Boston Harbor Sailing Club...More Time on the Water...

Lesson Learned

Wakes

We sail in Boston Harbor that has a lot of medium to large ship traffic. These boats generate a wake. The bow wave portion of the wake is easy to see, a series of waves. The second part is the stern wake, the turbulent water left in the path of vessel. This is sometimes not that easy to see as it tends to be flat water.

  Bow Waves from the Large Vessel.

Sailing  Windward,

When sailing through the bow wave portion, what one does depends upon the wind conditions, the direction of the wave relative to the wind and the course you are sailing.

1. If you are sailing to weather and the waves are coming toward you, you will have to power up so the waves do not stop you. Bear off a few degrees and ease the sails. The lighter the air, the more you will need to power up. In heavy air all you may to do is steer through the waves.

2. If you are sailing to weather and the waves are coming abeam, you will have to power up because the waves will rock the boat and destroy the air flow over the sails. Once the waves are past, get the boat back up to speed before re-trimming

3. If you are sailing to weather and the waves are coming from behind they may push you forward. In light air this may cause the apparent wind to go forward for a moment and the sails to luff. This is not a header, just hold your course. After the waves have passed you may have to head down and power up to get back up to speed.

Sailing Downwind.

1. If you are sailing downwind and the wave are coming toward you, head up and power through the waves.

2. If you are sailing downwind in a breeze and the waves are coming from behind and they are large you may be able to surf. When the waves lift the stern of the boat, steer the boat down the face of the wave. When the wave lifts the bow, steer diagonally up the face.

 

 
  Stern Wakes from a Large Vessel.

Do not worry about the stern wake from other Solings or any of the other sailing vessels in the Harbor, they are small. The stern wakes to worry about come from the tugs, ferries, large power boats, and tankers. These wakes are turbulent water. The amount of the turbulence slowly decays over time. It is possible to see the wake as it appears as smooth water and there is a clear demarcation between the wake and the unaffected water shortly after the wake formation. The demarcation also decays over time. The larger the vessel creating the wake, the longer the time. After 10 minutes, most wakes are gone. The keel of a sailboat provides lateral resistance that keeps the boat from sliding to leeward. The detailed hydrodynamics are quite complicated. However, it works well when the water is not turbulent. The turbulence from a wake degrades the flow around the keel. This is felt as the boat slows down and the helm feels mushy. If you must cross the wake going to weather, power up by easing the sails slightly and not pointing as high (At most 5 degrees). Again, the lighter the wind, the more this is a concern. Given a situation where tactically is it is even to cross w wake sooner or later, cross later.

 

 

Anyway - Power Boats making  big wakes always cross ahead
when going to windward.  (John Clark).

Written by Alan Palevsky.  Any comments? Send me an email

Lessons Learned

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BOSTON HARBOR SAILING CLUB
Mailing Address: 71 Commercial St #262 Boston, MA 02110
Sailing operations: The Private Marina at Rowes Wharf
Telephone: 617-720-0049 | E-mail: info@bostonharborsailing.com


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