Sail catchers

  • 18 Mar 2021 21:27
    Reply # 10211177 on 10208314
    Anonymous member (Administrator)

    Hi Jami it wasn't meant as a criticism, just to make discussion and new ideas.

    I recently replaced a sail catcher tube with a rather light, thin-walled aluminium tube. I think it was about 24mm diameter but by mistake it was very thin wall. As I have only one attachment point for each lift, I was afraid it might bend. With wood battens, the sail bundle on my boat is quite heavy too.

    However I did not put it to the test, because I realised also that to make it possible to slip the tube in and out of the pocket, it would be inconvenient to attach the lifts to the tube. I was forced to think of another way.

    Actually, while making the initial repair at sea, with a broken tube, the sail catcher became useless for supporting the bundle so I made a rope loop which goes under the bundle and up the other side, making the two lifts into a single line - rather like the so-called "mast lift" in PJR. The lifts alone could now carry the full weight of the sail bundle - the detail which is centuries old, but I had forgotten.

    (Its so simple and obvious but I never thought of it when making the sail catcher. At that time, my intuition told me to attach the lifts to the aluminium tube, same as you did).

    But here's the point: for anyone making a sail catcher for the first time, do not cut away a section of the sail catcher pocket to allow lifts to attach to the tubes, as Jami and I did. Instead, sew a strap of webbing which goes right around under the sail catcher and up the other side to provide a strong attachment point for the lifts on each side. This will carry the weight of the bundle. Then you can slide quite light tubes into the pockets at the top of the sail catcher which do not carry any weight but merely keep the top of the sail catcher straight, and open.  (And the starboard one can be slipped back at any time to allow the catcher and bundle to be removed from the mast).

    The bundle itself keeps the sail catcher straight, and you can make the aft attachment points as far aft as you like, subject to the length of the yard. All the tubes have to do is keep the top edge straight and open.

    Its just a fancy variation of what was in PJR all along, but with just two lift pairs and no lazy jacks needed.

    And no need for the tubes to carry any weight. 

    (So Jami: no need for carbon fibre sail-catcher tubes!!)

    Last modified: 19 Mar 2021 01:17 | Anonymous member (Administrator)
  • 18 Mar 2021 10:45
    Reply # 10209214 on 10208314

    I might hop in, as you have taken my sailcatcher as an example :)

    Originally I sew two openings on the catcher, because I wasn't sure how far aft the intended 35mm tube would tolerate the lazyjack to be fastened without bending too much. And as it happened, both of them were needed to prevent this.

    My battens and sail seem to be so heavy, that the tube bends way too much if attached only on one point - an especially so, if fastened as far aft as would be optimal for not interfering with the camber.

    If one just could afford carbon battens... if only.

    Do you think using square tubes for the sailcatcher would be better than round tubes (less bending with the same weight)?

    Last modified: 18 Mar 2021 10:58 | Anonymous member
  • 18 Mar 2021 02:50
    Message # 10208314
    Anonymous member (Administrator)

    Sail catcher

    I keep harping on about this, but with a sail catcher you don't need the lazy jack arrangement. It occurs to me that on Jami's sail catcher, that lazy jack arrangement with two attachment points on the aft part of the sail catcher may be intended as a way of spreading the load more evenly on the tubular frame of the sail catcher.

    Well, you don't need to do that, and the downside is, it presses on the leeward side of the aft part of the sail and interferes with its shape, more so than a simple pair of aft lifts. At least with the Amiina sail plan, the aft lifts should be attached to the sail catcher as far aft as possible (just forward enough so the yard can not escape when hoisting the sail). 

    And I believe it is better if the lifts are not attached directly to the aluminium tube frame.

    I collided with a channel marker the other day and broke one of the tubes on the sail catcher, at the mast, and it seemed at first like a disaster because of course the sail catcher is a necessary support for the bundle, when reefing. The result of the accident was that I made a discovery: attaching the lifts to the tubular frame, as Jami has done and as I had done, is a mistake.

    Better to attach the lifts to a reinforced attachment point on the sail catcher itself. Those aluminium tubes can then be lighter, as they then carry very little load, and only serve the purpose of stiffening the edge of the sail catcher. So those tubes can be made from lighter, cheaper stuff - and one attachment point for each lift is sufficient as the cloth sail catcher is carrying the load of whatever is in the catcher, instead of the tubular frames.

    My breakage also showed up another advantage - if the lifts are not directly attached to the tubular frame, this allows the starboard tube to be easily slid back in its pocket, to allow the bundle with its catcher to be easily released from the mast, a necessity for trailer boats. Previously I had the starboard tube in two parts, with a join at the mast for easy release. This is where it broke, and why it broke. By transferring the forward ("mast") lifts to the catcher itself rather than the tubes I was able to remove the broken parts easily - and later, to slide a singe full-length replacement tube easily into the pocket. Its an improvement now, every time the rig has to be dismantled.

    One last further tilt towards KISS: the U-shaped tube joining  the tubes at the front of Amiina's sail catcher frame appears to be un-necessary. I made one for the front and one for the back out of plastic. The back one interfered with the sheeting and I simply took it off. The front one broke and I never replaced it.

    Two simple parallel tubes appear to be all that is necessary as a frame for the sail catcher. 

    And two simple lift pairs, one pair at the mast and one as far aft as possible, attached to the catcher and not putting load on the aluminium tubes, interferes least with the sail and appears to be all that is necessary to guide the spars into the catcher and muzzle the sail when reefing or handing.

    Last modified: 18 Mar 2021 22:36 | Anonymous member (Administrator)
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software