Here is an attempt at demystify model boat hull design and construction. The hull is typically a big part of your model boat building effort, especially for scratch-building.
If judging from my own experience, most projects I’ve abandoned were during the hull building phase, often because I didn’t plan the construction in enough detail before cutting and gluing. Once planks are laid or chips carved, it's often difficult to go back and make corrections.
Some of my abandoned efforts also came s a result of snags I'd been unable to see before starting out. I'd chalk that up to lack of experience. Hopefully, these notes will help you avoid repeating my mistakes and increase your odds of successfully finishing your hull.
I suppose this page can also be helpful in reviewing different types of kit constructions and the various hull materials used. In a nutshell, this is meant to be a road-map for anyone curious about model boat hull design options.
Much of this page is a collection of free-floating thoughts, ideas and experience that I've collected over the years. Hopefully they'll help you succeed with your model by laying out different options for boat hull design and construction.
Different types and shapes of model boat hulls are more or less suited for certain types of construction. Generally, all model boat hulls are made with one of the following methods:
Each can then be further broken down, and in many instances, combined. Some may say casting is another method to create a model, and I agree that is true to a point. I did not include that as a separate category, since the master (or plug), most likely, has to be created from one of the methods mentioned above.
A planked hull has a number of bulkheads or frames, and a keel or keelson that form a structure. This structure is then covered in a "skin", i.e. planking. Sometime, a hull can be planked using sheets of plywood, balsa, basswood or even paper or card stock.
I've found that it is very difficult to build a true and straight hull unless:
Some other helpful notes:
Traditionally woods, such as Mahogany, Balsa and Basswood, are the most frequently used materials, at least in North America. Other popular woods include Alder, Poplar, Yellow Pine, Cherry and Walnut.
Some woods are less suitable, generally because they are either too hard or not particularly stable. For instance, I would not try and carve Oak or Hard Maple. American Beech is unsuitable, first because it is very hard, and secondly it is not stable and seems to have a mind of its own (warps).
All said, there is no reason foam materials could not be used, such as polystyrene or "hard" polyurethane. These materials are commonly used when making surfboards for instance.
One big benefit to a carved method is that there is very little stress and tension in the structure to contend with during the construction process, as opposed to those in any of the planked methods. Therefore the need to rigidly hold the hull during construction is merely a matter of convenience rather than necessity.
For Bread and Butter (aka Laminated hulls) there is a caveat: Laminating many thinner boards make the job of carving a lot easier, not only physically, but also visually, since there are more joints that help guide you find the true shape of the hull. Unfortunately, thin wood is often more expensive by volume than thicker wood of the same species.
Several thin layers require more work in the front-end: many layers are needed of the more expensive material, more transferring from templates and cutting out, more complicated aligning and gluing up.
On the other hand, shaping an intricate hull of modest size with just a few boards will no doubt save money, but will be more difficult to shape properly. As an example, The USS Olympia (pictured elsewhere on this page) at 1:144 scale with only six layers of 4/4 lifts was a challenge. In hindsight, I should have doubled the number of lifts and gone with 3/8-inch thin wood.
I tend to try and stick with trade sizes of lumber: FAS 4/4 S2S. 4/4, which is typically 3/4 - 13/16" thick (19 to 20.6mm) May not be the best choice for your first B&B model, but trying to make it a goal to conquer the technique to the point you feel comfortable shaping a hull from common size material will save you money.
There are typically three ways to carve a hull:
1. Carved solid block model boat hull
2. Bread and Butter (aka glued-up laminate) construction:
Another method to consider is a hybrid between a planked and a carved hull method. Typically the lower part (under and including the bilge) are made up of a solid piece or laminated boards and, the sides are covered with sheets or strips of plywood, styrene, card stock or wood to form a complete hull.
This method saves material and weight over straight Bread and Butter and is typically faster to build than a regular planked hull. It's relatively common for semi-scale working models where there is more leeway in regards to accurate representation.
A hybrid built approach is especially suited for large warships, cargo ships, tankers and the like, where the sides are flat or near flat. This method typically leaves more room for running hardware, motors and RC gear than you'd see in a B&B hull.
Here is a list of the most common model boat hull designs that you’ll typically encounter. Often a sheet planked hull is faster to build than one planked with strips. The time saved is two-fold: less bulkheads to cut out and line up and only a couple of strakes of planking.
Most hard chine boats are either small to medium sized motor boats, such as launches, torpedo boats, speedboats or small and modest sized sail boats. However, many modern tugs, commercial fishing boats and work boats have also been designed this way.
This boat hull design is often suitable for sheet planking which will save a lot of time as stated earlier.
On the other hand, be aware that just because a hull is hard chine, doesn’t automatically mean it can be planked with sheet. Good examples are the Elco PT boats and many launches and motor torpedo boats by Vosper and others. The side and bottom panels on these boats are actually scalloped (or concave) when looking at the original hull sections. The hull shape, and thus all bulkheads, has to be altered in order to be planked with sheet material.
Most builders would agree that for working models especially, simplifying these hull forms (to accommodate sheet planking) is not a serious offense even to the most hard-nosed scale model aficionados.
A hull being hard chine doesn’t automatically make it easy to build. If you’re looking for easy, look for a straight shear line (where the deck meets the upper part of the hull) or another flat plane that can be laid flat on your building surface.
A round bilge hull can not be planked with sheets, but has to be either carved or strip planked. A long and narrow hull will be a lot easier to plank than one that is short and wide.
Planking a round-bilge hull with sheet material, the way paper models often are constructed, is by all accounts a compromise. You also see build logs in forums, often scratch-builds, done this way with styrene sheet.
In this method the fitted panel span only between two bulkheads, the keelson and to a false deck at waterline (for instance). It’s a convenient solution for paper or styrene, but it's difficult to finish into a true and smooth hull this way.
It seems to work well enough if the model is kept relatively small. The larger the hull, the more noticeable the staggered shape will be. Also, the more bulkheads and closer together, the smoother the result.
For late 19th and 20th century steel hulls, I’d use solid blocks at the extremes whenever suitable. It is very difficult to get plank strips to form that sharp entry of a full size vessel – it always end up blunt. Using blocks at the stern you’ll bypass the headache of tight bends and awkwardly tapered strips. Naturally, this is not an option if the planking is exposed, but works great for hulls that are painted.
Whenever scale appearance comes second to simplicity, some round bilge hulls can be simplified by converting them to some form of hard chine design. Large ships for instance, can often be built up with balsa or basswood sheet of appropriate dimensions and sanded to take on a more rounded shape. The thicker the planking, the more material will be available to form a rounded bilge and other joints.
The benefit with a multihull over a monohull is that they achieve the same stability as a monohull but with less wave forming resistance, so they go faster with the same driving power. The most common are:
Multihulled vessels are built for speed and economy. Many sailboats and power boats for racing have this type of hull. Some small to medium sized passenger ferries have been designed with multihulls for speed and economy. Multihulls are generally not considered as seaworthy as monohulls.
Other less common boat hull designs include:
Hydrofoils and jet skis, along with RC surfboards belong to the novelties in the model boat building hobby. There have been kits and RTRs, but most seem to have come and gone. RC submarines on the other hand have a strong and dedicated following.