Pattern Boat Rebuilding - Frame Construction

Discussion in 'Wooden Boat Building and Restoration' started by WoodenBoatWill, Aug 7, 2017.

  1. WoodenBoatWill
    Joined: Aug 2017
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    Location: Nevada

    WoodenBoatWill Junior Member

    Howdy folks,

    My Experience:
    My dad purchased a 1939 Chris Craft U22. It was half submerged underwater in a lake in upstate NY and had the original Hercules engine. He purchased it for $200 back in 1966. My whole family joined in in the restoration, and I learned how to pack a seam long before I learned how to ride a bike! Each year for 10 years we meticulously pickled it for the winter and did whatever maintenance and restoration each year that needed to, and my dad was such a perfectionist that if a single board showed a ripple, he would strip down the varnish and not take the boat out until it looked "right."
    My dad then purchased an Argo 24' cruiser I/O with a flying bridge which my dad, brother, and myself all worked to restore and make ship shape. A friend of ours also had a 1928 Chris Craft three cockpit that my dad, brother and myself helped/showed how to restore.

    Since then, I've worked at a naval architecture firm as a designer, and as a Joiner designer for ships.
    Dad's gone, my brother has other interests so it's all on me, and with the last time that I worked on a boat was in my late teens, I'm a little nervous that I'm doing it all right. I even went out and purchased a book "how to restore your wooden runabout," but that didn't address everything.

    My New Project:
    I have the questionable pleasure of trying to restore a 1957 18' Philbrick. The boat in it's original form had a Pontiac 257 V8 engine (don't ask me). The steering wheel and gauges are from a 1957 DeSoto. The previous owner said it had a big block Oldsmobile engine. I wasn't aware they had big block engines back in 1957.:eek:

    Yes, I think I definitely want to put in a 5200 bottom and silicon bronze screws. Something my dad never did.

    The Situation and My Question (s):
    As I said, I have the questionable pleasure of restoring this very interesting boat. Part of me wants to restore it back as close as possible to "show room new" condition, but then I've seen some things like frames that have square gussets made from 3/8" plywood, that make me want to start making changes. Now that the engine has seen some changes, makes me think it's possible someone else has already made changes (and that's why some things are questionable).
    IMG_0008 mod.JPG
    Since this is a pattern boat at best, I will be replacing all the wood, but I'm halted at making squared off L shape gussets. That I'll be making them out of wood instead of plywood I think is a easy "give-me," but all my experience says the use of square gussets is just wrong.

    Primarily, as far as I know, you radius the inside corner of a gusset (or simply make it 45 degrees) to reduce a stress fracture from occurring. Now you can also go with a sharp L shape corner IF you de-stress the corner by drilling out the inside corner. Basically, by having a radiused inside corner, you are extenuating stresses from one fixed point (an easy fracture point), to the entire surface of the radius, which (hopefully) makes the frame like a wishbone which allows it to extend past it's normal braking point.

    Does this make sense or is a square corner gusset perfectly acceptable for boats (and just not for ships)???

    Thanks for any assistance
    WBW
     
  2. Nick.K
    Joined: May 2011
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    Location: Ireland

    Nick.K Senior Member

    Good quality ply would probably be a better choice than solid wood for that shape of gusset, do the original parts show signs of stress failure at the corners?
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    Agreed, the plywood gussets, though technically weaker than solid wood replacements in some regards are still a better choice as gussets. They're dimensionally stable and have higher cross grain strength than solid timber. You're correct in that the corners should have been radiused to some degree to prevent stress risers, but this wasn't all that uncommon back then. A better gusset would be bronze of stainless plate stock, let into the frame futtocks. Under paint these would be nearly invisible. You must remember they didn't have a clear understanding of these types of failure modes back then. The radius will make cutting in any sole pieces a bit more troublesome, slightly increasing tripping hazards, but a minor concern really. Lastly, I prefer to use a minimum of 1/2 the futtock thickness for gussets, per side, so if that's 1 by stock in the futtocks, use 1/2" on both sides of the frame.
     
  4. WoodenBoatWill
    Joined: Aug 2017
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    Location: Nevada

    WoodenBoatWill Junior Member

    Hey Nick,
    It's tough to say if there is or isn't failures because it looks like they used a circular saw to cut the corners. Is the sign of a large gap overcut an indication of the beginnings of stress failures, or did they just use a thick circular saw blade??? I don't know, I can't tell you.

    As such, they cut an extra 1/4" to 1/2" past the corner. In some places, the plywood started to buckle or warp from moisture, which doesn't denote failure because of shape, but the presence of moisture alongside water soluble glues in construction grade plywood. This is probably because they couldn't paint the inside of these "overcuts," which allowed water to permeate the plys. At least that's what I'm seeing.
    The point I'm proposing for consideration is the changing of my gussets; isn't that there ARE stress failures, but the potential for stress failures. However, as I initially asked, is it boatbuilding practice that it's okay to shape gussets like this?

    Thanks for the welcome PAR,
    In my adult life, I didn't have to consider wood grain when designing (metal) ships, so I'm a little out of my depth. However, I know a little bit about wood and I thought as long as I kept the grain (in the case of an angle gusset) running parallel to the angle of the gusset, then it would be as strong as plywood is. My only concern is that plywood edges, being exposed to water in the bilge, would delaminate. I am quite familiar that plywood, in some instances, exceeds solid timber; in strength.

    No, I understand. I think it was in the 1940's or 1950's that shipbuilders found that cutting a square hole in steel (for a portlight, or whatever), would exhibit stress cracks in the corners. Alternatively, they came up with two different types of radiused corners.
    Also, I don't think adding a radiused corner for the gussets, or frame knees, would increase trip hazards, depending on how it's done. The deck, or floor boards, would be somewhat smaller, but if used in conjunction with a toeboard, could mask any intrusion by the gussets into the walkway.

    I'll give the concept that plywood would be better than solid timber some additional thought, but I'd still like to go with an angled or radiused inside corner for the gussets.

    I am sorry, but what is this term "futtock"? All searches on the internet seems to suggest this is a term used for sailboat hull planks, or perhaps frames? However, terms from industry to industry tends to change, even from boat building to ship building, for instance, in shipbuilding, a "floor" is a vertical surface in a fluid chase, or trunk.
    So, you completely lost me when you were giving comparative sizes to the "futtock."

    For reference, the existing frames, or webs, or ribs, are 3/4" x 3" and the gussets, or frame knees, are 3/8" thick ply. The furring strip stringers, or seam battens, are 1-1/2" x 3/8" stock, and while the hull bottom is single layer 3/8" (unfiberglassed) plywood, the side planks are 4" x 3/8" stock. The chine is 1-1/2" x 7/8" stock.

    ****

    Edit: also, I think the boat builder "glued" the seam battens to the hull planks, which is why you see so much drip lines along the hull side planks.
    My point is, I don't believe the boat builder used any mechanical fasteners to join side planks. Is this something to be concerned with replicating?
     
    Last edited: Aug 7, 2017
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Futtocks are the individual pieces of each frame. You'd have a topside and a bottom futtock on each side of that style of frame (single chine). Between the lower (bottom) futtocks they may also use a "floor" which is a cross piece that attaches both sides of the frame assembly. Your frames are pretty typical and simply 1x4's (3/4" x 3 1/2" actual). The battens would typically be 1x2's (3/4" x 1 1/2" actual), so maybe they were trying to save some weight.

    Batten seam can be glued, though is usually also mechanically fastened, typically from the outside, into the battens, which is likely why you don't see fastener heads on the battens. Batten seam was a relatively short lived build method. The idea was to marry the edges of carvel height planking that was thinner and use a batten to hold them in place. As developed panel construction and adhesive development came along, batten seam fell by the side, pretty quickly. It can be a difficult build method to repair too, without some experience.

    There's no debate over a plywood gusset being better than a solid timber one. Even if the timber gusset is installed with the grain bisecting the joint (as it should and which you noted), fasteners tend to split them and of course moisture gain movement, none of which are common with plywood gussets. On that style of gusset, I like to install a filler piece in the corner, between the two gussets. It prevents moisture from collecting there and means you can make a slightly smaller gusset set too.

    Real marine plywood isn't going to delaminate, the glue is waterproof, the wood specie is rot resistant and the panel construction quality is far better than what you'd find at a big box store. This said some of the old plywood had questionable adhesives, so some delamination would make the whole lot suspect. If the frame assemblies (gussets and all) are fully encapsulated, then no rot, unless neglected.

    I don't know of a Pontiac 257, but it was likely a "Strato Streak" which was a 287 introduced in 1955. They didn't make many of these puppies as the cubic inch war was in full swing and each year after introduction they bored them out, with a 317 in 1956 and a 347 in 1957 (technically the 317 was stroked a bit over a 1/4").

    Lastly, good builders wiped the glue off the inside of the planks, as they hung material.
     
  6. WoodenBoatWill
    Joined: Aug 2017
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    Location: Nevada

    WoodenBoatWill Junior Member

    PAR,
    Aha, so, simply said, "futtocks" are the segments of frame/web/rib?

    Apologies, I like using "actual" and not "nominal" sizes for timber. It's more consistent when you include plywood sizes which don't have nominal sizes... I should shut my mouth before someone gets a "bright" idea... I'm a simple man and like simple, consistent forms of logic.

    To make sure we are on the same page, when you mention adding filler for "that (angle?) style of gusset," I presume you mean an angular filler made from the same stock as the rib/web/frame? I was about to contrary with this, but then I realized that the aft bottom of my boat is actually, perfectly, flat. The boat, in motion, should roll in turns which would/should check this problem, but I think you're right and I shouldn't rely on such an instance to insure water not standing. Which brings to mind a different/similar situation; "weep holes." On my dad's Chris, and in ship building in general, there are "weep holes" down by the keel and located on each frame/web/rib. This allows bilge water to not remain stagnant between frames. It's about a 1/4" radius hole. If I recall correctly, there aren't any on this Philbrick. Matter of fact I don't recall seeing a drain plug/hole either! (I HAVE to go back and look harder for these things.)
    In the meantime, in your opinion, would you say it's more trouble that it's worth to add these two items (if they are not present)?
    My understanding of structure, is that "as long as you don't remove more than 25% of a structural member's width; the structural strength will be retained," and of course, all holes in a structural member should be rounded. There was also some algorithm, or rule of thumb, used to describe how long a hole can be to the length of the structural member, but I can't recollect it...

    On my dad's '39 Chris, the battens were glued AND mechanically fastened in the manner you were saying. On his '73 Argo cabin cruiser, the hull blanks were... I forget the proper name, but it's the same method the vikings used... The planks were lapped to each other and there weren't any battens, nor mechanical fasteners used.
    On my current boat, I have seen carpet tacks (!) used to secure some boards together, and screws used in other places. The (countersunk and bunged) tacks were used to secure the ...for lack of a better term... "weather deck" planks to it's structure. Screws (countersunk and bunged) were used to secure the side blanks to the ribs/webs/frames. And If I recall correctly (the boat isn't stored at my house currently), there weren't any screws mechanically fastening the side planks to the seam battens. HOWEVER, in deference to Mr Philbrick, I'm starting to believe this boat has seen, at least, one rebuild, and the rebuilder might have enacted some of these questionable changes. Which I'll describe in the following...

    In regards to what you said "good builders wiped the glue off the inside of the planks" I've seen other photos I took that show were the inside planks were wiped, but some areas weren't and might look "newer." As to the engine debacle, The previous owner said the original engine was an Oldsmobile big block (hogwash, I say). An older document of an older owner showed the boat was equipped with a "257 Pontiac V8 engine." Now, as you mention, I could only find a 287 V8 Pontiac back in that era. Opposed to that, a there WAS a 250 straight 6 Pontiac engine made in '68 to '69. I should also point out that the current trailer on the boat was made in 1969 (as per registration).

    So, my point is, I have a 1957 boat, with two different engines; either a 287 from 1955 (unlikely (who would buy a brand new boat with a 2 year old engine?)), or a straight 6 250 from 1967, and a trailer that was from 1969. All which makes me think this boat has seen at least two rebuilds; one around 1967-1969, and also another later rebuild that had a big block Oldsmobile engine put in.

    My point is, with that many rebuilds, it's possible I'll have to correct for at least twice as many mistakes made in rebuilding. In other words, I'll take as many suggestions as I can on rebuilding the structure; properly.

    Lastly, PAR, please check your inbox for a private message, regarding an oblique topic.
     
  7. WoodenBoatWill
    Joined: Aug 2017
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    Location: Nevada

    WoodenBoatWill Junior Member

    Aha. It seems there are no private messages provided by this forum. PAR, where should I post a new thread to discuss painting/sealing wood, which I read in one of your blogs?
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Bingo . . . On a single chine hull there will be a bottom and topside futtock on each side of the frame (V bottom) or a single bottom futtock, connected to topside futtocks on a flat bottom.
    Most of us tend to use dimensional sizes, which is inconsistent, though most know what 1/2" plywood is, even if it's actually not 1/2" any more. The same is true of 1x2's, 2x4's, etc. and I'm as guilty of this as the next, though no apologies are necessary. I refer to 1x or 2x stock assuming most know that a 1x2 is actually .75"x1.5".
    Yep, you've got it. I like this approuch on flat bottoms and also on V bottoms. On V bottoms, you're correct it should self drain, but this space is a constant dirt catcher, so I like to "seal" it up with a filler.
    There are lots of rules of thumb, but common sense should prevail for most wood workers. Generally I ease every corner and edge, which also lets paint stick good, besides relieving stress risers.
    Boat restoration can involve some archaeology, though you can never tell who did what or even what they did at times. The usually and logical approuch is to remove the questionable stuff and do what you know is right.
    Who knows what the original engine was and it's really not all that important anymore, unless a concourse restoration. The same would be true of the rebuilds and repairs over the years. Yeah, fixing the sins of others comes with the game. Don't take it personal, they were working within their skill sets and budget, neither of which we actually understand.
     
  9. WoodenBoatWill
    Joined: Aug 2017
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    WoodenBoatWill Junior Member

    Well, my question was if adding a weep hole (1/4" radius hole in each frame alongside the keel) would be okay. (My fault for being too wordy)
    Unfortunately, I don't have any acquired common sense as it's been 30 years since I've done any manual work on a boat, so any common sense has drained away with the bilge water, heh (and years). And my ship design experience was to do whatever the naval architects told me to do (Union job) and nothing more. You try to learn and anticipate, but they liked to grow you like a mushroom.
    Lacking common sense, I've purchased a book to guide me through most of it, and anything that falls between I've posted questions here.

    Well, there's the rub. I am trying to do a faithful restoration of the boat. If I didn't say that explicitly in my first post, then I'll restate it here.

    That said, I sent an e-mail to the head of a local chapter, and he said that "restorations the Concours standard is 'As Delivered From the Factory'" but then he added, "3M5200, or any glue system is common in 99.9% of restorations. At the Concours, if all appears original, yet a glue is used (unseen) where it was not originally but is unseen, it is a 1/2 point deduction each for the sides, deck, and bottom."
     
  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Having some small number of restorations over the years, these are literally the most difficult and costly of them all. The boat needs to have a value to make it worth it and there has to be enough information still available to perform it correctly. This is easy enough (relatively) with the major builders, but nearly impossible with the small one off shops. Then again, if the information isn't available, the judges will not know what's right either. A concours job, by a novice is just a huge mountain to climb, unless not winning is the goal.
     

  11. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    I was going to say this is a novel idea for a boat...
    [​IMG]
    and then somewhere else I find this and see where the idea came from...

    [​IMG]

    I think it needs a gas pedal, an ash tray and a cigarette lighter. And some CONELRAD marks on the radio.

    Here's a 1948 Barnes Craft with the same notion. It's got the gas pedal AND a three speed shift lever on the column. Just needs a turn signal, dice and some dingle balls...

    [​IMG]

    I'm thinking maybe they didn't have turn signals back then.

    Barnes Craft Boat Back Home Again! | Classic Boats / Woody Boater http://www.woodyboater.com/blog/2011/04/26/barns-craft-boat-back-home-again/

    .
     
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