When communicating with your North Sails sail consultant about your sail's flying shape, a picture says a thousand words. Using a photo of your sail, a North sails consultant can make a quick visual assessment of the sail, but the photo can also be put through a more rigorous analysis using North Sails' proprietary SailScan™ software.
SailScan digitally analyzes photos of sails, providing fast and accurate measurements of critical sail shape characteristics such as chord depth, draft position, entry and exit angles, and twist. If your sail was made by North, your consultant can digitally compare your current sail's flying shape with the sail's original designed shape (mold).
Sailscan then compares the current flying shape of the sail with its original design files and quantifies the amount and location of any changes in shape.
From there, your consultant can recommend the best way to maintain your sail's peak performance over a longer period of time, whether it involves trim adjustments, rig adjustments or recutting the sail.
Digital images can be sent by e-mail to your North Sails sail consultant. Photographic prints are also usable for SailScan analysis.
Tips on photographing your sails
Mains and genoas are designed to be upwind sails. To capture the designed shape of the sails, your pictures must be taken while sailing upwind. Upwind performance is the result of the interaction of the two sails, so pictures of the main must be taken with a genoa flying in front of it, and vice versa.
35mm SLR cameras give the best results, but you may not want to risk exposing your expensive equipment to a marine environment, especially when down by the leeward lifelines in 18 knots of true wind. Disposable cameras are inexpensive and convenient, however they often have narrower fields of vision and can produce some image distortion.
Pick conditions that are within the designed wind range of the sail being photographed. A sail will experience exaggerated distortion in wind strengths beyond its designed range.
Start by sailing upwind, setting up the sail controls and trimming the sail as you would for maximum upwind performance in the current conditions. It is helpful to note wind conditions and sail control settings, as these will provide points of reference later. In particular, make a note of backstay tension, halyard tension, and other primary controls that affect sail shape.
Position the camera at the mid-foot of the sail. In most North sails, the 50 percent point on the foot is marked with a hash mark or a camera icon. For the main, the camera person is situated next to the boom at the midpoint. For the headsail, the camera person will be lying down on the foredeck, with his or her head at the midpoint.
Most North racing sails come with draft stripes at the top, middle and bottom of the sail. You want to capture all three draft stripes in their entirety in your picture. To fit the bottom draft stripe in the picture you may need to angle the camera on a diagonal (see example).
If you cannot fit the bottom draft stripe entirely within the frame, aim to capture as much as you can, starting with the luff.
A short countdown from the photographer will allow the helmsman to bear off three or four degrees from the optimum upwind course to ensure that the sail is fully pressurized.
Another camera angle you may want to consider when taking pictures of your genoa is from the leeward corner of the transom, aiming up at the middle of the sail. This shot from should be taken in the same conditions and with the same sail settings as the photos taken aiming up from the midfoot of the sail. Aim to get as much of the sail in as you can. This angle will capture the vertical profile of the sail, and show how close to the rig the sail is flying.
Most photo developers are now able to provide you with digital copies of your pictures, either on disk or delivered to you via email or over the Web. Digital images have two advantages: they can be sent to your North Sails consultant easily and quickly via email, and they are readily analyzed by North's SailScan software.
Capturing sail shape in a photograph takes some practice, but with the right equipment, proper set-up of the boat and sails, the correct camera angle, and careful note taking, you can gather quite valuable data.