Telltales on a Weekender mainsail

[umop_apisdn]

Should they be near the luff or the leech?

At what height?

Thanks,

Noel

[JTam]

Noel,

Tailtales on the leech of the mainsail for a marconi rig. Not sure about a gaff rig. I plan to put three on my main's leech. Placement, it is suggested that the upper tailtale be placed 15-25% of the leech's length from the top (e.g. 15 foot leech, set first tailtale about 3 feet from the top).

Use the same 15-25% for the bottom tailtale. The mid - tailtale splits the distance between the top and bottom tailtales.

The attached URL has some good rule of thumb:

Jtam'>http://www.wb-sails.fi/news/95_11_Tellingtales/Tellingtales.html

Jtam

[umop_apisdn]

hmm... my post ended up in the great bit-bucket in the sky.

So once again....

I've read a number of web sites on how to use telltales on your mainsail, and each one leaves me more confused. Some say put telltales on the luff, to aid in steering while headed into the wind. Others say those telltales are not useful because of turbulence from the mast.

Some say put telltales on the leech to assist in sail trim, to determine the right amount of sail twist. But gaff rigged sails always have a lot of twist in them, so is that still applicable?

So how exactly are telltales best used on a gaff rigged mainsail?

Thanks,

Noel

[Barry Pyeatt]

Placement of telltails on sails varies considerably for use and purpose. Different types of boats and sails most often require different placement of telltails on sails.

On the three Weekenders that I've sailed on with tell tails all had different placements and different purposes.

I'm of the opinion that the best use of them is in working upwind and helping to prevent over sheeting of the main, hence actually inducing too much heel and actually slowing the boat down from an "optimal" trim.

Ideally we would want the jib to be providing maximum lift and airflow off of it to help provide more lift to the mainsail. I want pulling power or pushing power to trim efficiently for both upwind/crosswind and down wind performance. This is going to vary considerably with wind speed, direction and relative course settings in addition to trimming and mainsheet pressure.

A single tell tail at 1/4 of the way down from the top of the leech of the standard jib or lapper and another 1/2 way down will help to see even air flow over the leech of the jib. You would trim for most even air flow off of the leech of the sail using these two telltails. If the top one is fluttering and waving about and the lower one is streaming evenly they leech is too loose and should be trimmed a bit tighter. If the other way around the clew is too far outboard and should be trimmed in a bit. Ideally you would find both of these streaming evenly directly back from the leech edge of the sail.

Placement of telltails on the mainsail varies considerably. In my opinion again, I would want to see evenly balanced airflow over the leading edge of the mainsail with even pressure flowing along windward and leeward sides of the sail near the upper edge near the throat. Placing the telltails on the leech will not show this. They need to be about 12-16 inches back from the luff. When the air flows over the mast and luff edge of the main a bubble of sorts forms on one side or the other depending upon how the main is trimmed out and how heavily it is sheeted. Twist doesn't have much to do with this. What I want to see is that neither tell tail is stalling. I trim so that the airflow is causing both sides to stream evenly. If the lee side telltail is fluttering or hanging or twisting about, it is caught in dead air, swirling air or air flowing back toward the luff edge after swirling about. Same with the windward side.

Over sheeting will most often cause the lee side to loose its flow and cause the sail to begin to stall. I would also add a single to the leech 1/4 of the way down from the peak and another 1/2 of the way down from the peak on the leech.

It seems to your senses that you are moving faster, but most often you will find that it only induces more heeling than is necessary and more weather helm. Letting the main sheet out until both stream evenly will create more lift to the sail working upwind and give you a more optimum airflow over the mainsail, less heeling, more actual speed and less weather helm. Also the rail will more than likely be above the water level. :wink:

Lower placement (say 3/4 of the way down) will help with seeing airflow on steering and leech trim. (Here is where seeing the effects of a vang help the most in my experience.) It will also show the effects of twist and stalling of the leech before it flutters. Similar stalling of the jib leech is indicated first on the lowest telltail most generally.

Watching both sets of tell tails on jib and main will help you to trim the jib to optimum for that heading and wind conditions and create more flow over the mainsail. "Often referred to as the Venturi Effect." Then tuning the mainsail for even flow will generally create the optimum sail trim for best speed and control.

On one boat the telltails were on the shrouds to show wind movement at the upper levels of the sails. There were also two sets of tells on leech edges of jib and main to show streaming airflow off of both sails. This helps in steering closer or a bit off of the wind better. Keeps you from pointing too high and loosing sail efficiency.

Capt. Jake has one set on his mainsail to help shape airflow over the mainsail. It helps to show optimum power being generated by the mainsail and airflow off of the lapper. Simple and effective. Trim is adjusted until both telltails stream evenly when working upwind.

Trimming is accomplished by Peak Halyard adjustment, throat tension, leech line length and main sheet tension plus steering. Most often the tendency is to try to point too high when falling off a bit will give better speed and sail trim for optimum pulling ability. The boat will sail a bit flatter and have less weather helm. It will have better tacking speed going into the tack and come out of the tack quicker and regain speed easier with less trimming changes necessary for the new heading.

A mast top wind indicator "fly" will help show true wind direction. Not entirely accurate but it helps when trying to work in light air or varying wind shifts.

Working downwind will change how they fly in many cases and often the lee side telltails will show nothing. Nor will the leech telltails. I watch for sail shape and leech flutter to balance trim on main and jib.

[Kidd]

How would this information apply to sprit boom sails? Say the kind found on my humble CS17. I Imagine the leach telltales would be of most use and should be placed to split the sails approximately into thirds?