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A new rig for Leeway

  • 12 Mar 2017 08:53
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    Reply # 4661765 on 4138614
    Anonymous member

    The situation is remarkably similar to that on Weaverbird, where I had to cut through a deck beam as well. I decided to add a deep plywood arch, bonded to the remains of this deck beam, extending down as far as the topside stringer, as an excess of rigidity in this area can't hurt. I think you might do something similar, and extend the triangular web athwart the mast partners to make it a quadrilateral that meets the stringer.
  • 11 Mar 2017 23:33
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    Reply # 4661394 on 4138614
    Deleted user

    This has been a big week in Leeway's refit.  After far too long taking care of other parts of the refit, I'm finally working on the Junk Rig (which was a big motivation for the refit). I've re-read PJR and searched the forum, but there isn't much information about mast partners in a metal (aluminum) boat.   I have the mast step fit in place but I'm a bit stuck on the mast partners and would welcome any thoughts on my proposed mast partners.  

    As a bit of background, Leeway came with freestanding masts as part of a staysail schooner rig.  Fortunately the main mast is in a workable location.  The main-mast-partners consists of a 11 3/4" (298mm) ID, 3/8" (10mm) wall tube to accept a 10" (254mm) OD aluminum mast.  The deck plating is 3/16" (5mm) thick and has a 3/8" (10mm) thick doubler around the tube as part of the mast partners.  This mast benefits from its location on the back of the coachroof which acts like a deep transverse frame. 

     

    Below deck the tube that forms the mast partners is supported by triangular webs made from 1/4" (6mm) plate.


    Unfortunately, I have to move the foremast to fit a junk rig.  The best location for the foremast is in the middle of the fore-deck and thus there aren't very heavy transverse frame members present.  The 3/16" (5mm) deck plate in this area has 2" (51 mm) angle transverse frames as the stiffeners.  Shown is red is the cutout where the tube would go for the mast partners.  It will cut through one of the 2" square transverse frames.


    Zooming out a bit, the hole for the mast partners would end up 12" (305mm) aft of the small bulkhead and 24" (610mm) foreward of the 6" (152mm) tall ring frame show in the foreground of the photo below.  My plan was to add triangular webs like those on the foremast to support the tube below deck.


    My original plan was to reinforce the fore-deck with two 1/4" (6mm) thick doublers.  The foredeck has a fair bit of camber, so the plan is to use two stacked doubler plates that can more easily be bent to follow the deck, rather than one thicker one.  One plate (shown in green) would be 30" diameter, with another 22" diameter (shown in blue) laid on top of that.  There are also some holes leftover from the windlass that will need to be dealt with.


    My question is, does this sound reasonable, or is more substantial framing required below decks?
  • 10 Aug 2016 20:22
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    Reply # 4182929 on 4138614
    Deleted user

    I posted the result of my test of the Dewalt drill as an electric winch handle in a new thread here.
  • 31 Jul 2016 23:12
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    Reply # 4165297 on 4138614
    Deleted user

    Annie,

    If only I had a cockpit!  Seriously though, I don't think there is space for boxes.  If you look at this drawing and this picture, you can see that things are a bit cramped as they are.  Also, making PJR-style storage reels shouldn't be too arduous (I know, famous last words).  The plan is to make the reels using PVC pipe and PVC sheet.  To mount them, I just need to weld aluminum spindles to the hull.
  • 31 Jul 2016 22:56
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    Reply # 4165288 on 4138614
    Anonymous member (Administrator)

    Darren,

    just a quick one before hitting the bunk:

    A power capstan needs not be destructive. Just pass the rope a single turn around it before starting up. Then you will need to haul a little on the rope and if anything jams, the rope will just slip on the drum. That is how it works for me, at least.

    Arne

    PS. Most of the ball bearing blocks I use (alle the single blocks) are so-called heavy duty, with steel balls and race.

     

    Last modified: 31 Jul 2016 23:01 | Anonymous member (Administrator)
  • 31 Jul 2016 22:49
    Quote
    Reply # 4165286 on 4165281
    Anonymous member
    I've drawn my line reels base on 10 mm line and a 3:1 purchase.  If 3:1 turned out not to be enough, then I suppose I could go for a high-strength line of smaller size and still fit it on the same reel.
    Most men find 8mm line too small to handle comfortably, simply because they can't get a good grip on it.  If you are planning to haul up the first part of the sail by hand, this is worth bearing in mind.
  • 31 Jul 2016 22:43
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    Reply # 4165281 on 4138614
    Deleted user

    Thanks Arne, that's interesting, as usual.

    You are right that Dewalt drill only has about 1/4 the torque of the winchrite.  This is largely a result of being a 12V tool.  The manufacturer for the winch bit lists the sister model to this drill as one of his preferred tools when really high torque isn't necessary.  I found one for sale second hand in my neighbourhood and figured it was worth a try.  The lower torque does have the one advantage of making it more difficult to really mess things up.  One of things I don't like about powered winches is that you have incredible power at the push of the button.  Thus, it only takes a moment of inattention to jam or break something thoroughly.  We'll see, right now it is a cheap experiment.  I'm still consider the Pontos 4-speed winch whose lowest gear has a power ratio of 112.9:1, so with that winch the lower torque of the Dewalt drill could be made up by the winch gearing, albeit with a slower haul rate.

    Given my high AR sails, a 5:1 halyard would be a fair bit of line to store.  I am interested to see what numbers you come up with for mast compression from the halyard.  I've drawn my line reels base on 10 mm line and a 3:1 purchase.  If 3:1 turned out not to be enough, then I suppose I could go for a high-strength line of smaller size and still fit it on the same reel.

    I was planning on using the Garhauer ball bearing blocks that I think David and Annie have had success with.  I'm not sure how these would compare to the Selden ones, but halyard blocks do seem like a spot where life can be improved by spending a bit of money.
  • 31 Jul 2016 22:23
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    Reply # 4165272 on 4164938
    Anonymous member
    Darren Bos wrote: Even just 3:1 leaves me with lots of line to store when the sail is up.
    Darren, I don't know why you're worrying so much about the line.  You're in the midst of a major refit - just make a couple of boxes that double as cockpit seats and have a lift-up lid.  Cut an angle off the forward, inboard corner of the lid so that the rope can run out without lifting the lid.  When you've raised sail, lift up the lid and flake the rope down into it.  End of problem.  If you want, you can divide the box, or put baskets into it, and put a halyard in one and sheet in the other.
  • 31 Jul 2016 21:37
    Quote
    Reply # 4165225 on 4138614
    Anonymous member (Administrator)

    Darren,

    Just for the record. I have fitted a 5-part halyard to the 35sqm sail of my 26’ IF, Ingeborg. This time I have used big, nice ballbearing blocks from Selden, all with 60mm sheaves. These can take 10mm rope but I only use 8mm halyard. As a result, even I can hoist the sail by hand, without using a winch handle (sb. genoa winch is used as a snubbing winch). The sail also comes down fast, so I have to follow it down with the rope around the winch. I have calculated my sail plus batten and yard to be a little over 40kg.

    I have to confess, for comfort I also use the Winchrite that I bought for Johanna, on Ingeborg. In practice, I quickly hoist about half the sail by hand, and let the Winchrite do the rest. Any reefing and unreefing is done by hand.

    http://www.winchrite.co.uk/

    A 5-part halyard may sound like an overkill on a 35sqm sail, but it is rather the ratio between the sail area and the guy or girl at the halyard which decides the needed purchase. In addition, I prefer an odd number purchase; 1,3 or 5, to let me terminate the bitter end of the halyard on the yard.

    Now I checked some of those Dewalt angle drills. Their torque does not impress me, compared to the Winchrite’s 130Nm (1150inlb or 96ftlb). However, the torque needed on a 3-5 part halyard is not big, but it depends on the size of the winch drum or if it has several gears.

    As for compression loads on the mast; now I dug out a digital luggage scale. That goes to 40kg. I can easily attach it to the fall of the halyard on Ingeborg and see how high the load is with the boat sailing full and by, and with her gunwale in the water. The compression load on the mast should be 6 times the read-out, plus the much lighter loads on the THP and YHP.

    I guess I am better at measuring than at making precise calculations...

    Arne

     

    Last modified: 13 Mar 2017 19:48 | Anonymous member (Administrator)
  • 31 Jul 2016 17:20
    Quote
    Reply # 4164938 on 4138614
    Deleted user

    Although I think Dyneema makes reel winches more attractive than they once were, I think that on balance I'd still be happier with a self-tailing winch married to rope clutches.  David, I also found some stainless reel winches with automatic clutches that fit the bill from industrial marine suppliers, but the prices were high (even relative to the new reel winches you found) and I agree that Leeway is better suited with a self tailing winch.

    Arne, I had been worried about mast compression as well, especially with the 4" dia at the top of my masts.  I'm sure David could spell it out explicitly, but my shade tree engineering would leave me happier with less compression on the mast.  A 2:1 or 3:1 halyard purchase seems to be the sweet spot in terms of lowering compression on the mast, while keeping the friction at a reasonable level to allow the sail to drop without too much overhaul resistance, as well as potentially reducing the wringing loads when the sail is let out on a run.  Even just 3:1 leaves me with lots of line to store when the sail is up.

    It seems like a two speed winch with a power ratio around 14:1 at the high end, and 30:1 at the low end is the tool for a 50 m2 sail.  I had started my winch shopping looking at "40" size winches, but looking at power ratio's, it looks like many "30" size winches would be up to the job.  Lewmar lists the SWL for a 30-size as 1500lbs.    

    David has estimated the largest halyard load on Tystie as 200-400kg when raising sail while running downwind.  Robert Self had calculated the sheet loads in the range of 75 lbs for his 550 sqft. split junk rig.  However, even if you take the maximum 900 lb load he calculates for a completely unbalanced sail, that is still only 300lbs force at a winch with a three part sheet.  So, it looks like both halyard and sheet loads would be within the SWL for 30-size winch.

    Arne, I had read your write-up on the winchrite and thought it was a good idea.  I have bought a "The Cranker" winch bit, and am going to marry it to a Dewalt 965 angle drill.  The plan is to modify the drill so it works directly from the ships 12V (14V when engine running) power so I don't have to charge batteries for the drill.  We'll see how it works out, but so far I have less than $100CAN invested in used drill and the winch bit.  I'm off for a week of camping, but will report back how it works when I return.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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