Mast arc?

I noticed my mast arcs back a bit. I stand at the base and look straight up and it arcs back about 2-3 inches. It is a 38-39ft mast and it is only the top 1/3 that curves back ever so slightly. I have a fractional rig on a Cal 2-30 (which I wonder is part of the issue). The curve is so slight I never would have noticed except when I happened to look up from the base there straight up the sailtrack. I am only brining this up because I am thinking about a new main and wondering if this will case issues with the sail shape. My current sail is old getting worn out & the leech ever so slightly flaps. Is this because it is old or because my mast is flexed back? I have a fully battened sail (4 full battens) and I am wondering if I need to make sure my new sail accommodates this very slight curve, or is it no issue, OR worst case do I need a new mast? Does this happen to old boats? Mine is a 1969. Have you looked straight up your mast from the base? Is it perfectly straight? Dyer Honu, 1969 Cal 2-30 #87 SF Bay.

If the sailmaker measures the boat he should measure the curve of the mast and make the sail accordingly. That said, the curve is adjustable by changing backstay tension. That is one of the points of a fractional rig. You tighten the backstay and put more bend in the mast and that flattens the main. Easing off on the backstay puts more fullness in the main. Just a few inches makes a big difference. You should talk to your sailmaker about it. Allen On Thu, Aug 25, 2011 at 8:14 AM, Crouch, Dyer <dx… [at] pge.com> wrote: > ** > > > > I noticed my mast arcs back a bit. I stand at the base and look straight up > and it arcs back about 2-3 inches. It is a 38-39ft mast and it is only the > top 1/3 that curves back ever so slightly. > > I have a fractional rig on a Cal 2-30 (which I wonder is part of the > issue). The curve is so slight I never would have noticed except when I > happened to look up from the base there straight up the sailtrack. > > I am only brining this up because I am thinking about a new main and > wondering if this will case issues with the sail shape. My current sail is > old getting worn out & the leech ever so slightly flaps. Is this because it > is old or because my mast is flexed back? > > I have a fully battened sail (4 full battens) and I am wondering if I need > to make sure my new sail accommodates this very slight curve, or is it no > issue, OR worst case do I need a new mast? > > Does this happen to old boats? Mine is a 1969. > > Have you looked straight up your mast from the base? Is it perfectly > straight? > > Dyer > Honu, 1969 Cal 2-30 #87 > SF Bay. > > > >

In addition to what Allen has said, if you do have a backstay tensioner, it should ALWAYS be slackened when back in port so it doesn't bend itself into a permanent banana shape. FYI. The rule I used when I had a tensioner on my 25 was: upwind tight, downwind loose. Ensuring it was loose but secure was part of her bedtime checklist. There are folks here that know much more about it than I do and they will chime in. That's the great thing about our little group! On 8/25/2011 11:30 AM, Allen Edwards wrote: > > > If the sailmaker measures the boat he should measure the curve of the > mast and make the sail accordingly. That said, the curve is > adjustable by changing backstay tension. That is one of the points of > a fractional rig. You tighten the backstay and put more bend in the > mast and that flattens the main. Easing off on the backstay puts more > fullness in the main. Just a few inches makes a big difference. You > should talk to your sailmaker about it. > > Allen > > On Thu, Aug 25, 2011 at 8:14 AM, Crouch, Dyer <dx… [at] pge.com > <mailto:dx… [at] pge.com>> wrote: > > I noticed my mast arcs back a bit. I stand at the base and look > straight up and it arcs back about 2-3 inches. It is a 38-39ft > mast and it is only the top 1/3 that curves back ever so slightly. > I have a fractional rig on a Cal 2-30 (which I wonder is part of > the issue). The curve is so slight I never would have noticed > except when I happened to look up from the base there straight up > the sailtrack. > I am only brining this up because I am thinking about a new main > and wondering if this will case issues with the sail shape. My > current sail is old getting worn out & the leech ever so slightly > flaps. Is this because it is old or because my mast is flexed back? > I have a fully battened sail (4 full battens) and I am wondering > if I need to make sure my new sail accommodates this very slight > curve, or is it no issue, OR worst case do I need a new mast? > Does this happen to old boats? Mine is a 1969. > Have you looked straight up your mast from the base? Is it > perfectly straight? > Dyer > Honu, 1969 Cal 2-30 #87 > SF Bay. > > > > >

Mast bend (or arc) is an importent part of tuning. I would apply backstay tension to pull 1.5 spar section out of my frac rigged Cal 20 to flatten the mainsail and apply more headstay tension at max bend. I would put 5 inches curve measured at midspar by pulling the M halyard tight on the M'sail track slot. Don't worry, It can take it. When you let out the backstay it will assume a uncurve unless you have too much tension on your fore lowers if you have fore lowers. My Best, Mike Farrell former owner of eight Cal 20's Now sailing SC 27 Yellow Jack USA 57313 From: mike <mi… [at] wahini.org> To: Ca… [at] yahoogroups.com Sent: Thursday, August 25, 2011 9:26 AM Subject: Re: [Cal_Boats] Mast arc? In addition to what Allen has said, if you do have a backstay tensioner, it should ALWAYS be slackened when back in port so it doesn't bend itself into a permanent banana shape. FYI. The rule I used when I had a tensioner on my 25 was: upwind tight, downwind loose. Ensuring it was loose but secure was part of her bedtime checklist. There are folks here that know much more about it than I do and they will chime in. That's the great thing about our little group! On 8/25/2011 11:30 AM, Allen Edwards wrote: If the sailmaker measures the boat he should measure the curve of the mast and make the sail accordingly. That said, the curve is adjustable by changing backstay tension. That is one of the points of a fractional rig. You tighten the backstay and put more bend in the mast and that flattens the main. Easing off on the backstay puts more fullness in the main. Just a few inches makes a big difference. You should talk to your sailmaker about it. > > >Allen > > >On Thu, Aug 25, 2011 at 8:14 AM, Crouch, Dyer <dx… [at] pge.com> wrote: > > >> I noticed my mast arcs back a bit. I stand at the base and look straight up and it arcs back about 2-3 inches. It is a 38-39ft mast and it is only the top 1/3 that curves back ever so slightly. >> >>I have a fractional rig on a Cal 2-30 (which I wonder is part of the issue). The curve is so slight I never would have noticed except when I happened to look up from the base there straight up the sailtrack. >> >>I am only brining this up because I am thinking about a new main and wondering if this will case issues with the sail shape. My current sail is old getting worn out & the leech ever so slightly flaps. Is this because it is old or because my mast is flexed back? >> >>I have a fully battened sail (4 full battens) and I am wondering if I need to make sure my new sail accommodates this very slight curve, or is it no issue, OR worst case do I need a new mast? >> >>Does this happen to old boats? Mine is a 1969. >> >>Have you looked straight up your mast from the base? Is it perfectly straight? >> >>Dyer >>Honu, 1969 Cal 2-30 #87 >>SF Bay. >> >