension was multiplied by 4 only between the car and jib clew. When the sheet was eased, the car moved out and the sail became fuller and if the sheet was tightened the car came in and the sail became flatter. I also learned that a batten connecting the jib luff to the clew corner of the jib made the car run slightly further outboard and it kept the jib from becoming too full as the sheet was eased for reaching. This batten acted something like a bendy boom. (And by the way Wouter, some Tornado sailors do let the jib car control line out for reaching. That is why the jib tracks are more than 18 inches long. The crew does have to come to the center of the tramp to uncleat and let out this control line. They also have to come back to the center of the tramp to tighten this car control line for sailing back to windward.)
I want to point out that ARC products have both straight jib tracks and curved jib tracks for various reasons. I happen to like the straight track system better myself on the 27 and 30.
Another comment for Wouter: Wouter, I have been going to international boat shows since about 1970. I have looked over hundreds of sailboats of all sizes and shapes. Most of these boats were "cruiseing boats". I have never seen one of these boats rigged with a self tacking jib system. Cruiseing boats do not give a hoot about racing/rating rules. These boats/rigs are designed to be "simple and easy to sail". Rules do not matter! I will make a prediction: Within the next 5 years you will begin seeing cruiseing boats rigged with self tacking jib systems like beach cats have today.
Bill
PS Wouter, there are self tacking jib systems pictured in Harken's catalogue. You will never see one of these arrangements on a boat because they do not work worth a hoot. The beach cat system, straight track, works very well and is very simple to work with one control line.
Hi Rolf,
The spark, the starter, for the self tacking jib system on beach cats in Europe came from an ARC22 that was sold in France in the early 1990s "with a curved track". This boat owner was visited by several top sailors and boat builders in Europe after they had heard about the system. They made pictures and asked many questions of the owner.
The main purpose of the jib bottom batten is to keep the sail from getting too full while reaching. It does not compromise the jib sail shape. It makes it better. It acts something like a bendy boom on the foot of the jib. It is about a 3 pound compression batten.
With the straight jib track the jib sail is sheeted tighter in puffs. It is only sheeted tighter in direct proportion to the increase in sail pressure. This holds a more constant sail shape than doing nothing.
Bill