To determine the placement of these section lines we look to the half breadth or sheer plan. The station lines along the base of these two plans are marked at the locations where the corresponding body sections are to be placed.
These preceding considerations are not meant to discourage the would-be scratchbuilder. They are meant to give guidance regarding the areas that are most likely to bring a scratchbuilding project to an abrupt halt.
Before actually starting any construction work, the vessel must be thoroughly researched. Sometimes this phase can take considerable time. It is axiomatic that you can't build what you don't know. The quickest way to find out what you really do or do not know is to have to actually start building something.
Accurate hull plans are the basis for a successful project. Marine architects have their own peculiar ways of communicating the shape of a hull. If you can't interpret these drawings, then they are of little use. A whole article could be written about ship plans but only a cursory overview will be given here.
Ship plans are representations of the three dimensions of a hull. Consequently
there are three views of the hull given in most standard ship plans.
The first view is the Body Plan. This plan shows port to starboard
cross sections taken at intervals from forward to aft. If a loaf
of bread was a ship, the slices would be the same as body plan sections.
The heel on one end would be the bow and on the other the stern.
The second view is the Half Breadth Plan. This plan shows cross
sections taken in a forward to aft direction parallel to the keel upward.
Again if this were a loaf of bread, the waterlines of the Half Breadth
Plan would be like cutting it for a sub sandwich. The cutting knife
would be parallel to the cutting surface from one end of the loaf to the
other.
The third view is the Sheer Plan. This plan shows cross sections
taken from a forward to aft direction along the length of the ship.
The section taken down the middle of the ship would produce a full profile
of the ship. If this were a loaf of bread, the knife would be vertical
with relation to the cutting board and would cut from one heel of the loaf
to the other with the knife remaining vertical.
All three views are useful for determining the shape of the hull at
any particular point.
A word about scale is in order here. The most important thing
to determine when trying to decide on a particular scale is how big you
want your model to be. Most modeler's inclination is to go with larger
scales (and the larger the better). The downsides of larger scales
are that models are so large that they cannot be easily transported or
displayed.
Another critical aspect of a larger scale is that the level of detail
required to faithfully model the ship also goes up. I have seen very
small models which blew their larger counterparts out of the water in terms
of scale fidelity and skill of execution. Bigger scale does not mean
easier or better. A big piece of junk is worse than a small piece
of junk.
With the advent of the photocopier, enlargement or reduction of plans
to a desired scale is simple. Usually a scale is decided on which
is either based on metric or English measurements. Whichever system
the modeler prefers, and which he is comfortable with is the one he should
use.
The discussion of how to convert a metric scale to an English scale
is kind of a dry mathematical exercise. If interest warrants, it
may be included in a separate article.
The next consideration prior to actual construction of the hull is what
building method will be employed. On of the primary considerations
is whether the model will be a radio controlled model, static, or static
with interior lighting. Museums usually specify construction primarily
with wood. For these models a construction method called "bread and
butter" hull construction is usually employed. This method will be
discussed later.
Most modelers today use a construction method known as "plank on bulkhead".
"Plank on frame" is a method almost exclusively used for wooden sailing
ship. A final method is the laid up cast fiberglass hull. The
advanced techniques needed for the all fiberglass hull are beyond the scope
of this article.
The "bread and butter" method of hull construction produces a solid
wood hull. Because of the limitations created by a solid hull, this
method has fallen out of favor among modelers. For that reason,
the method will only be described briefly. For this hull construction
technique, any of the plan views can be used but the most commonly used
view is the half breadth plan. In this method the waterline sections
are used to cut wood sections to be laminated one on top of another from
the keel upward. These sections are all glued together then shaped
using templates taken from the body plan to guide shaping. The "bread"
is the wood waterline section. The "butter is the wood glue used
to glue each section to the next. The number of sections is determined
by the desired thickness of the sections or "lifts" as they are called.
If the half breadth plan does not show the number of waterlines necessary
for the desired thickness of the lifts then new waterlines must be drawn.
This is done by utilizing the body plan to plot points at each fore and
aft station at the height desired from the keel. The process is somewhat
difficult to describe but relatively simple in practice. A more thorough
explanation of the method of creation additional lines as needed will be
given when discussing the plank on bulkhead construction method.
The waterline section lifts are different widths at their top and bottom
faces due to hull taper. Instead of cutting the bevels in each lift,
it is usually easier to cut the lift to its greatest width then bevel the
lifts when they are all assembled together. Each lift is cut and
stacked on the lower one and attached to it by wood screws and wood glue.
Each successive lift is attached to the one below it until the full hull
height is reached. The highest lift for the lull is different in
that it is not full thickness, Its upper contour is determined by
the profile on the sheer plan. The method of cutting or sanding the
top lift down to the hull profile is left to the modeler. To contour
the hull, the overlaps between the lifts are sanded or planed until they
are eliminated and the hull contours are smooth and fair. The wood
hull is then filled, sanded, and painted.
The most popular method of hull construction today is the plank on bulkhead method. This method primarily uses the body plan. The first thing that must be determined using this method is whether there are a sufficient number of sections on the body plan. If the planking material is not sufficiently rigid, there will be depressions between the bulkheads because of lack of support. This will give the hull a wavy appearance. There are two possible solutions. Either a stiffer planking material can be used or the number of bulkheads can be increased making the distance between the bulkheads smaller. Actually there is a third method whereby the hull is planked twice to giv the planking more rigidity. At the end of this section I will discuss how to increase the number of body sections.
Another preliminary consideration is deciding what planking material will be used. The thickness of the material must be compensated for when determining the bulkhead outline. On most plans , the lines shown are drawn to the outside of the planking. Bulkhead material needs to be strong and stiff and thick enough to provide a landing for planks to fasten to. The keel should be of a material like hardwood that will remain straight and true.
Up to this point we have talked generically about scratchbuilding. Since this article is being posted on the Titanic model website, I will be a little more specific about how these techniques could be use on a Titanic model.
To begin with, we will assume that there enough stations indicated on
the body plan to provide enough bulkheads for the planks to land on.
Now we move to the keel. I will arbitrarily choose a 1/2" square
piece of oak for the keel. During the building process the keel and
frames must set level and true. Therefore it is essential that we
construct a rigid building board. 3/4" plywood or particle board
with at least 6 inches excess in length and width is sufficient.
On the building board a centerline is either drawn or made with a chalkline.
Across this centerline the bulkhead stations are drawn at right angles
to the centerline and numbered (figure 1).
To determine the placement of these section lines we look to the half
breadth or sheer plan. The station lines along the base of these
two plans are marked at the locations where the corresponding body sections
are to be placed.
To determine the length of the keel we will measure from the forward
point where the keel ceases to touch the baseline then aft to the point
on the plan where the body plan sections where they meet the baseline are
narrower than the 1/2" width of the keel. Aft of this, in the area
of the propellers, a thin piece of plywood (model aircraft) rises above
the point where the hull lines are wider than the plywood piece.
This aft plywood piece forms both the bottommost hull outline aft of the
main keel and it also forms the vertical rudder post. It has
the cutout for the centerline propeller and the bottom profile associated
with it. To this aft plywood
piece the stern bulkheads will attach. These bulkheads will be
different than the main hull bulkheads which attach to the keel in that
they do not extend down to the bottom of the keel. These aft frames
will only extend down to where the width of the stern plywood equals the
width of the body lines at the that station.
For the stern counter and the forward part of the hull where the keel sweeps upward, the half breadth plan will be used to make solid wooden pieces to attach to the planked hull.
The aft keel extension is cut first of model aircraft plywood or some other suitable material. This piece will be cut approximately an inch longer than the measured length on the forward aspect and a one inch slot is made in the keel to receive it. This is done to ensure a secure connection between the aft stern piece and the keel.
The keel is mounted temporarily to the board with brads nailed through it in to the board to keep the keel from moving. The keel is mounted down the centerline that was previously marked on the board. The aft stern piece is inserted and glued into the slot in the aft end of the keel. Care should be taken to use a waterproof wood glue and extra care should be taken so that glue does not flow onto the building board. The aft keel extension should be aligned so that it is perpendicular to the building board. It should be supported in position while the glue dries 24 hours.
Now we turn to the process of cutting out bulkheads. We will be cutting out all the bulkheads from the forwardmost bulkhead which will join to the solid bow piece aftward to the last frame that attaches to the aft stern piece.
A copy of the body plan is copied as many times as there are bulkheads
between the solid bow and stern pieces. The copies are each numbered to
indicate the bulkhead that will be cut from that copy. Each half
bulkhead outline is cut out with scissors. One at a time, one half
bulkhead outline is traced around on the material which will be used for
the bulkheads. The half bulkhead pattern is then flipped over to
create a mirror image and this is traced next to the first outline so that
a single bulkhead is created. Now is the time when the planking material
must be compensated for (figure 2).
Just for discussion, let's say that the planking material is 1/16"
thick. The outer outline (not top outline) must be drawn 1/16 smaller
to compensate for the thickness of the planking. If any other material
such as putty or plastic plating is anticipated to cover the hull planking,
this material must also be compensated for by reducing the external size
of the bulkheads accordingly. To redraw the bulkhead outline a ruler
is placed at right angles to the exterior outline of the bulkhead and a
mark is made inside of the bulkhead outline the same width as all of the
planned planking and other materials. Several of these marks are
made and a new line is drawn connecting these marks. The bulkhead
is now cut to this line. A notch for the keel must be made
in the bulkhead. One crucial consideration is that the bulkheads
have been reduced around their external dimension (except for the top)
to compensate for the planking thickness. Therefore the notch created
for the keel will be shorter than the keel by the thickness of the planking
material. When the bulkheads are placed on the keel, the bottoms
will be at a level above the building board by the thickness of the planking.
Before beginning to glue the bulkheads to the keel, a centerline needs
to be drawn from top to bottom through each bulkhead It is very important
that the frames that are attached to the keel are perpendicular to the
building board in a fore and aft direction and that the centerline of the
bulkhead is perpendicular and lines up with the centerline of the keel.
The following is a method I have used to make sure the bulkheads are attached
in a square and true fashion. First a two pieces of left over keel material
are cut to a length that is at least an inch higher than the highest bulkhead
measured from the bottom of the keel upward. These two blocks are
glued to the building board both forward and aft of the extreme length
of the hull. They should be placed at least one inch forward and
aft of the extreme length of the hull (figure 3).
They are glued on the building board centerline. A piece of thread
is attached to the top of both of these forward and aft blocks. The
placement of the thread is to form a vertical centerline so it should be
adjusted so that it runs directly over the centerline marked on the building
board.
Each bulkhead should be checked to see that it has a snug fit on the
keel but it should be able to seat completely without being displaced either
to port or starboard. Now starting with the forward bulkhead, glue
is placed in the keel slot and it is placed over the correct station on
the keel. For each bulkhead 2 pieces of scrap keel material should
be cut to act as forward and aft stabilizers of each bulkhead. The
bulkhead is glued into place. One of the small blocks of keel material
is glued on the forward and one on the aft of each bulkhead. Each
of these stabilizing blocks is glued to both the bulkhead and to the top
of the keel. A lump of children's modeling clay is placed on the
building board on the forward and aft sides and on both port and starboard
sides. These lumps of clay are temporary adjustable stabilizers.
The frame is checked in the fore and aft direction to ensure that it is
perpendicular to the building board. The bulkhead is adjusted so
that its centerline aligns with the thread centerline that was constructed
earlier. Successive bulkheads are glued in this method until all
the bulkheads are glued to the keel. It is very important that all
glue joints be allowed to dry 24 hours before removing the stabilizing
clay pieces (figure 4).
For the frames which attach to the aft keel extension, a notch must
be created in the bulkheads to allow them to be placed at the proper level.
Two check measurements should be made on the body plan for these frames.
First the measurement from the building board to the bottom of the bulkhead
is made. This height is marked on the side of the keel extension
at the proper station. Next, the height from the building board to
the top of the bulkhead is measured. This measurement is recorded
for future reference. Now the notched bulkhead is glued to the keel extension.
The bulkhead is seated until the bottom reaches the mark previously placed
on the keel extension. The height to the top of the bulkhead is measured
and checked against the measurement previously taken for reference.
The frame is centered on the thread centerline and braced with clay after
being checked to see if the frame is perpendicular to the keel (figure
5).
Now that all the bulkheads have been glued to the keel and aft keel extension, planking can begin. The bow and stern pieces will be added after planking is finished. Planking can either proceed from the keel upward or from the top of the hull downward. In this particular example we are using it would be unwise at this stage to invert the frame assembly because of a lack of inherent strength. Planking will proceed form the upper part of the hull downward to the turn of the bilge. At that point, the hull will be much stronger so that the hull can be inverted and the remaining planks can be added from the turn of the bilge to the keel.
Since this is not a wooden vessel we are modeling and since all of the planks will be covered, we do not have to be concerned about the many considerations that we would otherwise have to plan for in planking the hull. The planking material will provide a matrix for the material or materials which will be used to smooth the surface of the hull. For planking material, I have worked with and would suggest balsa wood strips 1/16" thick and 1/4" to 1" wide depending on the area of the hull being planked. In areas of the hull where there is more curvature, such as the stern, the planks will need to be narrower. In order to prevent twisting of the hull, a plank should be placed on the port side then the starboard alternating through the whole planking procedure.
To glue the planks, I would suggest a thicker formula super glue. The plank is tried in place for fit and glue is placed where the plank meets the bulkhead. After the glue has peen applied, the glue joint is sprayed with a super glue setting accelerator. These sprays cause the glue to set immediately and allow you to proceed rapidly with planking without elaborate planking clamps. The main rules are to use planks that land on at least three frames, stagger the planks so that no two adjoining planks terminate on the same bulkhead and alternate the placement of planks first on the port and next on the starboard. Other than these few simple rules, the object of this stage is just to cover the bulkheads.
When planking reaches the turn of the bilge, the model can be turned over to plank the bottom. This is where you will learn the importance of not gluing your bulkheads to the building board. Also remember that you have nailed the keel to the building board with small nails which must be removed. A screwdriver or some other instrument is used to carefully pry the keel from the building board where it was nailed. When the hull is loose, the nails are completely removed so that the keel is facing upward. The remaining planking is finished on the hull bottom.
Using a piece of coarse sandpaper , the hull is sanded to remove some of the surface irregularities. The balsa wood cannot be finished all that smoothly so don't overdo it.
Now we turn to creating the forward and aft hull pieces. These will be created using the "bread and butter" technique described earlier. We will begin with the bow area. First we will need to make a profile guide. For the bow area we will trace or duplicate the forward part of the sheer plan. The bow profile will be taken back to the station where the last forward station of the main hull terminates. Since the most forward hull frame is slightly forward of the frame station by half the thickness of the bulkhead, the aft end of the bow profile will have to be shortened to compensate for the half thickness of the bulkhead. The shape of this bow profile is now traced onto the thin aircraft plywood that we used for the bulkheads. This profile is carefully cut. As we look at the halfbreadth plan we may discover that the distance between any two waterlines is different than the thickness of the wood we will use to stack to make the bow. Let's sat that the waterlines are 1" apart and the board thickness we are using to create the bow section is only 3/4". How do we create waterlines that are 3/4" apart? This is done relatively easily.
On the body plan we measure 3/4" up from the baseline. We now draw a line parallel to the baseline at the 3/4" level. From this line we mark 3/4" upwards from the first line and draw another line parallel to the baseline. This process is repeated until we have reached the last waterline that can be drawn under the upper hull profile from the bow back to our most aft station of the bow section. Starting with the lowest line that was drawn across the body plan, the distance from the centerline to where our line crosses the first body line is measured. That distance is taken to the half breadth plan an is marked outward from the centerline at the corresponding station. Back at the body plan the next measurement is taken from the centerline to the next body section. This measurement is taken to the half breadth plan and is marked outward from the centerline at the corresponding station. This process continues aft to the last body line of the bow section. Once these line points are made, they are connected together with a line that forms a sweeping curve like the other waterlines in this bow section. You have now drawn your first custom waterline. You now go to the next line you drew on the body plan which is 3/4" higher than the first. The same procedure is used to create the second custom waterline. All the successive custom waterline are plotted. the width of these waterline sections should meet the surface of the planked main hull since this piece will not be planked.After tracing the custom waterlines, the plan is copied as many times as are needed for the waterline sections. These waterlines are traced onto the 3/4" material we have . Instead of creating sections of full width we will be creating half sections. If our profile section which was previously cut is 1/16" thick then we must measure out 1/32" from the centerline to create the inside centerline for our waterline sections. This will compensate for the thickness of our bow profile piece.
Before we assemble the bow sections, the individual waterline heights
are drawn on the profile piece. To assemble the bow sections the
profile is set on the building board on its aft edge. Starting with
the lower waterline sections, the port and starboard sections are glued
to the profile piece. The assembly can be supported with clay.
The next higher section is glued to the profile board and the section below
it. If you are using wood glue, the waterline sections should be
clamped and allowed to dry 24 hours. To speed up the process, 5 minute
epoxy can be used with the sections clamped during the 5 minute drying
time. Each successive section is added until all the sections are
glued to the profile piece and the pieces above and below it (figure 6).
When the assembly has dried, final shaping can begin (figure 7).
You will notice that since the bow tapers from top to bottom that the
bottom of each section will overlap the section below it. It is this
overlap which needs to be removed to contour the sections. The contouring
can be done with the tools of your choice but care must be exercised.
The bow section must also be contoured down to the bow section profile
piece. After contouring is finished, the bow section is glued to
the forward bulkhead of the main hull (figure 10).
Screws through the front bulkhead into the bow section can be added
to add stability.
The aft section is created using the same bread and butter technique
with a few modifications. Instead of using pieces of constant thickness
to build up the stern piece we will use three pieces of different thicknesses.
We again draw the profile of the aft strern piece from the sheer plan.
The three pieces used to form the aft piece are the upper piece which is
white painted part of the Titanic stern. The second piece is the
section that begins just below the white painted section down to the rounded
moulding around the stern. The third piece is the part from the rounded
moulding to the bottom of the stern piece. You will notice (figure
8) that these pieces are not parallel with the keel. Their outline
is shown on the half breadth plan.
When the three pieces are cut then they are flipped and used to trace
the blocks for the opposite side. When all the pieces are glued together
and to the profile piece they are left to dry. When dry, the shaping
process begins. The aft piece is placed against the aft bulkhead
of the planked hull. The outline of the hull is traced on the forward
edge of the aft piece. This line is used to guide shaping.
The aft piece is also contoured to the profile piece in the center of the
blocks. This is a complex area of the hull and all the plan views
should be used to aid in shaping its many curves and contours. (figure
9).
Once shaping is completed the aft piece is glued to the aftmost main
hull bulkhead. Wood screws through the bulkhead into the aft piece
can be used to stabilize it.
The basic structure of the hull is now complete. Now comes the process of finishing. My preferred method is to cover the entire hull with a coat of polyester resin and thin fiberglass cloth, allow to cure, then apply second coat of polyester to cover the fiberglass cloth. This produces a very strong hull in the sections that were planked with balsa wood. After the fiberglass resin has cured, the hull is brought to a very smooth surface with Bondo automotive body putty. Much time will be spent in filling and sanding until the final results are achieved. As much or more time may be spent in this filling and sanding process than the actual building of the hull so don't get discouraged at the slow going during this process.
After the hull is sanded and is free of imperfections, then hull details such as portholes , windows, and anchor wells are plotted and cut out and finished. Plating joints can be scribed.
For a more realistic look, after the hull is finished smooth, individual hull plates made from thin sheet styrene can be plotted, fitted and glued for a more realistic appearance. The other hull details are then added to the plating.
Finally the hull is painted with the desired paints. I would suggest either automotive lacquers or Floquil Railroad Colors. Either should be applied with an airbrush.
In this discussion I have not discussed more advanced techniques for creating the rivet heads in the plating. Some of these methods could be discussed in a future article. Also I have not discussed the methods of creating an all fiberglass hull. The aim of this article has been to provide the basics for those modelers who might be attempting their first scratchbuilt hull.
Bob Read