SAIL Flashcards
Sailing Theory (73 cards)
1
Q
Sail: forces
A
- II. Newton Axiom: Kinetic Energy (force = mass * accelaration) => max pressure close to mast => keep sail profile in shape
- Bernoulli: pressure differential due to air slowing on luff and speeding up in lee (wind in lee reaches leech earlier than the wind in luff!) => lift
=> air envelopping wing profile: Coanda Effect
2
Q
Lift with
Upwash and Downwash
A
3
Q
Airflow: angle of attack
A
goal: laminar flow; little disturbance => airflow ‘sticks’
angle too small: luff will flutter
angle too big: airflow will tear off => no Coanda Effect
4
Q
Sail Power: vectors
A
SP (Sail Power = Lift) perpendicular to sail and centred in CoG (Centre of Gravity)
PF := Propulsive Force <=> WF (drag)
TF := Transversal Force => leeway
Running: II. Newton
Beam Reach: small TF, large PF
Close Haul: big TF, small PF
5
Q
Sails working together
upwash and downwash
A
6
Q
Forces to windward
A
- weatherhelm from TF (SP) ./. LP
- windward torque
7
Q
Leehelm ./. Weatherhelm
A
relative longitudinal position of transverse force (TF) of Sail Power = Lift (SP)
vs
Lateral Point (CoG of underwater area)
=> most important for upwind
=> balance LP and SP
8
Q
Windward torque
A
most important for downwind
Propulsion Force (FP) of Sail Power = Lift (SP) is outside of centreline, whereas drag is in centreline
- dynamic: increases with drag with ship’s speed and heeling (wetted area in lee increases and SP moves further outside centreline)
- design compensation: place SP in front of LP
- use big foresails on broad courses to counter weather helm
impact: either on forces or on arm
9
Q
Windward torque: influences
A
- heeling
- LP vs SP
- speed of ship
- windspeed
- factors intensifying drag:
* shallow/narrow waters (UKC)
* hull resistance (fouling)
=> adjust the sailpoint to counter
10
Q
Determining Sailpoint
A
- CoG of all sails close hauled
- split in triangles
AREAS: - triangle = 1/2 x base x height
- (otward) curved leech = 2/3 x base x height
Combining Triangles/Sails: - weighed leger lines corresponding with relative areas
- total: 1. foresails; 2. + Mizzen; 3. + Main
11
Q
Twist
A
- higher up: Apparent Wind more astern
- traveller midships: sail pulled down => less twist
12
Q
Trimming
A
- very, very little wind => flat
- little wind => very deep
- lotsa wind => Main flatter (less pressure, less heeling, better balance)
- trim staysail with halyard (tight => draft moves forward) => too tight => vertical fold behind luff => tighter backstay => straighter forestay => flatter sail => pointing higher
Deep Sail: much power, good accelaration, points less high
Flat Sail: less power, points higher
Increasing wind: flatten sail to decrease pressure
Bearing away: use deeper sails
Waves: deep sails for accelaration <=> calm sea => flat sail
13
Q
(Counter) Measures on a weatherly ship
A
1. move SP forward
* extra or larger foresail
* reef mizzen
* trim mast forward
* trim Main flat
* slack off Main / Mizzen sheets
2. move LP aft
* raise leeboards a little (or move the aft)
* move weight/ballast aft
bland ship: opposite measures
14
Q
Staysail: description
A
Yank: staysail upside-down between masts (with wishbone) like on Chronos
15
Q
Schooner Sails: names
A
16
Q
Schooner w Fisherman
A
17
Q
3M schooners
A
18
Q
Schooner: standing rigging
A
19
Q
Rudder
A
- rudder needs water flow
- rudder force = Lift : perpendicular to rudder profile
- drag (BF = Ra) will slow down vessel
20
Q
3 principles why you sail
A
- Newton (F=m * a)
- Bernoulli
- Coanda
21
Q
Angle of attack
(flat vs deep sail)
A
22
Q
Trimming
rules of thumb
A
23
Q
Trim
= react to changes
A
24
Q
Staysail trim
(halyard)
A
25
Names of a gaff sail
26
Gaff: running rigging
27
Cutter Rigg
28
Mast/shrouds/spreader
29
Mast band
= hounds band
halyards/stays not to cross each other
lowest mast band: **hommer**
30
Masts
31
Rake
32
Gooseneck
33
sheet attachment to boom
on a ring to avoid twisting (torsion) of boom
34
Gaff
details/names
35
Blocks
**MBL**: minimum break load
**WLL**: working load limit
WLL = 1/5 - 1/6 MBL
SWL : old
36
Blocks: parts
a) cheek
b) breech
c) cheek = face
d) nail
e) pin
37
Blocks:
inside/outside binding
the whole thing is held togehter by a metal binding or strap, which can be inside or outside
38
Forces in tackles
Force= 1 / Number of running parts
Friction: 5-10%/sheave
39
Shackles: parts
40
Shackles: basics
certified:
green pin: strength&durability; Maker: Van Beest; high tensile steel/galvanized
red pin: tested and certified for industrial use; with high(er) WLL; Maker: crosby
41
Shackles: adjusted WLL due to side load angle
Working Load Limit (**WLL**) is the maximum working load
designed by the manufacturer. (used to be SWL)
**MBL** is Minimum Break **Load**
**WLL**= MBL / 5 or WLL= MBL/ 6
42
winch maintenance
- grease
- replace broken/wornout parts
- train crew on handling
- ensure lines/cables in good shape (twists)
43
Sail handling
principles
- responsibility is the foundation of good seamanship
- sail choice depends on weather, sailing area, seas, course => maintain balance while hoisting, lowering, reefing
44
gaff sail foot / luff
attached foot is preferred to prevent bending stresses in boom and overloading of clew in strong seas
between mast and luff: 1/2 mast diameter space (hoops; **bead lines**)
45
Jigger
46
Hoisting a gaffsail
* Sailbands / -ties loose, on the windward side
* Peekhalyard slightly up
* Topping lift up => lift boom out of the **boom crutch**
* Peek and claw up together
* Sheet a bit out, sail loose but boom steady
* High enough: fasten claw halyard
* Adjust the peek halyard
* Lower the topping lift
* Adjust the sheet
* Adjust the tack
47
Dousing
Lower the sails
* Staysails are easy to douse, especially broad reach
* Gaffsails won’t come down on broad courses, or very difficult
* Sails attached to a rail at the mast will only come down with head in the wind
48
reefing
1. slack sheet slightly
2. topping lift
3. lower sail enough to connect **reef tack**
4. tighten **reefing line**
5. set **reef tackle**
6. haul halyard
7. slacken topping lift
8. adjust sheet
9. pack away lower part of reefed sail
49
Tacking
preparation
- maintain good speed before manoevre
- prepare and man sheets; running (back) stays
- notify crew and **guests**
- haul in mizzen; possibly keep foresail(s) backed
- move running backstays
- don't overtrim foresails on new tack
- big waves: stopping forward movement - dead in irons
50
Gybing
for square riggers: called wearing
danger of booms wearing involuntarily
**essential: you control when the boom(s) move over**
loss of sea room towards lee shore
foreward sails in wind shadow, don't need much crew - aft sheet require the manpower
51
heaving up anchor under sail
not a difficult manoevre - **falling away on the desired tack is the challenge**
52
Orgainization of ship's routines
**Safety
Administration
Operation (nav/eng)
Upkeep (maintenance)**
* Maintenance engineroom
* Corrections in maps
* Maintenance safety equipment
* Maintenance rigging and sails
* Check certificates
* Drills
– MOB
– Fire
– Evacuation
53
ISM for sailing vessels
* **organizing safety**
* system to **structure tasks** on board
* **inventory** of tasks
* structure of **command**
* tool to **coordinate** all activities on board
* MOB
* Fire
* Collision
* Checklist: leaving port
* Maneuvers
* Watch order
54
Instruction
guests
welcome + basic briefing + repeat next day
**tell & show**
* House rules
* Calamities
* Alarm signal
* Musterplace
* Escaperoutes
* Use lifejackets
* Boat drill
55
Instruction
crew
* House rules
* Function description
* Structure of organisation
* Work instruction
* Practice routines:
– Boat drill
– Fire
– Mob
– Colllision or grounding
56
watch instructions
watch orders: standing orders; night orders
57
"Standing Watch" orders
applicable all the time; **boundaries of responsibilities** between Master and OOW under normal circumstances
58
Night orders
specific for the actual situation, e.g.:
Keep these sails until…
Call me when we are …mile from …
Tasks for different officer
59
preparing for Heavy Weather
- good preparation is essential
- checked and deploying safety gear; plotting position; stowing all things
- **focuss on safe navigation**
- seasickness
60
waves
3 categories
Dangerous, where big waves enter shallow waters => speed down; steeper waves; shorter intervals
* **Seastate**
Waves created by the
current wind
* **Swell**
Created by Seaway further
away or wind from some
time before now
* **Land Wash**
Waves when Seaway or
swell arrives in shallower
waters
61
wind and current:
influencing each other
wind against current: short, steep waves
62
Stragegies in heavy wind
- **in irons** head into wind: w engine or sea anchor (if not much room to lee)
- **heaving to** (comfortable; minimum speed); stormsail+trysail
- **running**: riding the storm: going long distances to leeward (sufficient sea room?)
- **scudding** (under bare poles); long ropes or sea anchor from stern
63
Heavy weather
dangers
| SAIL
* **Damage** to the rigging or the hull
* Danger of **lee shore**
* **Less stability** on top of the wave ,rolling
* **Less rudder** on top of wave
* **Broaching**
* Crew and guests **seasick**
64
Reasons for hull shape
- water depth
- locks/sizes
- still water <=> waves
- speed requirements (clipper; pilot cutter)
- cargo
- taxes
65
Keel types
- Finn
- Bulb
- Long
- Twin
- Leeboards
66
Klink ./. Kravell
Klink doesn’t need caulking; overlap of planking creates lots of strength; water resistance
Cravell allowed construction of bigger, wider, stronger hulls with smoother surface; caulking
67
Cordage
68
kravell vs clinker
kravell: planks laid edge to edge; **smooth surface; greater strength due to more robust framing; larger constructions possible**
clinker: overlapping planks; **lighter due to less framing**
69
Sailtrim:
horizontal ./. vertical
| SAIL
Horizontal:
-Angle of attack
-Camber (depth of convex)
-Place of camber (closer to luff or leach)
Vertical:
-Twist
-Height of the sail
-Place of camber (up or down)
70
Block:
Parts/names
The inner/outer **strap** hold the entire thing together => inside/outside **binding**
**purpose**: change direction of pull; extra power (if combined in tackles)
tally plate
71
name: stay between masts
| SAIL
sparrow stay
72
Schooner: sail choices
(view exam)
| SAIL
considerations: **manoevrability + easy and fast to drop**:
3M schooner: Main + Schooner + Staysail => manoevrability
(add Jib for speed, if safe to do so)
2M: Schooner + Staysail (jib for speed/extra power)
extra power: e.g. swell to push through
**crew ready to drop anytime, lines ready to run**
73
Wind against current:
Wave buildup
1. counter-current slows wave propagation down => height building up
2. apparent wind at surface level increases beyond true wind => waves increase
3. because of the above: greater exposure surface where wind can transfer energy to water
