Chapter 6: Hull Assembly

The parts that have been pre-processed so far are shown in [Fig. 6-01]. Now it is time to assemble these parts as a hull.

Double frame assembly            F23-F24, A29-A30     1 ea.

At this point, the keel has been set in the assembly jig, but to ensure perfect verticality of the upper and lower jig plates, the square frames at the front and aft ends are first glued to the jig. Prepare square double frames F23-F24 and A29-A30. Apply a homemade square, which can be used in the jig, to check the position and verticality of the frame, and bond the two top edges and the center part with tight bond [Fig. 6-02] - [Fig. 6-05]. In the photo, the burn marks on the frame are still visible, but rough sanding has already been completed at this stage.

If the frames can be fixed in this position, the next steps (1) to (4) do not necessarily have to be in this order.

(1) Assembly of fore cant frame 

We will start with the front and rear of the hull, which requires a little more concentration when assembling the frame. Let us assemble the fore cant frame to the keel first. 

 * First, try to align each of the 8 sets of cant frames (F25-F32) with their respective positions on the deadwood steps [Fig. 6-06]. The figure also confirms the combination of the front-most cant frame and hawse timber.

* You will notice that there is some immediate interference here. While all deadwood steps are 8 mm in length, the bottom edge of the cant frame is longer than the 4 mm thickness due to angling, so it would protrude from the step as it is. Therefore, shave the pointy part to 4 mm as appropriate and assemble (Figure 6-07).

* Otherwise, if the angled area is not touching the step properly, it is recommended to correct it whenever possible.

* Once the above is confirmed, glue the two ends of each frame.

(2) Hawse timber assembly

Next, the hawse timbers set HT1 to HT5 are assembled. 

 * Each timber is assembled in position, and as with the cant frame, the positioning cutouts on the jig top make it easy and accurate to locate the position. It verifies the correctness of the design values.

Here, you check the degree of the fit between the apron and HT1, the fit between the top of the timbers and the jig, the contact between the bottom of the timbers and the front-most cant frame, the positional relationship between the timbers and so on. If there are, adjust to avoid gaps and misalignments.

* After the above checks and adjustments are completed, glue the timbers in order. Glue the upper part, lower part, and the center part [Fig. 6-08] [Fig. 6-09].

(3) Transom and rear cant frame assembly

Are you getting the gist of assembly? Next, we will assemble the transom WT, T1 to T5 and 8 sets of rear cant frames A31 to A38.

 * The transom is joined horizontally to the aft-most cant frame A38 on both sides, so the A38 cant frame is first assembled on both sides simultaneously. The procedure is the same as for the front cant frame, so before gluing, the bottom edge of the cant frame should be shaped to match the step width.

* To assemble the transom, the inner sternpost is first glued to the rear of the deadwood while checking the condition of the sternpost combination, and then the center dimensions and slope of each transom are finalized to fit into the notch. Since it may be difficult to maintain the transom level only by mating with the inner sternpost, mark the height of each transom at the rear position of the cant frame at the same height on both sides, and glue the transom ends at that position [Fig. 6-10]. If marking seems difficult, make and use the measuring device described in section (7) below first.

* All transoms are assembled and last, the sternpost is assembled [Figure 6-11] and [Figure 6-12]. Here IP3 is also glued to the inner sternpost.

Note: Wing transom WT and second transom T2 are cambered, so the gap between the transoms viewed from behind is not all parallel.

* Continue to assemble the remaining rear cant frames A31 to A37 [Fig. 6-13]. The procedure is the same as for assembling the fore cant frame.

* Finally, fill the opening under the transom. Fit the lower filling frame FF-L here while shaping it to fit into the surrounding shape [Fig. 6-14], [Fig. 6-15]. The sternpost complement SP3 is not shown in the figure, but it will be glued at this point.

* Here the entire rear section will be reshaped. The thinnest part is 3 mm thick at the lower left corner where the keel and sternpost intersect, i.e., 1 mm deeper from the keel. From this point, the lateral direction gradually returns to thickness up to the last square frame, and the upward direction follows the sternpost rabbet. Then a smooth concave surface is formed from each to the cant frame.

The transom is the part of the hull where the hull curvature converges with the stern and is responsible for the sudden change in curvature. There was no body plan for this portion, and the individual shapes were drawn by trusting the curved surfaces drawn with 3D software, so this was one of the major points to be verified the accuracy this time. The result was an excellent reproduction of the continuity of the hull curvature, including the reproduction of the bevel size.

(4) Assembly of square frames

The square frames are the main framework of the hull, but since the difficult part of the hull has been completed so far, the work is not so difficult, although there are many of them.

* Once all frames (F00-F23, A01-A29) are in place, check the status. The frame cannot simply be attached to the jig because the middle part of the frame is wider than the top end. Once through the top edge of one side of the frame under the top plate of the jig then insert the rest of the frame under the top plate. When the entire piece is almost under the jig plate, the frame can be safely set into the jig by peeking the first portion through the notch in the jig. The elasticity of the frame itself is also effectively utilized.

* Fit the frame in place on the keel and in place on the jig top plate, and check that it is vertical by applying a homemade square. Unlike tool squares, these squares allow the condition to be checked over a larger area, ensuring more accurate placement.

* Fit the frames one after another and check the alignment of all the frames [Fig. 6-16] [Fig. 6-17]. If there are any problems in this state, you will correct them accordingly. In some cases, adjust the hog or the notch in the jig top plate. In my case, no correction was necessary.

* Once confirmed, remove all of them and glue them in place one by one again. Although we have already checked them, it is important to keep in mind that

Is the verticality good?

Are the top edges at the same height?

Is it securely mated to the keel?

Checking such things, the condition is maintained until it dries. It can be done in a continuous operation by gluing the front and rear alternately from the edge side to the center of the hull [Figure 6-18].

* The frames were fixed without much modification, or rather, with surprising ease. I had previously done frame assembly with an imperfect jig on another model, and there was a lot of adjustment work before it was fixed. However, I still thought that was normal because of my preconceived notion that structural models are difficult. I had no idea that an accurate jig would require so little time for adjustments and reduce fabrication time. This is one of the major advantages of incorporating laser cutting.

(5) Hull fairing

Once the frame is assembled, the entire fairing process is performed. The first step is to grind the inner surface of the hull. Most of the inner surface is concave and large bevels at both ends, making it exceedingly difficult to grind. The micro belt sander was also a powerful tool here.

* First, the protruding portions of the inner surface, which are stepped from frame to frame, are ground first, and then shaped to form one continuous surface. This work does not require much force with the micro belt sander, and it can handle curved surface changes without difficulty. If manual sanding is used, considerable force is required to grind the unevenness, and depending on the size of the curved surface, various sanding blocks with different convex surface that can accommodate it are needed. The short cylindrical block shown in [Fig. 6-22], can be used for a wide range of concave surfaces by changing the way it is held, so it is a clever idea to have several ready, including one for finish sanding.

* Since the hull remains attached to the jig, it is stable even when it is turned horizontally or vertically, allowing work to be performed while freely changing its posture. The inside surface will not be able to accommodate the sanding block due to the upcoming structural assembly, so finish it until it is in satisfactory condition. See [Fig. 6-19] to [Fig. 6-22].

* Next, the outer surface of the hull is shaped. Since the entire outer surface cannot be sanded while mounted on the jig, you will remove the jig lower plate here. Remove the masking tape that held the upper board and stanchions and remove the two screws that held the keel in place. As shown in the figures below, the work is primarily done in the upside-down position.

* The part of outer surface, such as the stern, also has some concave areas and bevel steps, so a micro belt sander is also effective. However even with sanding blocks, it is not necessary to have as many types of curved surfaces as on the inner surface, and most of the grinding work can be done with flat blocks. Smoothing of the hull surface should be done to each person's satisfaction.

* Since there is still some processing work to be done on the hull, such as openings, the external shaping here should be limited to 80-90% of the finished product. Also, the protruding part at the rear end of the keel should be cut here to match the slope of the sternpost. See [Fig. 6-23] through [Fig. 6-28].

(6) Stern assembly

Stern assembly was left to the last minute due to interference from the sternpost support attached to the lower plate of the jig. With the hull firmly assembled and no longer in danger of deformation, the sternpost support is removed and the stern assembly begins by assembling the stern support to the upper jig plate instead. Stern is also an area where there are many areas to be verified, such as the positioning of the counter timbers and the accuracy of the laser machined window frames.

* Remove the sternpost support from the lower jig plate.

* Reassemble the jig (with hull) once.

* Assemble the assembled stern support to the back side of the upper jig plate. The center position is where the centerline of the support is aligned with the centerline of the top and bottom plates when viewed from above, and the front-back direction is where the rear edge of the support meets the rear stanchion of the jig. This ensures that the trailing edge of the support notch is aligned with the trailing edge of the hollowed-out portion of the upper plate. Check by applying a square. Glue the support legs to the upper plate in this position.

* Cut off the above parts and shape the burn mark area. Be sure to mark parts with similar shapes with identification number.

* Referring to the Stern drawing, counter timbers CT1 and CT2 are tapered to a thickness of 2.4 mm at the top edge. CT4 is glued to the bottom of CT3 and then the bulge is shaped as shown in the figure. Note that in both cases, the starboard and port side are different from each other.

* Assemble the two quarter-deck transom parts QDT-L and QDT-U by referring to the SternParts drawing. Since they have camber, do a little bending before assembly.

* The tie beam (TBM) was initially designed in the form of moldings, but since it would be difficult to support the window frames, I decided to divert 2mm thick parts (QDT) that had been prepared as an option for the quarter deck transom. If the length is insufficient, use the QDT as a template and cut a length-adjusted piece from a scrap piece of wood. After the counter timbers are assembled to the hull, notches are machined to match the spacing of the bent positions of the timber. This also needs camber bending.

* Referring to the Stern drawing, mark the assembly position of the lower end of the counter timbers on the wing transom, assemble each timber temporarily, and shape the lower end to match the slope. The outermost timbers are also shaped at the front end to avoid interference with the cant frame. The symmetry of the left-right tilt is also checked from the front and rear, and once adjusted, each timber is glued to the wing transom. The top edge is shaped later when the tafferal is assembled.

* Shape the sides of the outermost counter timber to blend in with the sides of the cant frame, and temporarily adhere temporary battens (using scrap wood) for the filling frame attachment. The filling frame FF-U is then assembled. The bottom edges will be almost close together and the top edges will be slightly spaced, so the overall balance should be maintained before gluing them together.

* Assemble the quarter deck transom. The height position is where the quarterdeck rides on the leading edge of the transom, so refer to the Stern diagram for positioning.

* Assemble the tie beam (2mm QDT). The lower edge of this height position is the counter timber bend, but it is also necessary to align it with the window frame that goes between the quarter-deck transom, so it is temporarily glued in place for the time being.

* Assemble the window frames SW1 to SW5 while shaping the outside of the window frames to match the outer timbers. The window frame is slightly tilted back, so some beveling is also required on the top and bottom edges. The sides must also match the inward tilt of each counter timber. They are designed to be longer to absorb the back inclination, so it should be possible to shape it, but process it with care. When well-shaped, shape the burn marks on the inner edge accordingly and glue and fix them in place along with the main gluing of the tie beams. The window frame should be tilted so that it is parallel to the back edge of the counter timber. See [Fig. 6-29] through [Fig. 6-32].

Note: Added as an official TBM in Version 2.0.

Tie beam     TBM     1     2mm

As the parts are assembled while maintaining the mutual relationship of several parts, such as sterns, there will always be a small number of steps and gaps due to assembly errors and correcting them is one of the assembly tasks. Gaps that occur in areas that should be close together can ruin the integrity of the model, so it is important to work with an awareness of how to assemble the model to avoid such gaps and how to correct them when they do occur.

This time, one of the elements to be verified was the quality of the window frames, which tilt back and forth, left, and right, and have four sides that are close to the surroundings, but the results were almost exactly as designed. The outer hull is now complete.

(7) Making measuring instruments

As we assemble various structures and outfitting from now on, measuring and marking inside and outside the hull will occur frequently. Since most of its target area forms a curved surface, it is not possible to simply apply a scale to it and measure it. Therefore, I decided to make some measuring instruments for this model for the sake of work efficiency and accuracy.

[External measurement]

For use in height measurement and marking on the outer surface of the hull, a prototype height gauge introduced by Ed Tosti on the Model Ship World forum was made, and a drawing was also made based on it so that anyone can make one [Fig. 6-37] (see the HeightGauge drawing). It is easy to make because it can be produced into two pieces by simply cutting one 10mm square x 1m bar [Fig. 6-33].

In addition, I added a device that allows dimensions to be read directly from the drawing and a pencil can be used when marking.

For actual measurement, as Ed Tosti's method, a square bar is passed over the reference line (bottom edge of the keel) on the drawing pasted on a flat plate and fixed, and a height gauge is placed on top of it and the pointer part is aligned with the height of the required position [Fig. 6-34], [Fig. 6-35]. This can be moved on the upper surface of the lower plate of the jig to measure or mark the height of the outside of the hull [Fig. 6-36]. The height of the gauge was also set at about 110 mm to avoid interference with the upper plate.

[Internal measurement]

In the same way, a crane-type apparatus as shown in the figure was fabricated for use in height measurement and marking on the inner surface of the hull. Rather than fabrication, it was simply a collection of materials on hand, attached together with double-sided tape, but even this worked well enough for positioning. If you understand the principle, I am sure you will be able to produce something more reliable in your own way.

* Fix the depth part of a depth-measuring scale called "Scale Depth" via a wooden frame to an appropriate aluminum angle, aligning the underside with each other. The wooden frame is to facilitate manipulation of the Depth’s screws.

* Fix the pencil to the end of the scale. It will not be stable at the leading edge, so offset it slightly, e.g., 10 mm, so that the pencil is centered [Fig. 6-38], [Fig. 6-39].

* Fix the pencil to the end of the scale. It will not be stable at the leading edge, so offset it slightly, e.g., 10 mm, so that the pencil is centered [Fig. 6-38], [Fig. 6-39].

* The reference plane for measurement is the top of the top plate of the jig (if the top edge of the frame protrudes, it should be ground to a flat surface). The assembly drawing shows the height of the top of the top plate, so the scale is extended from the bottom of the Depth downward from that position and fixed.

* In this state, the device can be placed on the jig top plate to accurately mark a predetermined position [Fig. 6-40].

* The stable flatness of the jig material, MDF board, makes this simple device usable.

(8) Processing of gun ports, etc.

This is the last part of the hull construction process, where openings such as gun ports and sweep ports are machined. Some kits have these parts notched or lightly incised in advance, but if the accuracy of these parts is poor, it will be difficult to correct them, so here it will have processed them after the hull assembly. Note that this has made some parts of the process a little more difficult.

* The height of each opening is marked with a height gauge. Keep in mind that the gun port opening height dimension is the location including the thickness of the sill.

* Cut one side of the frame along the markings, and then make the necessary additional incisions (1 mm on opposite side). It is better to start out with a smaller opening with the blade slightly inside the finished dimension, and then finish it to the specified dimension by shaping. The cut frame pieces can be easily removed by heating them with a hair dryer or the like (Fig. 6-41). The temporary batten shown in this figure is the position of the deck top surface at the port side position, also measured with a height gauge, and is used to confirm the height of the opening. The sweep port uses the gap in the frame as it is, so this cut-in process is not necessary.

* Process wedge-shaped machining where the ends of the sill fit together. If the side where the blade is inserted is open, there is no problem, but the side that is hollowed out cannot be inserted with a normal knife, so it is processed by modifying the blade of a metal saw or using a blade for line carving [Fig. 6-41 annotated part].

* The sill length and, in some cases, the tip angle are adjusted while assembling.

* The rough-formed opening is finished by paying attention to the squareness of the corners, the height of both sides, and the presence or absence of gaps on the interior and exterior surfaces of the sill. [Fig. 6-42] shows the almost-assembled state. The top of the gunport is open, and the sheer rail serves as the upper frame, but temporary spacers are attached to prevent frame shake and to accurately process the opening.

* The front end and rear openings use a different shaped sill than the center section upon close examination of the anatomy. The design needs to be modified, but this time, the same one in the center will be modified accordingly [Fig. 6-43].

　 Note: This later turned out to be a mistake. The same shape as the center section is acceptable.