Thread: White sails

howdy, 200gsm (6oz) is a bit heavy and might be a bit unresponsive in light winds. But it is so cheap .. who cares!

Around 130gsm (4oz) is about right for small boats like this.

Make every effort to get the centre of the sail in the right place relative to the centreboard or leeboard ... as this is crucial for sailing performance.

Best wishes
Michael.

Mik raises a good point about placing the sail in the right location. I find the best placement is aligned over the leading edge of a daggerboard. On centerboards and leeboards, just aft of the leading edge is preferred. Fortunately the CB (Center of Butt) on small craft, can be moved around to help trim issues.

I would agree with PAR ... mid point of the underwater section of the leading edge. For smaller boats like a PDR I would probably move it back a little ... maybe 100mm to play it safe. (oh ... smaller boats I use about 100mm, GIS size about 125 with increasing amounts with size. It also depends on the flexibility of the spars ... if they are flexible the rig moves back with mainsheet tension. So this amount is about right for the spars I design.

It is OK for the centre of the sail to be a little back from optimum but terrible if it is forward of of the optimum ... so I usually hedge a little. Lug and junk sails (though a junk rig without sheetlets is really a balance lug with an oriental outline - I do like the look of them too!) can be moved a bit (a bit) relative to the mast anyhow ... so some refinement can take place.

MIK

So what feel do I need to look for if the sail is a bit to far forward or back? I went out a week ago in quite strong wind and it felt unresponsive and I was having trouble tacking to port but was ok to starboard, it was also more prone to bogging (? ) in at the front, so I have done some maintenance and re grometed the sail with s/s gromets as the old one were rusting and retentioned the sail back on to the yard and boom. I think the sail had moved forward so I adjusted until the luff was 400mm in front of the mast ( was about 450-500) the next sailing day was much better but I noticed that at all points of tension the leech is ruffling in the wind. I'm guessing that the polytarp has streached a funny shape, does this reduces the efficiency of the sail a lot? I have the balanced lug on my ozracer

Plus thanks for the insiration Mik

If your sail looks similar to this you should be close. This photo was taken while sailing in heavy wind, in lighter wind I would have the tack pulled back 50 to 75 mm.

What you want is a balanced helm while sailing close hauled. On larger boats you can judge by feel but with the Puddle Duck I have to look at the tiller to see if it's centered. If the tiller is angled toward weather (upwind) you have weather helm, moving the sail forward should balance the helm. If the tiller is angled to leeward (downwind) you have lee helm, moving the sail aft should balance the helm.

When checking helm balance you should be sailing close hauled on both tacks. The best way to check that is with a compass. Sail what you think is a close hauled course on one tack and note the heading then tack to the other side and note the heading. If there's a 90 degree difference in the two headings you're doing well. If the difference is more than 90 degrees fiddling with sail trim, boom angle, hull trim, etc. will eventually get you there.

Don't expect to get all that figured out on your first outing, I think it was during my third time out that I got things working well and after sailing the boat two years it's still not always perfect.

Some tacking problems are due to bad technique. Watching Youtube videos can help some with that. This one is decent [ame=http://www.youtube.com/watch?v=JZAPz9BCqJM]Tacking - Start Sailing with Olympic Medalist, Shirley Robertson, - YouTube[/ame]

Hi, thanks for the replies, I think I have not been keeping the sail close hauled enough, I do get plenty of flex in my yard and boom, so next time out I will take a compass and check. Do you adjust the tack while sailing and how?

Originally Posted by ozsmithy

Hi, thanks for the replies, I think I have not been keeping the sail close hauled enough, I do get plenty of flex in my yard and boom, so next time out I will take a compass and check. Do you adjust the tack while sailing and how?

While going upwind I usually sheet in to where the boom is at the transom corner, then when the boat has good speed I sheet in to where the boom is at the inside corner of the deck.

When the wind is light, less than 5, my boat develops slight lee helm so I pull the tack back a couple inches while rigging the boat on shore. I also have a line running from the mast to the tack end of the boom, I've found that on my boat the sail rotates around the halyard attach point when sheeted in hard causing the boom to go forward.

In your photo it does look like the leech of your sail may be stretched, it also looks like you may have too much tension in the foot.

Rather then sailing with the boom over a particular portion of the boat, sail to your tell tails. If you don't have tell tails buy a pack and install them according to the instructions. Read and study the "cheat sheet" that comes with them. You'll learn more about sail trim from this little hunk of paper then anything else.

With the tells installed, head up wind and sheet in until the tells are streaming aft on both sides of the sail, regardless of where the boom is. On most boats, you'll want to ease out the sheet just a touch, until the windward tell is just barely starting to dance. This is the "groove" and you'll learn to find it every time you adjust your sails.

Hi Par, thanks for the feedback, I have been using my reef ties as teltails but after watching the vidio's sugest by BradLH had decided to improve my system with teltail's, the one I dont get is when pointing to wind I would think the pivot of the sheet should be the center of the boat but that is aparently wrong the closest hauled I can get mine is just off the side my boat due to the slider for the sheet block?

Tell tails are used to optimize the sails angle of attack relative to the wind. With my PDR I've found that optimizing the sail angle of attack, relative to the wind, with the boom somewhere between the transom corner and the inside corner of the deck gives me the best VMG while going to weather.

I've had tell tails several places on my balance lug sail but never could get the one on the mast side of the sail to work well. I now use leech streamers and a Laser style mast mount wind indicator. When close hauled the boat works well when the boom angle is about five degrees lower than the wind indicator angle. When sailing off the wind I trim the sail using the leech streamers.

I have a bridle at the transom for my main sheet then have it running along the boom to a block at mid boom. In light wind I let the block on the bridle run free and in moderate to heavy air I tie stopper knots in the bridle that will stop the block at a point where the sheet is nearly vertical when the boom is over the inside corner of the deck. Having the mainsheet vertical at the bridle increases tension in the leech and reduces twist in the sail.

I have limited experience with lug rigs, but I would suspect they should respond like that of a jib, if placed about 200 - 250 mm aft of the leading edge. I've seen tells on one of Ross Lillistone's designs acting precisely as they should. If your windward tells are dancing (more then barely fluttering), you need to foot off or ease.

The mast does confuse the flow, but it reattaches quickly. Generally I have found looking at the luff the best indication.

Leech ribbons about 6 x 3/4" (150 x 20mm) are great too ... three dividing the leach into four equal sections.

Luffing tells you if undersheeting or pointing to high ... leach ribbons should flow upwind and crosswind disappear behind the sail about 5% of the time or you need to ease the sail or point up higher.

Best wishes
Michael