Junket Boat

  • 27 Apr 2021 12:28
    Reply # 10369770 on 10235843
    Anonymous member (Administrator)

    Buddy is starting to look good Arne (though creeping up in size, a bit!)

    I am making my swinging centreboard (offset) with the pin placed half way up the case. I have not tried this arrangement before, but it looks to me mechanically better than having the pin at the front bottom corner. Something like on this R. D. Culler “yawl boat”.  

    A little bit of slot remains open when the board is up, but I don’t think that should matter much.

    (In fact, I decided this morning, I’ll worry about that bit of open slot later, in the meantime cut a bit more away and let the board swing almost to vertical – something the centrally located pin allows you to do. This gives a wide range of choice when it comes to rig placement).

    Another thing I’m going to try for the first time is a “push rod” mounted half way along the board, instead of Culler's lifting cable and ballasted board.

    Here’s my new board, light pine with iroko toe and leading edge, for hard knocks. I followed David’s advice and washed the surface of the hardwood with acetone prior to glueing. There's a few fastenings left in there too.

    As a junket boat, it should be possible to live aboard for a weekend – Buddy’s arrangement seems to be very nice. There will be ample room for two people to sleep, lots of dry storage – and with the two ends of the boat decked over, it requires no more than a short and simple boom tent to keep the crew dry on a warm summer’s night.

    Its looking good, Arne.

    Last modified: 27 Apr 2021 13:50 | Anonymous member (Administrator)
  • 26 Apr 2021 16:21
    Reply # 10359925 on 10235843
    Anonymous member (Administrator)

    Now I guess ‘Buddy’ is approaching the final layout. With the increased length, and with the bulkheads in place, each end will have great storage capacity and flotation volume.
    Unlike in my Oslo-dinghy, the shown cb. will not steal so much room in the cockpit. Two-three people should be able to change side quite easily.


    PS: Hopefully the chilly winds  we have had here since Easter will make room for a real spring, so that some 3-D, analogue boat work can be started.

    Last modified: 26 Apr 2021 22:58 | Anonymous member (Administrator)
  • 25 Apr 2021 22:59
    Reply # 10351609 on 10235843
    Anonymous member (Administrator)

    I think the Junket Boat idea is more attractive than the 2.4m tender competition, not least because I want an improved substitute for the 5.5 x 1.5m Oslojolle (Broremann) I once had. The main drawback with Broremann was that the cb. trunk stole most of the cockpit area. This ‘Buddy design, originally only 4.00m long, has now been lengthened at both ends to a total of 4.46m. This will let one carry 3-4 people without dragging the transom, and it will also give room for bigger combined buoyancy-and-storage compartments at both ends.

    I might even extend the cockpit 10-20cm at the aft end, and then put the bulkhead right there. The forward bulkhead is planned to sit right forward of the mast.

    That nasty bow-board has found its place, but now I start to wonder: The much roomier cockpit than in Broremann could make it possible to fit a normal cb. in the forward half of it. It could even do double service as a folding table. Now, that suddenly becomes a good excuse for a normal cb. I could then even remove that strip of shallow keel as well.

    This design is a to-and-from activity. Time will tell if it turns out to be good.

    Anyway, I reckon that ‘Buddy’ will be capable enough for my waters (with some fixed ballast), and should row well enough to get me home the last mile when becalmed...


    Last modified: 26 Apr 2021 08:50 | Anonymous member (Administrator)
  • 24 Apr 2021 20:40
    Reply # 10346286 on 10235843
    Anonymous member (Administrator)

    Hi Len, there may be some differences, we don't know yet.

    Yes, the extended Halibut rig began with an inspiration from Arne to not scale down a larger rig, but instead to take the top three panels of his Johanna rig . He conceived the idea of brailing it to the mast (via a pair of topping lifts) and the idea is a simplified system of sheeting and setting up, suitable for a 8' dinghy. David thought it could be reefed upwards - but later extended it with an extra panel for his larger SIBLIM dinghy design, and a different sheeting system. You can follow that development on the "dinghy design competition" thread.

    The "big eye chicken" mainsail is just taken directly from an old photograph and you will see that it has a shorter yard, longer luff and almost no balance - and may need different control lines, I don't  know. Something like this style has been tried on a smaller boat: Freebie, the latest rig designed by Marcus and built by Paul T.

    Will there be any difference in how they work? I don't know but we may be able to find out. If Marcus gets the time to make a sail for his Golden Bay, I am fairly sure he will follow the same Hong Kong style as we see on Freebie above. That being the case, I am rather tempted to make an extended Halibut sail for my Golden Bay. By performance, I mean setting up and dismantling as well as performing on the water.

    Maybe we can have a race some time.

    Last modified: 24 Apr 2021 22:20 | Anonymous member (Administrator)
  • 24 Apr 2021 20:00
    Reply # 10346222 on 10340183
    Anonymous wrote:

    The extended Halibut rig fits rather nicely (David's siblim 3.5 rig scaled up by a linear fact or 1.1). Another rig (perhaps the most beautiful) is the fanned "Hong Kong"-style which Marcus always seems to favour (see Freebie's latest). I took this one directly from the main sail of a "big eye chicken" in one of the lovely photographs Kevin refers us to in his thread "Old Junks". Almost zero balance. A 4-panel version might be possible?

    I have to wonder what the difference is between the Halibut and a 4 panel version of the the fanned "Hong Kong"-style. I think the Halibut is sort of a "chopped" version allowing better running of the sheets. The very steep yard fits in nicely with the idea of vertical stowage. The Halibut seems to be what you end up with if you take just about any starting point and redesign for small rather than shrink or remove panels.
  • 24 Apr 2021 00:51
    Reply # 10343914 on 10235843
    Anonymous member (Administrator)

    Thanks David. Never had standing batten parrels before, I'm going to be back on a learning curve here.


    This, from the SIMBLIM 3.5 thread:

    "One thing, which is essential in my view, is the ability to drag the boat and/or pull it up and run it along rollers. For this it is better to have any appendage start with a gentle entry and run through clear to the stern.."

    David T: This is for hauling the boat up a beach for camping? If the roller were to go under both bilge keels, they would need to be pretty long, more than the beam of the boat.

    Yes, I forgot that the SIBLIM bilge keels would be splayed out.

    I guess I was thinking of Golden Bay with its shallow, vertical, elongated skegs.

    You see the "nose" John always puts on his skegs?

    You see that sometimes on stub keels too. Complete pain in the neck when pulling on to a trailer over a roller. Mine are going to be changed into a taper to nothing at the front. Closely spaced and running clear to the stern, these appendages then will be ideal for rollers, particularly if they happen to be small diameter as you might have on a trailer.

    Last modified: 24 Apr 2021 00:54 | Anonymous member (Administrator)
  • 23 Apr 2021 09:56
    Reply # 10341842 on 10235843

    With the extended Halibut rig, you'll need to use long batten parrels, to be able to brail the sail up to the mast. So I'm thinking that you may as well also rig a running tack parrel so that when the lowest panel has been reefed upwards, the sail can be slid across the mast to make control easier when running in fresh conditions. 

  • 22 Apr 2021 22:53
    Reply # 10340183 on 10235843
    Anonymous member (Administrator)

    I have nearly competed the structural changes to the Golden Bay and thinking now about appendages, rudders, rigs, ballast – I would like to bounce some ideas as the Sibim 3.5 evolves, but it would be better to leave that thread clear for development of the Siblim 3.5.

    I’ll use this “Junket Boat” thread, and hope for some critical response


    Although the idea might not scale, I had hoped to put a Amiina ll  split junk rig on my Golden Bay as it is the only junk rig type I am familiar with, and I believe it can be made easily to fold up alongside a lowered mast. To keep the spars within reasonable limits, it has to be a low-aspect-ratio version and as my Serendipity performs well with one reef, it makes sense to eliminate one panel and fit a 4-panel version to the original sail plan, using the designer's mast length and sail area as a bench mark. The result is unacceptable, for two reasons. One: the mast is still necessarily too tall for a cruising dinghy of this length (its about 16' from heel to truck) and two: because of the high balance of the SJR, the mast has to be stepped further back in the hull. This interferes with the plan to be able to deploy a simple boom tent (without having to lower the mast.)

    The only way to use a SJR is to set it well forward and carry a jigger sail sheeted to a boomkin. (Similar to a configuration Marcus plans for his Golden Bay: a two-masted rig of ketch proportions, like Freebie's current rig. It has its advantages, including perfection for a boom tent, but I think I prefer a single mast for a boat this size.)

    A glance at the diagram below shows the unsuitability of SJR for this project, by comparison with the designed lug rig. We need a low-aspect ratio rig with minimum of balance (to get the mast as far forward as possible) and with a mast not too much longer than the original.

    The extended Halibut rig fits rather nicely (David's siblim 3.5 rig scaled up by a linear fact or 1.1). Another rig (perhaps the most beautiful) is the fanned "Hong Kong"-style which Marcus always seems to favour (see Freebie's latest). I took this one directly from the main sail of a "big eye chicken" in one of the lovely photographs Kevin refers us to in his thread "Old Junks". Almost zero balance. A 4-panel version might be possible?

    Last modified: 23 Apr 2021 06:06 | Anonymous member (Administrator)
  • 19 Apr 2021 08:25
    Reply # 10327449 on 10235843

    More on the displacement of the SibLim 4m:

    I would think it reasonable to aim for a basically equipped weight of 125kg with rig, oars and a 4kg Vulcan anchor (that anchor will self-launch and self-stow, obviating the need to teeter on the foredeck). I can put in a water ballast tank that is 30cm high and 20cm athwartships, so that free surface effect is minimal, and long enough to contain 75kg of water.

    At 0.2m draught, the displacement is 300kg - so that's one person, full ballast and some stores, for a short adventurous cruise, or two people and no ballast for sailing for fun.

    At 0.25m  draught, when the bottom of the transom is just immersed, the displacement is a massive 475kg - enough to act as a large tender to transport four people with no ballast, or for three people and ballast to sail at a Junket, or one person with ballast, equipment, water and stores for a lengthy cruise. 

    A canvas dodger on hinged rectangular hoops would suit her well, I think. Only a rolled up extension would be needed to cover the entire cockpit for camping. If only two people are to be accommodated, the foredeck could be extended to the after end of the board cases, and then a hinged dodger could cover the entire cockpit, with sitting headroom under it.

    Self righting? Possibly. 75kg of ballast low in the hull would have a similar effect to an average sized person getting onto the board, I would like to think.

    Last modified: 19 Apr 2021 17:20 | Anonymous member
  • 19 Apr 2021 00:44
    Reply # 10326595 on 10235843
    Anonymous member (Administrator)

    David: “Yes, I was thinking about wrangling the anchor on a dark and stormy night, and wondering how I'd get on with the SCAMP's cuddy

    Good point. Though in a boat the size of SCAMP on a dark and windy night I think I would rather be on a beach or up a creek and tied to a mangrove, than “wrangling” an anchor . I rather like SCAMP’s cuddy – you’d be able to kneel before it and reach over the top, wouldn’t you? It really is a good point to raise. On my Serendipity, which is too small for a forward hatch, attending to the anchor is seriously unpleasant, teetering on its narrow foredeck and hampered (threatened) by the sail bundle, narrow side decks and tender hull, and no standing rigging to grab hold of. (That’s the one-and-only advantage of standing rigging, in my opinion, and not to be entirely despised). On a dark and windy night it is a bit dangerous, so I carry my main anchor and chain in the aft cockpit locker and anchor over the stern, if I have to. Its an untidy compromise and not very satisfactory.

    I like Arne’s Halibut tender (without the bow board), and I like the 12' mini-siblim very much as a potential junket boat. I think it is a far better model than the Bay Cruiser with its wide, shallow-vee bottom. The Bay Cruiser would have massive initial form stability, a little bit like a scow – and with its flat sections aft it would plane readily and probably beat a siblim-type off the wind. Not so to windward, however – and imagine trying to row it? It beats me how well water ballast seems to work on those almost flat-bottomed Bay Cruisers. I learned something. But, you wouldn’t want those ballast tanks to be un-baffled and only half full!

    Once again, it is horses for courses and they all have their positive and negative features.

    The Bay cruiser type of hull, as far as I can see from the video clip, reminds me somewhat of the racing boat style which was popular here in the 1940s.

    That was before my time and that style was on the decline by the late 50s. Idle-alongs, zeddies - 

    - and the notorious “flying 18s” in which Kiwis competed with Aussies to see who could carry the most sail, I think.

    Big, wide, heavy, powerful, shallow vees. Some of them took half a rugby team to hold upright, with the sail they carried. Much sweeter models evolved later. But not for long. Look at what the flying 18s have morphed into now! (apologies for the commentary, its an Aussie. There's dozens of these videos. )

    Anyway. The narrow-flat-bottom 5-plank was never tried in New Zealand dinghies, to the best of my knowledge, and only in a very few keel boats.*  I can imagine it being the best of all worlds, a good performer at displacement speed, good on and off the wind, picking up wetted surface (and form stability) gradually with loading – with enough deadrise to make water ballast quite an efficient proposition when in cruise configuration - when unballasted, an acceptable boat to row - and it can even sit upright on a sand bank.

    The more I look the more I like.

     This type of boat is where the competition should have focused.

    Could you make it light enough to car-top?

    It strikes me (now that I have been educated) that you could probably make the siblim dinghy form self-righting, too - though I still think that to be little more than an unnecessary gimmick in the under-4-m category. A removeable Cuddy? I would love to try leaning back under a little low cuddy, with a cup of tea and a book. How about a cloth collapsible dodger-style?

    * Its interesting isn't it. We had a designer here called John Spencer who revolutionised dinghy design in New Zealand in the late 50s by putting forth a sweet and delicate little plywood dinghy (single chine) which just cleaned up all the heavy sail carriers and pretty much put them all out of business. One by one, from the Flying Ant to the Javelin, he changed most of the racing dinghy classes for ever. He progressed on to keel boat design, faltered at first, then began a line of single-chine plywood keelers all the way to the 60' Infidel (later renamed Ragtime) which won TransPac and Sydney Hobart races. After that he made even more wholesome hard-chine designs with developed sections that had the power and looks of round bilge - and power boats he designed too. Once referred to as "the plywood magician" - yet as far as I know (someone correct me if I am wrong) he never looked at double chine or 5-plank configuration. And oddly enough, it wasn't until John Welsford that New Zealand designers ever bothered much with cruising dinghy designs, though some of the older heavier racing boats could be cruised. Richard Hartley pioneered the cruising trailer boats, double chine, but they are too big to be called dinghies. We have a long history of designing and building in plywood in this country. I wonder why the 5-plank configuration has been overlooked for so long? 

    Last modified: 19 Apr 2021 04:00 | Anonymous member (Administrator)
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