Welcome to our series of articles on sail trim and ... - Dolphin Sails
Welcome to our series of articles on sail trim and ... - Dolphin Sails
Welcome to our series of articles on sail trim and ... - Dolphin Sails
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<str<strong>on</strong>g>Welcome</str<strong>on</strong>g> <str<strong>on</strong>g>to</str<strong>on</strong>g> <str<strong>on</strong>g>our</str<strong>on</strong>g> <str<strong>on</strong>g>series</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>articles</str<strong>on</strong>g> <strong>on</strong><br />
<strong>sail</strong> <strong>trim</strong> <strong>and</strong> care.<br />
With helpful facts <strong>and</strong> hints, this<br />
<str<strong>on</strong>g>series</str<strong>on</strong>g> is intended <str<strong>on</strong>g>to</str<strong>on</strong>g> help you get the<br />
best from y<str<strong>on</strong>g>our</str<strong>on</strong>g> boat.<br />
We cover upwind <strong>and</strong> downwind <strong>sail</strong><br />
<strong>trim</strong>, maintenance <strong>and</strong> care <str<strong>on</strong>g>of</str<strong>on</strong>g> y<str<strong>on</strong>g>our</str<strong>on</strong>g><br />
<strong>sail</strong>s.<br />
DOLPHIN SAILS email: <strong>sail</strong>s@dolphin-<strong>sail</strong>s.com Tel: +44 (0) 1255 243366 Fax: +44 (0) 1255 240920<br />
NO.2
SAIL TRIM<br />
<str<strong>on</strong>g>Welcome</str<strong>on</strong>g> <str<strong>on</strong>g>to</str<strong>on</strong>g> the sec<strong>on</strong>d in<br />
<str<strong>on</strong>g>our</str<strong>on</strong>g> <str<strong>on</strong>g>series</str<strong>on</strong>g> <strong>on</strong> getting the<br />
best from y<str<strong>on</strong>g>our</str<strong>on</strong>g> <strong>sail</strong>s. In the<br />
first article we looked at<br />
head<strong>sail</strong>s, the tensi<strong>on</strong><br />
applied <str<strong>on</strong>g>to</str<strong>on</strong>g> them <strong>and</strong> the<br />
effect <strong>on</strong> y<str<strong>on</strong>g>our</str<strong>on</strong>g> yacht's<br />
h<strong>and</strong>ling <strong>and</strong> performance.<br />
In this issue we are taking<br />
a closer look at main<strong>sail</strong>s.<br />
We will c<strong>on</strong>sider their<br />
settings <strong>and</strong> adjustments,<br />
relati<strong>on</strong>ship <str<strong>on</strong>g>to</str<strong>on</strong>g> the head<strong>sail</strong><br />
<strong>and</strong> overall <strong>sail</strong> care.<br />
Windward <strong>sail</strong>ing is where<br />
attenti<strong>on</strong> <str<strong>on</strong>g>to</str<strong>on</strong>g> detail in <strong>sail</strong><br />
<strong>trim</strong> creates most impact.<br />
This applies particularly<br />
<str<strong>on</strong>g>to</str<strong>on</strong>g> main<strong>sail</strong> <strong>trim</strong>ming.<br />
To windward the main<br />
needs <str<strong>on</strong>g>to</str<strong>on</strong>g> be set relatively<br />
flat (compared <str<strong>on</strong>g>to</str<strong>on</strong>g> the<br />
head<strong>sail</strong>). Adjusting the<br />
halyard, outhaul, backstay,<br />
<strong>and</strong> <str<strong>on</strong>g>to</str<strong>on</strong>g> a lesser extent the<br />
battens, will have a<br />
noticeable effect <strong>on</strong><br />
performance.<br />
By Matthew Vincent <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>Dolphin</strong> <strong>Sails</strong><br />
HALYARDS<br />
As with the head<strong>sail</strong>, <strong>on</strong>ce the main is up, the halyard tensi<strong>on</strong> will be the first c<strong>on</strong>trol you need <str<strong>on</strong>g>to</str<strong>on</strong>g><br />
check. The tensi<strong>on</strong> should be enough <str<strong>on</strong>g>to</str<strong>on</strong>g> just remove the horiz<strong>on</strong>tal wrinkles that occur in the luff.<br />
This should set the draft at the correct positi<strong>on</strong>, which is approximately 45-50% aft in the <strong>sail</strong>.<br />
You can check this by looking up the <strong>sail</strong> from the centre <str<strong>on</strong>g>of</str<strong>on</strong>g> the boom, where you can judge the<br />
draft positi<strong>on</strong> by the seams or draft stripes.<br />
Older <strong>sail</strong>s, <strong>and</strong> in particular those made from Dacr<strong>on</strong>, tend <str<strong>on</strong>g>to</str<strong>on</strong>g> lose their shape. As a result the<br />
draft will increase <strong>and</strong> move further aft. This means you will find it difficult <str<strong>on</strong>g>to</str<strong>on</strong>g> flatten the main<strong>sail</strong><br />
sufficiently <strong>and</strong> c<strong>on</strong>sequently a reducti<strong>on</strong> in overall performance will occur.<br />
OUTHAUL<br />
When windward <strong>sail</strong>ing in a breeze (Force 3-4+), you need <str<strong>on</strong>g>to</str<strong>on</strong>g> apply firm outhaul tensi<strong>on</strong>. Doing so<br />
will maintain a desired 5-9% draft in the lower secti<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> the main. More draft will increase<br />
backwind in the <strong>sail</strong>, likely <str<strong>on</strong>g>to</str<strong>on</strong>g> produce weather helm <strong>and</strong> a decrease in performance.<br />
BACKSTAY<br />
Increasing the tensi<strong>on</strong> in an adjustable backstay will straighten the forestay <strong>and</strong> flatten the<br />
head<strong>sail</strong>. Depending <strong>on</strong> y<str<strong>on</strong>g>our</str<strong>on</strong>g> rig type, this may also have a flattening effect <strong>on</strong> the main<strong>sail</strong>, which<br />
is desirable for windward performance.<br />
BATTENS<br />
Battens are best c<strong>on</strong>sidered as relatively passive in y<str<strong>on</strong>g>our</str<strong>on</strong>g> <strong>sail</strong>. A good <strong>sail</strong> is cut so that the battens<br />
will blend in<str<strong>on</strong>g>to</str<strong>on</strong>g> the shape <str<strong>on</strong>g>of</str<strong>on</strong>g> y<str<strong>on</strong>g>our</str<strong>on</strong>g> main. However, a sign that increased batten tensi<strong>on</strong> could<br />
improve y<str<strong>on</strong>g>our</str<strong>on</strong>g> performance is when vertical wrinkles occur across the battens. (Note: The windward<br />
side <str<strong>on</strong>g>of</str<strong>on</strong>g> y<str<strong>on</strong>g>our</str<strong>on</strong>g> main, which is in compressi<strong>on</strong>, will tend <str<strong>on</strong>g>to</str<strong>on</strong>g> look more wrinkly than the leeward side). In<br />
vertical furling mains the battens will be sewn in<str<strong>on</strong>g>to</str<strong>on</strong>g> the <strong>sail</strong> <strong>and</strong> will not be adjustable.<br />
For <str<strong>on</strong>g>of</str<strong>on</strong>g>f wind <strong>sail</strong>ing, in order <str<strong>on</strong>g>to</str<strong>on</strong>g> deepen the <strong>sail</strong> <strong>and</strong> therefore generate more power in y<str<strong>on</strong>g>our</str<strong>on</strong>g> main,<br />
a good rule <str<strong>on</strong>g>of</str<strong>on</strong>g> thumb is <str<strong>on</strong>g>to</str<strong>on</strong>g> decrease the halyard tensi<strong>on</strong> by approximately 0.5% <str<strong>on</strong>g>of</str<strong>on</strong>g> the luff length,<br />
<strong>and</strong> the outhaul by up <str<strong>on</strong>g>to</str<strong>on</strong>g> 1.5% <str<strong>on</strong>g>of</str<strong>on</strong>g> the foot length. You will also need <str<strong>on</strong>g>to</str<strong>on</strong>g> reduce any applied<br />
backstay tensi<strong>on</strong>.<br />
Once the overall shape has been set using these c<strong>on</strong>trols, the sheet, vang (kicker) <strong>and</strong> traveller<br />
are then used <str<strong>on</strong>g>to</str<strong>on</strong>g> positi<strong>on</strong> the <strong>sail</strong> relative <str<strong>on</strong>g>to</str<strong>on</strong>g> the centreline <strong>and</strong> head<strong>sail</strong>.<br />
MAINSAIL AND HEADSAIL INTERACTION<br />
A bird's eye view <str<strong>on</strong>g>of</str<strong>on</strong>g> a yacht (diagram) shows us that when <strong>sail</strong>ing <str<strong>on</strong>g>to</str<strong>on</strong>g> windward, the head<strong>sail</strong> is set<br />
at a relatively wide angle from the centreline at 11-13 degrees (slightly less <strong>on</strong> performance<br />
boats), compared <str<strong>on</strong>g>to</str<strong>on</strong>g> the main<strong>sail</strong>, which is set at an angle <str<strong>on</strong>g>of</str<strong>on</strong>g> 0-10 degrees. This indicates that the<br />
head<strong>sail</strong> provides more <str<strong>on</strong>g>of</str<strong>on</strong>g> the forward drive, whilst the main, which operates in a permanent<br />
header (from the head<strong>sail</strong>), is set closer <str<strong>on</strong>g>to</str<strong>on</strong>g> the centreline, <strong>and</strong> should be thought as more <str<strong>on</strong>g>of</str<strong>on</strong>g> a<br />
steering <strong>and</strong> helm balancing <strong>sail</strong>.<br />
TRAVELLER SHEET AND VANG<br />
The best way <str<strong>on</strong>g>to</str<strong>on</strong>g> judge if the <strong>sail</strong>s are well <strong>trim</strong>med is <str<strong>on</strong>g>to</str<strong>on</strong>g> feel it through the helm balance. You<br />
should be seeking <str<strong>on</strong>g>to</str<strong>on</strong>g> minimize rudder movement <strong>and</strong> keep it within a 0-5 degree b<strong>and</strong>. For<br />
example, say you are <strong>sail</strong>ing <str<strong>on</strong>g>to</str<strong>on</strong>g> windward in about 12 knots <str<strong>on</strong>g>of</str<strong>on</strong>g> breeze; the <strong>sail</strong>s are well set, the<br />
main is near the centreline; the helm is nicely balanced, then a str<strong>on</strong>g gust strikes y<str<strong>on</strong>g>our</str<strong>on</strong>g> boat. She<br />
could be kept <strong>on</strong> track by applying excessive helm. However, a much better move is <str<strong>on</strong>g>to</str<strong>on</strong>g> ease<br />
down the traveller. Enough traveller should be eased <str<strong>on</strong>g>to</str<strong>on</strong>g> keep the helm within the 0-5 degree<br />
b<strong>and</strong>. You will lose a little pointing ability for a moment. More importantly though you will be able<br />
<str<strong>on</strong>g>to</str<strong>on</strong>g> keep the helm straight, y<str<strong>on</strong>g>our</str<strong>on</strong>g> boat <strong>on</strong> track <strong>and</strong> you will probably increase boat speed. As the<br />
gust passes, you can <strong>trim</strong> the traveller back up. Easing the traveller is preferable <str<strong>on</strong>g>to</str<strong>on</strong>g> easing the<br />
sheet or vang, as pointing ability is more easily maintained. A c<strong>on</strong>sequence <str<strong>on</strong>g>of</str<strong>on</strong>g> easing the traveller<br />
down may be <str<strong>on</strong>g>to</str<strong>on</strong>g> increase the backwind in the main. Moderate backwinding is preferable <str<strong>on</strong>g>to</str<strong>on</strong>g><br />
excessive helm use.
The head<strong>sail</strong> develops a larger<br />
force, because it is fuller than the<br />
main. This force acts in a more<br />
advantageous forward directi<strong>on</strong><br />
because it is set at a wider angle <str<strong>on</strong>g>to</str<strong>on</strong>g><br />
the centreline. Therefore if either<br />
<strong>sail</strong> is eased out (set at a wider<br />
angle) the drive forces will propel<br />
the boat faster, although this will be<br />
at the expense <str<strong>on</strong>g>of</str<strong>on</strong>g> pointing ability.<br />
Good vertical shot showing relative sheeting angles <str<strong>on</strong>g>of</str<strong>on</strong>g> Main <strong>and</strong> Head<strong>sail</strong>
FACT BOX<br />
As with any <strong>sail</strong>, regular inspecti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
the <strong>sail</strong> for chafe <strong>and</strong> general<br />
wear <strong>and</strong> tear will be <str<strong>on</strong>g>of</str<strong>on</strong>g> benefit in the<br />
l<strong>on</strong>g run, <strong>and</strong> reduce repair bills.<br />
Particular attenti<strong>on</strong> should be paid <str<strong>on</strong>g>to</str<strong>on</strong>g><br />
batten pockets where they may<br />
<str<strong>on</strong>g>to</str<strong>on</strong>g>uch spreaders or shrouds. Chafe<br />
protecti<strong>on</strong> patches should be applied<br />
in the area <str<strong>on</strong>g>of</str<strong>on</strong>g> the spreaders. Carry<br />
spares in y<str<strong>on</strong>g>our</str<strong>on</strong>g> <strong>sail</strong> repair kit.<br />
Pay particular attenti<strong>on</strong> when folding<br />
away main<strong>sail</strong>s ensuring battens lie<br />
flat, not twisted, <strong>and</strong> the <strong>sail</strong> is curled<br />
rather than creased al<strong>on</strong>g edges.<br />
Annual washing removes salt <strong>and</strong> dirt<br />
which work their way in<str<strong>on</strong>g>to</str<strong>on</strong>g> the<br />
fibres <str<strong>on</strong>g>of</str<strong>on</strong>g> the <strong>sail</strong> <strong>and</strong> cause damage.<br />
After use ease the halyard, outhaul<br />
<strong>and</strong> batten pocket tensi<strong>on</strong>s,<br />
particularly if they have been heavily<br />
tensi<strong>on</strong>ed.<br />
Always cover y<str<strong>on</strong>g>our</str<strong>on</strong>g> main<strong>sail</strong> with the<br />
<strong>sail</strong> cover after use, particularly in<br />
areas <str<strong>on</strong>g>of</str<strong>on</strong>g> extended sun exposure.<br />
RECOMMENDED READING<br />
Easy reading: Looking at Sail,<br />
Bruce Banks <strong>and</strong> Dick Kenny<br />
Medium reading: The Art <strong>and</strong><br />
Science <str<strong>on</strong>g>of</str<strong>on</strong>g> Sail Making, Tom Whidden<br />
Reference book level: The Aero/<br />
Hydrodynamics <str<strong>on</strong>g>of</str<strong>on</strong>g> Sailing,<br />
T<strong>on</strong>y Marchjai<br />
Other interesting reading:<br />
Sail Power, Wallace Ross<br />
More <str<strong>on</strong>g>to</str<strong>on</strong>g> do with racing but<br />
n<strong>on</strong>etheless an interesting insight:<br />
Winning in One Designs:<br />
Robert Hopkins<br />
This is a <str<strong>on</strong>g>series</str<strong>on</strong>g> produced for Oyster Marine <strong>and</strong><br />
reprinted with their kind permissi<strong>on</strong><br />
REEFING<br />
If the main is c<strong>on</strong>stantly<br />
backwinding <strong>and</strong> perhaps even<br />
wiping out (<str<strong>on</strong>g>to</str<strong>on</strong>g>tally backwinding<br />
from luff <str<strong>on</strong>g>to</str<strong>on</strong>g> leach), it is time <str<strong>on</strong>g>to</str<strong>on</strong>g><br />
c<strong>on</strong>sider reefing. Most boats will<br />
benefit from reducing head<strong>sail</strong> size<br />
first. Either set a reduced foot<br />
length <strong>sail</strong> or roll some head<strong>sail</strong><br />
away. Once the head<strong>sail</strong> has been<br />
reduced <str<strong>on</strong>g>to</str<strong>on</strong>g> the point where the<br />
clew has reached the mast <strong>and</strong><br />
wind c<strong>on</strong>diti<strong>on</strong>s are still <str<strong>on</strong>g>to</str<strong>on</strong>g>o str<strong>on</strong>g,<br />
then look <str<strong>on</strong>g>to</str<strong>on</strong>g> reef the main<strong>sail</strong>.<br />
Generally it is best <str<strong>on</strong>g>to</str<strong>on</strong>g> try <strong>and</strong> match<br />
the leach pr<str<strong>on</strong>g>of</str<strong>on</strong>g>iles <str<strong>on</strong>g>of</str<strong>on</strong>g> the main <strong>and</strong><br />
head<strong>sail</strong>s (see Article 1 - Head<strong>sail</strong>s).<br />
If you have moved the head<strong>sail</strong><br />
sheeting car back a little <str<strong>on</strong>g>to</str<strong>on</strong>g> open up<br />
the genoa leach in slightly over<br />
pressed c<strong>on</strong>diti<strong>on</strong>s, you should try<br />
<str<strong>on</strong>g>to</str<strong>on</strong>g> match the leach pr<str<strong>on</strong>g>of</str<strong>on</strong>g>ile <str<strong>on</strong>g>of</str<strong>on</strong>g> the<br />
main<strong>sail</strong>. You can achieve this by<br />
twisting the main leach by easing<br />
the sheet or vang a little.<br />
Additi<strong>on</strong>ally if the head<strong>sail</strong> is eased<br />
then the main should be eased.<br />
WINDWARD SAILING MODES<br />
When <strong>sail</strong>ing <str<strong>on</strong>g>to</str<strong>on</strong>g> windward, you<br />
should try <str<strong>on</strong>g>to</str<strong>on</strong>g> decide which mode<br />
you wish <str<strong>on</strong>g>to</str<strong>on</strong>g> <strong>sail</strong> in. There are two<br />
Good comparis<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> high traveller <strong>and</strong> closed<br />
leach with eased traveller <strong>and</strong> more open leach<br />
modes. Mode <strong>on</strong>e when <strong>sail</strong>ing close <str<strong>on</strong>g>to</str<strong>on</strong>g> the wind is referred <str<strong>on</strong>g>to</str<strong>on</strong>g> as high pointing mode. Mode two,<br />
which is still <strong>sail</strong>ing close <str<strong>on</strong>g>to</str<strong>on</strong>g> the wind but slightly further away from it, is called footing mode. You<br />
can judge which mode by watching the main<strong>sail</strong>'s upper leach telltales.<br />
When high pointing (mode <strong>on</strong>e), is desirable, the upper leach telltales should be stalling about<br />
50% <str<strong>on</strong>g>of</str<strong>on</strong>g> the time. This means, having applied more leach tensi<strong>on</strong> through the sheet <strong>and</strong> or vang,<br />
the telltales should disappear behind the main about 50% <str<strong>on</strong>g>of</str<strong>on</strong>g> the time. High pointing is excellent<br />
<str<strong>on</strong>g>to</str<strong>on</strong>g> make a weather mark or keep above another yacht’s dirty air.<br />
When footing (mode two) the upper leach telltales always stream aft. This is achieved by reducing<br />
tensi<strong>on</strong> <strong>on</strong> the sheet <strong>and</strong> or vang. Incidentally this is how the main should always be set when<br />
<strong>sail</strong>ing <str<strong>on</strong>g>of</str<strong>on</strong>g>f wind. Footing is slightly quicker <strong>and</strong> is best used when you know you are going <str<strong>on</strong>g>to</str<strong>on</strong>g> lay<br />
the mark or you believe there will be an imminent wind shift.<br />
The overall difference in speed between high pointing <strong>and</strong> footing is approximately 10% <str<strong>on</strong>g>of</str<strong>on</strong>g> y<str<strong>on</strong>g>our</str<strong>on</strong>g><br />
overall boat speed. Whilst you may seek <str<strong>on</strong>g>to</str<strong>on</strong>g> adopt <strong>on</strong>e <str<strong>on</strong>g>of</str<strong>on</strong>g> the modes, by necessity you <str<strong>on</strong>g>of</str<strong>on</strong>g>ten find<br />
you are working between the two.<br />
An appreciati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> why you may want <str<strong>on</strong>g>to</str<strong>on</strong>g> be in either mode generates a better feel for <strong>sail</strong> <strong>trim</strong>.<br />
It also helps bring an awareness <str<strong>on</strong>g>of</str<strong>on</strong>g> where you would like <str<strong>on</strong>g>to</str<strong>on</strong>g> be <strong>on</strong> the c<str<strong>on</strong>g>our</str<strong>on</strong>g>se both strategically<br />
(y<str<strong>on</strong>g>our</str<strong>on</strong>g> positi<strong>on</strong> relative <str<strong>on</strong>g>to</str<strong>on</strong>g> the c<strong>on</strong>diti<strong>on</strong>s) <strong>and</strong> tactically (y<str<strong>on</strong>g>our</str<strong>on</strong>g> positi<strong>on</strong> relative <str<strong>on</strong>g>to</str<strong>on</strong>g> the other boats).<br />
In the next issue we will be looking at the art <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g>fwind <strong>sail</strong>ing with reference <str<strong>on</strong>g>to</str<strong>on</strong>g> spinnaker <strong>and</strong><br />
cruising chute setting <strong>and</strong> <strong>trim</strong>ming.<br />
DOLPHIN SAILS email: <strong>sail</strong>s@dolphin-<strong>sail</strong>s.com Tel: +44 (0) 1255 243366 Fax: +44 (0) 1255 240920