Hamish Norton
New member
Hi Guys, I sail an Javelin Skiff (javelins.org)
Fingers crossed this renders okay / is readable.
Could you please let me know how well I've done with the following and perhaps some feed back. You'll see I've got a few questions in there too that I'm not 100% on.
The Javelin is a two handed skiff (crew on the trapeze), square top main. And in my instance the main sheets off a bridal at the back of the boat and we use boom sheeting.
I've put this little grid to together of the main sail and it's controls, and then filled out the effects each has.
Controls and there effect on the mast and sail
Specific Questions...
Thanks for reading.
Hamish
Fingers crossed this renders okay / is readable.
Could you please let me know how well I've done with the following and perhaps some feed back. You'll see I've got a few questions in there too that I'm not 100% on.
The Javelin is a two handed skiff (crew on the trapeze), square top main. And in my instance the main sheets off a bridal at the back of the boat and we use boom sheeting.
I've put this little grid to together of the main sail and it's controls, and then filled out the effects each has.
Controls and there effect on the mast and sail
Mainsail... | Mast | Boom | Sail | Purpose |
Cunningham / Downhaul | Pulled On: Bends the mast forward in the middle. It will bend the mast the most where it is weakest (tip/tip) and the least where it is stiffest (Perhaps between the base and goose neck). | Pulled On: It will reduce the effectiveness of the Vang tension, and some load will transfer to the mainsheet | Pulled On: Primary effect - the mid draft is reduced, making the sail not as deep in the middle. Secondary effect - load is reduced in the leech allowing it to twist. Sheer - is to the aft compared with the middle of the sail, which increases tension between the aft square top corner and the middle luff of the sail | Primarily to control the power of the mainsail (flatten it for stronger wind, or for very light winds). Can be played even for gusts. Q. By preloading it more does it improve gust response of the mast (in the tip)? |
Vang / Kicker | Pulled On: It bends the mast forward at the middle and pulls the tip of the mast aft. Vang vs GNAV... The GNAV puts the bend further up the mast compared to the more traditional vang. | Pulled On: It places a bending moment on the boom to the outboard end by the Gooseneck and Vang load | Pulled On: Some tension... It makes the leech stand up, as the line of tension between the head and Clew pulls the roach to windward. Lots of tension... it flattens the sail in the middle and allows the leech to flatten off. Sheer - as this tension pulls the mast tip aft it creates a sheer to the aft compared with the middle of the sail. Q. What does this mean for the sail? | To control the twist of the main for the conditions. More wind more tension to hold the leech twist required. Choppy condition less tension to allow more twist widening the boats groove of power allowing you to steer more yet maintain power at these ever changing angles. |
Outhaul | Pulled On: Could add some tension to the head of the mast bending the tip back. | Pulled On: Places compression on the boom | Pulled On: Primarily pulls the bottom of the sail tight taking out draft, also pulls tension from the head to the Clew flattening it out along that line, and all of the rest of the sail between the head, tack and Clew. Q. Am I over using this and causing the stress lines I see in the upper half of the sail between the head and the Clew? | To control the depth of lower 1/3 of the mainsail |
Mainsheet | Very little, unless the vang tension is minimal and the mainsheet is sheeted on hard. Also depends on the amount of purchase setup. | Allows you to adjust the sail as a whole in and out to match the angle of the wind | Minimal, unless the vang tension is also minimal. This may be the case in very light wind where it's used to control the leech tension (sail twist) | Adjust the sail as a whole in and out to match the angle of the wind |
Baby Stays / Lowers (they attach to the up point of the GNAV) | Pulled On: Shifts the mast bend caused by the Cunningham and Vang to be moved further up the mast, and limits the bending effect of both controls | Tends to flatten the upper sail (perhaps at the 1/3 point instead of the 1/2 point) Vang and Cunningham tension affect the leech tension, and the flatness of the Square top. | Pulled On: Allows you to keep the main powered up and adjust the leech and square top to the right amount of twist for the conditions (flat, choppy) |
Jib... | Forestay | Mast | Sail | Purpose |
Cunningham / Downhaul | Negligible, perhaps a very small increase | Nil | Pulled On: increases luff tension, pulling the draft further forward increasing the angle of attack and thus causing lower mode. | Control the sails draft for the conditions. |
Inhaul (Jib car distance from centre line) | Nil | Nil | Angle to the wind | Angle to the wind and mast flow Q. How do you know when you have got this right? |
Jib Clew Plate | Nil | Nil | If set low, it pulls the foot tight. If set high, it pulls the leech tight. | Adjusted to set the twist for the conditions |
Jib Sheet | Pulled On: Depending on Jib cut it can add tension to the forestay and bend it aft | Can bend the mast further in the direction it's bending if the forestay tension increases | Pulled On: pulls the sail as a whole flatter, but typically setup to control the leech tension allowing the leech to twist off in a strong wind or choppy seas. | Control leech tension, thus controlling twist. |
Specific Questions...
- Jib - Inhaul: How do you know when you have got this right?
[*]Main - Outhaul: Am I over using this and causing the stress lines I see in the upper half of the sail between the head and the Clew?
[*]Main - Vang/Kicker: Sheer - as this tension pulls the mast tip aft it creates a sheer to the aft compared with the middle of the sail. What does this mean for the sail?
[*]Main - Cunningham/Downhaul - By preloading it more does it improve gust response of the mast (in the tip)?
Thanks for reading.
Hamish
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