Tuesday, 4 October 2011

Laser Clinic

Laser Clinic Notes
General Racing Tips
Steve Bourdow
These clinic notes were sent out on the Laser list service.
Note, they are not the property of the Iowa Sailing Club

MADISON, WIS, MAY 24-25 2006


What is he doing at:

20 minutes before the start: Sailing upwind. Get used to the conditions. Formulate an overall game plan for the first beat (which side to go, shifts, current, etc.)

10 min: Get the gun. Get the favored end of the line. He doesn't use a compass. Head to wind, stays there for a while with the boom gracing his head. Use the front end of the copkit to determine line at 90 from rumbline. Compares this line with the starting line to determine favored end. It is important to make sure that you are on the line when doing this. To do this, squad in the center of the cockpit, point the bow at the pin and look under your legs to see where the committee boat is (It is easier to look 180 in the other direction this way than by turning your head). In all, checking for the favored side is inaccurate (no matter what method it is used), so do it several times.

Next, takes landsights to get a reference on how close to the starting line is during the final approach. For better accuracy, one should use a landsight at the opposite end of the side of the starting line where one starts (i.e use the pin if you are starting closer to the RC). Unfortunately, landsights off the committee boat are often difficult to take, because of its size. A landsight taken at 9 min before the start is useful 70 % of the time (the other times the view is blocked by other boats).

Drift under the line for about 2 boatlengths and get a second landsight (** I think he meant "get a landsight for 2 boatlentgths"**). This is often more useful than the "on the line" landsight, since you are likely to loose sight of it very early in the final approach to the line (other boats will block it). Be careful with these "off the line landsights" , because they depend on how where you are on the starting line (i.e. how close to the pin or the committee boat). When starting at a different spot that the one you took your landsights from you must take into account the fact that the landsight will represent a different distance from the starting line. For example, if you are by the committee boat and take a landsight using the pin by drifting 6 boatlengths down the line, this same landsight will only represent 3 boatlengths if you start at the middle of the line. Once he has the landsight, he drifts down about 5 boatlengths and approaches the starting line at about 75% of full speed, while looking at the landsight. This is to get the feel on how fast the landsight moves with respect to the pin or the RC.

Check the favored end again. He tries to get a feel on how good the RC is and how attentive to windshifts they are. A sloppy RC tends to try to get away with a biased line and that usually results in multiple general recalls and black flags.

6.5-5 min: tuning and tactics (on what to do during the first minute after the start, the big game plan is already decided). Where do you want to go immediately after the start?
Get the landsights on the laylines leading to the pin and RC. This is very important in pin-favored starts, but it can also help build confidence in boat-favored starts (i.e. you are neither barging nor being too far to leeward). Make sure to drift and luff for a while and take this into account in your landsights for the layline.

5 min.: get/check the gun.
Go back to check the favored end of the starting line. By now the RC cannot change it. Also re-check land sights to see if they have changed.

3 min.: final tune for acceleration. Simulate a start: begin with the boat
almost at a full stop and get it to full speed as fast as possible. Get the time it takes to get to full speed. The only control that it is adjusted in this tuning is the vang. It is desirable to have it slightly looser than usual.

Final approach: The final 20 sec are essential. Boathandling takes over everything else. It is very important to keep control of the boat, keep enough steerage way although you might want to minimize it if you are too close to the line. Be very weary of excessive vang tension in the pre-start period. In heavy wind, do not power vang. Keeping the vang too tight closes the leach even if the mainsheet is loose and this will make you slide backwards and sideways when you just try to slow down. Also, if it is windy and you have to bail out by jibing, you are much more likely to have break down if the vang is tight.

Steering during the final approach is mostly sculling. In Steve's opinion this is legal as long as the tiller doesn't cross the center line. When the speed is too low and one is about to lose control (steerage), the sculling is to be done with the tiller to windward, turning the bow away from the wind. Most of the time one has to keep the bow from falling off the wind by sculling with the tiller to leeward. This can be done together with a slight trim of the sail (** I suppose you would do that to keep your bow ahead of that of a windward boat and preventing him from building up a hole**).
If you loose control, grab the boom with the hand,bring it to weather and release it immediately while sculling the bow down with the tiller to windward. The boat will slide down in the process.
Keep the slack out of the mainsheet. This way, you will be ready to accelerate or trim to head up the boat. Conversely, if you want/need to lee-bow someone, choose a boat with a loose mainsheet. They are vulnerable.
Also, avoid positioning yourself at 90 degrees of the wind and with a loose mainsheet. It is a very vulnerable position and difficult to correct (** I assume that there are two problems: 1 it will eat up a lot of space to leeward to get back to close hauled, especially if you have to build up steerage way, 2 If someone lee bows you on close hauled you will have to turn a lot in a very tight space and it will take lots of sculling and lots of time **).

In very light winds it is possible to drift to windward by backwinding the sail and skulling with the tiller to windward. Useful to steal a hole.

Within the last minute, you must open a hole to leeward. You will use it just before the start to accelerate. Don't try to do it to early (50 sec is too early), especially if there are "sharks" (port tackers) ready to eat up your hole. Turn your boat down if someone is trying to steal it (** I suppose you have to release mainsheet at the same time if you don't want to accelerate too early **).

25 - 20-15 sec (depending on conditions): Work hole, skull up and then "build potential" by:
1 turning the boat down (at about 15 sec before the start)
trim and let the boat heel
3 hike it down to accelerate.

Don't try to accelerate without having turned the bow down (below close hauled)
You need to get flow on the foils to have them generate lift, and the fastest
this is achieved the better. If you stay on close hauled and simply try to accelerate, you will sideslip a lot because it will take a long time for the foils to generate lift.
Even if you have a boat close to leeward, don't be afraid of waiting for him/her to bear off into his/her hole before you bear off into the space that this will create. Even if he/she is late in doing so, it is usually far better than trying to accelerate without bearing off and sideslipping behind his transom.

Remember that in pin-favored starts, the hole to leeward is even more important than when the line is square. Also, it will take you longer to cross the line on starboard tack). Conversely, in boat-favored starts, one reaches the line sooner and a good time-on-distance is critical.

Finally, don't be afraid of bailing out. For example, in pin favored starts, it is better to recognize soon that you are not fetching the mark and bail out to port instead of getting into a mess at the pin and hitting it. In this situation there are two bailout approaches:
1 slide down and tack into the space
that you have generated
2 jibe (not in heavy air).


Unlike many other boats Lasers have a rotating mast without sidestays. Many of the sail trim peculiarities of the Laser are due to this fact. The first peculiarity is the sail shape: it lays out flat (as opposed to having a built-in chamber/draft (**correct word??**) like in most boats). It has a very accentuated luff curve, whereas the mast has no pre-bend. The mast bend is the main factor in determining the sail fullness. The more bend one puts in the mast, the flatter the sail. Never sail with the mast straight.

There are two ways of applying mast bend when going upwind: with sheet tension or with vang tension. The sheet pulls directly from the top of the mast and bends mostly the top section. This flattens the higher part of the sail. When the sheet is tensioned without any vang or cunningham, wrinkles appear starting at the luff and going down at an angle (about 45 ). They are more dense at the higher part of the sail where the stress is strongest. A huge wrinkle also appears going from the junction between upper and lower section to the clew, but the sail is pretty much free of wrinkles from there to the tack, which indicates no stress due to mainsheet tension along the bottom section.
This large and undesirable wrinkle can be minimized by taping the joint between top and bottom section so that the transition is a smooth bend instead of a V shaped one. It is best to apply the tape so that the top section leans forward, i.e. put tape at the front end of the bottom section and at the aft end of the top section.

To keep the main fully powered, tension the vang slightly once the mainsheet is set. This way when a puff hits and the sheet is eased, the boom will go out instead of going up.
Stronger tension on the vang makes the boom push against the bottom section and bends both the top and bottom section. This flattens (depowers) the sail. Steve uses a 6 to 1 system on the vang, with a single (** unsure about this**) bowline loop. He emphasized how important it is to minimize friction in the vang system, and pointed out that some of the higher purchase systems (like the 12:1 used in the demo boat) where actually worse than the 6:1 he used due to friction. There are several purchase systems that work and he advised to keep an eye open for innovations. As for the technique to pull on the vang, use your body weight and keep the arm straight, rather than trying to do it with your arm.
Put marks on the vang so that you can set it . This is very useful when setting the sail for the reach/run when approaching the windward mark. Off the wind, it is better to err on the loose side with the vang tension. An overtight vang creates a tight leech and an underpowered sail. A vang that is too loose results in a sail with too much twist and will have to be overtrimmed to prevent it from luffing. Its leech is fluffy and spills air. A correct vang tension will create a "bouncy" leech.
Changing gears consists mainly in adjusting the vang . Steve changes its vang setting about 15 times in a beat of a major regatta course. To do this it is important to have the vang line handy when needed. Make sure it is the right length, it has a double line bowline (to be easy on your hand) and is on the windward side. Throw the vang line to leeward before every tack. It will first fall in the water, but the water itself will put it on the deck.

Remember to keep the vang looser than normal for the start (see section on starting).

Steve always puts some cunningham. Besides the well known effect of the cunningham (moving the draft forward), it also "cleans up" the sail, i.e . removes the wrinkles referred in the paragraphs above. It is important to tension the cunningham before the vang so that the vertical tension on the luff transfers all the way to the top of the sail. If the mast is bent, friction will prevent this. Take this into account when setting the sail before the leeward mark rounding.
The cunningham should be loose when sailing off the wind.

Steve (180 lbs) admits that there are other "schools of thought" with regard to the cunningham. For example, Mark Brink (200 lbs) never puts his on unless he is overpowered.

Steve also recommends the typical outhaul system with purchase and the outhaul line looping around the mast. Make the front purchase knot very small so that friction will keep the line taut and prevent it from falling.


The purpose of this section is twofold:
1 be able to tune better/go faster;
2 avoid breakdowns.

a) Boom and traveler:
First, note that purchase systems in the traveler are not legal. In fact they are not necessary. A high "natural purchase" can be obtained by making the loop in the traveler line as small as possible.
There is a design flaw in the boom and traveler system. The aft block of the boom is on top of the traveler only when the boom is in the middle. This makes it difficult for the traveler blocks to get all the way to leeward because they are are forced to stay over the traveler (which forms a straight line) while being pulled by the aft boom block, which describes an arc centered at the mast. This can be cured by bringing the traveler under the path of the boom block at its two ends, instead of doing it at a single point in the middle. (** Technically speaking, you don't want the line defined by the traveler to be tangent to the arc that the boom block describes, instead you want it to be a secant to this arc, i.e intersecting at two points . In absence of other forces, the traveler blocks tend to go to these points when the sheet is taut **).
This can be accomplished by doing two things:
1 - Make the loop with the traveler line so that the traveler blocks are ahead of the fairleads, and the bowline knot is aft (when there is no traveler tension). This is the opposite of what is normally done.
2 - Move the eyestrap of the boom block aft (class rules allow this, within certain margins). See section on thru-bolting later.

The boom plastic cap by the gooseneck wears out very fast. Don't try to take it out, instead (*** help!!!, I missed this***).

b) Thru-bolting:
All fittings in the spars are mounted with rivets at the
factory. These work well when they have to stand shear (force tangent to the surface they are applied to), but they fail easily when they have to hold to tension (force perpendicular to the surface). It is very important to thru bolt the latter type, which includes the eyestraps for the boom blocks, vang (** check nomenclature **) and the gooseneck. Except for the aft bolt of the aft boom block, none of the bolts is supposed to go all the way thru the spar.
To put these bolts remove one of the caps of the spar to be fixed. Get a long piece of thread and at one end tie something heavy that will fit thru the hole where the bolt has to go. Put the spar vertical, pass the thread thru the hole and use the weight at the end to bring it all the way to the edge of the spar. Tape the bolt to the end and pull it to the hole and pass its thread thru the hole. Then get a regular bolt (not a lock bolt) and thread it in. To tighten it use a vice script to hold the bolt (it has to be longer than strictly needed), then saw the extra length of thread. If you were to use a lock bolt, you would never be able to remove it after sawing the screw.
As mentioned above, the aft bolt of the aft boom block eyestrap goes all the way thru the boom, thru the aft hole of the boom block eyestrap in the lower part of the boom and thru the front hole of the outhaul fairlead at the top of the boom.
Always use stainless steel nuts, bolts and rivets; and always use an inhibitor sold at marine stores) to prevent electrolysis.

The gooseneck only needs one of the rivets to be substituted by a bolt on each side. Replace the top two rivets by bolts in the vang eyestrap.

Also, thru-bolt all blocks. The top traveler block is difficult to do because the pin rotates when trying to drill it out.

The hiking strap also needs to be thru-bolted. If you want, substitute only one of the screws by a bolt (the one closer to the inspection port is easier to replace). Make sure you impregnate the thread with silicone sealant before putting it in.

c) Tricks to keep the board from coming up:
1 - replace the rubber holder often
(they are cheap, buy a bunch at a time)
2 - Apply a line of silicone sealant
around the centerboard trunk (doesn't matter where in the trunk), so that the centerboard will stick to it. Don't overdo it. Changing the shape of the centerboard trunk is illegal.

d) How to deal with bent top sections if you can't afford a new one?
Always rig
your boat with the tip of the top section leaning forward. The action of the sail bending the mast (with the mainsheet and vang acting as described in the
section about tuning) will straighten it in most cases. If it doesn't, take the caps off the tips and reverse them, so that the top section will be used upside down from then on.

e) Bottom sections:
they can also be inverted following the procedure above.
You might want to do that if the holes for the vang eyestrap have been redrilled several times and are no longer usable. Fill the old holes by popping rivets in them. It is illegal to keep them open (this is to prevent people from playing with the mast stiffness by drilling holes in them).

Also make sure that the gooseneck pin is tight.

f) Tiller and rudder:
It is important to minimize friction in the tiller to be
able to feel the helm. Avoid having the rudder tie down rubbing on the stern. Also, build a roller with PVC tubing to minimize the effect of traveler friction. To do this, get a PVC tube of inside diameter close to the tiller diameter, cut two small pieces so that you can put them fore and aft of the roller, attached to the tiller to prevent the roller from sliding along it.

It is very important to set the rudder as low as possible (78 is the maximum, as shown in the ILCA rulebook). This is so important that Steve uses a bolt with an hex head and tightens it hard so that the rudder gets locked in place.

g) Blades:
Blades will wrap if left under weight or in certain positions under
high heat and humidity. The trunk of car with the blades under all the sailing gear is a perfect example. Try to avoid leaving the blades it hot and humid places and place them with the weight along the front edge of the blade. If a foil does get wrapped, get it hot with a wet towel and an iron. You will have to be patient and keep adding water to the towel (**check**). Once it is hot, manipulate it gently with your fingers.

Blades also need to be faired to perform well, specially if they hum when going at high speeds. Start by spraying the blade with paint of a different color that the one of the blade (**any other requirements as to the type of paint??**) Then sand it with a block and 280-220 sandpaper. The low spots will be easy to see because they will keep the paint until they are fair. Once the blade is fair, make the surface smooth by sanding it with a 400-600 paper without using a block. Then paint it.

Steve likes to sharpen the trailing end of his blades. This makes them fragile.

It is a good idea to mark the centerboard, just as you would do with lines.

h) Bailer: When installing it, seal the edge with a line of silicone sealant either on the bailer or on the hull). This will improve suction, and will make the bailer work even at low speeds. In heavy weather there is always the problem of kicking the bailer shut when you want it permanently open. To prevent this, take the rubber off and jam it under the grabrail.

i) Hiking strap:
Needs to be thru-bolted (see section on thru-bolting above).
It is important that the strap itself doesn't roll up. If you have a standard strap, have the seams reinforced (** or put extra seams?**) by a sailmaker or someone with a heavy duty sawing machine. Padded straps are good, i.e. they don't roll up but the padding is not necessary if you use hiking boots.
It is very important to have an adjustable hiking strap system. Several systems
work, but Steve prefers the one that relies on the line pinching itself rather than on friction. Make sure that the strap itself is short enough to allow maximum adjustment range.
Also, use a piece of shock cord looped between the aft end of the strap and the traveler cleat to keep the strap high when you are not using it (such as in the middle of a tack) and make it easy to slip your feet under when you need to hike.

When hiking, you have to lock your legs between the hiking strap and the inner edge of the copkit. The further out you hike, the harder it will be.

j) Outhaul:
The typical outhaul system with purchase
and the outhaul line looping around the mast is recommended. Make the front purchase knot very small so that friction will keep the line taut and prevent it from falling.

k) Leaks:
It is very important to seal the boat. This will eliminate one
variable if you find yourself being slow on the race course. There are several places where a boat can leak. The amount of water the boat takes can give clue on where the leak is. If it leaks a lot, the leak is provably in the centerboard trunk, the bailer hole or somewhere else under the waterline. A small leak can be due to defects above the waterline: inspection ports, grabrails, (** mast step??**), etc.
To find a leak, place a small piece of tape under the vent hole in the forward wall of the cockpit. Put very soapy water over all possible leak spots and blow air into the hull thru the drain hole. Bubbles will form at the leak spots.
For small leaks, you can blow with the mouth. Large leaks need the exhaust of a vacuum cleaner. Be careful not to blow too much air into the hull, since this can crack the joint between the upper and lower hull sections. If you use a vacuum cleaner, allow some air to escape in the path between the vacuum exhaust and the drain hole.

Most of the leaks are straightforward to fix with silicone sealant. The bailer hole and mast step require special attention.

l) Mast step reinforcement:
If the mast step has been leaking, it might be weak.
Mast step failure while sailing results in major damage, so don't overlook this point.
To hold the mast in place, there is a wooden piece on the lower hull section. The mast step tube in upper deck section comes onto this piece and is attached with an adhesive paste. This paste degrades with water, and it will fail if the mast step leaks for a period of time. If this happens, the mast will fall and will break the deck.
To avoid this, cut two inspection ports at each side of the mast step and chisel out the adhesive material. Then replace it with fiberglass.

m) Cordage:
Use 1/4 Yale light for mainsheet, 3/16 Marlow pre-stretch for
traveler, vang and outhaul. Any smooth line will work for cunningham.


*) Find the line drill: The drill consisted in setting a very long line and having people sail thru the middle of it and raise their hand once they were on the line.
People got the hang of it after a while. They started with the "on the line" landsight and after a few times were raising their hand when their bodies were on the line and the bows were over. This was solved by drifting down a couple of boatlengths at the boat end, then getting a landsight and raising the hand on it when starting at the middle of the line.

*) Two- minute starts: This was a series of consecutive starts with a two minute countdown sequence. The starting whistle for a start was the two minute signal for the next one.
On pin favored starts, make sure you get on the line (or very close to it) with enough anticipation. It takes a long time to reach the line. On boat favored starts be careful with your time-on distance. People who on the final minute spent a lot of time in the verge of loosing control , i.e. they kept the bows very close to the wind and where most of the time sculling to bring them down, ended up sidesliping more than those that kept them slightly lower but alternated between sculling up and sculling down.

*) Reach start: In this drill we started on a reach, went to a jibe mark and finished upwind. Our goal was to round (legally) next to the mark, no matter what. This might take a lot of thinking ahead, specially if there are many boats.
Talk to the other boats way ahead of the two boatlengths circle. You might be in a position (being ahead and clear astern or having an inside overlap) where an acknowledgement of your situation by the other boat will lay the onus on his her. If nothing else it will prevent getting into a big mess and loosing many positions.
Whenever possible, try to think how tight the mainsheet has to be at the second reach and try to come out of the jibe with the right amount of sheet tension.
On a reach don't go low unless you don't have boats immediately behind you.

*) Leeward start: we started downwind, rounded a leeward mark and finished upwind. The goal is the same as in the previous drill, but the consequences of rounding outside are much more severe. In this drill, slowing down the boat to give time to the boats inside to round is very difficult. Thinking ahead is even more important than before. The course was short and when the starboard end of the line was favored, it was difficult to decide whether it was worth starting there and running the risk of getting stuck outside of a pinwheel.

*) Jibing: It is very important not to rush the jibe. Trim the sail in before the jibe. This reduces the angle that one has to turn to get the sail across. Roll the boat to the old windward and pull the sail across. Make sure that when you roll the boat back up you have the sail full and trimmed in so that you can roll against it". Don't bear off until you have built up some speed. Steve does the hand exchange squadding down in the copckit in the middle of the roll.

Juan O'Callaghan

Last updated on Sunday, November 12, 2006 22:00:20
home: www.uiowa.edu/~sail/

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