Basic Concepts and Techniques

Moderator: GreenLake

Sailing to and from a dock

Postby GreenLake » Thu Jul 09, 2020 5:12 am

There are many situations where you can sail directly from or back to the dock. Here's the basic technique:

Sailing to and from a dock
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Sailing from the dock: When you rig your boat, you have it pointed into the wind, so that the sails don't catch the wind until you are ready. With tiller fixed, sails raised, and centerboard down, you push off the dock with a bit of forward momentum so that there's flow over CB and rudder and you can steer away from the dock (or if the wind serves, just push the bow out). Sheet in, accelerate and you are off.

Sailing back to the dock: The trick here is that you need to slow down and take the wind out of the sails as you approach the dock. You may have to do a U-turn to do it. I've shown fenders out, but the older DS1s with their rub rail may not even need that, depending on the dock (at least not right away). You set up your approach so you can coast upwind with the sails slack. With a bit of practice you'll know how far you need to coast to slow down in the conditions. You can further slow down with rapid tiller movements, or even setting the tiller at full 90 degrees, or by sticking a paddle into the water and holding it still (the same paddle, or pumping the tiller, will work if your approach fell short).

The DS doesn't need all that much space for a U turn, so this technique works often even for docks that are at the end of a sort of cul-de-sac. If you need to make a U-turn right after leaving the dock, just make sure that you have good flow over centerboard and rudder blade and that you don't stall the rudder by giving too much tiller. If you stall your foils, you'll find yourself sailing sideways when that's not your intention (same if forget to drop your CB).

Other wind directions: If the wind isn't nicely parallel to the dock, that's usually not too much of a problem, as long as the wind isn't blowing directly onto the dock. If it blows away from the dock, you may have to rig your boat with only the bow tied on so it can weathervane, and sailing back to the dock you'll approach at right angles and perhaps also tie up only the bow until the sails are down.

If the wind blows squarely onto the dock, you may be able to still sail off (especially if the dock space isn't as tight as in the diagram, so you can sail parallel to the dock for a bit). However, there's no way you can set up to coast against the wind coming in. There are techniques that work, but they require knowing how to "heave to" (a useful concept in and of itself). Or you could drop your sails a bit further out and have the wind drift you to the dock (best with a paddle handy).

Finally, if you are in a place that has multiple parallel docks, you may be able to use a line and helpers to maneuver your boat in spaces that are too tight to sail out of. (Getting into such places sometimes just requires a bit of momentum)
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Heaving to

Postby GreenLake » Thu Jul 09, 2020 3:58 pm

Heaving to is a simple and very useful technique to "park" on the water. Being able to put your boat into the hove to state is an essential skill that allows you to stop actively sailing the boat, whether to take a brief rest, or to sort something out with the rigging. It can also be used in some other situations.

The basic idea is that you adjust sails and rudder in a way that they balance: the jib is backwinded to drive the bow down and the tiller is pushed to leeward to drive the bow up. The centerboard is down and provides the common pivot for both of these opposing rotations.

Heaving to
heaving-to.gif (19.54 KiB) Viewed 17301 times

The result is a stable balance with the boat drifting slowly downwind. The main is eased, but may be sheeted in a bit to control forward reach of the boat or help with balancing the jib (if the main is engaged it will tend to turn the boat more into the wind). The drift is slow and controlled, more forward than true downwind: The boat will lie at about 60° off the wind.

Once the balance has been reached, the jib can be cleated, and the tiller lashed. The boat will remain in a stable attitude, even if the wind is gusty or oscillates. If the boat felt lively sailing upwind, you will be amazed how calm it feels when hove to. The boat will tend to itself: you can break out a snack; deal with anything you need both hands for; catch a needed breath or two; put in or take out a reef; or use the controlled drift to slowly move downwind. (The last can be useful in some circumstances: for example, in approaching a man or object overboard or in docking in a downwind direction).

How to heave to: The easiest way to heave to is to attempt a tack, but to not release the jib (so it ends up backwinded). As the boat turns, you put the tiller on the opposite side to stop and counteract the turn. You may find that it takes a bit of practice to prevent the boat from turning too far. If that happens, just release the jib and try again.

How to start sailing again: Just release the jib and sheet it in one the other side, sheet in the main and you are good.
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Controlled drift downwind

Postby GreenLake » Fri Jul 10, 2020 5:23 am

Here's how to use heaving to for controlled drift downwind.

We've seen that when you heave to the boat will drift at about 60° to the wind, that is, the wind and the drift angle will be a bit more forward than abeam. The reason that the boat doesn't simply drift downwind is that some small forward movement is required to keep the flow over both centerboard and rudder. Within some limits, you can adjust that drift angle by (slightly) sheeting in the main. Too much, and the boat will try to sail again.

Here's how you can use it to dock into a tight space when the wind is blowing towards the dock:

Docking downwind - controlled drift while hove to
docking-downwind.gif (18.32 KiB) Viewed 17297 times

You find a spot at some distance from the dock and behind the spot you are aiming for. You sail a U ending with an upwind course from which you can heave to. Once you are hove to, you'll drift at about 1kn, very controlled towards your destination. You can use the main to change the drift direction to be a bit more forward.

It looks more complicated than it is; the main thing to practice is to find the correct location to start the maneuver, so you end up where you want to be. It may be easier to turn into the wind, backwind the jib and then let out the main and fall off slowly into the hove to position (arresting the turn with counter-rudder) rather than using the technique of leaving the jib sheet cleated on the "old" side while doing a tack. That latter approach is simpler if all you want to do is heaving to, but since it adds another 90 degree turn to the boat, it can make it that much harder to predict where you'll end up.

It's worth practicing this a bit - the same technique can be used to drift downwind towards someone you want to pick up out of the water. Again, the hardest part for that exercise is selecting and hitting the spot where to heave to.

Heaving to is an essential safety technique, that's why I think it belongs in basic concepts; and in many ways it is really more basic than many other modes of sailing - for example there's little need to be fussy about sail trim, and you can safely cleat the jib and lash the tiller, no fine tuning there either.
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Light Wind Sailing

Postby GreenLake » Thu Jul 16, 2020 6:26 pm

There are a couple of principles and techniques to get the best from sailing in light and very light winds. In no particular order:

Don't rock the boat: every time you move the flow over the hull and foils changes as does the airflow over the sails. In light and very light winds, it takes a while for this flow to be reestablished. You may also cause waves and eddies and any energy carried off by them has to come from whatever little boat speed you have. Sit still.

Keep tiller and sail trim steady: for the same reason, don't touch tiller or sail trim unless necessary. Keep tiller movements small. Using a tiller tamer or a bungee rigged to hold the tiller steady will work better than holding it in your hand. There's little "feel" from the tiller anyway and taking your hands off avoids any small involuntary movements. Instead, nudge the tiller every few minutes to keep on course.

Heel boat to leeward: doing so does two things. One, gravity will now swing the boom (and the sail surface) to leeward. This helps a very weak wind to "fill" the sails. Two, you will reduce the wetted surface of the boat (hatched in the picture below).

Heeling to leeward in light winds
leeward-heel.gif (11.35 KiB) Viewed 17268 times

Reduce drag: at low boat speeds most of the drag is due to skin friction and is proportional to the surface under the waterline. At higher speeds most of the drag is due to generating a wave, and is influenced by the shape of the hull - so you want to sail the boat flat then, while at low speed, it helps to heel the boat.

Sail to the wind: when there's little wind, watch the water surface carefully for ripples (or darker patches) and, if possible, sail towards and in them, even if it means a bit of a detour. The shortest path may not be the fastest. On lakes, you may often find stronger winds near shore. (If you are out cruising and not racing, you may want to motor or paddle out of a calm spot)

Stick to your choice: it can be tempting to chase after fleeting patches of wind. Watch for areas of better wind and observe how they change. Are they stationary? Do they approach or recede? Will they still be there by the time you get there? Make your choice, but don't second guess yourself constantly - mid course changes will be slow.

Sail trim: in light winds, the wind is laminar, its speed and direction will change with height along the mast. Set your sails so they have twist. Jib fairleads back, vang off on the main, if you have a topping lift, use it to lift the boom a bit so it doesn't pull on the leech. In light winds, outhaul slack for a bit of belly in the sail, in very light winds, the sail needs to be flat again so the airflow can remain attached and doesn't separate.

Trim to the wind: when puffs alternate with calm, keep your sail trim to the expected wind, instead of trying to trim as you encounter the wind. Remember, it takes time for the airflow to establish itself. Set the course and sail trim for the direction you expect the wind from - which may not always be the direction the wind is shown at the masthead indicator! Blowing soap bubbles can be a fun way to "see" the direction of a very light wind.

Together, these techniques can get your DS moving even if it's hard to notice there is any wind at all, and you may have to watch some specks on the water to see that you are actually moving. On a day sail, this can be fun, almost meditative; in a race, it can make the difference between getting to the finish line or not in challenging conditions.
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Sailing backwards

Postby GreenLake » Sat Aug 08, 2020 8:01 pm

Sometimes you need to slow down or sail backwards. While you can always slow down with a paddle, if you are pointed into the wind, you can also use the sails. Or, if you are stuck "in irons" you can sail backwards to get out of it.

Sailing backwards
Backwards.GIF (16.28 KiB) Viewed 17041 times

The process is dead simple: instead of pulling on the boom with the mainsheet, you throw the sheet loose and push out the boom by hand. The sail will fill to the inboard side of the boom and the wind will start pushing against the boat, either slowing it down or starting to make it sail backwards.

When you've got yourself stuck in "irons", that is, pointed directly at the wind, the jib will luff and the main will weathervane out of the wind, meaning you are just going to sit there. If you stick out the main, the boat will begin to sail backwards. You can adjust the tiller so the boat sails a curve, until he bow points somewhere other than the no-go zone. At that point, you pull in the main and start sailing forward again. Note that while you are sailing backwards, to boat will go in the direction the rudder blade is pointing, and if you were to let go the tiller, the water would push the rudder to full deflection (90°) at which point it acts as a brake an is no longer effective in steering. So hold onto that tiller!

PS: don't throw out your paddle yet, you'll still need it, for example, if you want to slow down the boat when not sailing against the wind.
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Sailing Dead Downwind

Postby GreenLake » Sun Aug 09, 2020 1:33 am

When sailing downwind, especially dead downwind, the apparent wind is directly reduced by your boat speed: you are sailing away from the wind. The faster you go, the less force there is to drive your boat. At the same time, the jib in its normal position is blanketed by the main and once the wind comes from "abaft the beam" rapidly loses its effectiveness.

On a DS, because of the swept-back spreaders the shrouds are behind the mast, limiting how far forward the boom can go. With the wind hitting it broadside on, the sail operates almost exclusively as a drag device. There is no longer an attached flow that produces lift (or it is a secondary phenomenon). What matters is to get the largest surface area exposed, so we let out the mainsheet all the way and tighten the vang to force the boom down and increasing the projected sail area.

Wing on wing
Wing-on-wing.GIF (16.77 KiB) Viewed 17038 times

When sailing dead downwind (and for a few degrees on either side) the jib can be set on the opposite side of the mast, a configuration called wing-on-wing. You don't need any special hardware for it, but if you have a whisker pole you can use it to pole out the jib and hold it steady, and it will not collapse as easily if you are a few degrees off in your steering (or anytime you hit a wave).

With the jib poled out like this, the DS is noticeably faster going dead downwind than at angles that are slightly off the wind. (In the picture above) once you sail too far to starboard the jib will collapse or backwind if poled out. On the other hand, if you sail too far to port, the wind will be on the same side as the mainsail and you are sailing by the lee: you are at risk that the main will come over on its own in an uncontrolled gybe (which is hard on the rig).

You should watch your wind indicator and the sails carefully to steer your boat so it is in the middle of that window and then sailing wing-on-wing works really well. (If you don't have a pole, ask a crew to hold the jib sheet in their hand, just outward of the shrouds).

If you have a bit of warning before an unplanned gybe, you can sometimes grab the mainsheet right at the boom and try to slow down (not prevent) the transit of the boom, so it doesn't crash into the other side. If you try to prevent the main from coming over, depending on conditions you may risk a capsize. Now would be a good time to go back and look up the discussion of gybing again.

Your boat may be equipped with a spinnaker and rigging for downwind sailing or you may want to do the upgrade after gaining a bit of experience.

A spinnaker helps because it is
  1. larger than the jib and cut from lighter cloth, and
  2. set on a pole so that you can bring it out of the wind shadow of the main.
The techniques of setting, dousing and flying a spinnaker are quite different from how the other sails are operated, which makes for separate topic. In a small way, sailing wing-on-wing shares the concept of steering the boat so the sails do not collapse, something that becomes important for sailing downwind with a spinnaker.
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Re: Basic Concepts and Techniques

Postby GreenLake » Mon Aug 24, 2020 2:14 am

At the outset of these notes, I had warned that they might be presented somewhat out of order. The next post will in a sense return us to the beginning, by focusing on the five most basic controls on your boat. Motivated a bit by a recent discussion about the various original options and later refinements for the DS rigging. It’s easy to get lost in the weeds, so @tomodda thought to bring the discussion back to the basics. Following his inspiration, I’ll take a step back and summarize these five basic controls; and then perhaps discuss each of them in a bit more detail - bearing in mind how they all influence each other.
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The Five Basic Controls

Postby GreenLake » Mon Aug 24, 2020 2:23 am

These five controls are the most basic ones and every DaySailer will have them no matter what original equipment options or later refinements to the rigging are installed. Even if you have additional controls on your boat, these five are the primary ones and the ones you will normally adjust the most often. In mastering the basic concepts, it’s worth focusing on them. To various degrees, these all influence each other.

The five basic controls
Five-Basic-Controls.GIF (15.39 KiB) Viewed 16976 times

Let’s first look at how often and when each of them is put to use and then follow that up over the next few posts by a discussion of the individual controls.
  • The mainsheet is something you’ll adjust near constantly, pulling the main in when sailing upwind, letting it out in gusts, or more for reaches or all the way for running downwind.
  • The jib sheet likewise gets adjusted to the wind angle, but for example, when single-handing you may not play it as much for gusts as the main.
  • The tiller is in a sense in constant use; the trick is almost not to use it too much: large and varying deflections of the tiller will slow down the boat.
  • The centerboard gets adjusted mainly only when its raised for going downwind, or lowered again for going upwind.
  • Finally, like the tiller, your seating position constantly affects the balance of the boat, but you may only be aware of balancing the boat when hiking out during a gust to keep the boat level. That will happen quite frequently in gusty winds, but there are also other ways your seating position will affect how your boat sails. We’ll get to that when we look at balancing your boat in more detail.

The important thing not to forget is that these controls (as well as practically all the sail controls on your boat) do not act in isolation. For example, if you change the trim of main and jib, you’ll change the overall balance of the boat and you may need less or more tiller action to keep it on the same course.

Let's visit each of these in turn in upcoming posts; if not necessarily in the same order as presented here.
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The Centerboard

Postby GreenLake » Mon Aug 24, 2020 7:44 pm

The centerboard, or CB for short, is one of two underwater foils, the other being the rudder (controlled by the tiller). Together they counterbalance the sail plan. (Because they act in water, they are many times as effective per area as the sails).

There are several reasons for adjusting the CB. They all boil down to adjusting the amount of lift provided by the CB, and concurrently the amount of drag. And because the CB doesn’t lift straight up, but swings back, raising the CB also adjusts its effective fore-and-aft position.

  • Going upwind the CB is fully down. For this point of sail, any help the CB can provide in reducing leeway, or the tendency for the boat to slip sideways, is most crucial.
  • Going downwind, there should be no large forces pushing the boat sideways and the lift from the CB isn't needed. Therefore, any drag isn't offset by some useful contribution and the CB should be raised fully out of the way.
  • For a broad or beam reach, you would raise the CB part ways. About ¼ down or ½ down respectively.
  • For motoring, you might raise it almost all the way, but leaving just enough to help the boat track.
  • If you were sailing without the jib, you would adjust the CB for a different reason: by taking down the jib, the center of effort of the sail plan is now further back, as only the main contributes. To balance the boat (and to prevent excessive weather helm) you would want to move the CB aft as well: as you raise the CB slightly, it starts swinging aft, therefore shifting its effective position aft with only a small reduction in lift.
  • There are situations, such as during a gybe, or in strong, gusty winds, where the boat may experience sudden sideways forces that can be quite strong. In those cases, having the CB raised (fully or partially respectively) allows the boat to slip sideways a bit in response. With the CB fully down, on the other hand, the boat could "trip" over the CB, turning the sideways force into heeling and possibly ending in a capsize.

Centerboard with centerboard handle, shown slightly raised
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On a boat with a CB handle, like the DS1, these adjustments are straightforward and intuitive. On a boat that uses lines to control the CB, like the DSII, you may have try different adjustments at the dock or in shallow water and mark the positions on your CB line with colored sharpies or tape.

If you forget to raise the CB after turning downwind, you mostly just sail more slowly than with it raised. Conversely, if you forget to lower before turning upwind, you’ll soon notice that the boat feels strangely unresponsive: it tends to drift sideways instead of sailing where you want it to. As a raw beginner, you'd lower the CB and leave it down, while you focus on mastering the other controls.
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The Tiller

Postby GreenLake » Tue Aug 25, 2020 2:15 am

The tiller controls the rudder, the other half of the in-water foils. As a beginner, you may have to get used to the way you push the tiller in the opposite direction from where you want to go, but most people adjust to that aspect amazingly quickly. Still, a tendency may remain to think of "steering" the boat similar to the way you steer a car, or a bicycle. Unlike a car, if you let go of the tiller, or hold it at a fixed position the boat will not continue on a straight line, but sail in a curve, quite often turning into the wind. You need to adjust the tiller continuously to sail in a straight line.

A good technique when sailing near land is to look at the horizon and pick a tree or building that lines up with the forestay. You then steer a straight line by keeping the forestay aligned with that feature. When sailing upwind or dead downwind you may be more concerned with maintaining a steady angle to the wind as it shifts or oscillates - another area where a sailboat just isn't like a car or motorboat.

Somewhat similar to riding a bike without your hands on the handlebar, many things will influence the direction of a boat, and even allow you to "steer" the boat without using the tiller. If you heel the boat to one side, the immersed part of the hull is no longer symmetric and the boat will like to turn away from that side. If you tighten the main, you increase your boat's tendency to turn into the wind. To lessen that tendency, release the main, or tighten the jib.

If you sheet the jib on the wrong side, so it is backwinded, it will forcefully move the bow down, in fact, you may be able to just about balance that with a tiller, but not overcome it.

Tiller with tiller extension (controlling the rudder)
Tiller.GIF (15.48 KiB) Viewed 16971 times

If you push the tiller over all the way, or 90°, it will act like a brake. Water will no longer flow across it in an attached flow, the rudder ceases to provide lift and has become nothing more than a drag device. Actually, the rudder will stall at angles much less than that, and any visible rudder deflection will slow your boat. Like driving with a parking brake set. To avoid that, make sure your sails are trimmed so that your boat is balanced and has just a slight remaining tendency to turn into the wind: that rudder action needed to counteract that is called weather helm. A small bit of weather helm gives you positive feedback (and helps the centerboard to achieve the correct angle of attack for optimal lift).

When you turn, the DS will pivot around its middle, where the CB is located. If you make a tight turn, bow and stern may move sideways while the boat rotates. In that situation, the rudder may temporarily be deflected rather widely without losing attached flow: however, initiate the turn with much more moderate tiller angles and deflect more only as needed to let the rudder follow the stern through the water. Otherwise, especially at low speed you will stall the rudder and it will cease to help control the boat until the flow had a chance to reattach itself again - something that can be agonizingly slow at slow speeds and in close quarter situations where you depend on reactive steering.

The tiller comes with one or two accessories.
  1. A tiller extension lets you steer while sitting on the side deck or leaning out (hiking) to keep the boat level. The way to grab it is like a microphone, in the hand that is furthest aft (the other will hold the mainsheet - or both main and jib sheets if you are single-handing).
  2. A tiller tamer helps you single-hand by temporarily holding the tiller; while this helps in many situations where you'd otherwise need three hands, it usually doesn't do self-steering for an extended period. A simple one can be rigged from a couple of bungee cords.
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Balancing the boat (Seating position)

Postby GreenLake » Sat Sep 05, 2020 8:43 pm

A DaySailer does not have ballast, or a ballasted keel, to keep it upright. Instead, it depends on placement of crew weight, in conjunction with hull shape to counteract the heeling forces as discussed in an earlier post. As the wind increases, your crew and you will first sit on the same side, then one or both of you sit on the deck and finally, if the wind is strong enough, you may hike out. Many people fit hiking straps to hook their feet under, so they can lean out all the way, yet remain securely attached to the boat.

Some boat classes even use a trapeze, a wire from the mast that lets the crew "stand" horizontally suspended with their feet on the gunwale. (There's no technical limitation against adding a trapeze to a DS, but it can't be used in racing class-sanctioned events).

Balance (Seating position)
Balancing.GIF (15.92 KiB) Viewed 16872 times

The basic technique of using your weight in gust response has been mentioned earlier: release the main, hike out to flatten the boat, then trim to the new wind. The goal is to keep the boat flat, as it sails fastest that way. If the boat heels, the hull shape becomes asymmetric, steering the boat to windward, adding to any weather helm. This forces you to give more rudder, which slows the boat (higher rudder angles have more drag).

There's an exception in light winds. Here the goal is to reduce the drag, which at low speeds is predominantly due to skin friction from the wetted area. By heeling the boat to leeward (sitting on the leeward side), much of the windward hull is lifted out of the water, reducing wetted area. Try it next time when the wind drops to almost nothing.

Finally, placement of crew weight matters not only across the boat, but also in the fore-aft position. Many people make the mistake of sitting in the middle or even aft portion of the cockpit. As a result, the bow is lifted out of the water and the stern squats. (As shown in the picture). Dragging your transom through the water is slow. How slow? When motoring at around 3 knots my boat gains .5 knots between me sitting in the back to me sitting on the foredeck. Just moving to the forward end of the cockpit gains 10%. Be aware of this and purchase a tiller extension so you can sit as far forward as possible.

Going downwind in strong winds, the wind will push the bow down using the mast as a lever. In that situation you may well want to sit further back, to reduce burying of the bow. Likewise, if you sail fast enough to get your boat on a plane.

Your seating position is one of the controls that are adjusted more frequently - except, again, in light winds, where the goal is to keep the boat as calm as possible.
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The Jib Sheet

Postby GreenLake » Sun Sep 06, 2020 6:32 pm

Adjusting the jib sheet is only effective over a partial range of the possible points of sail, from upwind to about beam reach. In all other points of sail that are further downwind the jib does not contribute, because it is shadowed by the main. There’s an exception for sailing dead downwind, where you can sheet the jib on the opposite side to sail “wing-on-wing”.

When you pull on the jib sheet, you are moving the clew of the jib in three directions: aft, down and in.

Which direction predominates depends on the location of the jib fairlead. Most, but not all DaySailers have a short track so that position can be adjusted. The more forward the fairlead is positioned, the more the sheet pulls down (and tightens the leech or aft edge of the jib). With the fairlead positioned aft, the pull is more horizontal. The foot of the sail is straightened, but the leech remains slack and the upper part of the jib is not as tight: the sail has developed “twist”. Twist may be desirable in light winds because the apparent wind changes direction as you move up, but also in heavy winds, to allow some wind to spill.

To find out whether the fairlead is adjusted correctly, look at the telltales or the luff of the sail (its forward edge). If you sail a little bit higher on the wind, so that the jib starts to backwind, the luff should break evenly over the whole sail. (Or the upper and lower set of telltales should respond simultaneously).

The jib sheet
JibSheet.GIF (13.82 KiB) Viewed 16857 times

Generally, you sheet in the jib just far enough that the inner telltales begin to flick up or just before it starts to break (you can momentarily point higher to see whether you are close). At some point, you are sailing as high upwind as the boat will go and the jib is trimmed to its maximum (close-hauled). Trying to point higher will slow the boat and increase side slipping (leeway). You may think you are heading higher, but effectively the boat will sail poorly and you are making less progress upwind.

If the foot of your jib is bar taut, you also have gone past the optimal setting for sailing close-hauled. A bit of camber (curve) in the sail is what helps it generate lift. In lighter, but not extremely light conditions a bit of extra belly in your sail will create more power, at the cost of pointing ability. If you are sailing in choppy waters or against a current, you may likewise trade off power for pointing ability.

Once you are close-hauled, the jib cannot be adjusted further; instead, you would use the tiller to adjust the boat’s heading to any changes in apparent wind.

The jib sheets are always routed inside the shrouds. Some DaySailers have a set of Barber inhauls. These pull the jib sheet even further inboards, which has the same effect as if the jib fairlead could be moved inwards. In moderately strong winds, this allows a flatter angle of the jib, which helps in pointing.

Instead of one setting for light winds and the opposite setting for heavy winds, jib fairlead and Barber inhauls are adjusted in a U curve if you will. For both light winds and heavy winds they are at their zero position (aft, or off) and for moderately strong winds around 8-12 knots they are at their maximum position (forward, or in).
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The Mainsheet

Postby GreenLake » Mon Sep 07, 2020 10:02 pm

The mainsheet is the last of the five basic controls.

Unlike the jib sheet, the mainsheet only moves the clew of the main in two directions, in and down. That is because the clew is attached to the boom and the tension in the foot of the sail is controlled by the outhaul. The outhaul is another control that is adjusted on a U curve: tight for very light and heavy air, looser in-between and loosest for moderately light airs, or when you want extra power against chop. Flattening the sail depowers it, good for heavy winds, but also allows the flow over the sail to remain attached more easily, good for very light airs.

Sheeting in the main pulls the end of the boom in, changing the angle of attack of the main. At the same time, it also pulls the end of the boom down, tightening the leech of the sail. As for the jib, less tension in the leech means more twist. Because the jib changes the airflow, we can sheet in the main further than we sheet in the jib. To know how far, we use the telltales at the leech of the mast: if they all stream aft, but the uppermost flicks behind the sail every once in a while, the main is trimmed to the correct angle.

The Mainsheet
Mainsheet.GIF (13.93 KiB) Viewed 16849 times

For the jib, we are able to change the position of the fairlead to affect the relative strength of the pull in the fore-and-aft and down directions, for the main, we can use the traveler or the vang to change how much leech tension we get when sheeting in the main.

The traveler allows the angle of pull of the mainsheet to change from sideways to down, by allowing the mainsheet block to move from side to side. Not every DS has a traveler, and some that do, don’t have a traveler that is adjustable. If you are a beginner, you might start out with centering an adjustable traveler until you are ready to try to set the sheeting angle and twist of sail independently. When you do, remember that the traveler adjusts the sheeting angle and the mainsheet tension adjusts the twist.

A traveler is active only for a small range of angles when sailing upwind, basically only as long as the boom is inboards. In contrast, a vang acts over the entire range of angles. When sailing downwind, it is used to pull the boom down to maximize the area projected to the wind. If your DaySailer has a stock 3:1 vang, it is intended for that use. Some boats have a much stronger vang (12:1 or even 20:1) which can be used to directly control leech tension (or twist) even when sailing upwind. When used this way, the main sheet mainly controls the angle of attack for the sail. This technique is called vang sheeting.

As a beginner, you can leave the vang off (loose) except when sailing downwind, or when sailing upwind in stronger winds. If you tighten the vang, it will keep the sail flat so it doesn't power up when you let out the main sheet to respond to a gust. At all other points of sail, you can ignore it until you have sorted out the basic controls first.

If you don't cleat your main, but hold it in your hand, you will be able to respond faster to any gusts, a definite safety feature. This is made easier, if you install a ratchet block, which will help you hold the mainsheet while not cleated. (Ratchet blocks can also be used with the jib sheets). Ratchet blocks and a vang are useful improvements that make your boat more controllable.

Another safety improvement would be to add reef points to your main and to install jiffy or slab reefing. However, that's a topic of its own.
~ green ~ lake ~ ~
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Joined: Mon Jun 18, 2007 3:54 am


Postby GreenLake » Wed Sep 09, 2020 3:53 pm

Reefing is a method of reducing sail area when the boat is overpowered in the given conditions.

The sail is prepared beforehand by sewing in reef points, which provide a new clew and tack at some position above the boom. You start reefing the sail by heaving to. Next, you drop the halyard and hook the new tack into a reef hook at the gooseneck. Then tighten the halyard again and also tighten the reef line to pull the new clew down to the boom and away from the mast, tensioning the new foot of the sail. Flake the unused portion of the sail along the boom.

Some sails are fitted with a series of little ties that can be used to tie the unused part of the sail to the boom. However, they have to be released before shaking out the reef. Some sails are made of stiff fabric that does not need to be secured (at least not for the first reef).

When to reef? An old saying has it “as soon as you first think about reefing”.

Reefing the main
Reefing.GIF (17.09 KiB) Viewed 16836 times

The image on the left shows possible locations for a first and second reef, together with a typical placement of the reef line for the first reef (blue). Note that one leg of the reef line (going up from the boom behind the sail) pulls straight down, while the other leg, going to a block at the end of the boom, pulls aft. From there, the reef line is lead forward along the boom to a cleat.

The image on the right shows how what a reefed mainsail might look like for a second reef. Not only is the area reduced, but also the remaining sail area is now lower on the mast (and more forward).

A couple of things worth noting:
• Making the sail area smaller reduces the total heeling force and having more of the sail area closer to the boom reduces the lever arm for a double reduction in heeling moment.
• Because of this, even the first reef with about 18% reduction in sail area has a noticeable effect, and might be sufficient in many conditions.
• For people sailing in heavy wind areas on extended cruises a third reef may prove useful.
• Any sailmaker can add reef points to an existing sail, but there are also kits available.
• Reefs are often placed so that the boom rises slightly from the horizontal position.
• Some boats do not have a reef hook, but use a reef line for the tack as well.

Finally, the more severe a reef is put in the mainsail, the more the sail plan becomes unbalanced: the jib begins to dominate not only because of its unchanged size, but because the remaining area of the mainsail is also further forward. This can make it harder to point. Eventually, it may be advisable to switch to a smaller jib, especially in conditions where you might be using a third reef.
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Joined: Mon Jun 18, 2007 3:54 am

Tying up at the Dock

Postby GreenLake » Wed Sep 16, 2020 2:02 am

Some comments about tying up a DS at the dock.

If a dock has a simple vertical wall, no fenders may be needed, particularly for older DS1s which are equipped with a rubrail. That rubrail is often good enough, except for tying up for extended periods, or where there is strong wave or wake action. On other types of dock, the rubrail can be either too high or too low, so that some fenders are needed.

A 5.5" diameter fender extends comfortably from the hull past the edge of the rail to make contact with the dock. Sometimes it's enough to tie a single fender at the widest part of the boat and use three lines as shown to hold the boat in place. (Usually it's a good idea to add a second fender near the stern as well, because it could more easily make contact with the dock). Because there's not much freeboard even at the cuddy, it may be easier to tie off a fender on the cuddy deck cleat than on the chain plate.

Some boats come equipped with special clips into which a washer attached to the fender line is inserted. In that case, the locations for the fenders are pre-determined.

Tying up at the Dock
TyingUpAtTheDock.GIF (21.21 KiB) Viewed 16734 times

Note that I've shown the bow line as slack, and instead show a line attached to the foredeck cleat. That's because a sideways pull on the bow eye is not recommended. But the bowline can be used at a shallow angle to limit the fore-aft movement of the boat.

If the top of the deck for the DS is lower than the dock, the boat can "dive" under the dock. For that situation there are special L-shaped "low freeboard" fenders as shown in the sketch at the top. Not only do they protect the top of the deck a bit, they also hang over the rubrail and increase the distance between hull and dock. That fender works particularly well in the rear of the boat.

However, if wave action from the wakes of passing boats is likely to slam the DS into the dock from below, even a low freeboard fender may not be enough. To keep your DS safe, you need to tie a line to some post or dock opposite to hold it off the dock, as shown on the right.

A bit about terminology: a line that is tied going forward or back along the dock is called a spring line. It limits the fore-and-aft motion of the boat. A line that goes from bow or stern at right angles to the dock is a breast line or stern line.

When tied up at the dock, raise the CB and tie off the tiller so it's amidships.

If you plan on staying away for extended periods you may want to use additional lines or fenders for added security, as well as unship the rudder and storing it in the boat. For a short stay, it may be enough to loosely wrap the sails so they can't catch the wind, but if you are leaving the boat behind, you may want to remove the jib and cover or remove the main.

Every dock and every docking situation is slightly different. What works in one case, may not work everywhere, and conditions can change with weather and passing boat traffic. For that reason, the discussion here can at best serve as a starting point.
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