Intermediate Sail Trim Flashcards
What is twist in sail trim?
The angle between the true and apparent wind
The difference between angle of attack at the foot, and near the head of the sail
The angle between the mast and the boom
The listing of the boat in a seaway
The difference between angle of attack at the foot, and near the head of the sail
Because the wind near the head of the sail is stronger, the apparent wind there is a few degrees aft of where it is near the foot. For the entire sail to be properly trimmed, it must accommodate the angle of attack as it changes with height: the sail must have twist. Refs: CCME p 72, BCME p68
What is the most common way to increase twist in a mainsail?
Easing the traveller to leeward
Tightening the vang
Easing the mainsheet
Tightening the halyard
Easing the mainsheet
Easing the mainsheet is the most common way to increase mainsail twist and reduce weather helm and heeling. Ref: BCME p. 68.
When sailing at 6 kts of boat speed, your wind instrument indicates that the apparent wind speed (AWS) is 15 kts at an apparent wind angle (AWA) of 40°. What is the approximate true wind speed and angle?
7 kts at 60°
9 kts at 30°
11 kts at 60°
17 kts at 70°
11 kts at 60°
No nav instruments required for this one, the key is the relationship between true and apparent wind. With wind forward of the beam, AWA is less than TWA, and AWS is greater than TWS. TWA must be greater than 40°, and must be less than 15 kts. With a boat speed of 6 kts, the only reasonably correct answer is “c. 11 kts at 60.” Ref: BCME p 70
Weather helm is when:
The weather deteriorates and it’s difficult to steer
The boat has a tendency to head up toward the wind
The helm is lashed to the side and the sails are backed during a storm
The boat has a tendency to bear away from the wind
The boat has a tendency to head up toward the wind
A boat with weather helm will tend to head up into the wind. A little weather helm is beneficial as it gives some re-sistance to work against when steering, and allows the boat to head into wind and slow the boat if the helmsman must leave the helm. Ref: CCME p 60
When sailors talk about VMG to a waypoint, what are they talking about?
The time expected to arrive at the waypoint
Very Many Gusts
The component of velocity applied toward a waypoint
The angles and waypoints involved in celestial navigation
The component of velocity applied toward a waypoint
Velocity Made Good (VMG) is determined by the boat speed and the angle to the wind at which the boat is sailing. VMG to a waypoint is the component of speed applied towards that waypoint. Ref: BCME p 70.
You are sailing along on a steady course on a close reach. How will a sudden gust of wind affect your boat? It will: (Select all correct answers)
Cause the apparent wind to decrease and move forward
Cause the apparent wind to increase
Possibly create more heel and possibly induce more weather helm
Induce lee helm
Cause the apparent wind to increase
Possibly create more heel and possibly induce more weather helm
A sudden gust of wind is an increase in true wind. With no time for boat speed to increase, the apparent wind increases in speed and moves aft. If sail trim is unchanged, the boat will be overpowered and will likely experience excessive heel and weather helm. Be ready to ease traveler and/or mainsheet, or feather the boat. BCME p 71.
Under what conditions should you consider reefing?
When a small craft advisory is imminent
When your crew suggests reefing
When all neighboring boats are reefed
When de-powering techniques are no longer sufficient
When a small craft advisory is imminent
When your crew suggests reefing
When all neighboring boats are reefed
When de-powering techniques are no longer sufficient
You should consider reefing in all the conditions stated, but certainly when de-powering techniques are no longer sufficient to control the boat. Ref: BCME p 75.
The depth of a sail at any given height is defined as:
Another name for the chord
The angle at which the apparent wind strikes the chord
The longest perpendicular distance from the sail to the chord
The vertical curvature of the sail from head to foot
The longest perpendicular distance from the sail to the chord
The chord is a straight line from leading edge to trailing edge, parallel to the boom. Depth of a sail at any given height is the longest perpendicular distance from the chord to the sail. Ref: CCME p 72
Select all the methods that could be used to reduce weather helm whilst sailing close hauled:
Bear away to increase apparent wind
Ease the vang and mainsheet to create twist
Furl the jib to reduce sail area
Ease the traveller to leeward
Ease the vang and mainsheet to create twist
Ease the traveller to leeward
The most common cause of weather helm is too much sail power, typically from the mainsail. To depower the mainsail, ease the traveller to leeward and/or ease the mainsheet to spill the wind. Easing vang and mainsheet creates twist, which depowers the mainsail by spilling wind from the top of the sail. Ref: CCME p 73, BCME p71
In stronger winds, what is the easiest method to reef a furling jib?
Start the engine and head directly into wind
Head up to a close reach to increase apparent wind
Bear away to a broad reach and ease the mainsail and jibsheet
Point of sail doesn’t matter if you use the winch to furl
Bear away to a broad reach and ease the mainsail and jibsheet
Bear away and ease the mainsail, trimming to a broad reach. This blankets the jib, which can then be easily furled by easing the jibsheet and pulling the furling line. Ref: BCME p 66.
After reefing the jib by roller furling, what else should be adjusted?
Ease the halyard when furling the jib
Move the jibsheet car aft
Trim the jibsheet harder
Move the jibsheet car forward
Move the jibsheet car forward
When the jib is reefed, the clew moves forward. That makes it necessary to move the jibsheet lead forward to bal-ance the tension in the foot and leech of the sail. Ref: BCME p 75.
To reach an upwind destination in open water, you should tack:
As often as possible to keep the crew busy
Only when absolutely necessary
Only to avoid stand-on traffic
When the opposite tack will result in a course that is closer to the destination
When the opposite tack will result in a course that is closer to the destination
When wind, current and safe navigation permit, you will reach your upwind destination more quickly by sailing on the tack that points you closest to your destination (closest tack). Ref: BCME p70
You are sailing upwind in light air conditions and the wind speed increases a few knots to moderate conditions. What are some adjustments you might make to the mainsail? Select all correct answers.
Tighten the outhaul to flatten the foot
Tighten the halyard or cunningham to bring the draft forward and flatten
Ease the adjustable backstay if available
Ease the traveller to set the new angle of attack
Tighten the outhaul to flatten the foot
Tighten the halyard or cunningham to bring the draft forward and flatten
Ease the traveller to set the new angle of attack
