While boat handling was our primary objective in Newport, we managed to learn much more. An important part of controlling a 470 is related to powering up and depowering the sail plan. An understanding of how to achieve proper power for given conditions is a major aspect of boat speed. With these overlapping characteristics, we are bound to become faster as we learn the various ways to control the boat so it performs better. In Newport we learned the elementary principles of rig tuning and sail control, something we will refine in the coming weeks in California before the trials. Sailing side by side with other 470 teams will be a very important part of the fine tuning… a.k.a. speed tuning.
Since there weren’t any 470 teams training with us in Niantic or Newport, we were dependent on tuning guides put out by various sail makers, enhanced by our reconnaissance work among current 470 experts. At first, the tuning guides provided us with target rake, tension and bend numbers for the different wind ranges. There were references to the common masts used by 470 sailors and some guidelines for how the mast should be stepped to yield an accurate starting point. The key people who have helped us better understand what the numbers mean and how to actually apply them while sailing include Tracy Smith, Zack Leonard, John Morgan, Skip Whyte and David Hughes.
In Niantic and for the first week in Newport, Casey and I were sailing with a Proctor Cumulus mast. We had an old suit of Toni Tio sails. We had some basic settings for light, medium and heavy conditions. We didn’t bother thinking about mast bend except whenever I used the vang we would put puller on. Our sails looked terrible, but we cared most about boat handling. We made pin changes mainly to remain safe as the wind came up. Tracy Smith helped us clarify our settings a little bit, and we put a chart on the back of the boat with the various control settings for the different wind strengths. This sufficed for our first stage of learning the 470.
When we decided to jump into the short-duration Olympic campaign, Casey and I wanted to eliminate guess work and experimentation. We found out what boat, mast, and sails most of the top 470 sailors were using and determined that to be our starting point: MacKay boat, SuperSpar M7+ mast, North Sails – Japan design. We made a big jump into the technical realm of rig tuning when we purchased 2 used SuperSpar M7+ masts and changed out the Tony Tio sails for our newest set of North sails. We transitioned into our second stage of learning at this point. Here is a run-down of what we have achieved so far. I will spare you the details of the hot parking lot, the water jug, the saw horses, the number grids, the stepping of masts, the turning of the boat on its side, the returning of the boat upright, the measuring devices, the mix of English measurements and metric, the old Loos gauges and the acquiring of the new, the tension going on, the tension coming off, the Excel spreadsheets… just know that where we are now required a process of meandering and frustrating proportions. And ironically, where we are now is essentially a very simple place.
1) Mast deflection: All 470 masts are different. After measuring our 2 SuperSpar masts’ fore and aft bend and side to side bend under controlled circumstances, we have found one to be stiffer than the other, but both to be on the bendier side of the stiffness range. We plan to retest them one more time, and also test the Proctor Cumulus before we make a final decision on which mast to use in the trials.
2) Sails: While the jib and spinnaker sail order with North is relatively simple, the main sail we order depends on the mast we plan to use. Our current North main sail (the N9-L5) has a flatter cut and tends to work better with a stiffer mast. There are two modified versions of this sail that will work better with a bendier mast (the N10-L5 and the C21-L5). We will test out both versions and make our decision at some point in September.
3) Rake: There is a magic base setting (for light wind) that all 470 sailors use. By English measurement it is 22’2” from the top black band on the mast to the top of the transom. There is a growing movement of people (it’s up to 3 people now) who don’t believe in rake beyond this starting point. What this means is that measuring rake settings when you drop pins is not important. Of course there are rake measurements to take, and they generally decrease as the mast is raked back in increasing wind velocity.
4) Tension: There is a magic tension setting to try to maintain for all wind ranges. It is probably different for every specific mast and crew combination, but the common base number is 25-26 on the forestay using a PT-1 Loos Gauge. This number is specific to the jib luff wire we use (which is a standard European deiform 2mm).
5) Bend: The amount of mast bend at a given rake and tension is controlled by a lot of variables: fore/aft placement of the mast step, the pin setting, the spreader fore/aft position, the spreader length and the puller. Pulling the main halyard straight down from top black band to the gooseneck black band produces a straight edge. The distance from the back of the mast to the straight edge at the spreaders should be generally within the range of 45mm to 65mm depending on sea state and wind strength. We learned a couple of tricks to manipulate the bend of the mast. Depending on which trick we employ, we can affect where the bend is greater on the mast from top to bottom. For example, we can pull the mast step back in light air to produce a general increase in overall bend to flatten the sail; we can put the spreaders forward or back to induce bend or straighten the middle of the mast; we can put puller on to reduce lower bend. And we can use a combination of these controls to produce a desired result in the mainsail shape. What shape we want depends on the conditions we face.
Warning! The technical set up, all of the numbers (of which I have only presented a few), can be overwhelming. And we did at times become overwhelmed. What is most important to remember is what all these numbers really mean when applied to a sailing 470… The main two things they means are sail shape and feel, the former being an influence on the latter.
A balanced boat produces a balanced helm, and the boat goes straight. A boat not in balance will fight the skippers hand on the helm as he tries to keep the boat going straight. Try to isolate your sense of touch to detect the forces on the helm without distraction. Another aspect of feel is the obvious feeling of going faster. The more time Casey and I spend in the 470, the more sensitive our sense of feel becomes. We are now guided by a general rule of thumb regarding rake. As the wind increases, we rake back when we feel the boat is bound up and hard to muscle flat and move forward. For every ½ pin hole down we go, we move our spreaders forward to maintain our desired bend for the conditions. We also increase puller as the vang comes on harder so that we don’t produce too much bend down low. Puller is a feel thing too. If the chop kicks up or waves build with the wind, we can feel the need for power through the waves and puller gives it to us. Spreader changes and puller are still a bit elusive to us at this point. I think that once we have the trials mast and sails decided on, then sail shape will guide us in using them properly.
Sail shape is something we are also starting to understand more. Both John Morgan and Skip Whyte taught us how to read the wrinkles in the mainsail in combination with how the boat feels through the helm. We now can see when there is too much or too little bend and apply that to our trim for optimal boat feel.
