My
Rig
Picked up a new Quantum mainsail and genoa this fall…..details
to follow…
The Tanzer 25 came with a 179sf (P=32.57', E=11')
mainsail made by Sobstad installed on a tall, bendy, single aft swept spreader
fractional rig made by Francespar. I
have no idea how much mast pre-bend to set up.
I've been using J24 data as a guide.
I’m listing the J24 table below and as I come up with different numbers
for the T25, I’ll fill them in. Tuning
a bendy single spreader rig is fairly simple.
I’ve listed instructions based on multiple sources below.
1.
Step the mast.
2. Measure
the base of the mast position from side to side on the deck. Get it centered on the deck. This is important in order to have equal
tension on the lower shrouds when you are done.
3. Without
any shroud tension slide the butt of the mast forward or aft until the mast is
straight and the head stay is just taut. Mast should be straight at this point
fore and aft (a little aft rake will increase weather helm and is generally
ok). Putting slight tension on the
backstay can help pull the mast tip back and rock the butt forward. Mast rake is determined by forestay length.
Rake affects helm balance - raking the mast increases weather helm. To measure rake, tension the backstay
approximately 60%, then check rake with a weight attached to the main halyard.
(Boat must be floating level when you do this!). Adjust forestay as necessary
to obtain the desired angle. I have no
idea what the rake should be, so I have the head stay turnbuckle tightened half
way. Oh, BTW, my head stay is 32’3”
long.
4. Check
that the mast is upright athwartships in the boat. Use the main halyard to
measure from the masthead to the chainplate each side. Adjust upper (cap)
shrouds to get identical readings each side (but use minimal tension in the
shrouds).
5. A
certain amount of pre-set mast bend is desirable, to stabilize the middle part
of the mast and thus minimize rig pump in a seaway.
6. Ensure
the lower shrouds are slack. Induce the required amount of pre-bend in the mast
by tensioning the backstay. (Make a note of the amount of pre-bend by using the
main halyard tensioned down to the foot of the mast, and measuring the amount
of bend at the spreaders). Tension the cap shrouds equally, a few turns at a
time, until the fore and aft bend starts to increase. Check that the mast is
still straight athwartships.
7. Now
tighten the lowers in the same manner as the caps, until the fore and aft bend
starts to decrease. At this stage the caps should be tighter than the lowers.
8. Release
the tension in the backstay, check that you are happy with fore and aft and
sideways deflections. (Once the rig is
set up as described here, tensioning the backstay whilst sailing will affect
the curve in the upper part of the mast only, as the area around the spreaders
is fixed by the opposing forces of the shrouds).
9. Go
sailing! Set full sail to windward in smooth water in light winds (10-15
degrees heel to windward).
10. Tension
the backstay just sufficiently to straighten the forestay.
11. If
the leeward shrouds are slack, tighten them, but NO MORE THAN ONE and a HALF
TURNS AT A TIME. Go on the opposite tack and do likewise, then tack again and
check if the lee shrouds are still slack. If so, repeat the operation. DO NOT
OVERTIGHTEN the lee shrouds, as you may bend the boat or break the mast when
you tack!
12. Back
at the dock, check that the mast is still straight athwartships
13. As
a final check of the rig tune, measure the tension on the forestay.
14. Finally
check the amount of pre-bend in the mast by holding the main halyard at the
goose-neck and measuring the distance between the halyard and the mast at the
spreaders. If you have a J24, you are
looking for 2 ¼” of bend at the base 25/20 setting. I have no clue what the T25 settings should be.
15. I’ve
included the J-24 tables below, however, I am NOT using them yet. I’m just sticking with the basic tune
above. If anyone has any better ideas,
please e-mail me.
J24 Rig Settings
|
|
Knots |
Uppers |
Lowers |
|
||
|
|
|
Tension |
Numbers |
Tension |
Numbers |
|
|
|
19+ |
880 |
30 |
31 |
980 |
|
|
|
13-18 |
685 |
27 |
26 |
620 |
|
|
BASE |
6-12 |
580 |
25 |
20 |
420 |
BASE |
|
|
0-5 |
380 |
18 |
10 |
240 |
|
Base settings = At the dock, setup the uppers at 25 and the
lowers at 20 this will be your base setting. With the shroud tension at the
base setting of 25 and 20, the head stay tension should be -25 on the Loose
Tension Gauge. Headstay tension can be
adjusted through the backstay turnbuckles to a tension of -25.
† = Numbers are from the Loos Tension Gauge, Model B.
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