August 2017 - The Luffing vs Mark-Room at a Leeward Mark

placeholder image

August 2017 - The Luffing vs Mark-Room at a Leeward Mark

This month I will discuss two sets of actions – frequently seen when boats approach a leeward mark – and their consequences. In the diagram, Blue and Red are both sailing downwind on port. The diagram shows them with spinnakers, but the issues are the same in a whitesail race.


Red is sailing directly downwind; Blue is reaching a little more. The boats are overlapped and since Blue is leeward boat, Red must keep clear of Blue to comply with rule 11. We don’t know how the overlap was established, but if it was established by Blue from clear astern within two boatlengths of Red, rule 17 would then have applied. However, it doesn’t apply anymore, since at position 1, the boats are more than two boatlengths apart. Accordingly, since Rule 17 either never applied or no longer applies, Blue is allowed to sail above her proper course. They are not yet in the zone, so mark-room does not apply.

 

From here, two possibilities play out. Blue has the right to luff Red up, thereby taking her away from the zone. At position 5, the boats get close but Red does not respond, so by position 6, Blue is forced to alter course to leeward to avoid a collision. Red has broken rule 11 and Blue protests.

 

A second possibility – Red mobilizes one of two possible defences. The simplest is to get to the zone before Blue approaches. As soon as one of the boats touches the zone – which Red does just before position 7 – rule 18.2 starts to apply. Since Red is entitled to mark-room according to rule 18.2(b), Blue must now adjust her course to allow Red “to sail to the mark” (directly).

 

Many make a mark-room call far too early. If you know your speed, it isn’t too hard. One knot is about 1.7 feet per second. A 35-foot boat travelling at 5 knots takes a bit more than 4 seconds to travel 1 boatlength. So 12.5 seconds should elapse between an accurate call for room and the bow being level with the mark. If, on the other hand, it takes 30 seconds, your call came more than 7 boatlengths out – 4 boatlengths early. In the same 30-second interval, an Optimist travelling at 4 knots would have gone 25 boatlengths – a bit too generous.

Red’s second possible defence is to gybe onto starboard near position 2 – a simple option since she is sailing directly downwind. Once Red is on starboard, Blue – on port, remember – has to keep clear. Either way, Red is in the clear.

 

The things to remember are, if you are Blue, your luffing rights are powerful, but only if you meet the conditions that grant them. If you are Red, your defences are equally powerful, but only if you remain aware of what nearby boats are doing and act in good time.
 


 

Mark-Room Room for a boat to leave a mark on the required side. Also,

 

room to sail to the mark when her proper course is to sail close to it, and

room to round the mark as necessary to sail the course.

 

However, mark-room for a boat does not include room to tack unless she is overlapped inside and to windward of the boat required to give mark-room and she would be fetching the mark after her tack.

 

Room The space a boat needs in the existing conditions, including space to comply with her obligations under the rules of Part 2 and rule 31, while manoeuvring promptly in a seamanlike way.

 

Zone The area around a mark within a distance of three hull lengths of the boat nearer to it. A boat is in the zone when any part of her hull is in the zone.

 

11    ON THE SAME TACK, OVERLAPPED

When boats are on the same tack and overlapped, a windward boat shall keep clear of a leeward boat.

 

17    ON THE SAME TACK; PROPER COURSE

If a boat clear astern becomes overlapped within two of her hull lengths to leeward of a boat on the same tack, she shall not sail above her proper course while they remain on the same tack and overlapped within that distance, unless in doing so she promptly sails astern of the other boat. This rule does not apply if the overlap begins while the windward boat is required by rule 13 to keep clear.

 

18.2    Giving Mark-Room

When boats are overlapped the outside boat shall give the inside boat mark-room, unless rule 18.2(b) applies.

If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room.

When a boat is required to give mark-room by rule 18.2(b),

she shall continue to do so even if later an overlap is broken or a new overlap begins;

if she becomes overlapped inside the boat entitled to mark-room, she shall also give that boat room to sail her proper course while they remain overlapped.
 


 

© Copyright 2017 Andrew Alberti

Posted: 4/29/2019 9:26:04 AM by Andrew Alberti | with 0 comments


Trackback URL: https://rcyc.ca/trackback/3cc3efeb-4b72-4eeb-94ca-09de4d2600b7/August_2017_-_The_Luffing_vs_Mark-Room_at_a_Leeward_Mark.aspx?culture=en-US

This page provides links to a set of articles original published in Kwasind magazine. The versions here include animated diagrams. The original articles can be found within the original magazines which are available online back to January 2007. 

Articles before December 2020 are based on the Racing Rules of Sailing 2009-12 or 2013-2016 or 2017-2020 and have not been updated to reflect the changes that apply as of January 2021 with the publication of the Racing Rules of Sailing 2021-24. A copy of the new rules can be found on sailing.org.
ABOUT ANDREW ALBERTI
Andrew Alberti has been writing these monthly articles in the Kwasind since early 1997.  They explain the Racing Rules of Sailing. Andrew is an International Judge and National Umpire. He is a member of the Sail Canada Rules and Appeals Committees. The interpretation of the rules contained in the articles is Andrew's and not that of the RCYC or any of the committees he sits on. 

QUESTIONS & ANSWERS
Send your questions to Andrew at kyrules@alberti.ca.

 

ABOUT RCYC: 
166 Years of Tradition | World-Class Sailing | Toronto Island & City Clubhouse
 
Tacking II
Publication Changes and Tacking
How to Finish
Required Hails
Penalties and Sportsmanship
Post Archive
March 2024(1)
February 2024(1)
May 2023(1)
September 2023(1)
September 2023(0)
May 2023(0)
January 2023(1)
April 2022(1)
December 2021(1)
October 2021(1)
August 2021(2)
March/April 2021(1)
January/February 2021(1)
December 2020(1)
November 2020(1)
September 2020(1)
July 2020(1)
June 2020(1)
May 2020(1)
March/April 2020(1)
January/February 2020(1)
November/December 2019(1)
September/October 2019(1)
July/August 2019(1)
May/June 2019(1)
March/April 2019(1)
January/February 2019(1)
November/December 2018(1)
September/October 2018(1)
July/August 2018(1)
May/June 2018(1)
March/April 2018(1)
January/February 2018(1)
November/December 2017(1)
October 2017(1)
September 2017(1)
August 2017(1)
July 2017(1)
June 2017(1)
May 2017(1)
April 2017(1)
March 2017(1)
January/February 2017(1)
December 2016(1)
November 2016(1)
October 2016(1)
September 2016(1)
August 2016(1)
July 2016(1)
June 2016(1)
May 2016(1)
April 2016(1)
March 2016(1)
January/February 2016(1)
December 2015(1)
November 2015(1)
October 2015(1)
September 2015(1)
August 2015(1)
July 2015(1)
June 2015(1)
May 2015(1)
April 2015(1)
March 2015(1)
January 2015(1)
December 2014(1)
November 2014(1)
October 2014(1)
September 2014(1)
August 2014(1)
July 2014(1)
June 2014(1)
May 2014(1)
April 2014(1)
March 2014(1)
January 2014(1)
December 2013(1)
November 2013(1)
October 2013(1)
September 2013(1)
August 2013(1)
July 2013(1)
June 2013(1)
May 2013(1)
April 2013(1)
March 2013(1)
January 2013(1)
December 2012(1)
November 2012(1)
October 2012(1)
September 2012(1)
August 2012(1)
July 2012(1)
June 2012(1)
May 2012(1)
April 2012(1)
March 2012(1)
February 2012(1)
January 2012(1)
December 2011(1)
November 2011(1)
October 2011(1)
September 2011(1)
August 2011(1)
July 2011(1)
June 2011(1)
May 2011(1)
April 2011(1)
March 2011(1)
February 2011(1)
January 2011(1)
November 2010(1)
October 2010(1)
September 2010(1)
August 2010(1)
July 2010(1)
June 2010(1)
May 2010(1)
April 2010(1)
March 2010(1)
February 2010(1)
January 2010(1)
RSS