The first thing to realize is that the kit differs in many ways from the methods you would use to build a metal boat from scratch. The kit is far superior to anything you could achieve by starting with the plans and a delivery of raw steel plate and profile bars. Most metal boats built from scratch are built upside down; boats built from cut-to-size metal kits are built upright. Not only is this a more appropriate way to assemble the kit, it also saves the cost and inconvenience of having to turn the hull. And here’s one very important piece of advice: You must tack-weld the complete hull, deck, and superstructure together before you run any final welds. If you don’t follow this advice, you’ll almost certainly end up with an un-fair boat requiring a considerable amount of filler. In any case do not over-weld or try to run long welds at one time.
Your kit may arrive on a flatbed truck or in a container. Kits are normally packed on pallets and can be lifted off the transport by a small crane, front-end loader, or similar equipment. Provided your kit is on a pallet, you may find it more convenient to drag your kit from the truck or container, using a pair of planks as a ramp. Once you have unloaded your kit, you must keep it covered until assembly is under way.
With your kit, you should receive a packing list and large-scale assembly drawings. The drawings will show all the parts as flat surfaces grouped together as they will be assembled to make the finished hull. There will also be a number of drawings showing the assembly of the frames. Each part will be numbered, so that you can check it against the packing list and the corresponding drawing.
One of your first jobs will be to tack-weld the frames together, so make sure you sort the parts and store them in the order you’ll need them. On larger frames, it may be easier to tack only the bottom sections of the frames together at this time.
Once you’ve tacked all the frames together, it’s time to prepare the building jig. The transverse profile jigs will be supported by the metal “castles” that come as part of your kit. The setting-up jig is merely intended to start things off. It is not intended to support the boat during the entire building process. Usually, however, you leave the jig in place for the entire building program so you can weld a flat strip on the top of each web to spread the load of the plate where it rests on edge of the plate web. After you have both sides of the bottom plates tacked together you should consider adding extra support and bracing to the jig structure.
Set up two parallel I beams as shown in the instructions that come with your kit. These beams must be long enough to accept the number of support jigs mentioned above. Cross-tie I beams should be installed at the same location as indicated to install the support webs. Obviously, the whole support structure must be level in all directions and well braced as it will play a part in supporting the boat during construction.
Don’t attempt to fully weld the plates into one length on the floor. The plate joins should only be tack-welded in three locations: one weld at the each of the ends of the join, and one in the center of the join. These tacks should be no more than a 1/2 inch (12 mm) long. If you weld the plates on the floor, you’ll end up with a hard spot in the hull plating. Some plates of 1/4-inch (6 mm) or heavier material may need to be bevelled before you tack them in place. You may prefer to make the bevels after you’ve tack-welded the plates and before you run the final welds. In all cases, good metal boat building practices should prevail. After you have both sides of the bottom plates tacked together, you should consider adding extra support and bracing to the structure.
Sailboats with long keels, such as our Spray designs, as well as most powerboats, should have the keel structure assembled at the same time as the bottom plating. Take care that you don’t “squeeze in” the tops of the keel; use the webs as spacers. After you’ve positioned the bottom plates, the keel sections, and the transverse profile jigs, you may start to tack-weld the bottom plates to the keel sides. Sailboats with deep fin-style keels may have the keel installed after the hull is completed. The canoe body should be built from the bottom of the hull upward in a manner similar to that used to assemble a powerboat hull. The webs can be arranged so that they can be added along with the rest of the keel after raising the hull to the correct elevation.
The benefit of using this method is that it allows you to work on the hull, deck, and superstructure while the boat is lower and thus more accessible. The exact method and order of assembly depends on the availability of lifting equipment and your general work environment. Details given below are valid for the general assembly of all hulls.
With most powerboats, you can start by laying the bottom plates in the transverse profile jigs that come with your pre-cut metal kit. The frames will soon be added at the locations indicated by the transverse lines marked on the plates.
With any hull, the first step is to set up the bottom plates and tack them along the centreline. Next, start to install the pre-tacked frames on the appropriate transverse lines marked on the plating. From now on, the whole structure will grow upward. The better equipped your workshop is with overhead lifting and handling gear, the easier and more smoothly your job will proceed.
If you’re in doubt about your welding skills, seek the help of a suitably qualified person at the earliest stage. There is a great deal even the most inexperienced person can do to assist a qualified welder to assemble the kit. Generally, two people are required to handle the larger pieces of metal, so acting as labourer to your hired professional may be the best route for you.
If you have moderate welding skills, you’ll find that the kit comes with enough scrap material to allow you to get in some practice before tackling the assembly of the kit. Don’t try to weld aluminum or copper-nickel unless you have the proper knowledge and considerable experience in handling these materials.
The metal kits are constructed so that the strength of the finished hull comes from the build-up of the frames and stringers in interlocking sections. Heavy and continuous welding of frames and stringers should be avoided at all times. After the hull and deck is tack-welded together, the process of finish welding can proceed without fear of distortion.
The secret of creating a fair hull and deck is to use a welder of high enough amperage for the job. Welding with too little amperage and or too slowly, will create a lot of heat on the spot and less penetration of the weld material in the seam. This may make for a weak weld and additional grinding to remove excessive weld material. This, in turn may further weaken the weld.
