A sail for "Footprints"

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  • 05 Dec 2011 19:53
    Reply # 766399 on 766023
    Edward Hooper wrote:David,
    Can you help/advise.
    On my screen some peoples comments do not fit the template,
    and are therefore very difficult to read.
    Basically it seems one can type too long on a line, and then it gets cut off. Like this screen is longer/wider than the one the messages come up on.  Not sure if I am making myself very clear, but will keep typing to see if I can recreate the problem!!!  Maybe it is just my old computer and my old screen.  Please advise if you can as I particularly want to read all of your and Arne's contributions and sometimes I cannot.
    The problem is worst when an image, or a link, is bigger than the frame that the posting has to fit into. Text alone automatically fits within the frame, but an image or a link changes that.

    In the case of an image, the maximum size should be 300 pixels.

    If  the text of a link is edited and one or more "returns" are put in, so as to fit within the frame; or the text is shortened; or the text is changed completely; so long as the underlying link is the same, you will be taken to the same place when you click on it.

    I've gone back to Arne's postings in this topic and edited them in this way, and now all the other text fits within the frame.





    Last modified: 05 Dec 2011 21:29 | Anonymous member
  • 05 Dec 2011 17:16
    Reply # 766217 on 761646
    Anonymous member (Administrator)

                                                                                  Stavanger, Monday

    Dudley

    I asked if you only had problems with my writing or if you also had problems with postings from others. Now I am back to editing in Word again, but this time I will try another method for converting the text. My reason for using WORD is that the speller program there helps me in writing half-decent English. How does this look? Do you lose any letters?

    Arne

    PS: Below you'll find a copy of my posting from Saturday. Do you get all of it out this time?

    Stavanger, Sat. 3.12.2011

    Hi Gary K. The CE is just the geometric centre of the sail. On these sails it ends pretty close to mid-between luff and leech. The "real" CE is called the centre of pressure (CP) and this will as you say be noticeably forward of the middle when the max camber point is well forward of the middle. When I played around with different sails for my earlier boat, Malena, I noticed that adding symmetric camber to the flat sail (1991)increased weather helm, so the CP must have moved aft. When fitting a new sail with cambered panels and max camber 35%from luff (1994), the CP moved so far forward that I had to haul the sail quite a bit aft to avoid lee helm. I guess the CP moves 5-10% of the chord forward with my cambered panels compared to when using a flat sail. I keep this in mind when fitting junk rigs.

    Clear as crystal, right?

    Arne

    PS: Below is a link to a photo showing the symmetric camber of Malena’s sail with hinged battens (1992).

    Malena.jpg

    Last modified: 05 Dec 2011 20:09 | Anonymous member
  • 05 Dec 2011 16:46
    Reply # 766185 on 766060
    Arne Kverneland wrote:

    Dudley and Edward,

    Do you have more problems with my writing than with others'? In case of "yes", could that be because I draft the messages in WORD first. I doubt it. I store it as pure text before copying and pasting into this posting. This text, btw. I edit directly, so now you have the chance to see if it comes out differently than my posting about "Footprint"s JR. When editing here, a few letters goes outside the frame too, but it gets right when posted.

    Arne

    Arne,
    That works OK for me. All on the page and in the center. Thank you, Dudley
  • 05 Dec 2011 13:54
    Reply # 766060 on 761646
    Anonymous member (Administrator)

    Dudley and Edward,

    Do you have more problems with my writing than with others'? In case of "yes", could that be because I draft the messages in WORD first. I doubt it. I store it as pure text before copying and pasting into this posting. This text, btw. I edit directly, so now you have the chance to see if it comes out differently than my posting about "Footprint"s JR. When editing here, a few letters goes outside the frame too, but it gets right when posted.

    Arne

  • 05 Dec 2011 12:41
    Reply # 766036 on 766023
    Edward Hooper wrote:David,
    Can you help/advise.
    On my screen some peoples comments do not fit the template,
    and are therefore very difficult to read.
    Basically it seems one can type too long on a line, and then it gets cut off. Like this screen is longer/wider than the one the messages come up on.  Not sure if I am making myself very clear, but will keep typing to see if I can recreate the problem!!!  Maybe it is just my old computer and my old screen.  Please advise if you can as I particularly want to read all of your and Arne's contributions and sometimes I cannot.
    I still have the same problem with your messages Arne and the last nine words of each line of your message were missing. The only way I have been able to read the full message is by copying and pasting into MS Word. What am I doing wrong? 
  • 05 Dec 2011 11:53
    Reply # 766023 on 761646
    David,
    Can you help/advise.
    On my screen some peoples comments do not fit the template,
    and are therefore very difficult to read.
    Basically it seems one can type too long on a line, and then it gets cut off. Like this screen is longer/wider than the one the messages come up on.  Not sure if I am making myself very clear, but will keep typing to see if I can recreate the problem!!!  Maybe it is just my old computer and my old screen.  Please advise if you can as I particularly want to read all of your and Arne's contributions and sometimes I cannot.
  • 03 Dec 2011 15:19
    Reply # 765087 on 761646
    Anonymous member (Administrator)

    Stavanger, Sat.

    Hi Gary K. The CE is just the geometric centre of the sail. On these sails it ends pretty close to mid-between luff and leech. The "real" CE is called the centre of pressure (CP) and this will as you say be noticeably forward of the middle when the max camber point is well forward of the middle. When I played around with different sails for my earlier boat, Malena, I noticed that adding symmetric camber to the flat sail (1991)increased weather helm, so the CP must have moved aft. When fitting a new sail with cambered panels and max camber 35%from luff (1994), the CP moved so far forward that I had to haul the sail quite a bit aft to avoid lee helm. I guess the CP moves 5-10% of the chord forward with my cambered panels compared to when using a flat sail. I keep this in mind when fitting junk rigs.

    Clear as crystal, right?

    Arne

    PS: Below is a link to a photo showing the symmetric camber of Malena’s sail with hinged battens (1992).

    http://dl.dropbox.com/u/49284570/Arne%20Kverneland%

    27s%20Junk%20Rig%20Files/1992%20Malena

    %20med%20rev.jpg

    Last modified: 05 Dec 2011 19:56 | Anonymous member
  • 03 Dec 2011 14:10
    Reply # 765066 on 761646
    Deleted user
    Hi Arne, I noticed you have the CE really close to the middle of the your sail. At 49% width from the luff. In practice wouldn't a cambered sail's CE be closer to the luff?
    Last modified: 03 Dec 2011 14:21 | Deleted user
  • 02 Dec 2011 10:24
    Reply # 764258 on 761646
    Anonymous member (Administrator)

    Stavanger, Fri

    Yesterday I too sent David Thatcher a sketch for a sail for "Footprints". Basically it is a copy of johanna's sail, but with the batten distance increased from 1.2m to 1.3m in the lower panels. That raises the SA from 48.4 to 50.7sqm and the AR from 1.87 to 1.94.

    By sticking to the 5.8m long battens I hoped to reduce the weather helm. If you click on the link below, hopefully the file, stored on my Dropbox site, will open.

    Arne

    junksail.jpg

    PS: It is best to store the file on your pc and then open it in some program. This lets you zoom in and out and even make fiixes to it.

    Last modified: 05 Dec 2011 20:11 | Anonymous member
  • 01 Dec 2011 20:20
    Reply # 763767 on 761646
    David,
    I've sketched a sail for Footprints, and put it into "David's Doodles" in both dxf and pdf form. I think it satisfies the requirements. It needs to be set quite high on the mast in order to clear the guardwires when it is swung across the mast for downwind sailing. It would be rigged with a normal yard hauling parrel; an upper luff hauling parrel from the yard, to batten 6, to batten 4, to the deck (that's like Fantail's sail); a middle luff hauling parrel from batten 3, to batten 2, to the deck; and the running line from batten 1, around the mast to the tack, to the mast partners, to the cockpit, back to the mast partners, to the mid point of the boom, around the mast and back to the mid point of the boom. ( two single and becket blocks are attached, at the tack and mid point of the boom).

    Annie and I have just got the vane gear for Fantail to the same stage as yours – almost rigged and ready for sea trials. We'll compare notes soon!
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