Hobie Island Sail Trim
Hobie Island Sail Trim
The Hobie Island range are one of the easiest sailing vessels to learn to sail on. They are stable and will handle winds up to 25 knots. Learning to sail them will enhance your experience and allow you to get more from your Island. This article is intended to give you a basic understanding of how the sail works and how to set it for the best performance in different angles of sail.
The Diagram to the right shows the various names for different parts of the sail. The Main Sheet is the rope you trim the sail with and attaches to the rear of the sail called the Clew. The Luff of the sail is the part that the mast slides into. You also have a control line at the bottom of the sail that attaches to the mast. This we call the Down Haul and is used to apply tension to the sail.
The main sail of a Hobie Island has 2 steamers in the middle of the sail. These are called tell tales and are there to assist you with correct sail trim and sailing angel to the wind. Their function is to show the air flowing over the sail.
If we keep to this terminology everyone you talk to or ask questions of will know what you are talking about as this sail is no different to that of a sail on a racing yacht or a big cruiser. The same names and principles apply.
How a Sail Works
To learn how to trim the sail correctly then you need to first understand how the sail works. Consider the sail as an airplane wing standing upright. It is curved just like a wing and as the wind flows over it, differences in pressure are created. High pressure on the windward side and low pressure on the leeward side. This differential in pressure creates a sideways force on the sail, just like a airplane wing creates an upward force and lifts the plane into the sky. With a sailing vessel the energy is transferred to the hull which transfers the force into forward movement by way of the centre board or Keel and the hull shape itself.
The goal of sail trim is to have the most efficient sail angel to the wind at all times therefore maximising the pressure effect on the sail and generating more forward momentum. This is where the Tell Tales come in. They show us the air flowing over the sail and they should be flowing backwards as much as possible ensuring the air is flowing over both surfaces of the sail.
Setting Up The Sail
Generally your sail will be rolled up and stored in its sail bag. The only real concern is to attach the main sheet to the clew of the sail at the back of the sail. It’s important here to not have any twists in the lines as this will create friction and make the sail slightly harder to pull in so when rigging up always check the main sheet is clear. The second consideration is the Down haul control. This is the bit of rope at the base of the sail on the Luff that goes through the loop on the mast bast and cleats back to the sail. This actual control does more than just pull the sail and hold it in place. The more pressure your apply to this control the more tension you place on the sail which effectively flattens out the front third of the sail. If you refer back to the picture of the sail above with the wind flowing over it, the bigger the curve means it will create more power. By pulling on the Down Haul we apply tension to the front third of the sail and flatten it out. The effect is not huge on the Islands but it still works. So before you head out for a sail check it’s tension and if the wind is below 18 knots then keep the rope firm, but if it is over 18 knots, apply more tension.
By setting up the sail correctly before you leave will ensure that you are ready for the wind conditions of the day.
Up Wind Sailing
Now you know how a sail works you may realise that a sailing boat cannot sail directly into the wind. An Island sails about 45 degrees when sailing up wind, that is the boat is sailing as close into the wind as possible both tell tales should be streaming backwards. If you sail too high into the wind the windward tell tale with start to lift. If you are sailing too low into the wind the leeward tell tale will start to lift. When sailing upwind we actually steer the boat according to the tell tales, we do not make any sail adjustments while sailing upwind, our goal is to sail as close to the wind as possible.
To start your upwind sailing first you need to sheet the main sail in. My simple rule here is to pul it all the way in till the sheet is tight, then ease out 2 inches of rope and you should be about right. You don’t want the sail to tight and you don’t want it to loose. If you have the new model Islands then make sure the forward batten is not distorting the bottom of the sail where it attaches to the mast.
Once you have the sail set right, steer the boat up into the wind and keep an eye on the inside or windward telltale. Once this starts to lift then you are sailing to high and you need to adjust your course away from the wind very slightly to get the tell tale flowing backwards. If the outside or leeward tell tale starts to lift then you are sailing to low into the wind and you need to make a slight adjustment to your course closer to the wind.
There are times when we want the inside tell tale lifting. If the wind picks up say over 15 knots and the boat feels overpowered you can sail higher into the wind than normal which will effectively de-power the sail. By sailing to high, the front side of the sail does not have any airflow over it and the inside tell tale will be lifting. This is called feathering or pinching and is good for sailing in strong winds or gusts.
So that covers the tell tales for sailing close to the wind and that is how we drive a boat upwind using the tell tales to steer.
Reaching is when the wind is side on to the boat and is the fastest and most exciting point of sail. The same rule to sailing upwind applies to the tell tales however now you have more things to consider. Firstly set your course, then ease the sail out till both tell tales are streaming backwards. The same rule above applies to the trim however instead of steering the boat to adjust the correct angle of the sail to the wind. We now trim the sail. If the inside tell tale is lifting, trim the sail in, if the outside tell take is lifting then ease the sail out. When we say ease we are talking about very small amounts adjustment, don’t just let it loose, ease it out or pull it in slowly till you have the desired trim.
The same theory also applies to stronger winds. Sailing in stronger winds with the inside tell tale lifting de-powers the sail and allows you to sail longer without having to furl the sail in. However to get it to lift now you have to ease the sail out rather than steer the boat. For reaching it is far more important to not over trim or tighten the sail, we want it as eased as possible. If the winds pick up, do not be frighted to furl the sail in as this will be faster than sailing with too much sail out as explained in the Furling section.
Downwind is the slowest heading to sail. The wind is no longer flowing over the sail, instead it is pushing on the sail and the tell tales do not work effectively. The simplest trim to use for sailing downwind is to ease the sail out till it is flapping then pull it in till it is firm. Or a more accurate trim I use is to ease the sail out till the very top T section of the sail is at right angles to the boat. Then you should have about the best trim for downwind sailing.
To sail faster downwind, we actually sail slightly to one side of the wind. that is we do not ever sail dead downwind. We sail slightly away from downwind as this allows for some of the wind to flow over the sail and increases our speed.
When too much force is applied to the boat through the sails and mast, the boat will become overpowered and do 2 things. The first characteristic you will notice is that the leeward hull will dig in the water. What is happening is that the boat is at maximum hull speed and any additional power coming from the sail is not being transferred into speed. In this case it is faster to de-power the sail by either sailing higher or furling the sail. The other characteristic is that the boat will want to turn up into the wind and you will have to adjust the boats course through the rudder control to keep it straight. This is called Weather Helm and is more prevalent on bigger yachts and the Tandem Islands. By having to use the rudder to keep the boat going straight you are effectively increasing drag and slowing the boat down so again de-power the sail by sailing higher or furling the sail.
Furling the Sail
Some people think it is faster to sail with a full sail than rolling it up or furling it in. This is not true and here’s why. Your Hobie Adventure or Tandem Island can only be pushed through the water so fast. We call this hull speed. Once your sails are exerting more force than the hulls can travel through the water the boat will start to either dig the hulls in and slow you down or want to turn into the wind and you will have to use the rudder steer the boat on a straight course. Both these things create drag and loss of power. So when boat feels over powered roll the sail in one full turn at a time till the Island feels balanced and comfortable.
The wind range for furling the sail is 18 knots. Once the wind hits that speed you need to put a furl in the sail.
Other Methods to Control Sail Power
This next bit is for the sailor who has learnt how to trim the sail and now wants to do a bit more. Our club in South East Queensland , Australia often sails in winds above 18 knots. We go out in 25 knots with ease and will push through 30 knots if we have too but that is getting on the uncomfortable side. If you have seen our Windy Wivenhoe Videos then many of these are conducted in very strong winds. Whilst it is not recommended you sail in these conditions, and you are pushing the limits of the mast strength, you should be able to handle yourself when things get tough as your sailing with Mother Nature and she will do what she likes. Plus it is great fun.
If sailing upwind in strong winds you can, in an Adventure Island actually carry a full sail up to 20 knots with no furl. How you do this is to sheet the sail in as hard as you can which effectively flattens the sail out and de-powers the rig. You also need to sail very high into the wind as described in the feathering or pinching technique. We have seen this done and many of our club members who do not come from a sailing background manage this with ease and big grins on their faces.
Then you have the opposite where will be times when you might be in strong winds but want more power as is the case when you are sailing down wind or reaching. It’s much harder to do but the simplest way is to ease off the Down haul control at the base of the sail. This will create a deeper sail and create more power.
Tacking is when you change directions with the wind coming over the front of the boat. When the boat comes close to head to wind, all the power comes off the sail and the boat will slow down often resulting in the boat being stuck head to wind without enough power to complete the turn. Luckily we have peddles in the Islands and we can give the boat a couple of peddles and she will complete the tack however you can actually tack these kayaks without peddling at all. I personally do not take my peddles with me or have them stored away. I enjoy the feeling os sailing with less drag and treat the boat as a true sailing vessel.
The method to do this properly is very easy, just follow and practise these simple steps and you will be able to do it in any wind condition. When you start the start only use half the amount of rudder control, that is only turn the rudder a small amount to start the boat turning into the wind. As you do this sheet the main sheet in, that is pull the sail in as hard as you can. This will create a little more power for a little longer as the boat sails up into the wind. Then once you feel the power has completely come off the sail (it will probably be flapping) give the Island full turn on the rudder but don’t just jam it over, treat it nicely and push the rudder control all the way over. Leave it in this hard turn till the boat has gone through the wind and is starring to come back onto the other tack. Once your through reduce the rudder control to half turn again until you feel the boat come right around and the sail starts to power up again.
Don’t straighten the boat at the highest angel to the wind, let the boat sail a little lower than the normal upwind course and ease the sail slightly out. This will give you a faster recovery from the tack and get the boat back up to speed as quickly as possible. Once you feel you have the boat going again, sheet the sail in to the correct upwind trim and sail the back back to it’s higher course.
A little practise and anyone can do this. Keep in mind though “Tacking is Slow”, if you are racing then the fewer tacks the better simply because you loose speed in a tack, so plan it.
When to Tack
When to tack is a very good question. Firstly if you are sailing to a destination upwind you need to tack backwards and forth till you arrive where you want to go. A simple way to gauge where your new angle of sail is or to line a point up that you want to tail to is too look over your windward shoulder then slightly back and thats where you are going be sailing on the new tack.
Whilst our course is the best indicator of when to tack, the next most important consideration is the wind. Now the wind is never constant, it shifts around all over the place. So if your sailing one starboard tack too a point and the wind shifts slight left, you will now be sailing further away form that point. So we tack because the wind has shifted to the disadvantage on the starboard tack we should now be making a gain to the point for which we are sailing too. We call the shifts Lifts and Knocks, a lift is a wind shift that is taking us closer to our destination and a Knock is a wind shift that takes us away from our destination. This is one reason why we have compasses on a sailing vessel, not so much for the direction but to measure the wind changes.
Here’s some examples of when to tack
The figure A shows 2 boats sailing with the wind even. The distance to the destination is the same and there is no benefit on either tack. On the second diagram below, figure B, the wind has now shifted to the right and the boat on the left hand side of the course now sailing closer to the destination due to the shift. The boat to the left is on a lift and he does not tack. The boat on the right has received a knock where the wind shift and altered his course away from the mark. He now has a longer course to sail so this boat tacks.
Gybing means to change direction when the wind is behind you. Who you change direction the sail is swapped from one side to the other. The same principles apply as to when to gybe but are not so critical as when we sail downwind we have a larger range of course to sail whereas with upwind sailing we are trying to sail as close to the wind as possible whilst still be efficient.
When sailing downwind we want to sail as fast as possible as downwind is the slowest form of sailing. By sailing slightly away from Dead Downwind we create some air flow over the sail thereby increasing our speed. We will often sail from gybe to gybe to maximise our down wind speed.
One very important point to note is to watch your head, you have more chance of being hit on the head by the sail or the sheets when gybing. This is only highlighted in strong winds so if you feel unsure, furl the sail in one roll before gybing and you will be much safer. Always watch the ropes and sail as the sail swaps sides.
Alos in strong winds the sail will come across with some force so be prepared for it.
The below image is an example of downwind sailing to a destination. We are sailing as fast as possible by not sailing dead down wind rather just off to the dead down wind course to maximise boat speed.
We gybe when the wind shifts us away from our destination, just like when sailing upwind or we have reached the correct angle to head towards our destination.
Sailing and Tides
When we sail we are actually sailing on a conveyor belt as the water is always moving in one direction or another. This is most commonly due to tides and if your going against it you can struggle to get to your destination. Lets say you sail at 4 knots to windward yet the tide is moving at 2 knots, your are therefore effectively only sailing at 2 knots towards your destination.
Sometimes this just can’t be avoided so before you leave know what the tides are doing and how the water flows in the area you are sailing in. Secondly sail in the shallowest water possible for this is where the tide is the weakest. This might mean tacking close to the shore rather than sailing out into deeper water and then tacking back. It’s a simple point to keep in mind and can help you.
The opposite applies to sailing with the tide, here you want to sail as fast as possible and the tide will help this so sail in the deeper water.
As an aid to sailing one of the best investments you can make is adding a wind indicator to the top of the mast. Called a Vind vane they are arrows that point in the direction of the wind and make knowing where the wind is much easier. The ones we use come with a socket that you can rivet to the top of the mast. The Wind Vane then plugs into it. Remove after each sail.
It will have 2 tabs with it, do not use these, as the mast rotates they never work. You just need the arrow. You can buy the Ronstan model shown here from Sunstate Hobie or Whitworths sell a more up market product.
When fitting either rivet or screw the plug into the side of the mast at the top. ensure the tip of the plug is inline or slightly below the top of the mast.
Wind Ranges and Terminology.
Firstly Windward means the side of the boat the wind is coming from and leeward means the opposite.
The image below shows the different types of sailing the the terms used to describe them. The Dead areas are the region into the wind where we simply cannot sail due to the fact that the sail needs the wind to flow over it. The Dead area downwind simply refers to the slowest area of wind to sail in. You can do it but you will go faster by sticking to the right angel. This is where the wind indicator comes in handy. Up wind it pretty easy to gauge the wind direction as you have the tell takes but reaching and downwind is hard and the wind indicator or wind vane as it is know will be a very valuable aid.
Some of this can appear daunting as sailing is actually a science as well as a sport and we can get over whelmed with all this information. So the take it slowly and learn how to sail the boat upwind first and keep those tell tales streaming backwards by steering the boat. It will take you 2 sessions to get the hang and feel of it but you will do it. There is a special place sailing upwind called the Groove, and this is when the sails are trimmed perfectly, the angle to the wind is perfect and the boat just wants to go without any effort. Once you find this you will have found the fastest point of sail upwind.
Learning to trim the sails downwind and reaching is a bit more difficult but the difference here between good and bad sail trim is so tiny it’s not as critical as sailing upwind fast. The easiest ways I teach people to trim the sail is to ease it out till it flaps, then pull it in till it is firm. This will work and get you going and is the simplest solution for Reaching and Downwind Sailing. Flapping is slow, full is fast.
This article is written by Alistair Kelsall- Sailing Captain for the South East Queensland Hobie Island Club and is not to be reproduced for altered in anyway.