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Thread: First Build - Herreshoff Pram

  1. #1
    Join Date
    Apr 2016
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    Christchurch, New Zealand
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    Default First Build - Herreshoff Pram

    Hi all

    I've been lurking on the site for a while, but recently started my first build and thought I'd better post some pictures to share and document the process! There's a wealth of knowledge available on here and I've learnt a lot already, but I'm looking forward to the build and learning some more tips and tricks along the way.

    I'll be attempting a Herreshoff pram, from John Gardner's 'Building Classic Small Craft'.

    I decided instead of lofting the traditional way, that I'd give it a go digitally. Here's a couple of screen-grabs of the SolidWorks model;










  2. #2
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    Apr 2016
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    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    I liked the idea of the ladder frame that Gardner talks about, but thought I'd add a couple of temporary stringers at say 30deg and 60deg off the centreline. These should help hold the moulds rigid while planking and can be removed progressively as the planking progresses up toward the sheer, allowing a bit more room to work, and for the intermediate ribs between the moulds to be put in place. They're designed to notch into the moulds, so the moulds sit proud by a couple of mm. I've applied a similar approach to the 'ladder', although these are a bit deeper to add some stiffness, and have bevelled ends to match the inside face of the bow and stern transoms. Something along the lines of this;










    One of the benefits of lofting digitally was that I was able to get these bits cut by a local CNC business. Here's the moulds as I received them;










    Unfortunately, I didn't know exactly how thick the ply was going to be, so I had the slots cut a bit narrow. Here widening the slots to the appropriate width, plus cutting the slot for the keel batten (which I forgot to add on the file sent for CNC, doh!);







    I couldn't resist standing them up!



  3. #3
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    Apr 2016
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    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    I actually had the stringers cut in a separate batch, here they are when the arrived back from CNC a couple of weeks after I had finished the moulds;







    I had patterns cut for the bow knee and stern post at the same time (sitting on top of the deeper stringers in the above pic).


    The slots on these needed squaring up with the chisel as well, but was much quicker than the moulds.


    The stringers needed scarphing to make up the required length. I set up a temporary router jig on the bench, and made good use of the alignment holes I'd had cut in each piece with the CNC;










    I was pretty happy with the my first ever scarphing attempt! Lots of measuring as I went definitely helped;







    All ready for epoxy;







    ...and gluing up;



  4. #4
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    Apr 2016
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    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    After they were dry, I was finally able to put the building frame together and get a proper look at the shape;













    It all slotted together perfectly, was super happy. I'll need to add some cleats to firmly fix the two ladders together, and the moulds to the ladder. I'll do this once I get it up off the floor and levelled at a suitable height.


    Being in New Zealand it can be difficult (expensive!) to obtain some of the usual boatbuilding timbers that are found in North America and Europe, so I thought I'd try to use some more readily available species.


    Transoms, bow knee, stern post, and a select few other bits (as yet undecided what) will be Australian Blackwood. Keel strip and skeg will be White Oak as per plan. Planking will be Macrocarpa/Monterey Cypress. I'm hoping this should turn out an ok colour scheme.


    I picked up the blackwood and oak first. Again, I set up a temporary router jig on the bench to flatten one side, and then rough thickness;





    More catch-up progress/pics tomorrow. Thanks for reading!

  5. #5
    Join Date
    Feb 2002
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    Shubenacadie NS
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    3,517

    Default Re: First Build - Herreshoff Pram

    Almost looks like you're setting up to build them production line style with that jig. Nice work. Hope she turns out as you envision.
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  6. #6
    Join Date
    Dec 2003
    Location
    Sound Beach, NY
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    Default Re: First Build - Herreshoff Pram

    Very interesting. By using the computer and having the molds cut, you got a custom kit. Was it expensive?
    Is your build traditional plank on frame? Lapstrake or carvel?
    Thanks for sharing.

  7. #7
    Join Date
    Jan 2000
    Location
    Portland, Maine
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    14,114

    Default Re: First Build - Herreshoff Pram

    Looks great so far, Mark. I'll be watching with interest.


    Steven

  8. #8
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    Apr 1999
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    West Boothbay Harbor, Maine
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    Default Re: First Build - Herreshoff Pram

    I think one of the advantages of that style of pram is how easily they are planked (planks are close to straight which lie and fasten easily). Your jig is quite a work of art and design. You have clearly enjoyed working it out but I'm thinking if you'd gone with Gardner's ladder frame and molds you would have finished the planking already. It is good for a production jig as mentioned above. You should consider offering it for sale or donating it to a school after you've finished the boat. Good luck!
    "It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so."

    -Mark Twain

  9. #9
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    Apr 2016
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    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    Quote Originally Posted by johngsandusky View Post
    Very interesting. By using the computer and having the molds cut, you got a custom kit. Was it expensive?
    Is your build traditional plank on frame? Lapstrake or carvel?
    Thanks for sharing.
    It was actually quite reasonable, for the amount of time it saved me. Price for the CNC work was NZD$165. They also supplied the ply, at about the same price I would have bought it elsewhere. Plans call for 1/4" lapstrake planking. Should hopefully turn out something like this, except with a reversed colour scheme (dark transoms, light planking);




    Quote Originally Posted by rbgarr View Post
    I think one of the advantages of that style of pram is how easily they are planked (planks are close to straight which lie and fasten easily). Your jig is quite a work of art and design. You have clearly enjoyed working it out but I'm thinking if you'd gone with Gardner's ladder frame and molds you would have finished the planking already. It is good for a production jig as mentioned above. You should consider offering it for sale or donating it to a school after you've finished the boat. Good luck!
    There have definitely been thoughts of turning out more than one (if I enjoy the process!), so the frame was designed with that in mind. I'd definitely make sure it went to a good home as you suggest once I'm finished with it.

    If anyone is interested in the .dwg files to have a set CNC cut for themselves, please get in touch. I'd be happy to make the files available.

  10. #10
    Join Date
    Apr 2016
    Location
    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    My router had been dropped before I bought it, hence the pronounced ridges in the previous pic. I later shimmed the base, and got a much better surface quality.


    Here's the blackwood after a bit of planing to remove the router marks;







    I was curious to see how the blackwood would come up with some sanding and oil. Seeing this appear got me quite excited to hurry up with the transoms, it has some lovely grain!







    I was able to put the rest of the blackwood boards through my father-in-law's thicknesser and get them down to close to final thickness. I was a bit precious about my nicely planed side, and didn't skip plane this board like the rest. It's consequently got about a 1/8" bow over a 2 1/2' length. Here's trying to straighten it after wetting the concave side with some warm water;







    It took a bit of the bow out, but is definitely still there. Any tips/tricks for straightening it out? I don't have enough material to plane it flat again, and am hoping to avoid buying some more.


    Last night I planed the bow knee down to final thickness, flush-trimmed to size, and gave it a sand. Here's the finished bow knee;







    Very pleased with my efforts, I took it inside to show the other half. At which point I happened to glance at the open book on the table, and my heart sank when I realised I had finished it to 3/4" thick, while the plans called for 7/8". Next to the stern post at 7/8";







    I'm hoping it will be ok, on the basis that I'm also making the transoms 3/4" thick blackwood, which has a higher modulus of rupture and elastic modulus than the mahogany on the plans. At least it wasn't the stern post, as that pokes through the keel batten and mortises into the 7/8" thick skeg. Lesson learnt-keep the plans on hand, and keep checking them!


    Over the weekend I hope to finish shaping the stern post, and get the inner (setup) keel batten screwed into the moulds.

  11. #11
    Join Date
    Jul 2013
    Location
    Emerald Coast, FL
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    291

    Default Re: First Build - Herreshoff Pram

    Cheers from Florida. Looks great and I love seeing the blend of Herreshoff, Gardner and new tech.

    As for the bow knee, is that your little blue "Moaning chair" in the background? You do have one handy, right? It is also used as a place for the usual visitors to hang out and cheer.

    The moaning chair is defined by Chapelle as "a comfortable seat from which the boat can be easily seen and in which the builder can sit, smoke, chew, drink or swear as the moment demands. Here he should rest often and think about his next job. The plans should be at hand and here he can lay out his work. By doing so he will often be able to see mistakes before they are serious and avoid the curse of the amateur boatbuilder: starting a job before what has to be done to get it right." (Chapelle, Boatbuilding 1941).

    I cut not one not two but 3 transom frames before I got the right shape for our Penobscot




    kb
    Last edited by signalcharlie; 05-19-2017 at 07:00 AM.

  12. #12
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    Apr 2016
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    Christchurch, New Zealand
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    Default Re: First Build - Herreshoff Pram

    Thanks for the sage advice

    Looks like I should make some inroads past the first couple of pages...!




    Cheers
    Mark

  13. #13
    Join Date
    May 2015
    Location
    Port Elizabeth, South Africa
    Posts
    134

    Default Re: First Build - Herreshoff Pram

    Neat work on the jig. Reminds me of a mock-up light aircraft "canopy" I built once to check cockpit ergonomics and head clearance.
    I should have kept it and built a very nicely curved strip-plank cuddy or cabin-top!

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