Seajet
...
That's what I and a lot of people would call a flattening reef
...and I'd recommend ball bearing blocks for any boat under say 30' as they are a huge help reducing friction and aiding easy operation.
cunningham
- Thread starter TiggerToo
- Start date
That's what I and a lot of people would call a flattening reef
...and I'd recommend ball bearing blocks for any boat under say 30' as they are a huge help reducing friction and aiding easy operation.
Woodlouse
Well-Known Member
That's what I and a lot of people would call a flattening reef
So what would to call a cunningham?
In my opinion a cunningham's pull is vertically down, whereas a flattening reef will pull down and forwards towards the mast, thereby taking belly out of the sail.
sailorman
Well-Known Member
the "flattener" is to take out the boom shelf ( leach cunningham). another rule cheat
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Seajet
...
Boom shelves are an old idea, I thought they went years ago ?
A flattening reef nowadays tensions luff and to an extent bunt & leech, as long as the reefed clew outhaul is correctly set up to pull aft as well as down.
A flattening reef nowadays tensions luff and to an extent bunt & leech, as long as the reefed clew outhaul is correctly set up to pull aft as well as down.
RobBrown
Well-Known Member
So what (minimal) kit required to rig a cunningham on a 30'er? (I have the eye on the luff of the sail, but nothing rigged).
bbg
Well-Known Member
Basically you need a line that runs from one side of the boom - maybe from the reefing horn - up through the eye and back down the other side of the main to just below the boom. Then you need a way to tension that line with a purchase, maybe with blocks at the deck and up at the end of the cunningham line itself (just below the boom). You don't need a lot of purchase, and you can get away with very light line if you use dyneema. The purchase can either be made off at the base of the mast or led back to the cockpit.
Seajet
...
I would just add that on a cruiser / racer with a halliard winch and a gooseneck track, I find an easily adjustable clew outhaul a lot more useful than a cunningham, but one can never have too much control of sail shape !
sailorman
Well-Known Member
with a gooseneck track is is still possible when racing the haul down the boom "below" the black band thereby rule breaking. if cruising who cares.
most seem to be unaware what the significance of the black bands represent
most seem to be unaware what the significance of the black bands represent
TSB240
Well-Known Member
That's what I and a lot of people would call a flattening reef
Andy I beg to differ and have always understood that a cunningham is to be found on the luff of the sail and should not be confused with a flatting reef point on the leech.
In some cases especially on more race orientated sail designs a similar flattening reef point may be added at similar height above the boom but this is always on the leach.
It is more usual to find most cruising sails to only having a cunningham hole on the luff as a means of controlling sail shape.
The two are used independently of each other for maximum control of sail shape and maximum draft . Certainly on our fractionally rigged boat when combined with back stay adjustment they allow us to flatten the mainsail and maintain full sail area for a greater range of wind speeds than boats without them. For the racing fraternity this has obvious benefits as reefing is a much more time consuming than tweking the cunningham, back stay and flattening reef.
The flattening reef is also found on quite a few dinghies for the same reason. I certainly found it useful on a Scorpion as it had the additional advantage of letting a honeymonster of a helm get under the boom when the rig had been raked fully aft for strong upwind work.
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lw395
Well-Known Member
A flattening reef is mainly used on dinghies which rake the mast back a lot in strong winds.
It keeps the boom off the aft deck and out of the water.
Also clears sheet hoops, fat helms etc.
The actual flattening is done by mast bend to a great extent.
It keeps the boom off the aft deck and out of the water.
Also clears sheet hoops, fat helms etc.
The actual flattening is done by mast bend to a great extent.
sailorman
Well-Known Member
So tell me how & when iyo the luff Cunningham is used, right from hoisting the sail pls.
Seajet
...
Flattening reefs were common on cruisers in the late 1970's.
TSB240, the flattening reef on our first main had luff and leech cringles for the ' shelf foot '; it still set like a sack though and was soon discarded !
TSB240, the flattening reef on our first main had luff and leech cringles for the ' shelf foot '; it still set like a sack though and was soon discarded !
bbg
Well-Known Member
Main is hoisted to the top black band. As the wind picks up and the boat powers up you begin using the various controls to depower the main - outhaul, cunningham, backstay, traveller, kicker, sheet.
sailorman
Well-Known Member
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TSB240
Well-Known Member
Where does that asumption come from?
Must have been doing it all wrong for years then. I will have to empty the trophy cabinet, have my name removed off all the silver and go on a dazed kipper course then
Sailorman obviously doesnt need to read this guide
But I find it works with Dinghies, Dayboats, Fractional and Masthead boats.Booking my dazed kipper now!
Tuning Guide For A Fractional Rig.
Mainsail trimming
The mainsail is the most important sail on the boat as the speed of the yacht is dependent on the correct setting of this sail. In the case of the masthead rig boat, the mainsail is small and the main driving power for the yacht comes from the genoa. It is therefore very easy for those owners converting from masthead to three quarter rig to ignore the importance of the mainsail and the flow controls that are available to them. The mainsail has to be continually adjusted for maximum speed in a wide range of conditions and is dependent on good trimming and adjustment. The adjustments that need to be carried out to ensure the correct setting of the mainsail are as follows:
Luff tension – Luff tension is applied to the mainsail through the halyard and the luff Cunningham. The backstay induces mast bend which tends to flatten the mainsail luff and allows the flow in the mainsail to move aft to the leech. Increasing the luff tension will return the flow to the forward part of the sail and free the leech for stronger winds.
Backstay – Using the backstay adjustment to increase fore and aft bend and flatten the mainsail enables the yacht to carry sail in heavier winds and also tightens the forestay and increases the pointing ability. (To some degree this also so for a Mast head rig)
Mainsheet – The mainsheet is used to control the amount of twist in the leech. The harder the mainsail is sheeted, the less twist and the tighter the leech will be. The basic rule is that a mainsail with a very tight leech will point high and a mainsail with a slack leech will foot well but not point high. The secret is to sheet the sail with the correct amount of twist for a given wind condition. In very light airs, the sail should be sheeted with a large amount of twist and this twist should be grossly reduced as the wind increases. In very strong winds the leech of the sail will open itself by application of the backstay and the bend of the mast.
Flattening Reef or sometimes called Leech Cunningham– If you have one of these, the Flattening reef should be taken in progressively or completely to remove the flow built into the foot of the mainsail and this has the effect of flattening the sail substantially in the lower regions. This will widen the slot between the genoa leech and the mainsail and will enable the boat to stand up to its sail better. The flattening reef is an important part of the design of a racing mainsail although it may not be present on a cruiser/racer sail which is normally cut with a flatter foot.
Trimming for medium winds, 8 to 18 knots – As the wind strengths increase, the mainsail will have to be flattened with mast bend and the flattening reef. A considerable amount of luff tension using maximum halyard tension and pull on the Cunningham may be required to keep the position of flow forward and the leech open. If the mainsail back-winding extends further aft than half way(50%), then reefing or a head sail change should be considered. If the leech is allowed to trip by back-winding, the boat speed will drop considerably. The mainsail should always backwind evenly up its luff length if the genoa is trimmed correctly. A certain amount of backwind near the mast is acceptable.
New Sail Max Draft
If you ever have the luxury of a brand new sail designed,made and set up to match your mast . In calm conditions the sail's maximum draft or camber could be as much as 25-30% forward. In any sort of breeze this camber will rapidly move aft due to the inevitable stretch in your sail cloth.
After a bit more use the stretch becomes permanent.
On older sails that have "bagged" this can result in the draft being in excess of 55 -60 % which will cause very heavy weather helm.
The main purpose of a Cunningham therefore is to bring the maximum draft or camber forward and reduce weather helm.
Sail Bands
The effect of using the Cunningham on the depth and position of max draft is much easier to spot using sail bands or coloured horizontal strips that are sometimes offered as an extortionate option by your sailmaker.
Quite easily fitted DIY to a new sail.
Mast Head Boats
Whilst this is a guide for a fractionally rigged boat the basic principle of operation is just as applicable for a mast head rig except the mainsail will usually be cut flatter to start with. On most mast head rigs using back stay tension will not induce much extra mast bend but will help reduce luff sag on the Genoa which helps pointing ability and in some cases flattens the luff of the Genoa.
A consequence is that the Cunningham control will not be as necessary to move the draft forward to compensate due to mast bending.
On a mast head boat a Cunningham will bring the draft forward but may not be needed until higher wind speeds and will have much less effect on delaying the need to reef the mainsail or on reducing weather helm.
Consequently you tend to see more "masthead" boats reduce sail by reefing main before Genoa whilst the opposite is usually true for fractionally rigged boats.
sailorman
Well-Known Member
No mention of "BLACK BANDS" then & their function
Where does that asumption come from?
Must have been doing it all wrong for years then. I will have to empty the trophy cabinet, have my name removed off all the silver and go on a dazed kipper course then
Sailorman obviously doesnt need to read this guide
Booking my dazed kipper now!
Tuning Guide For A Fractional Rig.
Mainsail trimming
The mainsail is the most important sail on the boat as the speed of the yacht is dependent on the correct setting of this sail. In the case of the masthead rig boat, the mainsail is small and the main driving power for the yacht comes from the genoa. It is therefore very easy for those owners converting from masthead to three quarter rig to ignore the importance of the mainsail and the flow controls that are available to them. The mainsail has to be continually adjusted for maximum speed in a wide range of conditions and is dependent on good trimming and adjustment. The adjustments that need to be carried out to ensure the correct setting of the mainsail are as follows:
Luff tension – Luff tension is applied to the mainsail through the halyard and the luff Cunningham. The backstay induces mast bend which tends to flatten the mainsail luff and allows the flow in the mainsail to move aft to the leech. Increasing the luff tension will return the flow to the forward part of the sail and free the leech for stronger winds.
Backstay – Using the backstay adjustment to increase fore and aft bend and flatten the mainsail enables the yacht to carry sail in heavier winds and also tightens the forestay and increases the pointing ability. (To some degree this also so for a Mast head rig)
Mainsheet – The mainsheet is used to control the amount of twist in the leech. The harder the mainsail is sheeted, the less twist and the tighter the leech will be. The basic rule is that a mainsail with a very tight leech will point high and a mainsail with a slack leech will foot well but not point high. The secret is to sheet the sail with the correct amount of twist for a given wind condition. In very light airs, the sail should be sheeted with a large amount of twist and this twist should be grossly reduced as the wind increases. In very strong winds the leech of the sail will open itself by application of the backstay and the bend of the mast.
Flattening Reef or sometimes called Leech Cunningham– If you have one of these, the Flattening reef should be taken in progressively or completely to remove the flow built into the foot of the mainsail and this has the effect of flattening the sail substantially in the lower regions. This will widen the slot between the genoa leech and the mainsail and will enable the boat to stand up to its sail better. The flattening reef is an important part of the design of a racing mainsail although it may not be present on a cruiser/racer sail which is normally cut with a flatter foot.
Trimming for medium winds, 8 to 18 knots – As the wind strengths increase, the mainsail will have to be flattened with mast bend and the flattening reef. A considerable amount of luff tension using maximum halyard tension and pull on the Cunningham may be required to keep the position of flow forward and the leech open. If the mainsail back-winding extends further aft than half way(50%), then reefing or a head sail change should be considered. If the leech is allowed to trip by back-winding, the boat speed will drop considerably. The mainsail should always backwind evenly up its luff length if the genoa is trimmed correctly. A certain amount of backwind near the mast is acceptable.
New Sail Max Draft
If you ever have the luxury of a brand new sail designed,made and set up to match your mast . In calm conditions the sail's maximum draft or camber could be as much as 25-30% forward. In any sort of breeze this camber will rapidly move aft due to the inevitable stretch in your sail cloth.
After a bit more use the stretch becomes permanent.
On older sails that have "bagged" this can result in the draft being in excess of 55 -60 % which will cause very heavy weather helm.
The main purpose of a Cunningham therefore is to bring the maximum draft or camber forward and reduce weather helm.
Sail Bands
The effect of using the Cunningham on the depth and position of max draft is much easier to spot using sail bands or coloured horizontal strips that are sometimes offered as an extortionate option by your sailmaker.
Quite easily fitted DIY to a new sail.
Mast Head Boats
Whilst this is a guide for a fractionally rigged boat the basic principle of operation is just as applicable for a mast head rig except the mainsail will usually be cut flatter to start with. On most mast head rigs using back stay tension will not induce much extra mast bend but will help reduce luff sag on the Genoa which helps pointing ability and in some cases flattens the luff of the Genoa.
A consequence is that the Cunningham control will not be as necessary to move the draft forward to compensate due to mast bending.
On a mast head boat a Cunningham will bring the draft forward but may not be needed until higher wind speeds and will have much less effect on delaying the need to reef the mainsail or on reducing weather helm.
Consequently you tend to see more "masthead" boats reduce sail by reefing main before Genoa whilst the opposite is usually true for fractionally rigged boats.
TSB240
Well-Known Member
Oh is this Part 2 of my test then sir?
I am sure you are aware that this is only appopriate if Tigger Too is going to race his Duffer classic and has any part of his sail beyond the maximum bands.
He could be subject to a protest and held in a protest committe for said offence along with some obnoxious hooray who has probably photographed his offence on his blackberry.
If he is going fishing then I dont think it would be right to stop him and tell him he has stretched his knackered old sail beyond the bands....
But then he would probably be going faster than most of us in his 35 footer especially with his new found knowledge of sail trimming and newly fitted cunningham.
Appropro your earlier post surely Black bands were invented by sailmakers to tell you when your sails were knackered....So they get a new sale!
Steve
sailorman
Well-Known Member
You are getting much warmer.
most posting on this thread seem to not even know Black Bands exist,let alone what they are for
most posting on this thread seem to not even know Black Bands exist,let alone what they are for
Oh is this Part 2 of my test then sir?
I am sure you are aware that this is only appopriate if Tigger Too is going to race his Duffer classic and has any part of his sail beyond the maximum bands.
He could be subject to a protest and held in a protest committe for said offence along with some obnoxious hooray who has probably photographed his offence on his blackberry.
If he is going fishing then I dont think it would be right to stop him and tell him he has stretched his knackered old sail beyond the bands....
But then he would probably be going faster than most of us in his 35 footer especially with his new found knowledge of sail trimming and newly fitted cunningham.
Appropro your earlier post surely Black bands were invented by sailmakers to tell you when your sails were knackered....So they get a new sale!
Steve
bedouin
Well-Known Member
You don't have to have black bands to use a cunningham - they work quite well without
Woodlouse
Well-Known Member
Not everyone (in fact, very few here I'd guess) have boats that have been measured up for black bands. I'm not unaware of their existence or purpose, but I am aware that most boats don't have them.
