[C320-list] Mainsail Trim
William Russell
russellw at oacsd.org
Sat Sep 15 18:32:26 PDT 2012
Jeff and Chris got it pretty much right, I think. Here's how I've understood the various controls and what they do to sail shape under various conditions. I'm focusing on upwind sailing.
- The sheet controls the leech. Tighter removes twist, bringing the top batten parallel with the boom (looking up from underneath the boom). Looser allows the top of the sail to twist off, which is a very useful way to depower the main in heavy air, spilling air off the top of the sail so the boat won't heel so much.
- Upwind, you can use the vang to assist the sheet in controlling the leech, but it's not really necessary. I set the sheet the way I want it, then just tension the vang a little. Vang is much more important off the wind.
- Once you have the sheet trimmed properly (use telltales flying off the aft end of each batten pocket - 2nd, 3rd, and 4th ones should be streaming aft all the time. Top one should be "breaking" (curling) about half the time. Mainsheet control will achieve this setting), use the traveler to center the boom over the cockpit. Ease the traveler to leeward in a puff to stay on your feet - don't release the main; that will just mess up your sail shape. Then pull it back up to center the boom after the puff passes.
- The outhaul controls the foot of the sail. Tighter flattens the bottom third of the sail, which is useful in heavy air.
- The backstay adjuster tensions the forestay, making for a flatter jib entry, but it also bends the mast a bit, flattening the center section of the mainsail. Again, important in heavy air.
- Both the halyard tension and the cunningham control the draft position by adjusting luff tension. In a moderate breeze, the draft should be 45-50% aft of the luff. Tensioning the luff with halyard and cunningham (halyard for top two-thirds, cunningham for bottom third), will move the draft forward. This is very important in heavy air. It reduces heeling dramatically, and allows you to point higher and sail faster. If your sails are showing their age, with the draft consistently at 60% back from the luff, you can move it forward with luff tension (but it will likely move back as the worn sail stretches.)
Does that sound about right?
Bill Russell
"Little Wing," 1998 Catalina 320 #545
Ithaca, NY
>>> 09/15/12 3:01 PM >>>
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Today's Topics:
1. Re: double main sheet control? (Jeff Hare)
2. Replacement plug for depth gage and speed paddlewheel
transducer (Irving Grunes)
3. Re: double main sheet control? (Chris Burti)
4. Camcleat lock (Jerry Clayton)
5. Re: double main sheet control? (Annie Bennett)
----------------------------------------------------------------------
Message: 1
Date: Sat, 15 Sep 2012 11:38:24 -0400
From: "Jeff Hare"
To:
Subject: Re: [C320-list] double main sheet control?
Message-ID: <001201cd9358$255b54c0$7011fe40$@thehares.com>
Content-Type: text/plain; charset="us-ascii"
Here are my thoughts, I have a lot to learn here, and there may be many
different ways of looking at this or different explanations, so take it at
face value. Feel free to correct me wherever I'm wrong here.
In my simple mind, mainsail trim all boils down these 3 things: (anything
more complicated than this and my head pops).
1) adjusting the tension on the three edges of the main sail.
2) trimming the boom in and out to get the leading edge of the main lined
up properly with the wind.
3) adjusting the foil shape of the sail (DRAFT and DRAFT Position).. how
flat or curved the sail is allowed to be and how far away from the mast the
deepest part of the curve sits.
LEECH SHAPE is how straight you keep the back edge of the sail. ( to
controls twist).
DRAFT is how much belly you have/allow in the sail (controls amount of
power generated)
DRAFT LOCATION is how close to the mast the deepest part of the belly is.
(controls how far aft the center of power occurs which acts like a lever
against the mast)
Now, controlling the three edges of the sail:
Tension of the FOOT of the sail with the outhaul the sail helps flatten the
sail somewhat. Lots more when you have a loose footed main.
Tension of the LUFF with the Halyard and Cunningham moves the DRAFT LOCATION
(forward I believe to reduce the leverage effect and stop rounding up so
much).
Tension of the LEECH with the mainsheet/traveler when going upwind, and the
Boom vang when heading off wind controls twist.
The mainsheet traveler can be pulled to way to windward, but the boom itself
should NEVER (in my experience) be windward of the centerline. Generally I
find that if I needed to pull the traveler way up to windward, it's because
I'm close hauled in medium light wind and want a little twist. Without
pulling the traveler up to windward, I can't get the boom centerline without
pulling DOWN too hard on the boom and removing all my twist.
Keep in mind when you're heeled, your sail isn't straight up and down, so
the wind is running not horizontally across your sail but partially UP your
sail, so look at the shape of the sail along the path of the sail the wind
sees and look to optimize that foil.
Alas, I always lose when racing. Both times... :) But I like to cruise
FAST. :)
-Jeff
-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Dennis Harris
Sent: Friday, September 14, 2012 3:24 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] double main sheet control?
Chris or others,
On moving draft with mainsheet, please elaborate how/when this is done. If
boom height is controlled via vang, then it seems that mainsheet simply
extends the range of movement of angle of attack greater than allowed with
the traveler.
Dennis Harris C-320 #694
-----Original Message-----
From: Chris Burti
Sent: Friday, September 14, 2012 12:21 PM
To: C320-List at catalina320.com
Subject: Re: [C320-list] double main sheet control?
Proper sail trim dictates that you use the traveller primarily for changing
the angle of attack, the vang for pulling the boom down or raising it to
reduce twist, the mainsheet, outhaul and halyard/cunningham to move the
draft of the sail forward or aft.
If you wish to move the boom in heavy air without using the winch, either
luff up a little or ease the vang to reduce pressure on the sail. Either end
of the sheet may be used. Both ends of the traveler should be synced.
On Thu, Sep 13, 2012 at 4:35 PM, Gene Helfman wrote:
> Having sailed for 50+ years on boats with only one main sheet, I'll
> admit to being totally perplexed with the port and starboard sheet
> arrangement on the 320, especially when going upwind in anything other
> than light air.
>
> My instincts tell me that hardening the upwind sheet should pull the
> boom down and also bring it to windward (recognizing that the traveler
> also determines boom alignment). To do this, do you slack the downwind
sheet?
> When I do this, the boom moves quickly downwind, making it even
> harder to pull the boom and sail to the upwind side, often requiring
> putting the sheet on the winch and cranking hard. Is there a protocol?
>
> thanks,
> gene
> Satori #398
> Gene Helfman, Professor Emeritus
> Odum School of Ecology, University of Georgia PERMANENT address:
> 498 Shoreland Dr., Lopez Is., WA 98261
> (360) 468-2136
> genehelfman at gmail.com
>
> "Give a man a fish and he'll eat for a day, Teach a man to fish and
> he'll deplete the
> oceans."
>
> The Book of Bob, Ironies 24:7
--
Chris Burti
Farmville, NC
------------------------------
Message: 2
Date: Sat, 15 Sep 2012 11:50:20 -0400
From: Irving Grunes
To: C320-List at catalina320.com
Subject: [C320-list] Replacement plug for depth gage and speed
paddlewheel transducer
Message-ID:
Content-Type: text/plain; charset=ISO-8859-1
Hi,
Where can I get a replacement plug for the depth gauge and speed transducer
for a 2001 #851 hull.
Irv Grunes
Isle of Wight
Sue Creek, Middle River, Chesapeake
------------------------------
Message: 3
Date: Sat, 15 Sep 2012 11:55:04 -0400
From: Chris Burti
To: C320-List at catalina320.com
Subject: Re: [C320-list] double main sheet control?
Message-ID:
Content-Type: text/plain; charset=ISO-8859-1
I recommend Don Guillette's Sail Trim Chart and companion
publication, Sail Trim Users Guide. You can order these at
www.Sailboatowners.com.
I found his explantions to be the best and most accurate that I've read.
s author of the immensely popular On Sat, Sep 15, 2012 at 11:38 AM,
Jeff Hare wrote:
> Here are my thoughts, I have a lot to learn here, and there may be many
> different ways of looking at this or different explanations, so take it at
> face value. Feel free to correct me wherever I'm wrong here.
>
> In my simple mind, mainsail trim all boils down these 3 things: (anything
> more complicated than this and my head pops).
>
> 1) adjusting the tension on the three edges of the main sail.
> 2) trimming the boom in and out to get the leading edge of the main lined
> up properly with the wind.
> 3) adjusting the foil shape of the sail (DRAFT and DRAFT Position).. how
> flat or curved the sail is allowed to be and how far away from the mast the
> deepest part of the curve sits.
>
> LEECH SHAPE is how straight you keep the back edge of the sail. ( to
> controls twist).
> DRAFT is how much belly you have/allow in the sail (controls amount of
> power generated)
> DRAFT LOCATION is how close to the mast the deepest part of the belly is.
> (controls how far aft the center of power occurs which acts like a lever
> against the mast)
>
> Now, controlling the three edges of the sail:
>
> Tension of the FOOT of the sail with the outhaul the sail helps flatten the
> sail somewhat. Lots more when you have a loose footed main.
> Tension of the LUFF with the Halyard and Cunningham moves the DRAFT LOCATION
> (forward I believe to reduce the leverage effect and stop rounding up so
> much).
> Tension of the LEECH with the mainsheet/traveler when going upwind, and the
> Boom vang when heading off wind controls twist.
>
> The mainsheet traveler can be pulled to way to windward, but the boom itself
> should NEVER (in my experience) be windward of the centerline. Generally I
> find that if I needed to pull the traveler way up to windward, it's because
> I'm close hauled in medium light wind and want a little twist. Without
> pulling the traveler up to windward, I can't get the boom centerline without
> pulling DOWN too hard on the boom and removing all my twist.
>
> Keep in mind when you're heeled, your sail isn't straight up and down, so
> the wind is running not horizontally across your sail but partially UP your
> sail, so look at the shape of the sail along the path of the sail the wind
> sees and look to optimize that foil.
>
> Alas, I always lose when racing. Both times... :) But I like to cruise
> FAST. :)
>
> -Jeff
>
> -----Original Message-----
> From: c320-list-bounces at lists.catalina320.com
> [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Dennis Harris
> Sent: Friday, September 14, 2012 3:24 PM
> To: C320-List at Catalina320.com
> Subject: Re: [C320-list] double main sheet control?
>
> Chris or others,
>
> On moving draft with mainsheet, please elaborate how/when this is done. If
> boom height is controlled via vang, then it seems that mainsheet simply
> extends the range of movement of angle of attack greater than allowed with
> the traveler.
>
> Dennis Harris C-320 #694
>
> -----Original Message-----
> From: Chris Burti
> Sent: Friday, September 14, 2012 12:21 PM
> To: C320-List at catalina320.com
> Subject: Re: [C320-list] double main sheet control?
>
> Proper sail trim dictates that you use the traveller primarily for changing
> the angle of attack, the vang for pulling the boom down or raising it to
> reduce twist, the mainsheet, outhaul and halyard/cunningham to move the
> draft of the sail forward or aft.
>
> If you wish to move the boom in heavy air without using the winch, either
> luff up a little or ease the vang to reduce pressure on the sail. Either end
> of the sheet may be used. Both ends of the traveler should be synced.
>
>
> On Thu, Sep 13, 2012 at 4:35 PM, Gene Helfman wrote:
>> Having sailed for 50+ years on boats with only one main sheet, I'll
>> admit to being totally perplexed with the port and starboard sheet
>> arrangement on the 320, especially when going upwind in anything other
>> than light air.
>>
>> My instincts tell me that hardening the upwind sheet should pull the
>> boom down and also bring it to windward (recognizing that the traveler
>> also determines boom alignment). To do this, do you slack the downwind
> sheet?
>> When I do this, the boom moves quickly downwind, making it even
>> harder to pull the boom and sail to the upwind side, often requiring
>> putting the sheet on the winch and cranking hard. Is there a protocol?
>>
>> thanks,
>> gene
>> Satori #398
>> Gene Helfman, Professor Emeritus
>> Odum School of Ecology, University of Georgia PERMANENT address:
>> 498 Shoreland Dr., Lopez Is., WA 98261
>> (360) 468-2136
>> genehelfman at gmail.com
>>
>> "Give a man a fish and he'll eat for a day, Teach a man to fish and
>> he'll deplete the
>> oceans."
>>
>> The Book of Bob, Ironies 24:7
>
>
>
> --
> Chris Burti
> Farmville, NC
>
--
Chris Burti
Farmville, NC
------------------------------
Message: 4
Date: Sat, 15 Sep 2012 10:05:44 -0700
From: "Jerry Clayton"
To: "C320-List"
Subject: [C320-list] Camcleat lock
Message-ID: <4F8250FC4591434BABF61B855316070C at ownerccfbe0136>
Content-Type: text/plain; charset="iso-8859-1"
Does anyone know if you can replace the red lock (hold down) piece on the mainsheet camcleat?
Regards,
Jerry Clayton
#988 (2004)
Marina Del Rey, Ca
------------------------------
Message: 5
Date: Sat, 15 Sep 2012 10:31:55 -0700
From: Annie Bennett
To: "C320-List at Catalina320.com"
Subject: Re: [C320-list] double main sheet control?
Message-ID:
<27565837-E5DA-4220-826D-81D2CD5AF7BE at sydneyprivatesailing.com.au>
Content-Type: text/plain; charset=us-ascii
On Topcat I use the main sheet on the starboard side regardless of what tack I'm on as I'm very right handed and it feels more comfortable to me. I use the main sheet on the port side if I have non sailing guests who are sitting in the way of the sheet on the starboard sheet so I don't have to ask them to move. Probably not a very technical reason I know.
Annie Bennett
Topcat #1073
On 14/09/2012, at 9:21 AM, Chris Burti wrote:
> Proper sail trim dictates that you use the traveller primarily for
> changing the angle of attack, the vang for pulling the boom down or
> raising it to reduce twist, the mainsheet, outhaul and
> halyard/cunningham to move the draft of the sail forward or aft.
>
> If you wish to move the boom in heavy air without using the winch,
> either luff up a little or ease the vang to reduce pressure on the
> sail. Either end of the sheet may be used. Both ends of the traveler
> should be synced.
>
>
> On Thu, Sep 13, 2012 at 4:35 PM, Gene Helfman wrote:
>> Having sailed for 50+ years on boats with only one main sheet, I'll admit
>> to being totally perplexed with the port and starboard sheet arrangement on
>> the 320, especially when going upwind in anything other than light air.
>>
>> My instincts tell me that hardening the upwind sheet should pull the boom
>> down and also bring it to windward (recognizing that the traveler also
>> determines boom alignment). To do this, do you slack the downwind sheet?
>> When I do this, the boom moves quickly downwind, making it even harder to
>> pull the boom and sail to the upwind side, often requiring putting the
>> sheet on the winch and cranking hard. Is there a protocol?
>>
>> thanks,
>> gene
>> Satori #398
>> Gene Helfman, Professor Emeritus
>> Odum School of Ecology, University of Georgia
>> PERMANENT address:
>> 498 Shoreland Dr., Lopez Is., WA 98261
>> (360) 468-2136
>> genehelfman at gmail.com
>>
>> "Give a man a fish and he'll eat for a day,
>> Teach a man to fish and he'll deplete the
>> oceans."
>>
>> The Book of Bob, Ironies 24:7
>
>
>
> --
> Chris Burti
> Farmville, NC
End of C320-list Digest, Vol 1528, Issue 2
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