SEPTEMBER 19, 2017: WIND AND WAVES

WIND AND WAVES

Since I was not out for Tuesday September 19, I will not attempt to write a recap of the activities. I understand there were 10-12 boats out for the fun.

TUESDAY SEPTEMBER 26 IS BARBECUE NIGHT AT THE CLUB AFTER THE RACE. BRING YOUR BEST GRILLING FOOD.  BAR WILL BE OPEN!

For years, I have noticed that you can use waves to your advantage while going downwind. This does not always work, which has been a mystery to me.  Several months ago, I wrote a piece about using waves to your advantage.  I shared this piece with a few of my friends and had a great exchange expounding on this occurred. I would like to share this with you.

Waves and sailing

I came from a surfing background and when I took up sailing a Hobie Cat I always enjoyed surfing my Hobie.  Santa Cruz has a long point used by surfers.  When riding my Hobie, I would beat to weather for 20-30 minutes until a mile outside off the point.  At this point the wind was so strong, I would usually “chicken Jibe” and as a wave would approach, I would set my sails so they would be in trim after I made my drop down the face and made my bottom turn.  At the moment the wave would be ready to pop me out the back, the sails would POP into trim and I could ride the wave all the way to the beach for over a mile long ride. I did this over and over again.  It did not matter if the wave was a one foot wind chop or an 8 foot swell it all worked the same.

Mechanics of Surfing:

You never see a competent surfer surfing a wave straight to the beach.  Surfers always ride in a way so the board is basically parallel to the wave face surfing down the line.  This is much faster than riding straight to the beach.  Riding straight to the beach results in speed only as fast as the wave is travelling.  Riding sideways can lead to incredible bursts of speed depending on the speed of the breaking wave and the power of the surf.  When I am sailing I try to achieve the same feat that surfers do, surfing sideways down a wave. 

Sailing with waves:

Sailing in an ocean environment lends itself to skillful use of waves. In this setup, what you do with waves has a lot to do with your race results. Every boat is different.  Every day has different conditions.  Heavy wind, heavy short chop or long ocean swells, light wind and big waves.  Every day requires a different approach.  It is critical to recognize the conditions and apply different approaches for each.  My experience is now sailing on a Catalina 30, a rather heavy, beamy boat.

Sailing to weather Into waves:

The only way to do this in light wind is to not take the waves directly on the bow.  Cracking off 5-10 degrees can often allow you to glide over waves rather than bash into them.  This is even the case if there is heavy wind and heavy quick chop that stops the boat every time a wave hits.  If the waves get a little bigger, I find I can climb straight up a wave face, then take the back of the wave at an angle.  This uses the back of the wave as a longer slope to gather speed for the next wave.  Turning off at an angle, as a surfer would, also give you more power in your sails that helps you speed down the face.  This works for me in my boat in about 20 knot winds

Sailing down wind:

On my boat we do not fly a spinnaker, but we do use a whisker pole on the jib.  When the wind is light, there is not much you can do with my heavier boat.  When the wind gets to 20 knots or so, the game changes.  As I feel a wave begin to lift the back of the boat, I give a quick turn of the wheel to port letting the blade of the rudder take the power of the wave to propel the boat down the face of the wave. Since the water in the wave is moving faster than the boat, this quick flick of the wheel does not turn the boat, but you can feel the energy of they wave pushing the rudder. As I catch the wave, I turn the wheel to starboard using the power of the wind in the sails to increase the time I stay on the wave.  Once again, I do this by going sideways (remember the surfer).  I study the GPS knot meter to see how long I can keep the boat in the wave.  Maintaining a boat speed of 7.5 to 8 knots is the goal.  If you can accomplish this on wave after wave staying on each wave for 5-7 seconds, you can really make some headway.  I know this concept flies in the face of keeping a steady hand on the wheel or rudder, but it really seems to work well for me.

Sailing with waves into the wind:

This unusual occurrence happens when an Easterly wind starts working in Santa Cruz.  I witnessed this once when someone was steering my boat.  It seems the boat never slowed down.  I asked how he did it and he said, you steer down the face of the wave and as the wave is ready to fade and leave you behind, you fall off the wind using the power of the wind to maintain the speed of the boat to catch the next wave.

Conclusion:

It is a fine nuance of sailing, using waves and wind together to propel your boat.  Experiment with it and you may be surprised with your results.

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I got a response to this article from Chris Hofmann which really made sense as to why it doesn’t always work:

Barry,

Good Stuff!   Nice descriptions about the "feel" and finer points in surfing displacement sailboats.   Here are some added thoughts that come to mind.

There is probably some underlying math that could be added to get more precise for different boats that combines a boats polar plot that maximizes boat speed from the direction and velocity of the wind, plus surfing action related to the direction, speed, period, and height  of the waves.

For example sometimes you get the right conditions and everything falls into place on the exact course you want to steer and the surfing seems easy; other times its more of a struggle because everything is not lining up so weel.   Still other times you are just trying to optimize the fastest sailing for the longest period of time on a down wind leg.

In the Catalina 30 16 knots true wind at relative bearing 174 degrees

http://www.catalina30.com/techlib/Polar%20Charts/Catalina%2030%20Polars.pdf

would maximize boat speed and allow you to catch and stay on waves the longest just using the effect of the wind.

The next step would be to determine the direction, period, and height of the of the waves to understand the optimal steering angles and all the finer points that you mentioned that promote surfing on the correct jibe.

The wind and waves don't always line up.   So the result is that port tack relative wind bearing 174 degrees boat speed will be different that starboard tack relative wind bearing 174 degrees.  After rounding Natural Bridges or Wharf mark we often take the port jibe because this promotes the best surfing angle in the stronger winds  and  frequent westerly waves for the "longest leg" of the down wind course to finish or black pt.  In these conditions getting to port Jybe as fast as possible has a big advantage.

But if the wave pattern was more southerly the 174 relative wind bearing on starboard tack might be the favored set up and an early quick jibe at the mark is not so critical.

Usually as we get closer finish/black pt. the wind and waves die down a bit, so we all sail a shorter leg on the other jibe where the combined effects of polar VMG and wave surfing aren't as great.

Because the polar curves are different for different boats the general steering angle and the small adjustments (letting the boat glide down waves v. small or big flicks of the rudder) to promote surfing are going to change.

Hobie 16s are going to want to generally sail closer to 130 degrees where they can almost double their base boat speed, and would allow them to sail a lot longer on a wave with small steering adjustments.

http://www.trifoiler.info/Municipal/index.php?title=PERFORMANCE_COMPARISONS_AND_HANDICAPPING

A Santa Cruz or Express 27 has a pretty flat polar curve at about 170-130 degrees so in certain conditions they max out boat speed sailing anywhere between dead downwind and broad reach.  This mean they have a lot more options for lining up just the right angle on the waves.

http://express27.org/articles/polar

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Thank you Chris for this explanation.

See you at the barbecue this coming Tuesday after the race!

Barry Keeler

Sailing Pair a Dice