Soon it will be time to put mast on. What is the right way to properly tension forestay and shrouds? Shall I use a tension meter to ease the job? What would be the right numbers then? Or shall a real FE sailor tune shrouds like violin strings?
Alex
Mast, forestay, shrouds, tension
Mast, forestay, shrouds, tension
Hello,
Soon it will be time to put mast on. What is the right way to properly tension forestay and shrouds? Shall I use a tension meter to ease the job? What would be the right numbers then? Or shall a real FE sailor tune shrouds like violin strings?
Alex
Soon it will be time to put mast on. What is the right way to properly tension forestay and shrouds? Shall I use a tension meter to ease the job? What would be the right numbers then? Or shall a real FE sailor tune shrouds like violin strings?
Alex
Re: Mast, forestay, shrouds, tension
Helloalex wrote:Hello,
Soon it will be time to put mast on. What is the right way to properly tension forestay and shrouds? Shall I use a tension meter to ease the job? What would be the right numbers then? Or shall a real FE sailor tune shrouds like violin strings?
Alex
As you may have noticed that there is no optimal trim for the mast nor for the sails. Everything, I mean everything is dependat of circumstances.
But still I take a risk and give you sort of guide line for standard trim. You must have a starting point, don't you:
- rake some 5%
- Outher shrouds should be tensioned so that you'll have mast prebend 0,5-0,8 x mast profile's lenght. Some sailors are using so called 2 meter mark in outher shrouts. They keep on tensioning until this 2m is extended by 3-5mm.
- Inner shrouds are tightened acording to shape of your main sail and to prevent the mast profile to pump back and forth under big waves and bad weather.
- make it sure that your mast stands straight on the deck (left vs right) and mast profile is straight.
Ystävällisin veneily terveisin PR
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FE-Sillanpää
- luti
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- Location: Itä-Uusimaa
Hint for next spring
When we bought our FE we got a list of each stay with a 0,1 mm accurate measure how the stays are tuned. So after you're happy with your tuning this year, measure the gap between the ends of the shroud screws. It's handy to use slide gauge (työntötulkki eli mauseri). Next spring you'll have an easy task: Just measure the same gap for each screw that you had this yearalex wrote:Or shall a real FE sailor tune shrouds like violin strings?
Alex
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harald
- Hallitus
- Posts: 11338
- Joined: Thu Sep 19, 2002 14:32 pm
- Location: Sibbo
- Vene: Charlotta
- Contact:
First decide how much rake you want. Charlotta's forestay has been 869cm long
pin-to-pin-center (including the rigging screw) the last couple of seasons.
It think the stock forestay is some 833 cm (the wire part, pin-to-pin-center).
Pull the upper shrouds along the mast before stepping it, place a tape where the
shroud intersects the foot of the mast. Measure the distance from the tape to the
end of the rigging screw. Note the difference, if any. Use this difference to center
the mast in the boat. The difference between shroud lengths ought to be within
some mm's from each other. The tolerance for side lean measured from the
gap in the rigging screw should be well less than one mm. It's hard to measure
a consistent tolerance of 1/10mm, but this isn't rocket sience so anything under
half a mm is ok(?). Using this method we're assuming that the chainplates are
symmetrical (doublecheck with halyard, the genoa halyard is less prone to
"soft measurements", due to beeing at the hounds).
Step the mast, it's sufficient for the mast to remain standing to just connect
the forestay and the uppers. Tighten the uppers by hand and you can leave
the masthoist for the next boat.
This is how how we do it:
No boom connected, no backstay or lowers. Just uppers and forestay attached.
No tension on any halyard or other trimline.
1) center the mast (using a vernier caliper and/or halyards to the toerail).
You can use your main halyard (watch for the bendy top, also watch for any
curve induced from winterstorage) to double-check that the mast is in the center
of the boat. If it's in the middle, you can just use a vernier caliper to measure the
distance between the ends of the threaded parts of the rigging screw to check for
any mast lean SB-BB in the future.
When choosing the tightness for today's race we don't use a measure, but rather
how many turns looser the upper and lowers are. This is easier to remember and
to use in a tuning guide for your setup in different conditions. I'd say that 20%
and 0.5L bend (lowers) should be ok for most conditions.
2) hand tighten the uppers (without tools, just bare hands) as hard as you can,
this is the loosest setting you would use at any time (in a race, very very light
weather). Tighten equal amount of turns on each side.
3) When you're not able to tighten the uppers by hand anymore, measure and
mark (with tape) a 2000mm distance from the end fitting of the shroud upwards.
Methinks it's enough to tape one side, since the other one should be as tight as
the other.
4) Using an adjustable spanner and a box-wrench, tighten the uppers some
more, until that marked 2000mm distance now is 2004mm. Tighten equal
amount of turns on each side. This equals 20% of the breaking load and is the
recommended base-setting (both by Seldén, Dedekam's book and me). Is this
isn't enough,. you can further tighten the rig up to 2005mm (25%). This is the
max-setting, which we have been using most often.
The amount of turns from 0% to 25% is in the magnitude of 15 turns(?) on each
side.
5) Now connect the lowers and hand tighten them until you have a mast bend
of roughly 0.5-0.8 of the section length. The main halyard tightened some to
the gooseneck can help eyeballing this. Also while tightening the lowers, aim
along the luff-groove as to gauge the straightness of the mast. It's essential
that the mast is in column.
The lowers should be considerably looser than the uppers, the uppers giving
a gong-sound when whacked with an open hand. You'll be surprised at how
loose the lowers are.
6) Now you can connect the backstay. Also insert pins or string as to lock all
rigging screws, and tape all pins using Tesa reinforced tape.
Go out for a testsail. We have mostly just adjusted the lowers according to
weather, but you could loose some 5 turns on the uppers (make a note in the
cockpit so you remember the tightness next week) if the forecast is less wind
and chop.
pin-to-pin-center (including the rigging screw) the last couple of seasons.
It think the stock forestay is some 833 cm (the wire part, pin-to-pin-center).
Pull the upper shrouds along the mast before stepping it, place a tape where the
shroud intersects the foot of the mast. Measure the distance from the tape to the
end of the rigging screw. Note the difference, if any. Use this difference to center
the mast in the boat. The difference between shroud lengths ought to be within
some mm's from each other. The tolerance for side lean measured from the
gap in the rigging screw should be well less than one mm. It's hard to measure
a consistent tolerance of 1/10mm, but this isn't rocket sience so anything under
half a mm is ok(?). Using this method we're assuming that the chainplates are
symmetrical (doublecheck with halyard, the genoa halyard is less prone to
"soft measurements", due to beeing at the hounds).
Step the mast, it's sufficient for the mast to remain standing to just connect
the forestay and the uppers. Tighten the uppers by hand and you can leave
the masthoist for the next boat.
This is how how we do it:
No boom connected, no backstay or lowers. Just uppers and forestay attached.
No tension on any halyard or other trimline.
1) center the mast (using a vernier caliper and/or halyards to the toerail).
You can use your main halyard (watch for the bendy top, also watch for any
curve induced from winterstorage) to double-check that the mast is in the center
of the boat. If it's in the middle, you can just use a vernier caliper to measure the
distance between the ends of the threaded parts of the rigging screw to check for
any mast lean SB-BB in the future.
When choosing the tightness for today's race we don't use a measure, but rather
how many turns looser the upper and lowers are. This is easier to remember and
to use in a tuning guide for your setup in different conditions. I'd say that 20%
and 0.5L bend (lowers) should be ok for most conditions.
2) hand tighten the uppers (without tools, just bare hands) as hard as you can,
this is the loosest setting you would use at any time (in a race, very very light
weather). Tighten equal amount of turns on each side.
3) When you're not able to tighten the uppers by hand anymore, measure and
mark (with tape) a 2000mm distance from the end fitting of the shroud upwards.
Methinks it's enough to tape one side, since the other one should be as tight as
the other.
4) Using an adjustable spanner and a box-wrench, tighten the uppers some
more, until that marked 2000mm distance now is 2004mm. Tighten equal
amount of turns on each side. This equals 20% of the breaking load and is the
recommended base-setting (both by Seldén, Dedekam's book and me). Is this
isn't enough,. you can further tighten the rig up to 2005mm (25%). This is the
max-setting, which we have been using most often.
The amount of turns from 0% to 25% is in the magnitude of 15 turns(?) on each
side.
5) Now connect the lowers and hand tighten them until you have a mast bend
of roughly 0.5-0.8 of the section length. The main halyard tightened some to
the gooseneck can help eyeballing this. Also while tightening the lowers, aim
along the luff-groove as to gauge the straightness of the mast. It's essential
that the mast is in column.
The lowers should be considerably looser than the uppers, the uppers giving
a gong-sound when whacked with an open hand. You'll be surprised at how
loose the lowers are.
6) Now you can connect the backstay. Also insert pins or string as to lock all
rigging screws, and tape all pins using Tesa reinforced tape.
Go out for a testsail. We have mostly just adjusted the lowers according to
weather, but you could loose some 5 turns on the uppers (make a note in the
cockpit so you remember the tightness next week) if the forecast is less wind
and chop.
FIN-2674 s/y Charlotta [Mielipiteet on mielipiteitä] GSM: +358 50 594 1020
-
harald
- Hallitus
- Posts: 11338
- Joined: Thu Sep 19, 2002 14:32 pm
- Location: Sibbo
- Vene: Charlotta
- Contact:
Actually, a microphone and a PC (and oscilloscope software) has been considered,
that would be like (an engineer) tuning a violin and should produce quite an accurate
and reproducable rigtensions. The microphone could be attached to the inner part
of the chainplate, and a simple whack on the uppers could be read on the PC as
a relative value of rig tension.
I'll leave it as an excercise to calculate a kN-Hz table
that would be like (an engineer) tuning a violin and should produce quite an accurate
and reproducable rigtensions. The microphone could be attached to the inner part
of the chainplate, and a simple whack on the uppers could be read on the PC as
a relative value of rig tension.
I'll leave it as an excercise to calculate a kN-Hz table
FIN-2674 s/y Charlotta [Mielipiteet on mielipiteitä] GSM: +358 50 594 1020