The short answer
Plank-on-bulkhead (POB) is quicker, cheaper and more forgiving. It’s the standard method in most wooden ship kits and the usual starting point. Plank-on-frame (POF) reproduces the real ship’s framing. It takes much longer and needs more accuracy, but it can show internal structure that a POB model never will. If you haven’t planked a hull before, POB is the sensible first choice. POF suits builders who want a more authentic model and are ready for a long project.
What plank-on-bulkhead means
A POB hull is built on:
- A false keel (central spine), usually plywood
- A series of bulkheads: plywood cross-sections slotted onto the false keel at intervals, setting the shape of the hull
- Often a plywood false deck on top
- Filler blocks at the bow and stern in some kits, to support planks where the curves are tightest
The bulkheads are faired and the hull is planked over them, often in two layers. The inside of the hull is never seen, so the structure doesn’t need to look like a real ship’s. It only has to hold the shape.
What plank-on-frame means
A POF hull copies the way real wooden ships were built:
- A keel, stem and sternpost, often with a keelson
- Frames set up along the keel at close spacing, each made from several pieces (futtocks) like the real ship’s frames
- Internal structure such as clamps, shelves, deck beams and knees
- Planking fixed over the frames
Because the frames themselves are a feature, they’re usually made from close-grained hardwoods and finished carefully.
Admiralty-style and open framing
Many POF models leave part of the framing exposed. A common style, often associated with 17th- and 18th-century dockyard models, planks the hull only partway and leaves the lower framing visible, sometimes with the decks left partly unplanked to show the beams. These are often called Admiralty-style or Navy Board-style models. Both terms are used loosely in the hobby, so check exactly what a kit or plan means by them.
Side-by-side comparison
| Plank-on-bulkhead | Plank-on-frame | |
|---|---|---|
| Structure | False keel + widely spaced bulkheads | Keel + closely spaced built-up frames |
| Interior visible? | No | Often, by design |
| Typical source | Most wooden kits | Premium kits, frame kits, scratch builds from plans |
| Planking | Often double; first layer can be filled and sanded | Usually single, so planking must be accurate |
| Build time | Shorter | Much longer |
| Material cost | Lower | Higher, and finer timbers are needed |
| Tools | Basic hand tools | Benefits from small power tools for milling and sanding |
| Forgiveness | High | Low |
| Historical fidelity | Exterior only | Exterior and structure |
Skill, time and tools
POB is forgiving because each stage can be corrected. A low bulkhead can be shimmed, and a poorly laid first planking can be filled and sanded before the second layer goes on. Many first-time ship modellers finish a POB kit successfully.
POF puts more demands on accuracy from the start. Every frame has to be cut and faired to match its neighbours, and any error shows in the run of the planking or in the visible framing. Frame-building also tends to involve far more parts. Builders often find a small scroll saw, disc sander or thickness sander helpful. Expect a POF model to take considerably longer than a POB model of similar size, often a matter of years rather than months for a large ship.
Whichever you choose, fairing the frame is a key skill. See how to fair bulkheads before planking a model ship, which applies to frames as well as bulkheads.
Accuracy and historical fidelity
A well-built POB model can look excellent from the outside, but its insides bear no relation to the real ship. A POF model can show how the real vessel was actually built. For builders interested in historical construction, that’s often the main appeal.
That said, POF kits and plans still simplify things. Check how closely a particular kit follows its prototype if accuracy matters to you.
Cost and materials
POB kits generally use plywood for the structure and softer woods such as basswood or lime for first planking, which keeps costs down. POF models need many more pieces of good-quality hardwood, typically close-grained species such as pear or boxwood, and wastage is higher. Our guide to model boat timber and planking supplies covers which woods suit each job.
Other options: solid, plank-on-solid and hybrids
- Solid hull: carved from a block or a bread-and-butter laminated stack. Simple and sturdy, but nothing inside to show.
- Plank-on-solid: a solid or laminated hull planked over, giving the planked look with a very stable base.
- Hybrid kits: some POB kits include partial framing or frame-like bulkheads to give a more realistic interior in visible areas.
- Frame kits: some suppliers sell pre-cut POF frames for specific ships, which take much of the cutting work out of a POF build.
For an overview of every hull method, including strip planking and moulded hulls, see making a model boat hull.
Which should you choose
- First ship model: POB. It teaches planking and finishing without the accuracy demands of full framing.
- Second or third model, wanting more challenge: a better-quality POB kit with single planking, or a frame kit.
- Experienced builder interested in construction: POF from good plans, or a premium frame kit.
- Working model: POB or another method that can be sealed. Exposed framing doesn’t suit a model that goes in the water.
Whichever you pick, the planking techniques are similar. Our guide to planking a wooden model ship or yacht hull covers them.