I realise, David, that you are a fan of fan topped sails. (I just had to write that as I'm sure there must be a play on English in there somewhere).

The trouble is that I am lazy. Just bone idle. My understanding is that with flat sails and fanned battens you have to adjust yard hauling parrels and luff hauling parrels and maybe other pieces of string to get the shape you want and that is just too much for me. I'm happy to build the camber in when working on the kitchen table and when on the boat I simply pull it up and let it down and occasionally pull a bit at the sheet. In particular, when the wind turns nasty and the sea gets lumpy which it generally seems only to do in the dark then I do not want to have to start adjusting bits of string to adjust the shape of the rig with a torch in my teeth to see what I'm doing, just to make the boat go. No, I'm just too lazy for that.

Maybe that's another reason I like the split rig.

There is the problem that as you take reefs with a single sheet the sheet spans on the reefed battens tend to pull the bundle in more than the set panels causing twist to develop in the rig when you don't want it. A split sheet makes a better job of this situation so seems to be a complication worth using.

Sometimes it's not easy to be lazy.

Cheers, Slieve.

David Tyler wrote: I think there are two quite different scenarios, and don't see much of a middle ground between them:

1. The yard is high-peaked, so the top panels are fanned, and gain appreciable camber when they are twisted relative to the airflow. Here, sewn-in camber simply doesn't work, because the airflow is across the panels, not along them. But I'd still reduce the sewn-in camber in the more horizontally oriented panels immediately below the fanned portion of the sail, because the battens will bend in strong winds, adding camber. However, the split rig just doesn't work like this.
2. The yard is low-peaked, and there is no camber due to fanning. Here, it's not only possible but desirable to add some sewn-in camber to the top panel(s). This is the situation with a split rig, I would say (from an armchair perspective, admittedly).

Surprise, surprise, David,

but I am not with you here. When my sails are fully raised, they have little twist in them. I still sail regularly with all the leech telltales flying, as on the photo below. For best speed I generally trim until all but the top telltale keep flying. The upper one I generally keep in the “nervous flick back and forth” state. 

Only when I reef the sail, does the twist increase, but in deep-reef mode the lee topping lift keeps the twist moderate (see photo). That topping lift also appears to offload the battens, so they seems to be under less stress than when I am sailing at full load with 6-7 panels up.

As for the quality of the airflow or possible extra drag of the high-peaked top batten, I cannot tell. However, it is a fact that my boats go quite well to windward with only the three panels up, and with a bit camber in all the panels (least in the top panel). The tacking angle is a bit wider (5-10°?) than when sailing 7-up, but that must be expected when the parasitic drag from mast and superstructure plays a bigger role.

My conclusion is: Something must (for some reason) be right with those fanned tops.

Arne

 

FS sailing 7-up           .. and only 3-up

PS: I can see Slieve's argument that his clever, combined battenparrels-downhauls will keep the luffs taut, so if one is happy with a six-gear rig instead of one with seven gears, then go for it.

Yes, it's interesting that Arne is also talking around 30% area to get off a lee shore, and about the need for camber. In the MOB exercise I referred to in F8 wind the small storm jib was cut very flat, as most storm canvas is. It was extremely difficult to tack through the wind with it and when we did we lost ground to windward.  It just didn't have any drive. The small working jib we ended up with was a properly cambered sail with round and broadseam built in. I feel with the information we now have that it would be irresponsible to sail offshore without a decent camber in the storm panels.

Bermudan sailors do try to flatten their rigs in stronger winds, but you must remember how cambered their sails may be for normal sailing. The Hunter Pilot 27 we used in the Island Race to good effect had a deeply cambered main sail, and if I was told that it was over 20% camber (1/5) I would not be surprised, so to flatten that would still be quite a curved sail.

Regarding a 6 or a 7 panel sail, I used 7 on Poppy with the lower mast balance, but for the ease of shaping the jibs with more balance and wider jib chord I feel the greater height in the 6 panel sail would be advisable. I usually reefed two panels to start with as Poppy carried her area well, but also sailed so well even with reduced area. Due to some friction in the halyard set up it was easy to hoist 5 panels and the last two were harder work, so I often just used 5 panels and still got cruising performance if there was any strength in the wind. With 6 panels there's also less sailmaking to do. (Yes, I am very lazy).

I'm often asked about splitting the top panels for better performance and so far only Edward has talked me into it, but then he was not planning to be too far from shelter. I still feel that for offshore sailing where you could be caught out in a real blow I would prefer to have full length cambered panels. I'm now confident that the split panels could be built to stand up to sever conditions, but- - - -. I am not scared of the sea, but I have a deep respect it and therefore tend to be a little prudent The other point was, and you can call me lazy again, I was not sure I could design a good jib shape in the top almost triangular panel.

I see Arne reckons that having more panels which are less tall have less need for downhauls to keep the luff straight, but the split rig uses combined batten parrel/ downhauls as standard so that's not a problem. It's not often that Arnie and I don't come up with the same answer!

I hope this helps,

Cheers, Slieve.

Oh, and Arne - seven instead of six panels?

My initial thought is that fewer panels create a more surface area with even camber.  I'd think that each batten, because it forces the camber to disappear, creates a cost in lift.  At the other end of the spectrum, of course, is a balanced lug rig, in which the luff and leach are unsupported for a huge distance and suffer loss of shape, and lack the groovy reefing options of a junk.  So perhaps it's a search for the maximum lift/drag ratio and the maximum reefing choices?

Is it that you've found seven to be a magic happy trade-off of the factors above?   Here's a seven panel drawing of the same basic shape:

Slieve’s tale on testsailing in F8 is a reminder: In such conditions, Big is Beautiful when it comes to tacking to windward. As long as the crew can handle the rig, a big boat can make progress to windward and tack quite smartly, where lighter, smaller boats have to heave to or something.

I think that the junk rig has a huge advantage over most other rigs in the conditions Slieve describes: It is so easy to raise and lower a panel to see what area the boat can take. The lack of deck work and noise from a flogging headsail makes the whole situation much less scary.

My light 6.5m/750kg unballasted Frøken Sørensen demonstrated this scale effect frequently: With only me on board, F5 was a 3-panel wind, and the only time I went out in F6 or something, I found, after some wild gusts, that two panel were enough. Even then, I managed to tack, on only 6sqm sail out of 20, but the water was flat and it would have been impossible out in the open.

(To my defence; the wind was impressive  -  we ran before quite fast under bare pole, and the crew of the harbour’s leading Albin Express (Clark Kent) skipped that day’s regatta. They didn’t want to “break something”)

I have found that all my junks sail nicely to windward under only three (lightly cambered) panels. They even tack against the sometimes very awkward fjord chop. Three panels makes up about 43% of the full sail area. Even two panels (29%) panels are enough to keep us away from a lee shore. Still, the quick and dependable tacking needed for doing a MOB manoeuvre requires the third panel (depending on the boat design and authority of the rudder).

Scott is trying to settle on a sail area for his boat. How much is too much? I would rather start with the mast. The height of the mast depends on its location on the boat and its weight and windage. The fore-aft location looks very good here. The weight and windage depend on the chosen mast material. I would try to keep the weight below 3.0 or better 2.5% of the boat’s displacement. It is obvious then that a carbon or aluminium mast can be made taller than a wooden mast. With the mast issue settled, one can pile on all the sail area there is room for.

Personally I think I would divide that sail up in seven panels. Reducing the number of panels will just increase the luff and leech spans, and also the load on the remaining battens and on the sail material.

Cheers, Arne