10
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 1. Then
follow the steps in table 2 below. On fixed length forestays, verify WL by measuring the
stay length from centre of eye to end of stud (wire).
You can also use the FURLEX CALCULATOR on our web site. Go directly to the
calculator by scanning the QR-code with your mobile device.
Table 2: Calculation of top luff extrusion length and top distance tube length
Your forestay
Example
(104S/Ø5)
with rigging screw
50% extended
WL
Length of the new forestay wire (as per Table 1).
9850
A+B
1190
N
Number of full length extrusions to be used:
N = ( WL - (A+B) ) / 2400 (94 1/2”)
(9850-1190)
/2400=3.6
N=3
C
Total length of the number of full length extrusions (2400 mm) to be used:
C = N x 2400 (94 1/2”)
3 x 2400 =
7200
D*
Length of top luff extrusion:
D = WL – (A+B) – C
9850-1190
-7200 = 1460
E*
Length of the top distance tube:
E=D-200 (7 7/8”)
1460-200 =
1260
WIRE
Without rigging screw:
With rigging screw:
104S
Ø4 mm wire: 1260 mm (49 39/64”)
Ø5 mm wire: 1275 mm (50 13/64”)
Ø6 mm wire: 1290 mm (50 25/32”)
Ø4 mm wire: 1175 mm (46 17/64”)
Ø5 mm wire: 1190 mm (46 27/32”)
Ø6 mm wire: 1210 mm (47 41/64”)
*) If D becomes less than 400 mm it is necessary to recalculate as below and cut one of the
full length luff
extrusions
according to D
new
and one of the
full length distance tubes
according to E
new
.
Note that the original top luff extrusion and the original top distance tube will now be used as intermediate
extrusions.
Table 2B: Recalculation if D<400 mm
Your forestay
Example
N
new
Reduce the number of full length extrusions by one.
N
new
= N-1
C
new
C
new
= N
new
x 2400 + 2000 (94 1/2” + 78 47/64”)
D
new
D
new
= D + 400 (15 3/4”)
E
new
E
new
= E + 400 (15 3/4”)
