Drifts

[tlevine]

I am in the process of developing the next build, Glad Tidings, from Chapelle's plans.  Half of the frames are connected to each other by floors.  The other half have no visible means of support.  On the plan it states "Floors drifted to keel and deadwood."  What is meant by "drifts"?

 

Does anyone know how the remaining frames would be secured to the keel?  The frames are so lightweight (1.75" x 2.5") that I would think bolting them to the keel at the foot would compromise the frame.

[allanyed]

Hi Toni,

Have you contacted the Maine Maritime Museum?  They have various plans that MAYBE will be of some help.  This looks like a very interesting build and I for one look forward to seeing your progress!!

Allan

Edited January 21, 2023 by allanyed

[Jaager]

To guess, given the evidence above:

drift = a free floating rod in a hole that does not go all the way thru either the keel / floor or the keelson / floor?

a heavy duty locator pin?

A bolt - which is also listed - would have a head at one end and threads for a nut on the other? 

 

For your F1 between floors:

The floors are long - usually ~ 60% of the beam.

It seems to be forbidden - since forever - for the heels of F1 port to meet F1 stb. in the middle of the keel.

It could be F1 long arm/F1 short arm - alternating.

My compulsion would be to use a half floor instead - a floor timber that is ~25-30% of the beam.  Have the scarph (old definition = side to side) be the same length.  So those F1 would be longer - but not as long as the long arm/short arm option.

 

[tlevine]

Thanks for the suggestion, Allan.  I discovered that a drift is a type of fastener that is wider at the head than at the toe.

Jaager, I am not quite sure I understand what you mean by long arm/short arm.

[Charles Green]

In machine work, a "drift fit" describes class of fit between a shaft and hole.  At least it did while I was active in shop work.  I can't recall the tolerances, but a considerable amount of force was required to achieve a drift fit.  Descriptive terms for other fits include: loose, running, drive, shrink, etc.  It looks like these terms have been replaced.  Now fits are separated into classes identified by Roman numerals.

 

I will guess a "drift" in this case was a galvanized iron rod, driven in an undersized hole and held by friction, rather than by clenching or with a nut. 

 

In these times, a drift is a tapered tool, a wedge essentially, used to remove a tool held in an arbor by a taper fit.

Edited January 21, 2023 by Charles Green
Additional information.

[Jaager]

The heel of the port F! would start a few feet on the stb. side of the keel.  The stb. F! would butt against it and be shorter.

The next frame would have the stb. F1 be the longer one.

 

Ignoring the occasional exception,  I see three options for the F1/F3 frame.

1 - cross chock  over the keel  - several variations - the French had some complicated joinery in some ships

2 - half floor  -  gets interesting at the ends if it is an actual ship - easier to use Cant frames.  In a model, the opposite obtains.

3 - long arm/short arm.   

 

Using half floors really reduces the length of the F1 timbers.

[tlevine]

Thanks for the explanation.

[druxey]

Drift in this context would be a longer bolt with different diameter sections, the narrowest near the tip. The changes in diameter would be in small steps.And yes, it would be a friction fit.

Edited January 21, 2023 by druxey

[tlevine]

Thanks, Druxey.

[Bob Cleek]

2 minutes ago, tlevine said:

I discovered that a drift is a type of fastener that is wider at the head than at the toe.

Not necessarily, but sort of, I suppose. A drift is a thick wooden or metal rod, in this case 5/16" to 3/8" in diameter, with a slightly pointed or rounded end which is driven into a tightly-fitting blind hole in order to fasten major timbers in a vessel. After driving, the top of the rod may be somewhat galled and so could be said to be "wider," but that's of no matter. Properly, a "drift" was the term used for the hole into which a trunnel (wooden) or drift rod or bolt (metal), was driven, but in later times it seems the term "drift" became synonymous with the rod stock used as well. 

 

In modern times, drift bolts became more common. The drift bolt is a metal rod which has threads cut in the top end and a washer and nut are attached before the drift bolt is driven into the drift hole.  Two nuts are screwed onto the rod but only not far as to allow any of the rod to protrude above the face of the top nut.  The drift bolt is driven with a sledgehammer striking the face of the topmost nut. When the drift bolt is driven to its full depth, the topmost nut is removed, the lower nut is tightened and the excess threaded rod extending above the nut may be cut off if so desired. The use of the doubled nuts provides a "head" so the drift bolt can be driven without galling the threads on the rod by striking them with the sledge.

 

Drifts are generally set in pairs driven at opposing angles. In the case of a floor-to-keel fastening, as was common, the drifts would be driven through the top of the keelson and/or frame into the keel at approximately 30 degree angles, or whatever angle the size of the timbers would accommodate. In addition to the friction of the tight fit of the tight blind hole (i.e. not through-drilled at the bottom) and the washer and nut in the case of a drift bolt, the opposing angles of the paired drifts operate to sufficiently oppose any tension between the timbers and keep them from pulling apart. From an engineering standpoint, this is an extremely effective fastening system. 

 

In short, drifts work like big headless nails that are driven into big timbers at an angle and the opposing angles of the drifts keep the timbers from pulling apart. Modernly, drifts have been replaced by rod threaded at each end and fitted at right angles to the timber joint, being secured in tension with washers and nuts at both ends. This method has the advantage of permitting the removal of keel and other major timber fastenings for inspection and/or replacement if needed. The tightly-driven drifts are often impossible to remove without destroying the surrounding structure. Iron bolts, especially keel bolts, can rust to the point of ceasing to exist in the middle of their length inside the hole, at which point, replacement is generally impossible. Replaceable keel bolts potentially extend the life of a wooden vessel exponentially.

 

As I recall, Chapelle explains the use of drifts in his book, Boatbuilding. He was quite comfortable with this fastening method which appears to have been somewhat dated by the time Chapelle was writing. It was then still a well-accepted "workboat" construction practice, but high-quality "yacht" or "naval" scantling practice was transitioning from drifts to threaded bolts. Chapelle's agenda was to encourage the continuation and preservation of locally evolved watercraft, many of which he felt were well-suited for use as pleasure craft and his plans often retain earlier construction details. 

1 hour ago, tlevine said:

Does anyone know how the remaining frames would be secured to the keel?  The frames are so lightweight (1.75" x 2.5") that I would think bolting them to the keel at the foot would compromise the frame.

The structural design is indicated on the construction plan:

 

 

You can see the cross-sections of the floors below the cabin sole. These have been "darkened" with cross-hatching to indicate a cut-away "sectioned" view. (Note the three "dark" floor sections supporting the mast step.) Every other frame is fastened to a floor timber.  Glad Tidings has steamed frames.  These would have been fastened with fore and aft fasteners through the side of the frame and into or through the floor timber. The intermediate frames would have been similarly steamed and likely simply fitted into a notch cut into the edge of the keel inboard of the rabbet, or not, depending upon the preference of the designer. (There's a long history of controversy between various naval architects regarding whether a notched keel is best or not. It's one of those "six of one and half dozen of another" type things.) The intermediate frames can simply be "toenailed" to the top of the keel, or be set into a notch and fastened with a single screw set into the center of the notch. The stress on the plank-to-frame structure is primarily in shear to the plank fastenings, and the frame foot fastenings to the floors are more than adequate to keep the hull attached to the keel. In this construction, there's no need to fasten every frame to the keel. Notice also that the spacing of the floors and the deck beams alternate, with the frames terminating alternately to a floor or a deck beam. This structure is further tied together by an (apparent) shelf and clamp at the sheer and a bilge stringer.  That said, the problem to be overcome is figuring out how to build it with scale-size parts that aren't going to have the relative strength that the full-size parts have. 

 

2 hours ago, tlevine said:

I am in the process of developing the next build, Glad Tidings, from Chapelle's plans. 

I'm not certain if I understand you completely, but from your statement I presume you are planning to build a model of Glad Tidings from Chapelle's plans for the actual vessel. Please don't take offense if I am stating the obvious to you. If so, consider my comment offered for the benefit of others less experienced. Directly put, there is a world of difference between plans for a vessel and plans for a model of that vessel. The questions you're asking indicate that you aren't experienced with full-sized wooden boatbuilding. It's frequently quite different from scale model building if for no reason other than that the parts at scale size often lack the strength to serve the structural purposes they were designed for at full size. In order to build a model of Glad Tidings from Chapelle's plans, which are the construction plans for the full-size boat, you must determine whether you are going to build an exact structural copy of the vessel as designed but to a smaller scale, which is possible, but will require a complete familiarity with full-sized boatbuilding practices, or a scale representation of the vessel which will not necessarily bear any relation to how the original was constructed. Solid hull or plank on bulkhead construction will require devising an entirely different manner of building the hull entirely.  Plank on frame will require inventing an entirely new construction sequence. If you read Chapelle's books, Boatbuilding and Yacht Designing and Planning, you will be able to learn all you need to know about building his Glad Tidings full-size and from that be able to translate it all to the model scale you want.

 

Translating a full-size construction plan for scratch-building a scale model is always a fascinating challenge. There are loads of full-size construction plans available for all sorts of vessels. Re-engineering those plans for modeling purposes is essential if one is going to enjoy all the opportunities of scratch-building. I'd urge you to start a log at the real beginning, the development of plans for a model, and share the process with everyone. There are plenty of tricks of the trade for developing plans for models. I'm sure that the population of MSW can come up with solutions to every challenge you encounter along the way!

 

 

 

 

 

[Bob Cleek]

1 hour ago, Jaager said:

The heel of the port F! would start a few feet on the stb. side of the keel.  The stb. F! would butt against it and be shorter.

The next frame would have the stb. F1 be the longer one.

 

Ignoring the occasional exception,  I see three options for the F1/F3 frame.

1 - cross chock  over the keel  - several variations - the French had some complicated joinery in some ships

2 - half floor  -  gets interesting at the ends if it is an actual ship - easier to use Cant frames.  In a model, the opposite obtains.

3 - long arm/short arm.   

 

Using half floors really reduces the length of the F1 timbers.

Jaager, it appears from Chapelle's construction drawings that Glad Tidings has full-length steamed frames. They aren't built frames. There aren't any futtocks. They're just fastened to the side of the floor timbers. 

[Bob Cleek]

1 hour ago, druxey said:

Drift in this context would be a longer bolt with different diameter sections, the narrowest near the tip. The changes in diameter would be in small steps. And yes, it would be a friction fit.

I've seen lots of drifts in my day and I've never seen one that was "a longer bolt with different diameter sections... ever. They are just "big nails" without heads or even sharp points to speak of. (Often one end will often have its sharp edge hammered round so it won't hang up when being driven.) They are  driven into a tight hole in pairs at opposing angles. It's the opposing angle of the fastening that keeps the joint from separating in tension. They were a very common type of heavy fastening method in the days of wooden ships.

 

Below: A piece of a shipwreck with nails and a drift rod through it.

 

 

 

Sunken hulk with numerous iron drifts in structural timbers revealed by decay of the surrounding wood. The large number of drifts driven into large vessels was the reason they burned worn-out ships for their fastenings back in the old days. There was a serious amount of scrap metal in those old wooden ships. 

[Jaager]

46 minutes ago, Bob Cleek said:

They aren't built frames.

My bias towards POF warped my view.  I probably would not have guessed this.   It does explain what is on display.

 

Imagining how I would approach a model of this vessel,  I cannot see trying to replicate the actual vessel's construction.  Getting the outside done correctly would be challenge enough.   I am totally dedicated to POF,  but some hulls just look better fully planked.

[tlevine]

Bob, your response is exactly what I needed.  As I mentioned earlier, this project is still in the planning stage.  As with Swallow, I was captivated by the looks of the boat.  Details to be worked out as I went along.  My hope is to build a reasonably accurate recreation but if necessary, I will fully plank her and hide my errors.

[druxey]

Bob: I respectfully disagree. 17th and 18th century vessels had these long bolts (not always 'drifted'), typically through deadwoods and other structures that required longer bolts. 'Drift' in the period sense of the word meant a change in level, such as the topside of a ship or diameter of a longer bolt.

[Bob Cleek]

7 hours ago, druxey said:

Bob: I respectfully disagree. 17th and 18th century vessels had these long bolts (not always 'drifted'), typically through deadwoods and other structures that required longer bolts. 'Drift' in the period sense of the word meant a change in level, such as the topside of a ship or diameter of a longer bolt.

 I'll defer to your expertise with 17th and 18th Century period craft. I have no first hand experience with vessels that old. The 19th and 20th Century "drifts" to which Chapelle was referring were the same diameter for their entire length, however. Apparently, the meaning of the term changed over time. 

[Bob Cleek]

8 hours ago, tlevine said:

Bob, your response is exactly what I needed.  As I mentioned earlier, this project is still in the planning stage.  As with Swallow, I was captivated by the looks of the boat.  Details to be worked out as I went along.  My hope is to build a reasonably accurate recreation but if necessary, I will fully plank her and hide my errors.

Glad I was able to answer your questions. I wouldn't say that a "fully framed" model isn't possible and a "Navy Board style" partially-planked model of Glad Tidings would be quite nice. Given her relatively small size, the model at 1:24 would be 30" long allowing a lot of opportunity for detail or 1:48 scale would give you a 15" model that wouldn't chase you out of the room when cased. You will have to put a lot of effort into setting up molds and laying off battens to create the "basket" for forming your steam-bent frames. You would then have to remove the battens as you planked from the sheer down to the waterline, then remove the molds and replace them with steam-bent frames, and then install the stringers, clamps, and shelves. After that you could install the interior furniture and the deck beams over that. Any one of the good practicums on fully-framed construction like Tosti's or Antscherl's with show you the way. You will also find a good treatment of "basket" construction in Underhill's Plank on Frame Models, Vol. I. This won't be simplified kit model construction, though. You will have to steam your frames in place in the basket and then tie each to the longitudinal battens in order to form a fair framing system to which you can fasten your planks. 

 

If you like the looks of Chapelle's Glad Tidings, a hull from the Smithsonian's collection that Chapelle customized as his personal yacht, you might want to take a look at some of R.D. ("Pete") Culler's designs. These are published in a number of study plans books he wrote, as well as full plans drawings sets available from Mystic Seaport. Pete Culler's Lizard King, a Baltimore Clipper, is a favorite of mine. Lizard King has built up frames which would be easier to build a model around than steamed in place frames like Glad Tidings'. She also can carry a fore course and rafee fore topsail and/or a main topsail.

 

See: Chapter 55: Baltimore Clipper Schooner Lizard King - Pete Culler on Wooden Boats: The Master Craftsman's Collected Teachings on Boat Design, Building, Repair, and Use (zoboko.com)

 

 

 

 

 

 

 

 

Edited January 22, 2023 by Bob Cleek

[bruce d]

Toni, this is from Steel 1805. Be sure to read the last entry.

[druxey]

Bob: I agree that word meaning shifted with time, and I think we are agreed now! Thank you.

 

Bruce: You've smoked me: I'm rotten to the core.

[Charles Green]

In reference to post #12 - Bob Cleek mentions the burning of worn-out ships in order to reclaim their metallic components.  

 

In two of his poems, Robert Service mentions vessels made on-site by miners on the Yukon Trail in the late 1800's.

From The Trail of Ninety-Eight:

We built our boats and we launched them.  Never has been such a fleet;

A packing-case for a bottom, a mackinaw for a sheet.

Shapeless, grotesque, lopsided, flimsy, makeshift and crude,

Each man after his fashion builded as best he could.

 

The greed of the gold possessed us; pity and love were forgot;

...Partner with partner wrangled, each one claiming his due;

Wrangled and halved their outfits, sawing their boats in two. 

 

Then, in The Ballad of the Northern Lights:

We poled and lined up nameless streams, portaged o'er hill and plain;

We burnt our boat to save the nails, and built our boat again;

 

 

[tlevine]

If I go ahead, my plan is to build at 1:24 scale.  I will not be steam bending any frames; they will be cut out like "typical" frames.  Unlike Atalanta, I won't have to deal with chocks between the frame components!

[druxey]

But you must be so  practiced with chocks by now....

[Bob Cleek]

14 hours ago, tlevine said:

I will not be steam bending any frames; they will be cut out like "typical" frames.

Glad Tidings' frames are 1.75" x 2.5". At 1:24 scale, they'd be .073" x .104". If you are building a fully-framed model, it would seem very unlikely they could be "cut out like 'typical' frames." The frames would have no strength where the grain ran out across the frame and they'd break easily at that place. On the other hand, it would be possible to mill .073" x .104" strips of one of the "more bendable" modeling wood species and fit them into place "hot," as in full-size construction, and tie them onto the battens with thread or thin wire. They'd then cool and take the needed curve in place against the battens.  One of the advantages of steamed frames, in addition to their light weight, is that they are twisted when bent into place so that fairing the frame faces is in large part unnecessary. 

 

You could cut bulkheads out of plywood for a plank on bulkhead or plank on mold build, but it's very difficult to get any sort of fastener to hold plank in plywood endgrain and it doesn't do well holding with adhesives either. To avoid grain runout weakness, I have had success with making molds out of laminated pieces of birch tongue depressors, which can be bought in quantity from craft stores. The tongue depressors are cut at angles to achieve the shape desired without encountering grain runout. The lamination joints are staggered so that they don't occur on top of each other. As I recall, a lamination of three tongue depressors is about a quarter of an inch thick. The tongue depressors are about an inch wide, so you can cut the joints (I use a paper cutter) to yield a rough laminated shape and then saw the frame out of that. This method requires careful fairing of the bulkhead edges, of course, but it's much easier than using plywood where every other lamination is 90 degrees to the other and so is endgrain.

[tlevine]

Thanks, Bob.  I will keep an open mind when construction begins.

[Roger Pellett]

The steam bent construction  that Bob describes was used particularly in Downeast New England to produce cheap serviceable working craft.  The famous Friendship Sloops were built with steam bent frames toe nailed into the keel without floor timbers.

 

The picture below of me “supervising” my father building an L. Francis Herreshoff H-23 sloop back in the late 1940’s illustrates a major reason for using this building process.  It reduces and simplifies the lofting required.  Instead of lofting each frame, bevels, etc. only the major longitudinal structural elements, the transom and some widely spaced moulds need to be drawn.  It likewise simplifies construction.  It is POB construction in 1:1 scale.  The ribbands and moulds were of course later removed.  Unlike the Friendship Sloops, Herreshoff did specify that each frame be fastened to a sawn floor.  This particular boat took my mother and father and sometimes me cruising in all kinds of weather on Lake Erie and was still being sailed by a different owner into the mid 1960’s.

 

Howard Chapelle was a proponent of adapting traditional working craft designs for affordable pleasure boats.  His early work was done during the Depression.  By adapting this construction method to the Pinky hull form he produced a boat that could be built by amateur builders like my father.  This does not mean that someone did not take Chapelle’s design and loft it for sawn frame construction. It also means that your choosing to build this model with sawn does not make it less authentic.

 

Roger

 

[tlevine]

Great photo, Roger.  Let's face it, nothing we do as modelers is completely authentic.  We use alternate materials and various construction techniques.  The whole idea is to learn something new and, most importantly, have fun.