What’s the difference between “bread-and-butter”, plank-on-bulkhead, and plank-on-frame construction?
Author: admin
In bread-and-butter (← "B&B"), successive "slices" (sawn out of planks) of the hull (either parallel to the keel or to the waterline) are stacked and then carved to final shape, using templates. The individual planks are frequently "hollowed" so that the resulting hull is only a thick shell of wood — this make the hull lighter, and helps prevent cracking which might result from a solid hull.
Related to B&B is the "Block Model" (→); here the hull is carved from a single block of wood. Hulls of this type are found in some kits.
Plank-on-bulkhead (← "POB") uses cross-wise slices of the hull to shape "bulkheads", which are fastened to a "backbone" with the profile of the hull; these are normally made from plywood and are common in the European kits.
Plank-on-frame ("POF" →) models actual "frames", fastened to the keel.
The latter two methods are then planked (although nothing prevents one from planking a bread-and-butter hull). Both methods require beveling the surfaces of the bulkheads or frames (see about beveling).
POB models have excessive spacing of the bulkheads to support the planking; these are normally double-planked, so that the first layer of planks (the "learning layer") can be sanded fair to produce a smooth surface for the second layer (the "finish layer"). Unfortunately, the bulkheads are often so far apart that the planks "sag" between fastening points — many modelers get around this by filling in the surface between the bulkheads with some soft wood (balsa is fine for this) and sanding this to the shape of the hull before planking… this essentially results in a more-or-less solid hull (like B&B, with the bulkheads serving as built-in templates).
One side advantage of POF is that the fastenings ("trunnels") of the planks are properly located and have a solid backing to connect to.
Dockyard and Admiralty are alternate names for Navy Board models.
The 16th century British Navy did not build their own ships; these were built by contractors, after approval from the Lords of the Admiralty or the Admiralty Board (both names were used) - a collection of aristocrats, nobility, and civil servants. Since these people could not read plans, proposed ships were presented to them in the form of a model.
These Navy Board models were a variation of Plank on Frame that quickly became stylized in construction; instead of frames that were continuous from keel to sheer, with gaps between the frames, Navy Board models have interrupted frames.
Here, "futtock" timber would extend from the keel to a point near the turn of the hull; a second futtock timber would overlap the first, forming a solid band of timber at the bilge. These would extend above the wale, and be overlapped again with more timbers that extended the run of the first, keel futtocks.
The Navy Board models had the ends of the futtocks finely finished and beveled to lie in a plane, and it was claimed that ships had never been built like that! Archaeologists are now finding evidence that - at that time - ships were actually constructed in this fashion.
The B&B model (←) has had a center line drawn on each lift, as well as station and water lines. The lifts have been assembled temporarily, and the hull sawn to profile. Lift 3 is shown in BLUE. The next step is to saw each lift to its waterline. (The lifts may also be hollowed at this time, to reduce the weight of the finished hull, and reduce the likelyhood of it cracking from moisture changes.)
Once all the lifts are sawn out, they may be reassembled permanently for the final carving to shape. This proceed much faster than in the Block Model, since one need merely "knock off the corners" of the individual lifts in order to get the hull to the nearly final shape; then work with the templates to bring the hull to the final form.
In POB (→) each bulkhead (station( is cut out and asembled to the backbone; after beveling the edges of each bulkhead, planking may commence.
John O. Kopf
I guess "plank on frame" in a strict sense would imply that the ship is built with a hollow set of frames as opposed to a set of massive plywood-style bulkheads, as you say. However, it is often commonly referred to as plank-on-frame whether you use massive bulkheads or proper frames.
Proper plank-on-frame could be used if you wanted a complete interior in the ship, or at least on the gun-decks. This is rather hard to do with massive bulkheads. Also, I am convinced that adding a complete internal structure with deck-beams et al will make it easier to get the outside right - you will have far more references to the placing of wales, gun-ports etc. (always assuming that the internal structure is put in the right places 
It has certainly been a problem with my massive-bulkhead Neptunus, 80.
I haven’t tried building proper plank-on-frame myself, but from what I gather it:
a) is a lot more work than plank-on- bulkhead (all those frames to build and put in place), and
b) makes for a better hull shape and a more solid model.
Think about it - you would be defining the hull shape for each and every frame, instead of just at the bulkheads, and the external planking will be supported by an almost continuous array of frames instead of just the occasional bulkhead.
Staale Sannerud
Most of the plank-on-frame models I have seen omit the planking on the lower hull, in order to show the detail of the keel and futtocks and all that. I suppose you could do a fully planked plank-on-frame model just for your own satisfaction, but there would be little other point.
As I understand it, the actual planking process is a little easier, because there is more material underneath the planks to support them. However, this is more than outweighed by the extra time and effort (not to mention material) necessary to accurately model the frames. Unless you want to demonstrate the construction of the original ship, you might as well go plank-on-bulkhead.
David C Graf
Look at it this way. A 200’ ship might have only 10 bulkheads, but 100 frames. If you were doing an admiralty model, you would want to show all of the frames, so any planking would be plank on frame. If you are building what would be considered a completely finished hull, then you are depending on the bulkheads (as defined in the ship’s lines) to give you the hull shape.
Here is a tip for you, if you fill in the space between the bulkheads with pieces of balsa wood, and sand them down to the ship’s lines, you have the equivalent of a solid hull to plank.
Thomas Burkman Sr.
Why would anyone plank a model anyway? By that, I mean after the hull is planked you cannot see bulkheads either. There are at least two reasons for plank on frame that I am aware of. One, that’s the way a real ship is made, so I want to do it that way. Two, maybe I am going to put in some internal detail, leave hatches uncovered, etc., and don’t want to have bulkheads visible (that were not there on prototype). With large warships this internal detail might be the guns, and the interior is clearly visible through open ports.
I might point out that there are a number of hybrids that are neither fish nor fowl. Some POB kits feature the bulkheads cut back to look like frames starting at the lower gundeck.
It is also possible to build a hybrid with a solid hull up to the lower gundeck, with frames above that, this whole structure then planked. In this case, of course, the hull is smaller by the dimension of the thickness of the planks from what it would be if it were a carved hull not planked over.
Don Stauffer
A scale plank-on-frame model is the highest expression of the wood modelmaker’s art: The keel, stem, sternpost, frames and all hull timbers are accurate scale reproductions of the prototype vessel. In some British "Admiralty" models, the planking was purposely left incomplete to allow the viewer to examine the hull timbers.
Septimus