i) If you are not concerned about building the model exactly to scale you can omit step 6. Doing so will make the hull a little deeper and wider than scale size. If your plan shows the outline for cutting the deck piece, you will have to make it wider to compensate for the width of the planking. The same applies for the external templates for bow and stern described in step 16. You need to add the thickness of the planking on the outside of the line, and then cut internally to this new line.
ii) Instead of the vertical cuts illustrated in step 10 and Figure 12, you can make the cutout larger so that the cuts to remove the extension are horizontal, as shown in Figure 16. It’s a matter of personal preference.
The information provided so far has illustrated a particular type of hull, the “round bilge hull”. The bilge is the area where the side of the hull meets the bottom, and this location is ‘radiused’ or rounded. An alternative is what’s known as a ‘hard chine” hull, where there is a sharp corner between the side and the bottom.
Figure 17 shows a section through a shallow vee fast boat, which has a hard chine hull. The edge where the side and the bottom meet is the chine line. In some examples you may see the chine line referred to as a ‘knuckle’.
Hull types do not always fall neatly into one of the two categories. Figure 18 shows the body plan for a cruiser which has a round bilge form on the forward part, and hard chine on the after part.
Planking the hull.
Before you begin planking, you must decide what material you are going to use. Balsa is light, easy to cut into strips, but soft and not very strong. Plywood, basswood, cedar etc. are stronger, but not so easy to cut into strips. It’s a good practice for all materials to be fibreglassed after planking for strength and water-tightness when the hull is complete, and even a balsa hull is quite strong when this is done.
Another decision is required on the width of planks to be used. Where the hull changes shape rapidly, narrow planks are better than wide ones. Planks do not have to be the same width all over the hull; the width can be varied to suit.
There is lots of information on the internet about planking, mostly directed to the construction of wooden warships. Two useful sites are: Knight Dreamers website and Ship Model Society of New Jersey website.
Some key points can be highlighted.
Calculate how many planks you will need by first measuring the length of the outside edge of the ribs – lay a piece of string on the rib and measure it. Repeat this action for each of the ribs. You will see that, at bow and stern, the rib length is shorter. This will give you an idea of how the planks must be trimmed to fit as you add each one. Decide how many planks you will fit. You will need 4 planks ¼” wide for each inch, etc. As you fit each plank, lay it on the ribs next to its predecessor, and hold it in place with pins or tape. Mark where it overlaps, and then trim the plank to fit.If you are planking a hull that has a chine line, you probably want to lay the first planks along the chine line, one above the line and one below. From that line work up and down towards the deck and the keel. The next location to consider for planking is the topmost plank. Most ships and models have some sheer, which means that the deck rises up near the bow and the stern. The topmost plank needs to follow this line.
It is important to alternate between each side of the hull when attaching the planks. This helps to prevent twist or distortion.
Where there is a lot of twist or curvature in a plank it is a good idea to soften it before glueing. There are a number of ways of bending the planks to make them easier to fit. These include soaking the planks in Windex, or a similar cleaner containing ammonia, steaming, or using a plank bending tool.
If the planks to be used are not long enough to run from one end of the hull to the other, it will be necessary to butt two planks end-to-end to form one strip. It is recommended that you stagger these butt joints, otherwise the joint line will become a weakness in the hull. You may wish to make the ribs at this join from thicker material so that there is adequate surface for the two planks to adhere to. Or you can make two ribs of the same shape glued together.
Figures 19 and 20 show two hulls partway through planking. Figure 19 is planked with ¼” wide strips of 1/16” thick balsa attached with CA glue. Note that the two ribs either side of amidships are double thickness where the butt joints are placed. Figure 20 is planked with ¼” wide cedar strips ⅛” thick attached with Gorilla wood glue. It is important to alternate between each side of the hull when attaching the planks. This helps to prevent twist or distortion.
Once the hull has been planked, the bow and stern can be shaped to match.The external surface will be uneven in places and need smoothing and filling. Where small amounts of filler are needed, Bondo Glazing and Spot Putty works well, and there are also equivalents made by the model suppliers such as Tamiya. For larger amounts, either Bondo Autobody Filler or Minwax High Performance Wood Filler are good for the planked areas. Both of the latter are two-part pastes that require mixing. The wood filler is a little softer than the autobody filler. For the areas where the foam insulation is used, Polyfilla is good as it is softer again than the above-mentioned fillers. Most modellers apply fibreglass cloth on the inside and/or outside, and secure it with epoxy or polyester.
Sheets for flat areas.
As already mentioned, many model hulls have areas where a flat sheet can be used instead of planks. This occurs most often on a ship’s bottom and sides in the midships area. If you look back at Figure 1 you will see that ribs 8, 9 and 10 merge together at the bottom and the side. This means that the hull is flat where the lines merge. A straight line forming a part of the outline of a rib means that the hull is flat in that area.
Also on Figure 1 you can see that a lot of the ribs in the forward part of the hull have straight portions, from rib 11 all the way to rib 17. On the after part of the hull there is not so much. From ribs 1 to 6 the only straight portions are above the deck edge line.Because the sides of ribs 15, 16 and 17 are sloping, a flat sheet extending over these ribs will have a twist in it. A template must be made to check the size of the sheet that will fit.
So if there is a large area of the hull that is flat, you can consider using flat sheets instead of planks. You will probably need to use planks near the bow and stern, and so you should consider thicker (or double) ribs where the planks butt up to the sheets.
Above the deck line.
Every commercial vessel will have either railings or bulwarks around the edge of the deck, so that passengers and crew don’t fall over the edge. Railings always consist of horizontal bars supported by vertical bars called stanchions. Bulwarks are solid steel continuations of the hull above deck level. On some vessels they extend maybe to knee height, on others up to chest height. Your plan should indicate their height. The bulwarks always have supports welded to the deck, and these supports may be made from plate, angle iron or pipe, or a combination.
The final step in the hull planking process is to remove the extensions from most of the ribs. Two or three can be left in place to support the hull while it is filled, sanded and fibreglassed.
If you are fitting the deck as one piece, you have to remove the rib extensions to get the deck on. However, you will need some means of supporting the hull upside down so that you can paint it, after you’ve fitted the deck. A pair of T-shaped supports should be made and screwed to suitable ribs, after fitting the deck. If the ribs have a cutout, you should leave the horizontal strip in place until after painting so that you can attach these T supports.
The deck can be wood or styrene. If you are using styrene, it is recommended that you glue a sheet of plywood on top of the ribs, and then firmly glue the styrene to the plywood. Styrene expands more than wood, especially out in the sun on the pond, and if the styrene is not firmly glued down it is likely to buckle.
If you are using styrene for the bulwarks, it is best is to fasten the styrene deck very securely in place on the wood hull, and then start adding all the additional styrene parts you wish, on top of the deck. Wooden blocks can be taped to the deck to help support the bulwark as the glue is setting up. You can also use a bit of strip styrene glued to the side of the bulwark, flush with the bottom surface of the bulwark, to increase the gluing surface of the bulwark.
Providing for Anchors.
There are 3 ways that anchors are housed.
1. On the deck. A derrick is used to lift and lower the anchor. This method requires no more work on the hull.
2. Against the hull. This requires a hole be made in the side of the hull, and a tube (known as the hawse-pipe) run from it to the deck. When the anchor is hauled up, the anchor shank sits in the hawse-pipe, and the anchor flukes sit flat against the hull, but outside it.
3. In a recess. Similar to 2 above, but with a part of the hull wall sloped inwards so that the anchor, when housed, does not protrude. This is common in tugs, for example, which often contact the hull of other ships.
The location of the anchor is shown on a side view of the hull. Because of the shape of the hull near the bow, you cannot copy dimensions read from the plan directly onto the hull.
We’ll describe the method for an anchor recess. A side view of the hull will show the recess as a kind of distorted rectangle. What we need to do is locate the four corners on the hull, and then draw straight lines between them. Ideally this can be done while the hull is still attached to the building board, but it’s not necessary.
The hull should be upside down on a flat, level surface so that it’s also level. Measure the height from the flat surface to the bottom of the hull, call this dimension ‘H’. For example purposes, let’s say it’s 6 inches. From the side view plan, measure the distance from the bottom of the hull to one corner of the recess; call this dimension ‘X’. Let’s say it’s 3.5 inches. Subtract X from H; in our example 2.5 inches. Mark a line on the hull at this distance up from your flat surface. Repeat this procedure for each corner of the recess.
Now stand the hull up on the floor (or a bench), so that it’s vertical. It’s easier to do this if the hull is still mounted on the building board. Measure the height from the bow to the floor (or bench). On the plan, measure the distance from the bow to one corner of the recess. Add these two dimensions together and mark a horizontal line on the hull at this distance from the floor. Draw the line where it intersects the line you marked when the hull was horizontal. The intersection of these two lines is one corner of the anchor recess. Repeat this for the remaining three corners. Draw the lines to connect the corners and then cut out the rectangle.
If there is no recess, you treat the centre of the hawse hole as if it were a single corner.
Other methods of hull-building.
There are a few different ways of building a hull.
i) Horizontal “Bread and butter”. This method involves cutting planks to the outline of the hull and then glueing them one on top of another, as you would build a sandwich. This requires a different plan, a “Half-breadth” plan which shows horizontal slices through the hull, called “waterlines”. The planks can be hollowed out before or after glueing together. The outer surface has to be shaped and sanded to obtain the correct external shape.
ii) Vertical “Bread and butter”. This is a very similar method except that the planks are arranged vertically. This uses “buttock lines” to define the shape of the planks. Buttock lines are shown on the Sheer Plan. The lines marked A to J on Figure 14 are examples of buttock lines.
iii) Plank base. Think of turning the building board into an integral part of the hull, slotting the top of it and fitting the ribs into the slots. This is the plank base method of construction.
iv) Solid. This means starting from a block of wood the overall size of the hull, and then shaping it internally and externally to match the plan.
v) Foam core. These methods use building foam insulation, usually pink or blue in colour. Not while polystyrene foam.
vi) Rib and foam. This method uses insulation pieces between the ribs instead of planks. They are made oversize and then shaped to fit, using the ribs as guides to shaping the foam.
Any of methods i to iii above can be built using slabs of insulation instead of wood. After shaping, the hull is fibreglassed externally. After fibreglassing, foam can be left in place or removed, by physically cutting it out or by dissolving it with acetone.
Supplementary information obtained from www.greatlakesgraphics.net , www.cruisersforum.com.
Confederation Marine Modellers