Wednesday, May 2, 2012

Swedish Sailing Pilot Boat - Lotsbat Skum

Geoff Leedham is a teacher at St. Philip's College Alice Springs, here in Australia. Alice Springs is right in the centre of Australia, thousands and thousands of kilometres from any coastline, right out in the desert country. Yes, you have to have schools everywhere, but what makes Geoff unusual as a teacher is that in this arid and remote location he runs a boatbuilding program for high school students. Geoff's program involves at least four different designs (to my knowledge - there may be more) and exposes the participants to a range of differing construction methods and techniques - for this I commend him.

Geoff with some of his students. The beautiful boat they have built, and are displaying here, is an Iain Oughtred-designed John Dory
Imagine what sorts of problem-solving issues have been dealt with by the high school students who built this boat
Another view of the John Dory as she sits in the school foyer, displaying the complexity of work required from a young team - art, engineering, chemistry, arithmetic, manual arts, project management and housekeeping to name a few.
As you may have determined, Geoff Leedham is an enthusiast, and like all nautically afflicted people, he has his own dreams. Some months ago, Geoff approached me by email and 'phone, seeking help with a pet project. The design he wishes to build represents a Sailing Pilot Boat from around 1910, and Geoff has obtained basic historical drawings from Bertil Andersson in Sweden. http://www.batritningar.se/Default.aspx.

There are two problems: -
  • there is no table-of-offsets;
  • Geoff wants to build in glued lapstrake and therefore hopes to minimise reverse curvature in the hull to simplify construction.
With this in mind, and having spoken with the plans supplier, Geoff asked me whether I could produce a modified set of lines which avoid the use of reversed sectional curvature, supply a set of building offsets, and draw up a schedule of scantlings for the new construction method. And just to top it off he wanted a heart-shaped transom in place of the original wine-glass.

An outboard profile and plan view taken from Bertil Andersson's website. I'd like to show you the body plan so as to give some indication of the extreme reverse curvature, but I do not want to show material without permission. However, you can take it from me - this is a curvatious boat in the extreme!
Here are the principal dimensions courtesy of Bertil Andersson: -

LotsbåtSkum
20½ foot.Length 6190, width 1800 mm.From Kalmarsund. Build in 1910's by Pelle Fräsare in Kalmar, Småland. Completely in oak.


Wondering whether my friend Mr Leedham had handed me a poisoned chalice, I gave it my best shot, and here are the results: -

These are my lines incorporating many changes from the original boat (which I commend to you, with the suggestion that you purchase plans from Bertil Andersson). You can see that cross-sectional reverse curvature has been reduced greatly, particularly amidships and in the run, but that the profile and plan have remained in the spirit of the original. This will be a lighter boat, reflecting her changed construction method, but she retains the character of the original with minimal changes. 



The above renderings show the modified Skum at 6.197m x 1.836m x 0.525m draft ( 20' 4" x 6' 3" x 1' 8-1/2") at a displacedment of 1041kg (2,290 lbs)

Below is a youtube video showing a fibreglass replica of the same, or similar boat to the one in the original drawings, under sail.


In addition to the lines drawings and off-sets, I have supplied Geof Leedham with a fairly detailed scantlings schedule, which I may publish if there is interest, and if Geoff agrees. He has paid me some money, and I need to be sensible with what I publish in case he refuses to take me for a sail!

Isn't it amazing to see what comes from a scheme to build boats in the desert?

4 comments:

  1. Hi Ross--Just came across your blog and have shared the story re: Geoff and students on our WoodenBoat Facebook page https://www.facebook.com/WoodenBoatPub

    What a great story--beautiful work. Where do they find water to go boating? Looking forward to following the story of the Swedish boat--oh my, is she ever pretty.

    Regards,

    Pat Lown, WoodenBoat Publications research assistant
    pat.lown@woodenboat.com

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  2. I did a double take when I saw Alice Springs in the post. Boats in Alice Springs?

    Funny, I've admired that same boat at Andersson's website. He has a regular little treasury of lines and plans of this kind. I've bought a couple of his drawings of 14 foot prams called rundbottnad eka. I'd like to build one of those in natural timber sometime.

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  3. This Noorderraid 2008 video gives a look at a smaller version of this boat. Look at how the wake barely leaves a trace behind her in what looks to be a decent breeze. Very nice, I think. Dennis Marshall

    http://www.youtube.com/watch?v=mhvtJCLzlqM&feature=relmfu

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  4. Was the boat ever built?
    I would like to build one either in glued lapstrake or with strips.

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