Diagrams will be added shortly...
Photo: Ding Hao our Dash 750 that we develop our ideas on. In this case heading on a fetch in one of the Club Series. First thing to note, weight placement. Lightwind, upwind move the crew forward & leeward to get the nose in and the boat flat on its water line.... A long water line is fast upwind.
The Corsair is a great platform. It's not a race boat but what it is, is a very good platform that anyone can enjoy. Especially the 750 series as that is like the Swiss army knife of the trimaran world, it can do it all! If you aspire to have better performance you are going to have to understand some basics, but don't let that scare you. Remember, these are the notes that work together with our training course.
We'll keep the basics of boat handling to these 4 things.
1. Apparent wind - if you can't get your head around this one, you won't progress far
2. Sailing a true course - easier said than done
3. Tacking - needs to be second nature
4. Gybing - needs to be better than second nature
1. Apparent versus True Wind
Apparent wind is everything on a fast multihull and is the biggest component of being a ‘fast’ sailor.
The wind when you are stationary is called True Wind and will blow from a True Wind angle.
Apparent Wind is the ‘wind’ that you feel as soon as you start moving. To highlight, on a totally windless day the moment you start moving you will feel ‘wind’. It’s really you moving through the air molecules but has the same sensation as ‘wind’.
Next step up.
If you stand sideways to the True Wind and hold a flag in your hand the flag will be pointing sideways at the TW. It will do this for as long as you are stationary. Now, walk forward at the same speed as the wind and the flag will begin to point at an angle away from you. If you move at exactly the same speed as the wind the flag will be at 45 degrees from the direction of travel - that is apparent wind!
Apparent wind is the component of our movement ‘added’ to the component of True Wind. So in the case above it is, 1 unit sideways 1 unit forward (45degrees). If we doubled our speed and kept the True Wind the same it would be 1 unit sideways 2 units forward or 30 degrees. If you map it out, as soon as you move the ‘wind’ swings forward. The faster
Translate this to the deck of the Corsair
We start at 0 boat speed, as soon as we start moving the wind will swing forward.
Having the ability to sail above wind speed gives us a big boost as it swings the wind. Speed up, the wind swings ahead. Slow down and the wind swings aft again. That bit you need to really grasp as this is constantly going on.
Start on a nice close hauled course, we sheet the sails in firmly to get the boat heading upwind. Once we hit the target speed it should just be a matter of keeping the boat sailing in the groove and maintaining a constant speed/heading. Simple.
Considering that the wind speed doesn’t change, if we bear away just a little (1 to 2 degrees), the boat speed will increase. As the speed goes up, the wind angle will swing forward a little more. At this stage, if you are watching the tell tales in the sail, the inner ones will start to point upwards telling you to bear away. Most folks will follow this and bear away. Again the boat will accelerate even more and you will compensate by bearing away more… so on and so forth. At this stage you will probably be 15 - 20 degrees below the heading that you started on and that's the biggest beginner's mistake!
There are a couple of key indicators of this,
The heading keeps bearing away
The speed increases to a point where the sail completely stalls and boat speed tails off.
To get this aspect well in hand, you need to be able to steer an accurate course upwind. Accurate means a +, - window of 2 degrees. Watching beginners, I’d say the average steering error window is 20 degrees.
For every wind strength/sea condition, there will be an optimal angle to sail upwind at.
It is downwind that understanding apparent wind can give us the biggest advantage! Upwind apparent wind swings take us below our heading. Going downwind this works out as sailing a shorter distance to the downwind mark.
We see this all the time!
Scenario: Sailing from A (upwind mark) to B (directly downwind mark)...
A boat without a spinnaker heads straight downwind from A to B. In traditional terms, this was called wing-&-wing as the mainsail and jib are on opposite sides of the boat. This is the shortest distance from A to B, direct on the rhumbline.
A beginner with the spinnaker up and blazing is going at reaching angle, almost perpendicular to the rhumbline. Spinnaker up sailing fast and zip zip, 10 gybes later still no closer to the B mark and even worse, still behind the boat that didn’t even put the spinnaker up! I’ve seen it countless times.
All that speed through the water doesn’t help if you are not aiming at the ‘B” mark!
The success you have on every leg depends on the Velocity Made Good. No use having heaps of Velocity if you are not pointing it at the mark (Made Good). In fact this is a whole subject that we’ll cover much later in the Advanced Mode.
So, what is supposed to happen is…
You set the boat up for a good broad reach get a nice deep course, set the spinnaker and get it filled. Take a note of the boat speed (not an instrument, just in your mind). Every time the boat accelerates above your Target speed, just gently bear away. If you do it gently enough, you will be able to sail a deeper heading i.e. one more towards B mark.
Beginner Mistake one
We start off at a nice deep broad reach angle, the boat accelerates the helm bears away either
(a.) to rapidly and the boat stalls as the apparent wind doesn’t match the rate of turn
(b.) steers nicely but keeps on bearing away until the spinnaker collapses
The correct idea is to bear away firmly but smoothly all the while keeping an eye on the luff of the spinnaker and feeling when the boat speed levels off and then drops. Once the boat speed levels off, there’s no need to keep bearing away.
2. Sailing a true course - easier said than done.
In section 1. Apparent wind, you will have already come across references to steering. Every time we sail a performance oriented multihull (def: one capable of sailing above wind speed), we are always sailing the Apparent Wind. The steering has to match all the we are doing to the wind.
To kick things off, we say that sailing a great course (upwind or downwind) at speed is a matter of staying in a +,- 2 degree steering window. That does take a lot of focus!
Initially, beginner helms will wander all over the place sailing to low upwind and to high downwind are the most common mistakes.
Exercise: On any given day with a relatively steady breeze, sail upwind. Pick a comfortable speed to sail at. On the Corsair 750 we can easily do 7 knots upwind (normal for winds of 6-10 knots). Be mindful of the boat speed, any increase in boat speed (without the wind changing) indicates that you are “bearing away” so head up a little. Conversely, if you feel the boat speed dropping then you’ve been “heading up” too much. Try to focus on keeping the speed as constant as possible.
It’s just the reverse downwind. If your speed is going up, you need to put the heading down (bear away a little bit). Going to slow, come up a little…
It all sounds simple but it’s going to take a lot of hours on the water!
The absolute best way to practice all this is on the race course with other boats of the same class. We use the Changi Sailing Club weekend as the best place to start as the are enough Corsairs on the water and its friendly racing.
You’re going to do this a lot, so better get used to it and polish it up!
The great thing about a trimaran is that it can really spin on a dime! With every little in the water, the platform will easily pivot around the daggerboard.
The first thing to know
The mainsail is located behind the daggerboard. If you sail the Corsair without the jib up, you should feel a bit of weather helm (the boat wants to head up into the wind). In engineering terms, the Centre of Effort of the sail is located behind the Centre of Lateral Resistance. Simply put, this creates a tuning moment into the wind.
So making a great tack starts with, having the mainsheet in. If it’s not in, the boat will probably turn albeit a lot slower than if you pull the sheet in.
There are a lot of owners coming into our fleet from dinghies and the first thing they do is, push the helm hard over and head for the other side of the boat.
What you need to do is,
Feed the helm in firmly but smoothly. Don’t shove the helm all the way over!
Initially use 30% rudder and then as the boat slows, give it some more
Don’t cross sides yet and as the boat gets head to wind you will watch the jib backwind
Pause the backwind on the jib for a second or two then,
Put the helm back to centre to prevent oversteering
Get the jib sheeted on to the new side
Let the boat recover then change sides
A good tack A lot of folks assume a fast turn is a good tack but in reality,a smooth turn, not too slow, not too abrupt.
4. Gybing - needs to be better than second nature
The difference between a tack a gybe, with the tack the boat speed will naturally slow down. A really well executed gybe will lose only a bit of speed so there’s more to lose when you foul up a gybe!
This assumes we are always flying the spinnaker downwind.
As with most things, you are only as good as your weakest link and in the case of the gybe, how your crew control the spinnaker is the weakest link. If you turn before the crew are ready, it’s a mess!
Start the bear away with a firm/gentle pull on the tiller
Make sure the traveler is cleated so that it won;t run from side to side
Initially use about 30% rudder
As you bear away, make sure the spinnaker trimmer eases the sheet so that the clew of the spinnaker flies to a position slightly ahead of the forestay.
Watch the trimmer as you bear away, if they don’t run the sheet don’t turn anymore.
Assuming the trimmer has the clew in the right place, pull another 30% rudder to c complete the gybe
As the sails come to the new side, put the helm to centre to prevent over steering and give time for the trimmer to get all the new spinnaker sheet onto the winch and hauled in
Once you confirm that the sheet is under control, head up slightly to get the kite filled and accelerate away.
Absolutely, bearing away and not paying any attention to the spinnaker and trimmer.