After you’ve carefully checked over your hull to ensure that it’s fair, you may start to prepare patterns for the plating. The plating patterns or templates are made from a number of 6-inch (150 mm) strips of inexpensive 1/4-inch (6 mm) plywood or hardboard. The outer edges of the templates represent the outer edges of the plate. It is seldom necessary to use a complete sheet of plywood or hardboard for a template. Usually, these patterns are made up of straight strips and corner gussets, like a frame, and made to fit the particular area to be plated. To strengthen large areas, cross-brace your templates by nailing on reinforcing pieces where necessary. The templates are built right on the hull by clamping the strips in place in between the chines. The length of each panel may vary; you want the patterns as long as possible, but not so long as to be unmanageable. Do not end a template on a frame, otherwise your plate will have a bulge in that area; always end a pattern between two frames. The ends of the patterns are always vertical; this helps in getting one pattern to join to the next with the minimum of error.

   After you’ve formed the outline of the pattern, you can trim it to exact shape with a grinder or jigsaw, or, in fact, any tool that will help you achieve a perfect pattern. Check and double-check the template to ensure that it’s a neat fit. After you’re satisfied with the pattern, you can mark in the frame locations and use them as guides when you’re positioning the sections of plate. See the welding details on your plans to decide on the welding gaps between the various plate edges.

   When you have an accurate template, lay it on the floor where it should lie flat if the plating is to lie on your hull in a fair manner.    Successive sections of patterning templates can be joined to make a pattern for one long plate. The longer the section of plate you intend to have in one length, the more accurate your patterns must be. Small discrepancies are greatly magnified over the length of a long plate. The patterns can contain other information, including stringer locations and any other information that you feel will help you to match the plate precisely to your hull framework.

   It’s usually best to pattern the largest panel first, then the pattern can be trimmed and used for the next section. This will save on patterning material. You should start at the keel and work either downward or upward, depending on the aspect of your hull. Make the patterns as sturdy as you can, and they will serve you well.

Preparing the Plate

   You must decide how long each plate will be before it is installed on the hull. Some builders prefer a plate as long as possible. The actual length will depend on the size of your hull, your previous experience, and the capacity of your scaffolding and lifting gear. Panels that are welded to full length on the shop floor where they will lie flat will be easier to install in a fair curve. This helps in eliminating any humps and hollows in the finished hull plating. On smaller boats, say under 30 feet (9.10 m), you should be able to plate the full length in one operation. Larger boats will require more sections. For instance, one man with a helper plated a 75-foot (22.86 m) hull using three 25-foot (7.62 m) panels. In general, use the longest sections you can comfortably handle. Builders of aluminum hulls will have some advantage here, as the material weighs only about one-third that of steel or copper-nickel and is therefore much easier to handle. You can transfer the outline of the template to the steel plate by laying the pattern on the plate, (it must lie flat), clamping it in position, and then carefully scribing around the edge. Mark in the frame and other pertinent locations on the plate.

   Start plating at the keel and work either up or down, making sure that you work on alternate sides of the hull: that is, never plate up one side completely before plating the other. Keep the plating balanced so no undue stresses are placed on your hull framework by the plating pulling one way or the other. This can result in a twisted or otherwise deformed hull. The transom is best installed after the remainder of the plating is completed. The open transom will provide access inside the hull for the welders and let in light. Once you have marked the template outline onto the plate, you can cut it to shape.

   Once you’ve cut the plate, you’ll want to serve the panel up to the correct area. Using the alignment marks you’ve previously marked on the boat, pattern, and plate, clamp the piece in position. If there are any discrepancies in the fit, take the panel down and make the necessary adjustments before reinstalling the plate. It’s worth noting that professional boatbuilders often find it necessary to “serve up” the plate several times before they achieve the desired fit. It’s obviously easier to trim off excess than to put back areas that are over-trimmed. Keep this in mind when making patterns and cutting the plate.

  On no account try the sloppy practice of installing an oversized plate and then trimming it by simply torching off the excess. If you plate your hull in this manner it will clearly show in the finished job. Buckles, hollows, and other large imperfections will tell all who care to look at your boat that you were indeed a sloppy builder. Always remember that one day you may want to sell your boat, and an unfair hull is one of the greatest factors in reducing the value of any used boat.

Before the plates are finally installed, make sure you have ground off any imperfections on the edges. Unless your plate is shotblasted and pre-primed, which we recommend, make sure you clean up the face of the plate as well. It’s easier to clean the plate before installation than when it’s in place, especially in the case of interior surfaces partly obscured by the frames or stringers.

   For steel, there are several ways to clean the faces of the plates before you install them. Grit-blasting or sandblasting is the easiest and best method, but in the case of steel, prime coating must follow immediately to protect the sandblasted surface. You can use a disk grinder, a power-driven wire brush, or one of any number of similar methods. These techniques are very noisy, and are only for tidying up the plate, rather than preparing it for painting.

   You should remove mill scale and any other foreign matter so that the panel of plate has no imperfections before you install it. Before you paint the hull, you must bring the surface back to bare white metal. You must paint this within a very short time, minutes rather than hours, to ensure a rust-free surface in the future. Finishing techniques are discussed in Chapter 10, Painting a Metal Boat.

   The edges of the plate will need to be bevelled before you install them. The amount of bevel will depend on the thickness of the plate and the metal you’re using for plating. Note that aluminum and copper-nickel need to be prepared in a different manner to steel. Before hoisting the plate, you’ll need to make provision for it to be supported while you’re fitting it into position, and later welding it to the chines and stringers. One method is to tack-weld a few lengths of angle to a chine bar, frame, and stringer to support the bottom of the plate. Support the chine bar with another piece of angle that extends to the shop floor, thus transferring the load, so that the weight of the plate doesn’t deform the fair line of the chine. The “plate holders” should be tilted inboard, so the plate will naturally slip into the correct location and not slip out of the holder as it’s moved from side to side to get the exact alignment required.

   You can use a selection of homemade C-clamps to draw the upper edge of the plate to the chine, the centreline bar, and the stem. As you tighten the clamps, you’ll be drawing the steel plate into position in all planes. In a well-designed chine hull, you’ll find that the plating will naturally conform to the shape provided by the framework of chine bars, frames, and stringers. Most plating is between 1/8 and 3/16 inch (3 and 5 mm) thick, so it will lie in place without your having to resort to extreme bending methods.

In cases where more pressure is required, several techniques will help you. A popular method is to tack-weld lengths of threaded rod in the area where you need assistance. You can judge the length of the pieces of rod needed for the job. Use 3/8-inch (8 mm) diameter rod that is tacked at a 90-degree angle to the inside of the plate, and use a prepared section of 2 by 2 by 1/4 inch (50 by 50 by 6 mm) L-angle behind the stringers and chine bars to receive the inboard ends of the threaded rod. By tightening up on the rod, you’ll be able to coax the plate into its correct location. Another method is to weld U-shaped eyes to the inside of the plate and then attach a “come-along” or other suitable device, such as a Spanish windlass, to pull the plate into position.

   As you will have only tacked the stringers and chine bars into the slots, as we advised earlier, it’s permissible and often desirable to “relieve” the stringers and even the chine bars by allowing them to come out of the slots to meet the plating. It takes some judgment to know when to let out the longitudinal, instead of pulling the plating in harder, to make the correct shape and fit. Do not hesitate to weld eyes, U-shaped round bar, and threaded rod to your plate, to help you get the result you want. You can knock off these temporary protrusions when you’ve fully welded the plate in position. Don’t compromise on a good fit.  Butt joints (where two sections of plate meet end to end) can be drawn together with bolts and large washers. The butt joints must be in near perfect alignment to achieve a smooth hull surface, otherwise they’ll show as bulges or uneven patches. Drill several holes in the bevelled seams between the plates, and insert bolts fitted with large washers and nuts. When you take up on the nuts, you’ll be exerting great pressure up and down the vertical butt joint and you’ll even out any bulges or other irregularities in the joint. After you tack-weld the plates along the bevels, you can take out the bolts and close the holes with weld.

   Once again, as you install the various plates, be sure to work from one side to the other and keep the plating evenly balanced. Be certain to achieve a good fit. A little grinding here and there can make all the difference in making the plates fit as perfectly as possible. The plates may need to be slid back and forth to correctly position them. A “come-along,” or a tap with a hammer (using a wooden block to protect the ends of the plate) can work wonders. The foregoing is another reason to ensure that you have the plate held securely, but with some freedom of movement, as you prepare to tack it into place.

   Don’t rush; you’ll be looking at your hull for a long time. Don’t fully weld any plate into position until you’ve installed all of the hull plating. Don’t forget to work from side to side along your hull, never get more than one plate ahead on one side, and keep the plating balanced. Once you’ve tacked a few plates into position, you’ll notice a considerable stiffening of the hull structure. Sight along the hull as each plate is installed to ensure that you are maintaining a fair curve and that no plate looks out of line. If you find you have incorrectly installed a plate, take it off and correct the problem before proceeding. The first plates will be the hardest to install, so make sure you get them right and you’ll find that the plating process gets easier as you proceed. Most builders are able, after some practice, to pattern, fit, and install one or two plates a day. If you’re achieving more than that, you may be working too fast at the expense of quality.

   Any boat hull must look absolutely perfect before painting if it’s to look reasonable after it’s painted. If you’re in doubt, splash some water on your hull to bring up a shine, and then judge how well you’re doing. Another trick is to take a flashlight and examine your hull at night. When you shine a flashlight along the hull, all the imperfections will become more apparent. Aim for perfection; you may not achieve it, but if you aim high, you should finish up with an attractive and fair hull.