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Thread: Lofting the Brewer catboat

  1. #4271
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by andrewpatrol View Post
    Jim, how are you going to finish the ends of knees
    Okay, Andrew, the bottoms of the knees will get cut off square to fit against the shelf that will appear in the area shortly after the installation of the knees. The top ends of the knees will be handsomely rounded into the mast partner...except for the forwardmost pair. This pair, ahead of the mast and skirting the forward edge of the mast partner, will meet on the centerline and get capped with a doubling piece.




    Last edited by Jim Ledger; 07-16-2017 at 01:55 PM.

  2. #4272
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    Default Re: Lofting the Brewer catboat

    Now if I had known about this a while ago I would have described the lodging knees on a locally built schooner. The arms along the shelf were long enough to be scarfed together creating staple knees. Ah well, never mind.
    It really is quite difficult to build an ugly wooden boat.

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  3. #4273
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    Default Re: Lofting the Brewer catboat

    Ah, Nick, I coulda scarfed them together but I didn't want to show off.

  4. #4274
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    Default Re: Lofting the Brewer catboat

    I vote tear 'em out and build scarfed knees.
    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.
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  5. #4275
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    Default Re: Lofting the Brewer catboat

    Looks spectacular Jim but....

    I vote using em for a pattern to cast a bronze single one.

  6. #4276
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    Default Re: Lofting the Brewer catboat

    OOOO. I like that idea too. You could save a ton of space making a bronze one instead of those big clunky wooden ones.
    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.
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  7. #4277
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    Default Re: Lofting the Brewer catboat

    They look neat, good and strong to me.

    Rick

  8. #4278
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by RFNK View Post
    They look neat, good and strong to me.

    Rick


    Thanks, Rick, and thank you all for your ideas and support.


    Things are starting to come together under the forward deck. The chalk was removed from the hull with paint remover on a rag. The ends of the knees were trimmed off square and then everything clamped up for a look-see. The doubling piece can be seen under the forward set of knees, having its top fit but the rest as yet untrimmed.




    Last edited by Jim Ledger; 07-16-2017 at 01:57 PM.

  9. #4279
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    Default Re: Lofting the Brewer catboat

    There is a lot going on in that small space! Not easy to fit together even without the planks on. Beautiful job as always Jim.
    -Jim

    Sucker for a pretty face.
    1934 27' Blanchard Cuiser ~ Amazon, Ex. Emalu
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  10. #4280
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    Default Re: Lofting the Brewer catboat

    It's beautiful!

    Thank you for showing your work, very inspirational!

    /Fredrik

  11. #4281
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    Default Re: Lofting the Brewer catboat

    Jim,
    I am just struck by the engineering of these component parts and how they contribute to the strength of the whole. I wonder when you consider the knees, do you think of them primarily as giving support to the massive deck beams and planks, or as helping to hold the sides together, or giving rigidity to the deck where the pressures of the mast may try to push it apart? Or all of this - and more? At a glance they look like little lever arms that, with enough weight on the deck, might push the planks out, but I can't imagine those deck beams experiencing anywhere enough deflection for that to be an issue. Just looking in awe at the structure and thinking how this kind of design has evolved to take all these forces into account. Beautiful!
    Proud but humble member of the LPBC

  12. #4282
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Baltimore Lou View Post
    Jim,
    I am just struck by the engineering of these component parts and how they contribute to the strength of the whole. I wonder when you consider the knees, do you think of them primarily as giving support to the massive deck beams and planks, or as helping to hold the sides together, or giving rigidity to the deck where the pressures of the mast may try to push it apart? Or all of this - and more? At a glance they look like little lever arms that, with enough weight on the deck, might push the planks out, but I can't imagine those deck beams experiencing anywhere enough deflection for that to be an issue. Just looking in awe at the structure and thinking how this kind of design has evolved to take all these forces into account. Beautiful!
    The leverage from the mast causes racking at the bow of the hull
    con_struct_forces.gif
    Beam knees resist the forces and stop the joint between the deck and the sides working.
    It really is quite difficult to build an ugly wooden boat.

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  13. #4283
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    Default Re: Lofting the Brewer catboat

    Thanks for your interest, guys. It would be good to have a look at the rig at this point. The forces generated by the cat rig are handled differently than those of a sloop, with it's more centrally located mast and supporting shrouds. Here there are no shrouds, only a forestay, and the rig is designed to be self supporting, with a free-standing mast. Consequently, all the drive of the sail and weight of rig must be handled by the forward deck and the mast step.

    One of the signature features of the Cape cat is the strong sheerline and high bow. This feature evolved, because earlier cats had a less pronounced sheer, in order to put some distance between the mast step and the deck, to increase the mast "bury". Increasing the bury reduces the torquing force acting on the hull.

    The beamy, shallow hull will resisit mightily any attempt to roll it off it's waterline. Even sailed hard the heel is quite moderate compared with other types. A guy told me once he saw an old cat whose transom would stay on the waterline as the mast heeled in the gusts...kinda flexible, like. Yeah, I believed him, why not.

    Gotta get back, I'll pick this up later...



    Last edited by Jim Ledger; 07-16-2017 at 01:59 PM.

  14. #4284
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    Default Re: Lofting the Brewer catboat

    "Well", he told me, and picture a guy tonging clams off a boat anchored fifty or a hundred feet away, yelling, and pausing as he worked the tongs closed, the story coming in loud dribs and drabs..."this catboat... it had a big make and break...a Palmer...stood waist high...he go down the creek... every few seconds the engine'd give a terriffic bang...when it did...cloud a smoke...the corner of the transom would dip down...just a little bit...but ya could see it...made little ripples..."

    True story.

    Here's the knees with their ends shaped, and the doubler on the forward pair cut to a profile.

    Next, drilling for the bolts and rounding the edges of the knees, sand and seal.





    Last edited by Jim Ledger; 07-16-2017 at 02:00 PM.

  15. #4285
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    Default Re: Lofting the Brewer catboat

    I thought you said you didn't wish to show off?

    Rick

  16. #4286
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Jim Ledger View Post
    "Well", he told me, and picture a guy tonging clams off a boat anchored fifty or a hundred feet away, yelling, and pausing as he worked the tongs closed, the story coming in loud dribs and drabs..."this catboat... it had a big make and break...a Palmer...stood waist high...he go down the creek... every few seconds the engine'd give a terriffic bang...when it did...cloud a smoke...the corner of the transom would dip down...just a little bit...but ya could see it...made little ripples..."

    True story.

    Here's the knees with their ends shaped, and the doubler on the forward pair cut to a profile.

    Next, drilling for the bolts and rounding the edges of the knees, sand and seal.




    You don't tend to see that in a fibreglass boat

  17. #4287
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    Default Re: Lofting the Brewer catboat

    Mmmm, mmm. Nice curves.
    --------------------------------------------------------------------------------------------------
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  18. #4288
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    Default Re: Lofting the Brewer catboat

    Exquisite.

  19. #4289
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Jim Ledger View Post
    "Well", he told me, and picture a guy tonging clams off a boat anchored fifty or a hundred feet away, yelling, and pausing as he worked the tongs closed, the story coming in loud dribs and drabs..."this catboat... it had a big make and break...a Palmer...stood waist high...he go down the creek... every few seconds the engine'd give a terriffic bang...when it did...cloud a smoke...the corner of the transom would dip down...just a little bit...but ya could see it...made little ripples..."

    True story.

    Here's the knees with their ends shaped, and the doubler on the forward pair cut to a profile.

    Next, drilling for the bolts and rounding the edges of the knees, sand and seal.




    You mentioned a Palmer make and break engine in your little story. So not to have those experiences, I'm putting electric power in my Palmer launch. Nice and quiet, no surprises.
    I was born on a wooden boat that I built myself.

  20. #4290
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    Default Re: Lofting the Brewer catboat

    Considering the forces that must come into play those spars look kinda light in the drawing above ?? But I spose that's so flex can be built in to cope.
    What diameter was the mast again Jim?
    Last edited by andrewpatrol; 03-17-2017 at 09:28 PM.

  21. #4291
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    Default Re: Lofting the Brewer catboat

    After recently wrestling with steam bending some coamings for my new boat, I can't wait to see how Jim deals with the curved house and the cockpit coamings. Steamed or laminated? Of course, that's miles down the road from now.
    I was born on a wooden boat that I built myself.

  22. #4292
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    Default Re: Lofting the Brewer catboat

    It really is beautiful. Like a cathedral - with clamps .

    Pete
    Don't underestimate the power of stupid people in large numbers!

  23. #4293
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Baltimore Lou View Post
    Jim,
    I am just struck by the engineering of these component parts and how they contribute to the strength of the whole. I wonder when you consider the knees, do you think of them primarily as giving support to the massive deck beams and planks, or as helping to hold the sides together, or giving rigidity to the deck where the pressures of the mast may try to push it apart? Or all of this - and more? At a glance they look like little lever arms that, with enough weight on the deck, might push the planks out, but I can't imagine those deck beams experiencing anywhere enough deflection for that to be an issue. Just looking in awe at the structure and thinking how this kind of design has evolved to take all these forces into account. Beautiful!

    It's like Nick said, Lou, the knees are there to hold the angle between the deck and the sides There's little chance of any downward deflection of the foredeck, the king plank alone would be impossible to bend and it's supported by the mast partner. The forces in the foredeck that need countering are lateral, sideways forces generated by the sail and fore and aft forces generated by the pitching of the boat acting on the rig. These same forces also act on the mast step, which also has the burden of supporting the weight of the rig.

    The knees then, are not to support the deck, but, as I mentioned, to reinforce the joint between the deck and sides, to allow a smooth dissipation of the driving force of the rig from the deck to the planking.

    Thanks for asking,

    Jim




    Last edited by Jim Ledger; 07-16-2017 at 02:02 PM.

  24. #4294
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by RFNK View Post
    I thought you said you didn't wish to show off?

    Rick

    I seek no accolades, Rick...you can ask anyone. I wish only to guide and instruct and to help others.


    Looks pretty good though, eh?

  25. #4295
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by andrewpatrol View Post
    Considering the forces that must come into play those spars look kinda light in the drawing above ?? But I spose that's so flex can be built in to cope.
    What diameter was the mast again Jim?
    The spars are anything but light, Andrew. It might be the scale of the drawing that makes them look so.

    I have all three spars roughed out and their dimensions are as follows...

    mast, 10" dia, 35'
    boom, 5" dia, 28'
    gaff, 4" dia, 20'.

    The spars will all flex to a degree, absorbing temporarily the force generated by the sail and acting as a shock absorber against the inertia of the hull in the water.

    Cheers,

    Jim

  26. #4296
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Rich Jones View Post
    After recently wrestling with steam bending some coamings for my new boat, I can't wait to see how Jim deals with the curved house and the cockpit coamings. Steamed or laminated? Of course, that's miles down the road from now.
    You steamed it already, Rich? I missed it! Last I looked you couldn't find any decent oak. I'll have to take a look.

    My cabin sides be laminated, and it's not that far away. I have a pair of Honduras mahogany three by twelves which I'll have resawn into a suitable thickness for bending. The interior laminations will be Alaska yellow cedar.

    Jim

  27. #4297
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Rich Jones View Post
    You mentioned a Palmer make and break engine in your little story. So not to have those experiences, I'm putting electric power in my Palmer launch. Nice and quiet, no surprises.

    Rich, I used to have a motor would have been perfect for that launch of yours, but I sold it. It was a sweet little Atlantic make and break, all green paint and shiny brass, and I will forever kick myself for parting with it.


    One last picture before I go and make some more. Here you can see the bolt pattern penciled on the face, three 3/8" bolts up through the mast partner. The bolts will be made of SB rod, riveted over roves on the lower end, and threaded for a nut on the upper. The upper ends will be counterbored into the top of the mast partner.




    Last edited by Jim Ledger; 07-16-2017 at 02:04 PM.

  28. #4298
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    Default Re: Lofting the Brewer catboat

    Thanks for that Jim.

    Now another q.... what's a make and break engine, I'm assuming it's got to do with ignition on a gasoline engine ??

    and another, am I seeing right that those knees aren't parrelel in plan view? (Pic #4299)

    edit: don't worry about that last one, #4284 answered my q .
    Last edited by andrewpatrol; 03-18-2017 at 08:52 AM.

  29. #4299
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by andrewpatrol View Post
    Thanks for that Jim.

    Now another q.... what's a make and break engine, I'm assuming it's got to do with ignition on a gasoline engine ??

    and another, am I seeing right that those knees aren't parrelel in plan view? (Pic #4299)
    A make and break engine was an early type of gasoline engine, marine types were usually single cylinder with a big flywheel. They were fired with a low tension spark coil at low voltage. Inside the cylinder were a pair of contact points, usually in contact, the "make". When the time came to ignite the mixture in the cylinder the contacts "broke", moved apart, which created a jumping spark. It was a low tech system that worked well on marine engines as it wasn't affected by stray current leakage like high tension coils are. I'm told you could pour a bucket of sea water over a running engine and it wouldn't miss a beat.

    Those knees are very parallel...extra parallel, in fact. The photo makes them look out of line.

    It was some work getting the knees parallel, as it were. An armchair dreamer (my other job) might be forgiven thinking that you could just clamp those knees to the frames and they would line up at right angles to the centerline. They almost never do. That surface that contacts the face of the frame must be planed off just so in order to bring the knee into line. This must be done before any of the other fine fitting because moving the knee off its correct marks changes every angle and line very quickly, due to the rapidly changing shape of the hull in the bow.




    Here's a make and break engine just like the one I sold. It might just be the one...




    Last edited by Jim Ledger; 07-16-2017 at 02:06 PM.

  30. #4300
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    Default Re: Lofting the Brewer catboat

    The one lunger could be an option, but my dear wife would not be amused with that thing banging away right at her feet. It's hard enough as it is to get her out on a boat.
    Anxiously awaiting whatever component comes next on your cat. Always fun to watch.
    I was born on a wooden boat that I built myself.

  31. #4301
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Jim Ledger View Post

    Here's the knees with their ends shaped, and the doubler on the forward pair cut to a profile.






    Nice, especially the concavity of the doubler, love seeing these details handled with care, true workmanship! Were these the laminations you did with TBIII? can't remember
    Last edited by Skegemog; 03-18-2017 at 11:33 AM.

  32. #4302
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Skegemog View Post
    Nice, especially the concavity of the doubler, love seeing these details handled with care, true workmanship! Were these the laminations you did with TBIII? can't remember


    Thanks for the kind words, and yes, those are the Titebond III laminations.



    There are now a number of parts finished and waiting to be fastened in. I have to admit here that I have not been at this long enough to have lost the trepidatious feeling that comes with finally nailing something on..."the boat". There's real commitment there, let me tell you. It's gonna be there forever. Foreeeeeeevvvvvver. So minimum standards must be met.

    That being so, here's the breasthook in its final resting place, bolted in with handmade artisanal bolts. Those are 3/8" bolts through the sheer clamp, rivet heads over roves one end and threaded the other. The hole for the stem bolt is clearly visible.

    The king plank will be bolted to the top surface



    Last edited by Jim Ledger; 07-16-2017 at 02:08 PM.

  33. #4303
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    Now that looks nice.
    -Dave

  34. #4304
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    Default Re: Lofting the Brewer catboat

    Aim true when drilling for the kingplank bolts. Would really suck to hit one of those artisanal bolts of yours.
    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.
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  35. #4305
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    Default Re: Lofting the Brewer catboat

    Quote Originally Posted by Sailor View Post
    Aim true when drilling for the kingplank bolts. Would really suck to hit one of those artisanal bolts of yours.
    Thanks, Wox!

    Sailor, ain't that just the worst...drilling for a bolt and hitting something metal? It's...it's...just humbling. Not for long, but at the moment, yeah. It's always when I'm just dialed in and can do no wrong and thinking I'm Gods, gif...brrrrtttt...WTF...where did that come from! Oh, yeah... Got so bad I have to rest my drill hand on something to get the tremble under control before I start drilling. Why, just the other day, there I was, bunging up yet another wayward hole, pouring epoxy in from the top and thanking my lucky stars there's no one from the Forum here to see my now.

    It's not all bad, tho, here's the breasthook from underneath. Those rivets are ever so slightly counterbored, like the hole for the stem bolt. They're set in just enough that the roves sit flat, no more. None of the bolts are bored at a right angle to the face, so something needs to be done so that the roves bear evenly on the wood. On rougher work in softer wood the bolts would just be drawn up to crush the wood, but this work demands a more careful approach, for appearance and to maximize the effectiveness of the bolts. The washers on the other ends of the bolts have been counterbored also, just enough to sit flat.




    Last edited by Jim Ledger; 07-16-2017 at 02:10 PM.

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