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PLANKING PROCESS

(Part 2)

Greg Meyer
greg7118@uneedspeed.net

I’m trying to formulate ahead of time the method I will follow in planking the bottom of my Constitution model and models thereafter. I’ve built the AVS and learned to plank two different ways; I’ve also read the practicum planking procedures for the Constitution and Rattlesnake – all of which present widely differing ways to plank. With all the input I’ve recently received, my re-thinking the planking process and re-reading my references (listed at the end), the following write-up is the method I’ve come up with and will use in planking my Constitution hull. I’m sure that along the way I’ll make changes - I will incorporate them into this write-up as I go along. And … the procedures set forth are very tedious and I’m sure short cuts will be taken. Kit instructions for planking the Constitution are generally fair, at the best, for upper planking down to the wales, but not acceptable for bottom planking … So … I’ll not cover upper planking to the wales, but start with planking just below the wales. But first, what is planking?

PLANKING: covering an irregularly shaped hull with a fixed number of wood strip planks. This may seem like a straight forward process – but read on.

As one author said – it’s time to plank our model-ship’s hull. We have all our bulkheads correctly seated on the center keel and our bulkheads are faired – that is – planks will lie flat and in full contact against the bulkheads. And there … on our bench … is all that beautiful hardwood, just waiting to be assembled onto the contours of our ship’s hull.

Where do we go from here?

What I hope to do is come up with a planking process that will look like the real thing, be easy enough to implement and use no wood filler … just the real thing.

Often we beginning modelers proceed with planking as if we were ‘siding a house’. Then, after attaching a half-dozen planks, the painful truth becomes quite clear ... it becomes necessary to force planks into strange, if not impossible, bends and under unbelievable stresses. The remaining shapes of unplanked areas look irregular and certainly cannot be filled with stock of even, regular dimensions. The whole job suddenly becomes a nightmare. However, the confusion disappears, when it is realized that planks can be tapered fore and flared aft because the areas to be covered at the bows and stern are drastically different from those at midships. Thus the cause for concern starts to disappear and project difficulties apparently can be overcome - a successful planking job is over the horizon! Sounds easy, but is it?

The planking process can be broken down into several categories, which I’ll address individually: spiling; butt joints; stealers and joggle planks; shaping; and seams.

SPILING

SPILING is the process of tapering/flaring plank widths, beveling plank edges and determining plank lengths, so planks fit their assigned location on the hull with minimal stress and bending.

1. Subdivide hull. We begin by subdividing each side of our hull, below the wales, into an upper and lower belt. These belts are further subdivided until we reach manageable belt sizes, belts which can be covered by 4 to 8 strakes (rows of planks). This is covered later.

The initial line of division between upper and lower belts should run from somewhere around the joint formed by the wing transom with the sternpost, down under the turn of the bilge amidships (midships’ bulkhead inflection point) and up again to the bows, somewhere near the waterline. These points are given on the Constitution plans and should be used to start.

In determining and refining these lines, we first use a batten (later I plan to replace battens with strips of tape) to identify this line over the face of the bulkheads. It is best to first position a batten at the amidships’ inflection point and then adjust the stem/stern points of the batten. The inflection point can readily be identified by running your finger along the midships’ bulkhead and noting the location where the bulkhead curve starts to change from one direction to the other (in example above, clockwise to counter-clockwise).

2. Adjust batten. By eye, adjust batten so it runs in a fair curve (lies flat – in full contact - on the bulkheads) from stem to stern, whether viewed from broadside, bottom, aft or front. We are in the process of trying to transfer three-dimensional points to a two-dimensional plank. As we adjust the batten, the aft point may move away from the sternpost joint as well as the stem point moving slightly below the waterline point.

As we proceed in bending the batten around the hull, the batten will tend to naturally twist to conform to the hull. This natural twist to conform to the hull is referred to as “sny”.

3. Duplicate to other side. When one side is satisfactorily battened, duplicate it on the other side. In fact, using a height gauge, the battened line can be duplicated identically and then adjusted. I’m trying to duplicate the line for symmetry sakes as a start; however, since both sides will not be exactly symmetrical, some adjustment will have to be made to get the line faired along the bulkheads, which is most important – symmetry takes a back seat here.

Micro-Mark’s surface gauge that I use

4. Mark line. Mark this batten line on the bulkheads permanently, either with an indelible marker or knife cut, so that it remains throughout the planking process.

Replace batten with a strip of tape (if you so desire). If necessary, subdivide the top and bottom belts into smaller belts (using a batten first to check fairness and sny). The belts should be small enough to contain 4 to 9 planks – a number determined by the selected width for the planking stock (henceforth, I’ll use the word average) – which is usually given in kit instructions. In reality, we could use one strake belts – that is, put every strake on individually. This would be tedious and using belts that have similar plank curves is simpler. Too few strakes would get us away from detecting errors early.

5. Place tape on midships’ bulkhead. Place a short length of tape on the face of the midships’ bulkhead and label it (A) – the distance along the midships bulkhead from the wales down to the turn-of-the-bilge batten (or next lower line belt division); cut it to fit the distance between the under side of the wales and the turn-of-the-bilge line. I like to use tape vice proportional dividers because the distance to be measured is not a straight line, but is along a curve. But for short distances, proportional dividers can be used.

6. Remove tape (A). Remove tape (A) and place it on a flat drawing board.

7. Determine the number of average plank widths required to cover the midships’ tape (A) distance, allowing at least ½ plank width extra. I use a group of average planks coupled together as a bank as shown below. The number of average planks that just exceed the required distance (A) is number that we will use for the number of strakes in the first upper planking belt (6 in this example).

NOTE: planks on ships (full size) vary from 4 inches to 12 inches in width. The Constitution practicum is 5/32 scale (5 inches on model = 32 ft on the full-size ship). Multiplying both sides by 12/5 gives: 12in or 1 ft on ship model = 76.8 ft on full-size ship, the 1:76.8 scale size given for our model. If our ship hull planking uses plank widths of about 10 inches wide:

10 inches = 10in/(12in/1ft) = (10/12) ft

(5in/32ft)(10/12)ft = 0.130 inches; thus, we should use

1/8” planking billets for our average stock width.

8. Subdivide tape (A). Draw lines on midships’ tape (A), such that the tape will be subdivided into our required number of average plank widths (drawing above shows midships’ tape (A) divided into 6 equal parts for this example). Repeat this process for all other midships’ upper belts. Replace tapes to bulkheads (don’t want to loose them in the meantime!).

We want all planks along the midships’ bulkhead to be as close to the average plank width as possible ... a nice aesthetic look ... with taper or flare toward the bows and stern.

9. Repeat procedure for lower belts. Repeat procedure for lower midships’ belts, measuring a length of tape that extends up from the keel rabbet up to the next upper line of division, and so on. We should now calculate the number of strakes that will occur in each lower midships’ belt, as we did for the upper belts. Subdivide tape accordingly using a marker. Do this for all upper and lower belts for the midships’ bulkhead.

10. Measure shortest distance belt. Now place a piece of tape along the bulkhead that represents the shortest distance between the keel and wales. Normally this will be a bulkhead near the bows; but, be sure to select a bulkhead that runs the entire distance from the keel, not one that terminates higher up on the stem. Repeat placing short pieces of tape on all lower belts using this bulkhead. These shorter tape distances are labeled (B). No subdividing needed for short belt tapes.

11. Repeat procedure. Cut similar tapes (B) to match the short upper belt distances. Again no subdivision marks are needed.

12. Remove short pieces of tape (B); no marks or subdivisions required. Note: annotate all short pieces of tape (B) as to their bulkhead locations, prior to removing.

13. Determine remaining bulkhead subdivisions for each belt.

- With a T-square and a piece of paper on a drawing board, draw a horizontal line and place one of the short upper-belt tapes (B) in a vertical position at the right end, against the horizontal line;

- Now draw a second parallel line to the first at a distance equal to the length of short tape (B);

- Place marked-off midships’ upper tape (A) diagonally between the two lines, so that its length exactly fits. And of course, use tape (A) that corresponds to tape (B).

14. Tape remaining bulkheads. Tape the faces of the rest of the bulkheads (stem to stern, upper and lower belts), annotate to what bulkhead it measures, and cut them to belt length. Annotate each one so that you will remember which bulkhead and which belt it goes to. No subdivision needed. Also, tape only those bulkheads that reach from the keel to the wales; on the remaining bulkheads (ones very aft and very forward) we will “eye-ball” the subdivisions.

15. Remove tapes. Now remove all these bulkhead tapes from the model and place diagonally between tapes (A) and (B) and the parallel lines on the drawing board, in the same manner as the amidships’ tape (A).

16. Draw subdivisions. With a T-square draw parallel lines through all of the tapes, using increment lines drawn on tape (A). The result will be a series of tapes of various lengths, subdivided into an equal number of equal parts (6 in our example), each part representing the correct width for the strake at each designated bulkhead. Do this for each belt. In reality, the lines should be perpendicular to the tapes, not at a slight angle as drawn. This error will be very minor.

THEN ...

17. Replace tapes. Replace tapes to the faces of all bulkheads.

The stern and bows present a different problem; the stern should be broken into two parts:

18. Divide stern area.

a. Divide the length of the sternpost – the distance between the keel and to where the turn-of-the-bilge batten fell back aft – into the determined number of midships’ belts and each belt into the total number of strakes assigned to that belt. Use tape and mark appropriate locations.

b. Divide the length of the wing transom – the distance between the turn-of-bilge batten and the wales – into the determined number of midships’ belts and each belt into the total number of strakes assigned to that belt. Use tape with appropriate marks. This is not rocket science – just eye-ball the lines would be fine.

19. Divide stem. Similarly, divide the stem distance above and below the waterline into belts and the total number of strakes in each belt. Use tape and mark appropriately. The width of the belts and strakes on the bulkheads forward of the bulkhead used to determine distance (B) follow from tapers already established and should be plotted closely enough by eye.

The basic planking pattern has now been transferred to the face of all bulkheads, such that the face of each bulkhead has been subdivided into belts; the belts have been subdivided into calculated number of strakes. The pattern so assembled provides definitive specifications for most of the average planks, but not for all. We should note that as the strakes approach the bows, they become very narrow; in some cases tapering to out right points. We should also note that the width of strakes at the sternpost become wider than those at midships, if left to fan out. Both of these circumstances call for adjustments and should be considered when transferring the tape pattern onto our model at these critical areas.

Note: don’t get confused by my figure above which shows a forward bulkhead that doesn’t extend to the keel – this bulkhead was not used to determine distance (B); the second from the front was used for this purpose. Distances (A) and (B) are different from bulkhead A and bulkhead B. We would interpolate belt/plank marks for all bulkheads not extending to the keel. Those bulkheads aft of the midships’ bulkhead were taped as those forward of the midships’ bulkhead and these tapes placed between tapes (A) and (B) as the above procedure. We interpolate divisions for the extreme aft bulkheads like we did the very forward stem bulkheads that don’t reach down to the keel.

Reference (b) addresses the aft problem of using “median” planks (I refer to these planks as “average”) – the calculated average plank widths at midships – of not being wide enough aft to cover the area. Also discussed are three solutions:

First, make the bottom two strakes (garboard and first broad) on each side of the hull, those closest to the keel, from considerably wider stock than the rest of the lower hull planking. If we use an average plank width of 10 inches, we could safely increase our planking width to 14 inches (full size), a 30% increase over the average plank width, an amount close to which reference (b) recommends for warships. This approach allows planks to be cut wider at the after end, leaving us to use narrower (average width planking stock) in the middle and stem and at the same time obtain a sweep of the planking line, which should roughly follows the line of the ship’s sheer and provide the necessary “reach” up the sternpost. The remaining hull area would then be evenly divided among a fixed number of average hull planks.

Secondly, we could use “stealers”, additional short-length planks inserted into the gaps left between the ends of “average” hull planks that fan out in this area. This method, however, does not give us the total adequate rise to the line of planking.

Nearly all wooden ships require the use of some stealers in their planking layout, but this should be held to a minimum, so as not to introduce too many weak and troublesome planks;

Thirdly, we can use a combination of wider garboards and broad planks, coupled with the use of a few well placed stealers.

A similar problem occurs up front – but using joggle planks. The stem planks taper almost to a point, which if allowed, would leave us without a sound base to attach plank ends (as well as causing end splitting). Thus in this case, instead of adding an additional plank or two, a plank would have to be dropped – that is - two planks would fuse into one plank. Some references refer to a ‘joggle’ plank as a ‘drop’ plank.

BUT … there is an alternative … the Constitution plans suggests

Don’t be confined to the same “average” plank width for all belts!

This is the approach I will take. Note: I will keep the original number of planks the same in each belt – just use wider plank stock in some aft planking belts. Check each belt and determine on what bulkhead the widest area that needs to be covered – and if it isn’t the midships’ bulkhead – use this larger area to determine what a new plank width should be, such that the aft belt area will be covered and the midships area covered as usual with average planks. And on those special occasions where the area can not be covered (plank widths exceed what was readily available), we use stealers, but to a minimum, so as not to introduce “too many weak and troublesome planks” into our planking scheme.

OR ...

We can always go back and see if we can use a little wider planking material for the garboard/broad strakes – but still remain within limits of what was available for planking material.

We’ve talked around having to add additional wood – but just what is this all about?

JOGGLE PLANKS AND STEALERS

A cardinal rule in any ships’ planking is that no plank should taper to a point, since there is no practical way to fasten very narrow plank ends – such planks would be very weak and apt to spring from its fastening. So, as we approach the bows, if a pair of strakes taper to a width of four or five inches, full-scale (1/16” Constitution kit scale), the strakes should be terminated and replaced by a single plank - joggle plank - that would be fitted to match the flow of the two planks and this single plank would continue the flow up to the bows.

Above is a prime example that illustrates what we are trying to avoid. At both the bows and stern, the planking does not follow the sheer line of the wales (dotted red line). When planking, we need to keep an eye on the sheer line and at the first sign of departure, we need to start thinking stealer or joggle planks.

Jim Roberts, reference (b), states:

If the measurement taken at a belt aft of the midships’ frame shows that more than an average plank width is needed, then a stealer is called for; and if:

1. the discrepancy is less than one-and-one-half plank widths, then one stealer is required;

or if:

2. the discrepancy is greater than one-and-one-half plank widths, then two stealers are required.

However, the two stealers should be installed with at least one strake in between them.

Forward, something entirely different happens. When plank narrowing reaches a point where the total width of any two planks equals no more than the average plank width, then a joggle (drop) plank is called for. The difference between a joggle plank and a stealer is that joggle planks reduce (or drop) the number of planks; whereas, stealers add planks between the ends of planks.

Strakes on bluff-bowed ships taper radically at the bows and may drop from as many as three or four planks to one plank.

The picture below shows the flow of bows planks, which follow the sheer of the wales. Also planks terminate with ends of about the same widths. This looks aesthetic and smooth.

Summarizing:

As mentioned, the lower belts of strakes flow aft toward the sternpost, following the natural bending of the planking material; they have a tendency to fan out (flare). If the planks are force-bent to the planking pattern, ugly curves result. So rather than force the planks into unnatural bends, they are allowed to fan out and any triangular gaps created are filled with stealers. Since ship planks never ended in a point, stealers are squared off and adjacent planks notched (nibbed) to accommodate their shapes. The tape-planking pattern on our model must be interpreted by the modeler to account for both joggle planks and stealers.

Thus we modelers must decide if a pair of increments on our bulkhead tapes represents two planks up to a certain bulkhead near the bows and thereafter merge into a single joggle plank.

Similarly, we modelers must decide back aft if 2 or 3 increments on the sternpost tape represent the endings of perhaps 4 or 5 planks, including stealers.

The example below shows a four average-plank belt amidships, the point where the belt starts to diverge, and the triangular gap at the sternpost that will appear. This gap looks like it could hold two planks, which is nice and will give an aesthetic appearance.

There are two alternatives to shaping stealers (half-checked and quarter-checked). Joggle- plank butts up front are either straight or tapered, as shown on earlier figures. Below, shown in several figures, is a procedure for accomplishing both half- and quarter-checked stealers.

First, I will address half-checked stealers, which gets its name by cutting a notch half way into the width of a surrounding plank. Pictured below is the planking position before adding a stealer ….

Draw the area to be cut away from the plank as shown below. That is, draw a line starting where the stealer should start (depth of line should penetrate the plank half way) and then taper that line to the very end of the plank, as shown. Obviously the lower plank is only temporarily attached and can be removed so it can be notched.

Cut away area so defined.

Use the cut-away plank as a pattern to cut the bottom end of the stealer; attach (temporarily) the stealer; check the fit - adjust as necessary.

After a good fit is achieved, temporarily fit the stealer in place; place the next plank to be attached over the stealer and trace the top-line pattern onto the stealer.

Finally, cut the top-line pattern into the stealer and shape to fit. Below is what a “half-checked” stealer should look like. Notice how the plank ends are about the same widths and there is no interrupt to the plank flow. The tapered end of the stealer can either be straight or angled. Wood is only removed from one plank.

A quarter-checked stealer is very similar with a few differences: the notch depth is one-quarter the width (vice ½). The upper plank is cut the same way as we did on the lower plank – ¼ of the plank width and tapered to its bottom aft edge. The stealer is shaped to fit between the upper and lower planks. Wood is removed from both upper and lower planks. This choice appears to be the most aesthetic – symmetric.

All these decisions are part of the planking process, separate from the spiling process. But the spiling and planking processes both include the determination of plank length. So … the next topic of butt joints has to be addressed to complete the spiling/planking processes before implementing and shaping individual planks – which is the purpose of this paper!

BUTTS

The final step in the planking/spiling processes is working out a planking-joint pattern - the location of butt joints. The general rule for determining butt joints is that:

1. butts on adjacent strakes would occur on frames at least five feet apart;

2. butts of two strakes separated by a third would have to be at least four feet away; and

3. butts of two strakes would never occur on the same frame unless there were at least three intervening strakes.

To determine the location of butt joints on our model, we first need to determine the number of individual planks it will take to make up the longest strake. Each plank in full-scale should be of about 24 feet, 30 feet being longest. So, if our ship requires a maximum strake that is 192 feet long (longest run on the Constitution) and using 30 foot planks, we will need at least seven planks to make up a strake - six of them will run full length of 30 feet, the seventh will be a ‘short’ plank, 12 feet long.

(192 ft)/ (30 ft/plank) = 6.4 planks (we need seven planks)

(5/32 in/ft)(30 ft) = 4.69 inches (scale model)

Based on the above numbers, we’ll need seven planks (maximum) per strake; and, individual planks should be held to less than 5 inches to keep the model in scale.

Each strake on the ship’s underside planking will include a plank called a ‘short’ plank, a plank of length which is determined from the length of the longest strake and allow the maximum of full-length planks to be used (12 ft in the example above). The short plank in our example would be around 2 inches (ship scale). The short plank should also span at least 5 ship-size bulkhead stations. Thus we need to make sure that short plank length meets these criteria; if not, increase its length.

Assign positions for the ‘short’ planks on the bulkheads nearest midships, keeping the butts of adjacent strakes as far from one another as possible using criteria above. Build down a sequence of four strakes, starting at the wales, and then repeat the same sequence for the balance of the strakes – that is, after every four strakes the butt pattern repeats. Use the same short plank length for all belts; however, at the bows and stem, the last planks to be laid might be extremely short – keep lengths to a manageable length, covering at least a few bulkheads.

Once butts of the ‘short’ planks are established, the rest of the butt joints in the planking follow, simply assuming that all other planks will be used full length or as close to it as the bulkheads allow. Bob Giles pointed out to me in an email that there are other considerations that we must consider in our butt-joint planning: Rather than arbitrarily starting your butt pattern planning based on plank lengths, you would first realize that no butts could be adjacent to keel scarphs, stealers and drop planks would be treated as butt joints, none would be near the bilge pumps or mast steps, and multiple other structural items. After these, you get to consider the typical pap we read about vertical and horizontal separation which we are told had to do with longitudinal strength which is over rated. The real reason is distribution of local stress caused by the fact each butt requires twice the number of treenails per butt, and too many too close together would weaken a frame.

It will readily be seen that what we have designated as ‘short’ planks will not, in fact, always turn out to be the shortest planks on the hull. Each belt length run is not the same, thus when extending planks along the full length, fore and aft from those amidships, some of the final lengths at the stern and bows will turn out shorter than the so-called ‘short’ planks. What a revolt’n development this turned out to be! A plank shorter than short!!

SHAPING

The next topic involves shaping – the translation of our spiling measurements and patterns into our hull planking billets.

To this point, our model should be completely spiled – planking-belt tapes in place on the faces of all bulkheads with belts defined by a tape running the length of the model; marks for planking widths; plank lengths; butt joints; and stealer or joggle-plank joints annotated.

Here we deviate from reference (a) – we’ll shape and bevel the top of the plank first to fit snuggly against the plank above it – and then – we’ll go back to the method of transferring the bulkhead tape increments to the now shaped plank. This means that we’ll shape both sides, the top and bottom sides of the plank!

Up to this time we should have established our planking belts. I prefer to use tape once the belts are established (easier to move if adjustments are deemed later on).

I’m going to start, assuming we have our wales in place and everything will be referenced to the bottom of the wales.

We must shape (some books refer to this process as ‘spile’) the plank that goes just underneath the bottom wales strake.

20. Hold a plank against the hull and just under the wales strake;

21. Mark frame positions across its surface. Fit the upper plank edge as closely as possible to the lower edge of the wales strake (no tapering at this point, just a raw plank). We may have to temporarily attach this plank if we are using a long plank (I plan to use long planks and cut them into smaller useable planks later on) – a clothespin up front and a spot of CA glue on the aft end should suffice.

22. Open a compass so that the legs span a bit more than the widest gap between the lower edge of the wales and the upper edge of the raw plank (or strake). If the gap is too wide, use a shorter strake and cover a shorter distance.

23. Hold the compass pin against the lower edge of the wales, with the compass lead on the plank to be shaped. That is, use the pin leg of the compass as a tracing stylus, moving it along the lower edge of the wales, and tracing the line of the wales onto the plank with the compass lead. Shipwrights did this off-ship in a lofting area and brought the plank to the ship to be hung – literally hung - using ropes.

The shaping process goes as such:

1. Bend a plank to the hull, so that it lies easily and is not stressed;

2. Mark the frame locations on the plank at this time;

3. Trace the wales bottom edge to the top edge of plank that is fitted against wales;

4. Cut top plank edge to shaping line drawn in (2) above;

5. Bevel top plank edge to fit snuggly against bottom wales strake;

6. Fit plank back onto hull and mark rabbet and butt lines and trim;

7. Cut first increment off bulkhead tapes – this is the first plank width;

8. Transfer plank widths to the plank at each bulkhead station, using the same edge we just shaped;

9. Cut using ship’s curves as guides.

24. Plank belt next to wales first; when done, plank the same belt on the other side of the ship. After the top belt is planked, plank the lowest belt next, the one next to the keel; and when done, plank the same belt on the other side; keep switching back and forth. This alternating planking procedure between the upper and lower belts allows us to work toward the “turn of the bilge”, such that the last plank to be installed, “shutter plank” (sometimes referred to as “whiskey” plank – I guess because it’s the last and when finished we all go to the pub for a well deserved whiskey), falls in the middle of the hull and will not require much shaping.

If difficulty occurs concerning adjoining plank butts along the same strake line not matching, or coming out to the same width, consider making each plank a complete, full length strake of one continuous length of stock – as I’ve alluded to earlier – and then cut into plank lengths. The one long run of stock can then be subdivided into smaller planks.

SEAMS

On finely planked ships – the strakes fit snuggly and are almost imperceptible to see. In these cases, all our planking work is for naught; and in fact, it won’t even represent reality. On full-scale ships the outside edges of the planks were slightly beveled, leaving a “V” shaped groove into which caulking material was inserted. We can simulate this by filing in a grove (bevel on both edges of the planks).

If the above planking procedures are followed, there should be a good fit. The bevel should only be minor. It is an interesting point that all planks had to be caulked; else the hull would have leaked like a sieve. I personally would either opt out of beveling or if used, put minor bevels on the planks before gluing and not afterwards.

REFERENCES

a. PLANKING Model Ships by Richard Mansir (Moonraker Workbook – No. 1)

b. PLANKING THE BUILT-UP SHIP MODEL by Jim Roberts, 1987)

c. Constitution Plans (comes with the kit by Ben Langford)