Sea-swing: new variation, part II

Discussion in 'Stove Paraffinalia' started by Pitsligo, Sep 29, 2012.

  1. Pitsligo

    Offline
    Joined:
    Jul 12, 2009
    Messages:
    485
    Location:
    Olympia, WA, USA
    A while back I wrote up this post regarding a new variation on the Sea-swing that I had designed and patterned. As it happened, the foundry went through some turmoil and the project got delayed at about the same time that I realized I could do better. My first design is good, and I still like it, but it would have taken up a lot more room on my boat than I really wanted to devote to a stove. What's more, I could do it cheaper, and cheap is really good right now.

    For reference, this is my boat:

    1348894656-Bucephalus_lo_res_crop_opt.jpg

    Bucephalus is 19' on deck, 6'6" beam, 3'3" draft (full keel), 3000# displacement; cedar planking on oak, silicon bronze fastened; no motor or electrics. As accommodations go, she's the nautical equivalent of a pup-tent, but for all that, I've had her out for as much as a month at a time, when I was living back in Maine, so whatever I do to change those accommodations can't be in the category of "I'll just live with it since it's only for overnight". Overall, I'm working toward developing her into the perfect "tabloid cruiser", as she would have been called in the Victorian era: a small, minimalist cruising boat for one or two people.

    Knowing that I wanted something that took up minimal space when in use and when stowed, capable of fitting different stoves, to be used most typically with a standard set of MSR pots and tea kettle, and (ideally) attractive, this is what I came up with for her gimballed stove.

    I started with an Op45 kero roarer, fettled with the patient assistance of all you folks. However, when Herself complained about the kero fumes, I knew I'd need whatever I came up with to work with an alkie stove, too. Enter Op45 #2, with a regulated alkie silent burner, via the Incomparable BernieDawg.

    As I described in that first post, I hit upon the idea of securing the stove into whatever design I came up with --call it the "frame"-- by clamping the existing riser tube within the frame rather than using the Bremer method of a specialized riser. (Excellent photos of a Bremer Sea-swing are here.) Fortunately, the risers of my two principle stoves are relatively similar in diameter: 0.677" for the roarer and 0.652" for the alkie.

    The owner of Port Townsend Foundry, where I do some freelance pattern making, was very generous in letting me trade work against castings, so I was able to start with what I've come to think of as the "trapeze" (you'll see why in a bit), cast in manganese bronze, one of the more heat-resistant bronze alloys. I'm afraid I didn't photograph the raw castings, but they look very similar to the pattern itself. Into the edge of the trapeze I drilled and tapped two #8-32 holes, then (with the assistance of my next door neighbor, a machinist) through the center drilled a 0.677" hole. Next, with the bandsaw, I cut from the casting a wedge, so that the machine screws could clamp the piece back into place around the riser. The saw kerf allows enough play that the wedge can clamp securely onto the smaller riser, too.

    The ends of the trapeze I drilled and tapped 1/4"-20. When all was said and done, I had this:

    1348894689-IMG_3122CCS2.jpg

    Into the ends of the trapeze I set two lengths of 1/4" silicon bronze rod --salvaged from a past project, so not as pretty as they might be-- threaded at the bottom, with locking nuts, and at the top bent 90deg and threaded to take acorn nuts. Call these the "hangers":

    1348894712-IMG_3123CCS3.jpg

    From another pattern I had cast two "wings" from the same manganese bronze. The ends I drilled 3/16", the center point 1/4", and into the side of the center point, I drilled and tapped for #8-32 set screws. The set screws themselves are threaded brass rod, with knobs turned from of a scrap of ipé I had lying around:
    1348894743-IMG_3124CCS4.jpg

    After several early designs for sea-rails, to keep the pots in place atop the pot stands, I developed what I'm now calling "whiskers": 1/8" hard brass rod, set into bronze posts turned from more bits of scrap 1/4" silicon bronze rod, that mount at the ends of the wings:

    1348894814-IMG_3125CCS5.jpg

    They're held in place with hardware store brass knurled knobs and bronze lock washers, and more ipé knobs mean they can be manipulated without risking burnt fingertips.

    The yoke is the only part of the original frame's design that I retained --they'd already cast it, but hadn't done anything with it, and the foundry owner very generously let me have it at discount. I reamed out the cast socket to take a 1/2" silicon bronze pintle and drilled it #10-32 for a set screw of brass and more of that scrap ipé:

    1348894842-IMG_3126CCS6.jpg

    The pintle --with an annular groove for the yoke's set screw, just like the Bremer Sea-swing's-- is socketted into a bolster fitted to the side of the cabin trunk, the bolster being bolted in place with 1/4" bronze machine screws. A bronze bushing, pressed into the bolster, reinforces only the outermost 1" of the socket, but the socket is drilled right through the (ipé) bolster, (oak) cabin trunk and (oak) carlin, so all told, the socket provides 3 1/2" of hardwood support. Yet another set screw, threaded into the bushing, means I can shorten up the pintle, sliding it back in under the deck, so that the yoke is right up against the bolster, or extend the pintle out 10" so that the stove hangs right at the side of the companionway. And I put in sockets on both sides of the cabin trunk, so I can set the stove up to either port or starboard, as my whimsy takes me.

    So...

    Stowed, the frame folds up to one side, held up by a piece of twine. The pintle set screws keep it from swinging about:

    1348894869-IMG_3113CCS7.jpg

    To unlimber it, I untie the twine to lower the trapeze, and extend the pintle to whatever length I like...:

    1348894895-IMG_3114CCS8.jpg

    …Raise the wings up from their stowed position, unfold the whiskers, and attach the fount (recognize it, Parramethtrol? Thank you!) --the red flag is to remind me to open the air screw before removing the reserve cap, otherwise it burps kero all over the cabin; mount the wind shield (borrowed from an Op111), flame ring, and new, extra-long pot stands of 304 stainless (thank you, Murph)…:

    1348894938-IMG_3115CCS9.jpg

    And away we go:

    1348894972-IMG_3118CCS10.jpg

    1348894997-IMG_3129CCS11.jpg

    Brewing tea under way is so much more civilized than simply bringing it along in a vacuum flask, don't you think? And it'll be nice to be able to hot up some soup when I get becalmed and need to row home in the middle of the night. So far I've just fired it up at the dock --we've had almost two weeks without much wind to speak of, so no sailing-- but aside from needing to replace a heat-resistant washer between riser and spirit cup (thank you, Kerophile!), the preliminary run looks very promising. There will need to be some working protocols established, such as always having a pot on the stands, even in pre-heat (otherwise the overhead gets too warm), and being very careful how much meths to prime with (even with the gimbals, it sloshes a little), but those are details I'm comfortable working out as I go.

    And I like the gaslight/steampunk way it came out not just because I like that aesthetic, but because that's the way it looks because that's what works. That's just thrilling for me.

    However, beyond the immediate desire for a small, minimalist gimballed stove system, the idea was to create a frame that could accept any discus-type stove (or at least many of them) with minimal modification, and I think it ought to work pretty well for that. One of these days I will have an Op00 or Pr210 to test in the frame, as a stove better sized to the single-handed sailing I often do, but until then, my two Op45s (and my Op48, should I want to use a silent burner) work in it equally nicely.

    I think this arrangement might even work with my Sv123, though it would need a different trapeze, drilled to accept the much smaller riser, and a different pot stand arrangement since the windscreen would be incompatible with the trapeze. I've got such an arrangement in my head, though (described below), and it should be pretty easy. However, the trapeze might get too much in the way of the preheating, and as much bronze as is in the trapeze might also prove too much of a heat sink to keep the tank pressurized --or might allow too much heat to accumulate too close to the tank (it gets pretty warm). Cautious experimentation would be needed. More optimistically, keeping the height of the Sv123's tank as low as the Op45's are, relative to the yoke, would mean that the weight of the pots would be similarly lowered, and the frame should remain adequately ballasted, where the Bremer, with its trivet fixed in relation to its yoke, would become considerably less stable with a light stove down low and a heavy pot up high. With this frame, the pot moves down to meet the stove, lowering the CG, rather than the stove moving up to meet the pot. I don't currently have any plans to bring the Sv123 aboard, but I'm curious.

    My one remaining concern is that the weight of the pot, on the pot stands, is transferred to the frame through the connection between fount and riser. In other words, it isn't just the 4lbs or so of fount and fuel that's hanging from the riser-to-fount connection (a situation adequately proven safe by the Bremer), but another 4lbs+ of water, assuming the 2qt MSR pot (the largest in my set) is full. Eight pounds --call it ten, for safety margin-- isn't a huge amount of weight for that size screw, and with all the structure inside the fount preventing it from ripping loose, I'm not hugely worried, especially given that the gimbals should minimize any sort of shock loading offered by the boat's motion. I would hesitate to play games with white gas, but as so many of you so often point out, kero or meths isn't half so dangerous (I've had stoves leak there before, without drama), and I'm content to watch and see.

    I do have an alternate pot support arrangement I'm working on, as I suggested in my thoughts on the Sv123: suspend a U-shaped pair of pot rails (a la Op111, only inverted) from the ends of the wings, so that the weight of the pots goes through the wings directly onto the hangers and thence to the yoke, leaving that riser connection responsible only for the weight of the fount. Loosening the wings' set screws and skewing the wings would also narrow the distance between the rails and allow them to support smaller pots --like my ibrik. It would also allow me to adjust the height of the rails for silent or roarer burners and minimize flame quenching (despite the detailed data in a recent thread, I still got the stands a wee bit short! :doh: ). The drawback would be that then the wings' set screws would take the weight of the pots --which may be a non-issue, and would certainly lend itself to a less dramatic failure than a failure of the fount-to-riser connection could provide. The whiskers will mount on the upper ends of the rails. The hardware store was out of 3/16" ss rod, and their new stock not due in for another two weeks, otherwise I'd have tried them by now --and I was in a hurry to show off.

    Anyway, thank you, one and all, for all your help. This has realized a wish I have had since I first got the boat, 25 years ago, to give her a proper stove.

    Alex
     
    Last edited by a moderator: Jul 2, 2015
  2. itchy

    Offline
    Joined:
    Feb 10, 2009
    Messages:
    3,675
    Wow. It is a work of art.
     
  3. Sparky

    Sparky Subscriber

    Offline
    Joined:
    Mar 20, 2010
    Messages:
    4,934
    Location:
    Houston, Tx area
    A beautiful and elegant solution!
     
  4. dwarfnebula United States

    Offline
    Joined:
    Apr 23, 2012
    Messages:
    356
    Location:
    Colorado
    :clap: An elegant solution for a lovely little boat. I especially like your boat's name.
     
  5. Murph

    Murph United States Subscriber

    Offline
    Joined:
    May 14, 2010
    Messages:
    2,557
    Location:
    Milwaukee WI, USA
    An excellent bit of engineering!

    The whiskers are a very clever way of dealing with a problem, simple, yet very efficient, and allowing for the entire assembly to be collapsed into a minimal footprint for storage in situ.

    Now, having designed all that into a aestectically pleasing package that combined style AND function--! :thumbup: :thumbup:

    Murph
     
  6. islandpiper

    Offline
    Joined:
    Apr 3, 2011
    Messages:
    332
    All i can say is......STEAMPUNK HEAVEN!! Amazing creation!! piper
     
  7. Matukat

    Matukat Subscriber

    Offline
    Joined:
    Jan 7, 2008
    Messages:
    4,774
    Location:
    Pueblo West, Colorado, U. S.
    Awesomeness. :clap: :clap:
     
  8. Ian

    Ian Subscriber

    Offline
    Joined:
    Jul 26, 2004
    Messages:
    7,106
    Location:
    West Yorkshire
    That's nice.
    Makes me wish I still had a boat.
     
  9. ulysses

    ulysses Subscriber

    Offline
    Joined:
    Jan 9, 2008
    Messages:
    1,578
    Location:
    Manasquan, New Jersey USA
    A very beautiful, very craftsman-like solution. It has a late Victorian look that fits your classic boat well. Consider a small production run...who would have thought that there would be a market for silent caps...

    Paul
     
  10. Pitsligo

    Offline
    Joined:
    Jul 12, 2009
    Messages:
    485
    Location:
    Olympia, WA, USA
    I'm happy to say that it both looks cool and works very well. Between sailing and cooking I was a bit too busy to get any photos, but I plan to remedy that next time Herself is out and can take the helm while I play with the camera. Anyway, it gimballs beautifully, even in the wakes left by the local plethora of inconsiderate idiots --er, powerboaters-- and after a couple minutes for the stands and burner to cool, even provides a stable trivet for the teapot, which I somehow hadn't forseen. So Alex is happy.

    Ulysses: I'd love to build a few more, but just the castings --raw, no machining-- would probably run about $150, and that doesn't include a simple bolt-on bulkhead bracket which most people would want (rather than fabricate something from scratch, as I did). Factor in machining the castings and fabricating the additional elements and the cost probably doubles, making it rather impractical. Which is really too bad, since I'd hoped to see a few more of them out there.

    If anyone who wants one has a foundry available, let me know and I'll loan you the patterns.

    Alex
     
  11. nzmike

    Offline
    Joined:
    Dec 15, 2005
    Messages:
    2,955
    Outstanding, Alex! :thumbup: Orders of magnitude better than the Trangia rig I suggested to you a ways back. :oops:
     
  12. Doc Mark

    Doc Mark SotM Winner Subscriber

    Offline
    Joined:
    Dec 12, 2004
    Messages:
    19,157
    Location:
    So. California Mountains
    Good Morning, Alex,

    VERY nice and elegant solution to your problem, Sir! Done in the finest tradition of real fettling, and the results speak for themselves!! HUZZAH!! :clap: :clap: 8) :thumbup: :D :D I look forward to seeing your system in use, once you do get some time to take photos whilst underway. Thanks for sharing this entire adventure, from conception, to finished product! Again, WELL done!! Take care, and God Bless!

    Every Good Wish,
    Doc
     
  13. Pitsligo

    Offline
    Joined:
    Jul 12, 2009
    Messages:
    485
    Location:
    Olympia, WA, USA
    Mike: Not better, just different. I expect your idea would have been a lot more reasonable, but being hard-headed, I had to give this a shot. Hmm... Though now that you remind me, I wonder if I could modify it for a Trangia...

    Thank you all for your excitement and your kudos. I've gotten so much advice and inspiration from you all, I can't begin to apportion credit properly, but know that I can't possibly have created this critter without you.

    Now, if I can ever get the wind to cooperate on a day when Herself and I are both free for a sail (it has gone flat calm again here in WA), I'll try for photos. Keep your fingers crossed for about 12-15kts, so I can show the 'swing in a properly dramatic pose!

    Alex
     
  14. kerry460

    kerry460 Australia R.I.P.

    Offline
    Joined:
    Aug 20, 2010
    Messages:
    2,357
    G,,day i really like it, versatile , practical.
    it could have been fabricated, BUT on a lovely little yacht like that it would have looked wrong.

    i saw my father scalded when a pot got launched out of the fiddle sticks, lovelly design, and beautifully executed.
    cheers
    kerry :thumbup: :thumbup:
     
  15. Pitsligo

    Offline
    Joined:
    Jul 12, 2009
    Messages:
    485
    Location:
    Olympia, WA, USA
    Finally got out for a good sail. A couple friends came over, one of whom reliably brings good wind with her --don't ask me how-- so a short pause to gather sweets and a bottle of milk, and off we went.

    I think autumn has finally arrived in Cascadia. 10-15kts SSW, overcast, bottom of the ebb, and downright chilly. A southbound ebb made for a good tide jump once we got outside and sent the stove whizzing around in its gimbals --and never spilled a drop. Herself was good enough to take the helm while I got a photo:

    1350833775-DSCN0709CCS.jpg

    Lapsang souchong under way. Good friends, a good boat, and a good breeze. A project that functions just as well as you had hoped. What could be better?

    Sorry my photography is so bad, but at least you get the idea.

    (Speaking of which, I need to credit that first photo of my boat properly: it's by Thomas Dunkersley, an excellent local photographer who happened to be passing by as we were headed out for a drift.)

    Alex
     
    Last edited by a moderator: Jun 26, 2015
  16. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

    Offline
    Joined:
    Aug 9, 2005
    Messages:
    9,636
    Location:
    Durham, N.E. England
    Seeing the sea-swing in action is great. It is very impressive.