12
Note! If the calculation gives a top extrusion length (D) that is shorter than 400 mm, the
calculation must be reworked by exchanging one of the 2400 mm extrusions with the uncut
2000 mm top extrusion. By doing so the top extrusion will be cut from a 2400 mm length
and its length will then exceed 400 mm. If the calculation gives a top extrusion length (D)
that exceedes 2000 mm, the top extrusion must be cut from one of the 2400 mm extrusions.
In this case the 2000 mm extrusion will not be used.
2.6 Calculating the length of the luff extrusion
The Furlex luff extrusion consists of a number of shorter sections. Starting from the bottom there is a 700 mm
luff extrusion connected to the drum unit and extending up to the sail feeder. Then, from the sail feeder and up
there are a number of full length luff extrusions (L=2400 mm) and finally there is a 2000 mm top extrusion that
has to be cut to length to suite the actual forestay length.
To find out the cutting length of the top extrusion (D) and the length of the top distance tube (E), start with the
length of the forestay wire (WL) that was calculated in table 2. Then follow the steps in table 3 below. On fixed
length forestays (incl. rod stays), verify WL by measuring the stay length from centre of eye to end of stud
(wire) or end of rod head.
Table 2. Calculation of top luff extrusion length and top distance tube length
Your
forestay
Example
(304TD 10mm)
With rigging screw
50% extended
WL
Length of the new forestay wire (as per Table 2).
15815
A+B
1025
N
Number of full length extrusions to be used:
N = ( WL - (A+B) )/2400
(15815-1025)
/2400=6.16
N=6
C
Total length of the number of full length extrusions (2400 mm) to be used:
C = N x 2400
6 x 2400 =
14400
D*
Length of top luff extrusion:
D = WL – (A+B) – C
15815-1025
-14400=390
X
Fixed deduction:
204TD: 200mm
304TD: 250mm
250
E*
Length of the top distance tube:
E=D-X
390-250=140
WIRE
Without rigging screw:
With rigging screw:
204TD
ø6mm wire: 1030mm
ø7mm wire: 1040mm
ø8mm wire: 1050mm
ø6mm wire: 970mm
ø7mm wire: 980mm
ø8mm wire: 1000mm
304TD
Ø 8 mm wire: 1075mm
Ø 10 mm wire: 1100mm
Ø 8 mm wire: 1000mm
Ø 10 mm wire: 1025mm
ROD
Without rigging screw:
With rigging screw:
204TD
Rod -8 1070mm
Rod -10 1070mm
Rod -12 1085mm
Rod -15 1085mm
Rod -8 980mm
Rod -10 980mm
Rod -12 1000mm
Rod -15 1000mm
304TD
Rod -15: 1100mm
Rod -17: 1115mm
Rod -22: 1125mm
Rod -15: 1015mm
Rod -17: 1030mm
Rod -22: 1040mm
