Castle Semple Sailing Club

Sailing at Castle Semple means dealing with lots of gusts,  wind direction changes and wind power changes.

Most sailors lose time to this, going sideways and slowing down on every gust.

Let consider what most sailors do.

-Sailing along flat, then gust comes
- Boat heels
- Both crew and helm hike like hell until the boat comes back almost flat
- They both get the sensation of speed

Actually this is dead slow and every time this happens you lose out. The sensation of speed is fooling you. As the gust comes the boat becomes overpowered, as it leans in the water the following happens:

1. the shape of the boat in the water is no longer symmetrical and is banana shaped . This causes the boat to steer into the wind. To counter this the helm pulls on the tiller to bring the boat back in line. The rudder acts as a massive break slowing the boat down.

2. As the boat leans the rudder and center board become less effective. Remember their job is to “suck” you into the water keeping the boat on its close hauled course. As the boat slides sideways the centerboard stops working as effectively and your boat just slips sideways away from the mark you are heading for.

3. Your boat is now going slower and working less effectively so if a second big gust come it can easily blow you over.

90% of all sailors sail like this. It is so slow.

Here is a technique that I use that makes me go faster, not slower in gusts, so relatively to others thats a double gain.

As the gust hits, my first job as I sense the boat start to heel is to ease and armful of main sheet. I do this very aggressively. This keeps the boat flat and stop the heel

Now I very carefully adjust the direction of the boat into the wind by a few degrees, letting my jib luff (flap) a little. I then hike hard (asking my crew to do the same, the boat is flat, so you need to trust the helm) as I hike out the boat I pull the main sheet  back to the centerline with a quickly pump. As I do this my boat gets a boost through the water. I have measured this with a GPS. A gentle heel slows the boat by 1kt, but a aggressive mainsheet ease and pump adds 1kt to my boat speed for a short period. As the gust dies off. I slowly return the boat back onto the wind and back to a normal course. I gain speed and distance upwind in one go.

If you practice this technique you can watch yourself go faster and sail higher than other boats on the beat.

Johnathan

As strong wind is forecast for the weekend I thought I’d add some hints and tips about sailing in strong winds.

First thing to understand is that we need to set the boat up to sail in its sweet spot. Too much power and we will not be able to control it – which is slow, too little power and we will have no boat speed.

Each boat has suggested rig setups, but as  general rule the windier it is the more we want to rake back the mast. Why? To flatten the sails.

Think about when you last flew on holiday. As you approach landing you will notice that the wings of the plane wings increase in size as the flaps are lowered. As the flaps come out they change the shape of the wings from a very flat, shallow aerofoil shape to a deeper more pronounced curved.

The plane does this so that it can fly slower as it approaches the runway, so now it can remain in the air still generating lift at  just 100MPH instead of 300MPH.  If it tried to fly at 300+MPH with the flaps down then the wings would generate too much drag and would not work very well. If the plane slowed down to 100MPH without the flaps the wing would stall. generate no lift and the plane would fall.

So a deep aerofoil is good for generation lift at slower speeds but at faster speeds this creates too much drag and the faster airflow creates plenty of lift off a flatter shape.

It’s the same in a sailing boat, but instead of the speed through the air that governs the optimum aerofoil shape of the sail it’s the wind speed.

In windy conditions sails that are too deep (sometimes called “too full”) and create drag. That drag causes the wind to detach from the sail instead of flowing around it. The result is mass instability and a boat that wants to throw you in the water.

The solution is to flatten your sails, just like the plane doing 500MPH. Raking your mast backwards by changing the pins on your shrouds forces your mast into a banana shape. This pulls the “bag” out of the middle of your main flattening it.

On the water if you are overpowered swing on your outhaul and get it as tight as you can – again flatten the foot of the sail. Then pull your kicker on tight. TIP: Try to align the top batten of you main with your boom. Finally consider Draft.  Normally as the wind increases the deepest part of the main sail is pushed further aft. This is slow and creates lots of drag and instability. You must move the deepest part of the sail forward towards the mast. As a rule most sails are cut so they work best with the deepest draft being 40% of the way down the mast. Use the Cunningham pulling until the draft is correct again.

Remember “Flat is fast”, heeling over feels fast, but is very slow.

Johnathan