Hey guys, I don’t even have my boat yet, but had a few ideas that would be appropriate here…
Has anyone tried to run a seperate servo for sheeting their jib. Seems that you could possibly manage to run wing and wing if it were seperately sheeted… Anyone want to try it??
Also, I know this would require some clever sheeting arrangement, possibly a fourth servo, but what about running genoa foretriangles? An additional servo could "winch the clew forward so as to clear the mast…
You don’t need a seperate servo to wing your main and jib, any boat with a self-tacking jib (which is 99.9% the boats today) will do that for your. Some classes allow and some people use a “jib twitcher” which is nothing more than what was called 30 years ago a jib flipper that does just that… it has no strength as winch… but can flip the jib over to the other tack in light air conditions when running.
As to the genoas, we are developing a new winch specifically for running a genoa on those boats where they are legal such as the J boats, AC class, “A” Class and a couple of Open Class boats as well. They require a single servo to operate and you use your normal winch to sheet the mainsail, so you actually have the option to sail in either format if you want to switch back to the self tacking jib (and you still have your winch set up that way)
We are on the 3rd generation prototype and are looking at a News Year’s release (along with the whole operation) with a bushed version selling around $60 and a bearing equipped version for around $85.[:-bigeyes2]
2005 is going to be a good year for model yachts.
Larry,
I have a victoria. Is the jib self tacking on my boat? Will it automatically tack to opposite side of main downwind? Is a jib boom counterweight to help the self tacking? Last of all, are you aware of whether twitchers are allowed in my class?
Thanks,
Wes
wes
install a jib boom counter weight
ed
HI Wes,
Yes the jib on your Vic is self-tacking… will it flip over wing and wing when you are downwind… well… yes but you have to help it there by steering the boat into a position to where it can do that.
If the jib doesn’t flip opposite the main, it hangs limp in the wind shadow of the main. Usually as you bear off slightly the jib will pop out.
If you have enough sheet available to let the jib out far enough (you would be surprised how many people don’t make sure that they have enough travel from their winch to do this) the jib will sit out there happily until you gybe the boat.
The counterweight on the end of the jib boom is there to counterbalance the sail and make it easier for it to swing… particularly in light air.
No, can’t use the twitcher because the Vic Class Rules say a max of 2 channels
a jib topping lift?
-Wis
_/ if it isn’t broken, don’t fix it! _
Wis,
The jib topping lift would serve the same purpose as the counterweight without adding weight over my bow correct? I think I’ve seen that this line runs from the aft end of the jib club to the same attachment as the jib halyard. Is that correct?
Larry,
Is it possible to rig a twitcher onto the arm from your sail control servo? I think that I had seen such an arrangement somewhere else. Just for my knowledge, how is a twitcher rigged?
Thanks,
Wes
The twitchers that I am familiar with are always on a dedicated servo/channel. Could you rig one on your winch servo… hmmm I suppose if you were a clever lad you could put an alternating pulse switch that was activated every time the sails were sheeted all the way OUT.
You would have a 50/50 chance each time, that your twitcher would be flipping to the correct side. If it was not correct, and flipped the jib behind the main, you could sheet in a portion and back out causing the pulse to flip the other direction.
OK, this will work… but while you are not in violation of the rules that limit you to 2 channels… you would be in violation of the “spirit of the rules” in that you were attempting to secure an advantage through a purely mechanical means. I don’t consider it an advantage… and might well cause you more problems than it is worth… mechanical things often do.
I don’t think that you would be very popular with the other fellows at the lake if you were to pursue this actually.[B)]
Wes,
You are not correct on the toppinglift. The counterweight does not do the same job as the toppinglift.
If you picture the foretriangle that consists of the jib boom, the jib stay, the jib pivot and the toppinglift. You will see that the jib pivot forms a fulcrum for the tensions of the jibstay and the toppinglift. Tension is applied to the jibstay because the mast is being pulled back (by a combination of backstay tension and sidestay tension). The tension in the jibstay tries to pull up on the front of the jib boom. The jib boom toppinlift prevents the front of the boom from going up and reacts the tension of the jib stay. If you do not have the toppinglift, the leach of the sail must carry the tension which can cause the leach to be pulled too tight and cause a bad sail shape.
The counterweight perfoms a completely different function. If you lay the boat on its side, the jib boom will want to pivot so that the front of the jib boom points up in the air. It pivots about a axis between the jib pivot and the halyard fairlead. The front of the boom wants to point up because there is more weight behind this pivot axis than in front of it. There is more sail material and more jib boom weight behind this axis. By adding a jib boom counterweight, you can balance this system so that the boom does not want to point upward anymore.
Now picture the boat back upright again. The pivot axis is angled back because the mast is behind the jib pivot. Without the jib counterweight, the heavier side of the foretriangle is going to want to “fall” as low as it can get. Because the axis is angled aft, this means that the heavy part of the jib will want to point aft (the front of the jib boom will want to point straight forward). Thus, if you do not have enough wind to hold the jib out in a wing and wing, it will “fall” back toward centerline. The jib boom counterweight balances the weight of the aft part of the sail so that the sail does not want to “fall” to centerline any longer. Thus, it takes less wind to hold it out in the wing and wing setting. It also means that you need less backwinding flow along the back side of the mainsail to push it out in the first place.
Some people even “over balance” their jib boom (add more weight than is needed to balance the foretriangle). If the boat were laying on its side, the front of the jib boom would actually want to point down because of the weight. By doing this, the jib will want to swing out to the side when the boat is upright and sailing. This can be very effective at actually causing the sail to swing out to a wing and wing. If you can picture the physics of this situation, the sail will want to wing out to windward when you head up due to the momentum of this extra mass in front of the pivot. This means that if you pull you sails to centerline as you gybe, then as you head up onto the new gybe, the sail will have a natural tendancy to wing out to windward. In practice, it never quite works that cleanly, but it does help make it easier to wing out with very little wind pressure.
I hope you can see how the counterweight does a completely different job than the toppinglift. It is important to understand how each of these items work, so that you can use them to your advantage.
Will Gorgen
wis,
i believe that the jib topping lift is used mainly to control the jib twist and has no influence when inducing a wing to wing setting<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by wismerhell
a jib topping lift?
-Wis
_/ if it isn’t broken, don’t fix it! _
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
hmmmm…not sure…but it helped me…I think I read somewhere here that it did in fact help…
-Wis
_/ if it isn’t broken, don’t fix it! _
Just a guess but I think that having more twist in the jib in effect allows the leach to bag out. This would put the leach out where it could catch the wind more and assist wing on wing. Sound logical?
Don
Don Case
Vancouver IslandThanks for all the insight guys. I have now read elsewhere as well, that the topping lift relieves some of the tension in the leach caused by the fore/jibstay tension. Relieving the leach tension allows the jib leach to open up more/ match the shape of the main leach and feed more wind into the slot… I think I maybe spending too much time reading about sailing, and not enough time just doing it!! Of course, I’ve got to finish the boat first…