Interesting proas

  • 24 Feb 2019 15:53
    Reply # 7184447 on 7168940
    Anonymous wrote:

    For all you proa fans, here's a link  to an interesting blogspot and a couple of photos. 

    It's a pity the study doesn't include Indonesian watercraft. I encountered this outrigger canoe off Bali (left) and East Java,(right) in 2017. It's called a JUKUNG. Not many of these wooden ones left. But there are hundreds of fiberglass versions, still working. The crab claw sail is mounted on a short, vertical mast. I noticed when a gust blew, the booms pinched together, like claws, billowing the sail and reducing area. Self reefing!

    These are not suited to big open seas with lots of fetch. But in the Bali Sea, shown here, surrounded by islands, they are at home.

    I confess I was smitten. I wanted one to take home. But these are beach-boats. to be mounted and dismounted in the shallow, warm water of a sandy beach. (Of which there must be thousands in Indonesia.)

    Click on the photo for a better view.

    Last modified: 24 Feb 2019 15:54 | Anonymous member
  • 17 Feb 2019 23:36
    Reply # 7170200 on 6931325

    Having had the experience of hitting a reef and tearing a fixed rudder clean off the transom (taking a  bit of the transom with it) I have ever since rather preferred kick-up rudders on shallow draft boats.

    (And although there are some distinct advantages to dagger boards, I feel the same way about swing-up centreboards too)

    Another advantage of the rudder which Arne and David comment on, is the ability not just to swing up, but to rotate 180 degrees to vertical. The Noelex 22 has this feature, which allows it to be trailered with the rudder instantly out of the way - and with a little hat on top, provides a neat and convenient crutch for supporting the lowered mast. Also, a nice little touch here - note the hardwood plank which gives a little stiffness and weight where needed - and a more durable bearing for the swivel pin. 

    Just to add to Arne's/David's comments about scaling this up to a larger boat - on a larger boat where the rudder is trailing a substantial deadwood, the cheeks, if streamlined, can extend down to the bottom of the deadwood, making for a very strong attachment detail (gudgeons, or whatever) and the horizontal stiffener which can be seen here at the bottom of the cheeks, can then also act as an end plate. I am planning something like this on a shallow draft boat with with twin rudders, in the hope that the boat may steer in very shallow water with the blades up.

    Sorry to jump in here (off topic, I know) but this rudder design which was spotted by Arne and David is indeed well thought out, and shows some interesting details.

    Last modified: 18 Feb 2019 00:10 | Anonymous member
  • 17 Feb 2019 13:07
    Reply # 7169680 on 6931325

    I agree about the design of the Viola rudder, Arne. It's actually quite similar to the proprietary cast aluminium rudder stock that I had on my International Moth (if I remember correctly half a century later).

    This is a good design, and would scale up to small shoal draught cruisers. There is no balance area showing on this photo, but there easily could be some. At the least, the LE ought to be brought forwards to just beneath the axis. 

  • 17 Feb 2019 10:33
    Reply # 7169582 on 6931325
    Anonymous member (Administrator)

    Thanks a lot for the link, Annie.
    Although these wet and open multis are not for me, at 59°N, I find the shown rudder designs very interesting, with a better mechanical design than the ones I have seen and used. They would be fine rudders for many small, shallow-draught boats and could easily be turned into aux-rudders for bigger boats. The way they are fitted in the rudder box lets one adjust (increase) the balance until windvanes can control them directly, with no need for servos or trimtabs. The ability to kick up instead of breaking is a bonus.


  • 16 Feb 2019 23:25
    Reply # 7168940 on 6931325

    For all you proa fans, here's a link  to an interesting blogspot and a couple of photos.  Sorry, I'm being a bit lazy and attaching them as files, rather than going through the whole rigmarole of putting them in my photo albums.

  • 25 Nov 2018 09:23
    Reply # 6931392 on 6931325

    Here is a junk rigged, shunting Pacific proa, designed and built by the legendary Tim Mann some years ago in the Central Pacific.  I have not been able to find any details of where the halyards, topping lifts etc are secured, but the double sheets are clearly visible. It obviously works and looks good!  I am beginning to think you can get away with fixed masts if you rethink the position of the masthead crane.  Normally it is angled 30 degrees off-centre on the aft side of the mast, on the same side as the sail is rigged.  That won't wok when you reverse the sail, if the mast is fixed.  But if it was 90 degrees to the centreline, or even angled 30 degrees forward, then there will be minimal twist when the sail is reversed.  Time to make a model!  Click on image to view full size.

    Last modified: 25 Nov 2018 09:32 | Anonymous member
  • 25 Nov 2018 07:30
    Message # 6931325

    I thought I'd start a thread where I (and others) can post interesting proa designs.

    I found some images of the 10m multichine Jester Class proa design by Russell Brown.  One has been built in the Pacific Northwest.  Here is the main hull and a artist's impression.  Click on the images to view full size.

    I'd like about 300mm more beam in the main hull.  And I'd simplify the rig and beam design.

    There are some more drawings in my pro file located in my member albums.  I'll add more as I find them.

    Last modified: 25 Nov 2018 07:39 | Anonymous member
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