Weather Limit - Wind Reading - Rule Change Proposal - Snipe Class International

Weather Limit – Wind Reading – Rule Change Proposal Image

Rules Change – Submitted Proposals

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From Antonio Bari and Pietro Fantoni

Summary: Weather Limitations – Wind Reading

Affects:

Constitution By-Laws Class Rules

Deed of Gift Rules of Conduct NoR or SI Template

Other

Objective:

Proposal (include current & proposed changed wording- changes to be shown in red): Example: By Laws: Section 1. Racing Season

The official racing sailing season of this Association shall extend for the full twelve months of the year starting on January 1^st and ending on December 31^st.

Rules of Conduct For Conducting National and International Championship Regattas

Weather Limitations (Course and Starting)

…[omissis]…

9.3 Wind reading instruments shall be between 2 and 3 meters above the surface of the water. The duration of reading shall be 3 consecutive minutes prior the race warning. The wind reading shall be taken from an unobstructed area on the boat, it is recommended that there be a minimum 4 meters of free space surrounding the wind instruments. If during the race the wind speed goes over the maximum wind speed allowed for more than 5 3 consecutive minutes the race shall be abandoned. If frequent heavy gusts go over the limit even for less than 3 consecutive minutes, the Race Committe and the SCIRA representative, for ensuring a fair and safety race, may decide to not to start or abandon the race.

For Masters events … [omissis] …

Reasons: With this proposal we want to guarantee fair and safety races, avoiding unnecessary damages on the boats.

Currently a race shall be abandoned if the wind speed exceeds the maximum for 5 consecutive minutes, but it often happens (and it seems happened in several events last year) that the puffs/gusts last less than 5 minutes, but are very frequent. Now, under the current rule, the RC cannot abandon the race but the teams are actually racing in winds above the max limit.

We say: base wind at start 24 knots; 3 minute gust at 30, 2 minutes at 22, 4 minutes at 27, 2 minutes at 20, 3 minutes at 28. The race can’t be abandoned but you are sailing in winds stronger than allowed.

The problem is when the wind is very gusty, with huge difference between the average wind speed and the gusts (particulary with an offshore wind or when we are sailing in an area surrounded by land). When almost half of the fleet is forced to abandon the race due to boats problems is not (only) a problem of skills of the sailors or lack of mantainance on the boats, but it is a knockout competition

15-05WeatherLimit_WindReading_1.pdf

Viktor Sinding-Larsen

11/16/2016 - 19:48:15

The force on the sail from the wind speed is also affected by the density of the air. Cold air is heavier than warm air. Cold air cause higher force on the sail according to Bernoulli`s Equation. Dynamic force in Pa =1/2 m v^2
m = air density kg/m^3
v = m/s
Force = N/m^2 = Pa
N = newton kgm/s^2
Air at 5 grad C is approx.10% heavier than air at 35 grad C.
Density of air at 5 grad C is 1,27 kg/m^3
Density of air at 35 grad C is 1,15 kg/m^3
A gust with 5 seconds duration is sufficient time to turn the snipe upside down according to my experiance.

A gust with 3 minutes duration can cause a lot of capsized snipes. A gust is much shorter time than 3 minutes.

Therefore:are
Be more restrictive by cold air regarding maximum accepted wind speed.
Take notice to the fact that a gust with 5 seconds duration can turn the snipe upside down.
If the gusts also arrive with different direction or angle towards the sail, it is more difficult to sail and to avoid a possible capsize.
Some times the gust direction is not parallell with the sea level,

Regards
Viktor Sinding-Larsen