A new rig for Leeway

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  • 29 Aug 2017 23:32
    Reply # 5054923 on 4138614

    I was told that soluble oil is the recommended choice as it won't float on top of any water that gets in through pinholes, but it was very expensive so I ended up using vegetable oil (Canola).  When I welded the patch on, I pumped out the oil from the airspace above the ballast with a vacuum pump but the oil that soaked down through the ballast was inaccessible.  A little was still oozing through the pinholes in the area of thin plate, but it didn't catch fire when we welded the patch on.  I also figured that the plates welded over the ballast would both limit oxygen and contain any flames.  Still I was relieved not to set the boat on fire!  The bad thing about metal boats is that they can corrode, but the good thing is that any subsequent weakness is highly localised and it is easy to repair.  And when you are crashing off waves at 0300hrs, there is some comfort in knowing how strong the hull is!  My ideal boat is about 11-12 metres LOA, metal of course, with 4-5 watertight bulkheads and small portholes!

  • 29 Aug 2017 18:02
    Reply # 5054293 on 4138614

    Graham, I think we have a fair bit in common, both in design philosophy and in the benefits/drawbacks of metal boat ownership.

    There are times when plug welds are the only solution I've been able to come up with.  As long as the slots are wide enough, the welding isn't difficult with Mig.  The plug welds in the mast step were trickier as the thicker plate means you have to pay a lot more attention to make sure the first pass is fusing both the the lower and upper plates.

    You are right about rebuilding the keel being a nightmare (well maybe more like a very uncomfortable dream).  We had steel punchings/concrete for ballast in an aluminum boat with only an soft epoxy coating on top.  In the end I found circular holes being galvanically drilled in the aluminum by the steel punchings.  After removing 10' of keel, removing 5000lbs of concrete/steel, welding new keel plating and stacking/pouring 8000lbs of lead, it's not I job I would care to undertake again.   In the end we now have better ballast that is down lower.  Because the lead is more dense, we used a double wall and an airspace to separate the ballast and we now also have integral water tanks above the ballast in the keel.  I also have an oil reservoir a bit above waterline that feeds into the ballasted section of the keel.  Any further failures will result in a slow leak of oil rather than corrosion.  I just have to decide on an appropriate biodegradeable or inert oil.  Silicone oil seems like a good choice that would allow further welding, but is expensive.  Biodegradeable hydraulic oil is also an obvious choice, but I worry what it would be like to deal with if I ever need to weld on the keel again.


  • 29 Aug 2017 01:09
    Reply # 5052991 on 4138614

    Very interesting Darren, great report and photos.  I was particularly interested in the way you cut slots in the doubler plate to weld the doubler to the deck.  I have some rust issues in my keel behind the ballast and sometimes think of putting a doubler plate over the entire keel and sewing it together in a similar way, since rebuilding the keel in any other way would be a nightmare.  After cutting out several small thin areas and replating, I stabilised the situation by doing what should have been done when the boat was originally built, welding plates over the ballast and topping up with oil.  But last year I found an area of thin plate I had missed that forced me to put a patch over the outside of it.  Also if you have too big an area to replate you cannot weld the new keel plating to the existing floors etc unless you cut the whole bottom off the boat and start again.  Hence the thoughts about doubler plates. 

  • 28 Aug 2017 02:35
    Reply # 5051446 on 4138614

    I've finally completed Leeway's mast partners.  We are refitting the entire boat and sometimes starting one thing leads to another and so the mast partners took longer then expected.  Access and the most logical workflow had me complete our chain locker, rode locker, windlass mount, anchor rollers, saltwater washdown outlet and some deck cleats as part of building the mast partners and mast step.  I've added some photos to my album for those that are interested and will describe what we did below.  Before that, thanks to all who contributed to the thread and helped guide the process.  

    Our boat came with freestanding 10" diameter aluminum masts.  The mainmast was in the right position so it was left in place, although the mast step had to be rebuilt as part of reballasting the boat.


    Our foremast from the previous staysail schooner rig, was not in the right location and we moved it as far forward as possible while maintaining adequate bury below decks and keeping the mast step within the boats waterline fore-aft.  The new mast has 4 degrees of forward rake.

    To reinforce the deck I added a 1/4" (6mm) double plate.  It has eight slots cut in it so that it can be plug-welded to the deck, as well as welded around its periphery.


    The doubler was 1/4" because that was as thick as we could reasonably get to bend to conform to the camber of the deck.  Even then, temporary chocks and wedges are needed to coax it into place.


    I was worried about warping the deck, so I added some temporary reinforcing below deck and carefully skip-welded the entire doubler in place.  Only after the doubler was fully welded did I cut the hole for the tube that would form the mast partners.  The cutout is slightly inside the weld that joins the double plate to the deck.


    I had the mast step temporarily in place and used a laser level and a Tilt Box II to precisely align the mast with 4 degrees of forward rake.  The tilt box is really useful when you want to align something that is not going to be level.  After the tube for the partners was welded from above I went below to make the lateral webs to support the mast.  A bit of careful template works yields pieces that fit precisely which makes the subsequent welding much easier.


    Finally the mast partners are complete.  All the webs are 10" high against the mast tube.  The lateral webs extend 24" to the hull sides, while the fore-aft triangular webs are 20" long fore and aft the mast.  All are made from and capped 1/4" plate.  The white tube to the left is the chain locker that was installed at the same time.


    Having the webs to support the tube-of-the-mast-partners below decks leaves the area above decks relatively free of toe stubbing obstructions


    The mast step is made primarily from 5/8" plate.  I drilled and tapped holes before putting in place as I was growing tired of working in the 2 square feet of cramped space available to me in the bow!  The keelson was extended to support the bottom of the plate.


    Before the top plate was welded in place, I welded the vertical end-plate inside and out to the keelson as well as the 3/8" doublers on the hull plate.


    After the top plate was welded to the doublers on the hull, the end plate and plug-welded to the keelson, then the aluminum extrusion was bolted to the plate and the mast step was finally done.  It was a lot of welding in a very small space.  I managed to set myself on fire twice and my knees are still recovering despite wearing knee pads.  However, I'm pleased with the final result.


    Last modified: 28 Aug 2017 16:39 | Anonymous member
  • 15 Mar 2017 08:18
    Reply # 4667890 on 4138614

    I don't see any problems with positioning the reinforcing webs wherever convenient. They might be angled aft, so that they are still orthogonal to the partners tube, for instance. The main thing is that they act to stiffen the partners-to-deck join and the deck-to-hull join.

  • 13 Mar 2017 03:41
    Reply # 4662630 on 4138614

    Thanks David and Graham, that helps.  Graham, I think I should be able to implement webs of the scale you have, but put them below decks, so it is nice to know what you have is working.

    David, I like your implementation of the arch that extends all the way to the topside stringer and I will extend the triangular webs for Leeway such that they continue to the topside stringer.

    David it looks like your reinforcing arch is aft of the mast partners.  This makes me wonder if I might simplify things for myself by attaching my triangular transverse webs to the aft 1/4 of the tube that forms the partners.  If you look at the location where the tube goes through the deck, the existing 2" angle deck-stiffener passes slightly ahead of the mid-point of the tube.

    null

    Thus, I either have to remove this stiffener to make room to weld the triangular webs, or I could attach the transverse webs slightly further aft on the mast-partners-tube and leave the existing deck stiffener in place and welded to the side of the tube.  My first instinct was that the transverse webs should be located on the midpoint of the sides of the tube, but if they could be moved further aft that would simplify the installation and allow the additional stiffening of the existing framing to be left in place as well as adding the triangular transverse frames (see Option B below).


    Any thoughts appreciated.

    Last modified: 13 Mar 2017 05:26 | Anonymous member
  • 12 Mar 2017 10:41
    Reply # 4661799 on 4138614

    HI Darren,

    On Arion, another steel boat, I welded a steel tube, with braces to the hull, for a step, then cut a hole in the cabin top into which I inserted and welded another a steel tube.  Because my cabin is so small and I wanted to minimize intrusion, I added the bracing structure to the outside, as you can see in the attached photo.  I had to cut through a fore and aft stringer in the cabin top, but welded this to the tube once it was fitted.  I also put small knees fore and aft of the partner tube on deck, then added an athwartships brace that went right out to the gunwale.  The part of this athwartships brace on the cabin top gave me attachment points for halyards, lifts etc, and the part on the side decks formed a cutwater that keeps mud from the anchor chain on the foredeck, so it has more than one purpose.  I felt the need to brace it securely but may have overbuilt it, as is my tendency.  After 5000 miles of often vigorous ocean sailing, it is well-tested.  I do feel a shudder in the cabin top occasionally when the boat is pitching hard, but there has been no signs of serious movement.

    Click on the image to see full-size.

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

    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
    Reply # 4661394 on 4138614

    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
    Reply # 4182929 on 4138614

    I posted the result of my test of the Dewalt drill as an electric winch handle in a new thread here.

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