Pacific Spray - Booms, Battens and Sheeting

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  • 27 Jan 2015 03:01
    Reply # 3210937 on 3205809
    Walter Flanagan wrote:

    I have sourced 65 x 3.5 6261-T6 from Ullrich, which is our preferred candidate at present. Lengths are 6 m

    Walter &Estelle 

    Sounds great!
  • 27 Jan 2015 01:46
    Reply # 3210904 on 765598
    Deleted user

    We have 7+5 existing, to be replaced with only 10 new. So we keep 2 existing to make up the shortfall, possibly +1 spare. Leaves 9.
    "Blondie" has a prior option to purchase 6. I think he wants 4m lengths. Price yet to be negotiated.
    Any good?

  • 26 Jan 2015 22:35
    Reply # 3210776 on 3205809
    Walter Flanagan wrote:We now have lots of 38x3 tubes available for anyone interested. :)
    Are you still in the Town Basin?  I've managed to bend one of my 38 x 1.5 spars and should maybe 'invest' in a few heavier ones.
    Last modified: 26 Jan 2015 22:36 | Anonymous member
  • 20 Jan 2015 23:24
    Reply # 3205809 on 765598
    Deleted user

    I have sourced 65 x 3.5 6261-T6 from Ullrich, which is our preferred candidate at present. Lengths are 6 m, which is another requirement as our battens are all longer than 5 m, the other standard length. This material is a standing order by a Tauranga company, that has agreed to release some of the stock to us. 

    We now have lots of 38x3 tubes available for anyone interested. :)

    Walter &Estelle 

  • 20 Jan 2015 22:15
    Reply # 3205783 on 765598
    Deleted user

    Arne and David
    Thank you both for sharing your views.
    I will go back to Ulrich to explore the 63 mm tube option in my preferred 6261-T6 alloy.
    I heard from a friend last night that there might be an alternative to Ulrich in NZ too. Any comments on the 'minimum acceptable' alloy?
    Walter & Estelle

  • 20 Jan 2015 20:16
    Reply # 3205674 on 765598


    I used square section GRP battens for quite a long time, and over many ocean miles, the edges were chafing through the sail pockets.

    Also, square tube is not as good as round tube in terms of strength per Kg.

    My calculations give these results:

    50 dia x 3 round tube: weight 1.2 kg/m section modulus Z = 4903

    50 x 50 x 3 square tube: weight 1.52 kg/m section modulus Z = 5904 ( on the diagonal), 8340 (perpendicular to a face) - it's strange-but-true that square tube is weaker when loaded on its diagonal.

    63.5 dia 3 round tube: weight 1.54 kg/m section modulus Z = 8222

    A square batten tries to rotate to the orientation in which it can bend most easily, which is on the diagonal, so that presents an edge to the mast - not good.

    So you'd get better value from a round tube. If your pockets will accommodate a 50 x 50 square tube, they will also accommodate a 63.5 round tube, and that's what I would go for. But Pacific Spray being so heavy and stiff, I'd make the upper battens from bigger tube still, if they'd fit in the pockets. 

  • 20 Jan 2015 10:38
    Reply # 3205214 on 765598
    Anonymous member (Administrator)


    The 38 x 3mm battens sound very thin so it is no doubt a good idea to beef them up.

    The square battens you describe will be much stronger (about twice) than the round ones you describe.  This is partly because the square tube will be about 20% stronger when the square sides are the same as the diameter of the round tube( and with same wall thickness). In addition the 6261-T6 alloy appears to be very strong at 270MPa (270 Newton/square mm) versus 150 - 170MPa of the 6061-T5.

    I would certainly have opted for the square battens, at least in the upper half of each sail. Even then, I suggest that you have a good test sail along the coast. This will let you see how things look  -  and you will be able to limp back to harbour if you get any problems. A 38’ (over 12 tons?) Spray is outside my usual area of experience, so I cannot give a more exact advice.



  • 20 Jan 2015 02:01
    Reply # 3204863 on 765598
    Deleted user

    An old topic, re-awakened.
    Pacific Spray (20 T Roberts Spray) has 38 mm diameter alloy (apparently double-sleeved total wall about 3 mm) battens on the 600 sq ft main and the 380 sq ft fore. Lengths are < 6 m.
    As we are preparing for our offshore trip and haven't had a serious shakedown in home waters, we are contemplating stronger battens, especially the upper battens. We have increased all pockets on both sails to 60 x 60.
    Ulrich here in NZ can only offer 50 x 3 mm 6061/T5. Or alternatively 50 x 50 x 3 mm 6261/T6 square. I can identify with the latter.
    Square or round? Scantlings?
    Any views or referrals will be gratefully received.
    Thanks in advance.
    Walter & Estelle

  • 16 Jan 2012 11:18
    Reply # 800017 on 765598
         My main sail sports two old dingy masts yard and boom with wooden extentions free from a boat yard ,  lenghts about 11 feet ,the sail track seems to add strength while being light ,   . Might help cheers .
  • 07 Dec 2011 15:57
    Reply # 768173 on 765598

    I was trying to get to Karmsundet to race on saturday. The wind was 35 knots and coming from 3/4 rear and I started with 2 panels down. That was a bit much as the wind increased to 38 knots, and I took down another panel. As poor Edmond was trying desperately to surf, I had to bring down another panel. I was now 4 panels down and had 8-9 knots falling down the waves. I tried to take an inshore route to awoid the biggest seas, and my heart sank a bit when I met the ferry that crosses the relatively open strech of water. I know when they stop going, it is rough. I came to the end of the shelter and looked at the seas running, the line between being a hero or a fool is quite thin, so I decided to seek cover and hope for better conditiones next day. The wind became tamer the next day but too late to get to the start. I tried if I could make progress agaist the wind, and I could. It was more a rodeo than a sail, though. Reading this thread make me think: I did not have any problems with the battens, nor the rather flimsy sailcloth we use here in Stavanger. My thoughts were more in the way of loosing the mast by a break in the mast step. Then the mast would act as the biggest can opener in the world, and to quote Arne: That would be a sad day on the fjord. My mast and sail is direct copy of Arnes.


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