What's the difference between "bread-and-butter", plank-on-bulkhead, and plank-on-frame construction? "Navy Board", "Dockyard" and "Admiralty"?

Bread-and-Butter

Block hull for "Young America" (by Model Shipward)

Plank-on-Bulkhead

Plank-on-Frame

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.

Such Navy Board models were produced from the middle of the 16^th century to the middle of the 18^th century.

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. (And, because rigging changed very slowly with time, Navy Board models were frequently produced unrigged, with only simple "stump" masts.)

Here, a "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.

There appear to be three reasons why such models were constructed in this period:

1. 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. Many models which are not identified with a particular ship may have been failed proposals.
2. In the world of apprentices, when a Journeyman shipwright advanced to Master shipwright, he would make a piece of work (hence our word "Masterpiece") that demonstrated his knowledge and abilities. It is likely that some of the models which are not unidentified with a known ship arose in this fashion.
3. Certain ships, because of their importance, had additional models built of them. This is likely the source of multiple models existing of known ships.

The two images below show a set of drawings for an arbitrary cutter/schooner. Four of the lines have been picked out in color: station 2 (red) and 7 (orange), waterline 3 (blue), and the deck line (brown); these colors can be used to identify the corresponding curves in the following drawings.

Shear Plan and Half-breadth Plan for a Schooner	Body-plan of Schooner

Block for Model Cutter

The Block Model shown has already been cut to profile; a center line as well as station and water lines have been added to the surface. The next step is to saw out to plan using the Deck Line.
Then comes the tedious process, using a template for each station, of carving away the wood until the template almost fits. Then the hull is brought to final shape by fairing in all the surfaces between the stations, and sanding so that the templates fit exactly.

" B&B" method for the Cutter

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.

"POB" method for the Cutter

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}

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:

1. is a lot more work than plank-on- bulkhead (all those frames to build and put in place), and
2. makes for a better hull shape and a more solid model.

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}

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.}

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}

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