At this time the model boat hull should be ready for some details to be added. The classic way of boat construction includes a stem, sternpost and keel.
Many modern vessels built from steel don’t have a protruding stem and sometimes no external keel either. In the same way, many planning hulls (think PT boats and MTB’s) don’t have a sternpost. However, most sailing ships through the ages were built this way, with all three.
There really isn’t much to it, but here I’ll explain how I add these details. From your plan, trace the shape of the stem and skeg onto thin wood, plywood or material of choice with the correct thickness. Make sure the grain goes in the direction of the length of each piece. Then cut them out with some room to spare, especially the sternpost I like to leave slightly longer so I can trim it back once it is glued on.
Prep the model boat hull – at the stern, where the sternpost goes, make sure the hull has a flat and straight area to attach it to. If not prep it for a nice fit. The fit is a lot less critical if the model will get painted. The joint can be easily filled in with putty before final sanding.
Some hulls need what is termed a skeg. That is a triangular "filler piece" that goes between the hull, sternpost and keel.
If the boat you are building is constructed this way, it's easiest to fit it before the sternpost and keel goes on.
Trim the inside (where it mates with the hull) of the stem close to the tracing you did from the plans. Try to maintain a square inside edge with defined corners. Then trim the hull to accept the stem.
Glue the stem and sternpost in place – one at a time. Pay attention so they get on there vertically and aligned with the centerline. I like to use the thin CA glue for this. I line up the piece – when I’m happy with the location I put a small dab of glue on while I hold it steadily in place, letting the glue wick into the wood.
Once cured, I let off the pressure and let it sit for a half hour or so. Then I inspect, if I’m happy with the result I’ll put some more glue on, along the entire joint. Let dry fully and scrape and sand off the excess glue.
Once the stem and sternpost are in place, it’s time for the keel. I usually try and make the keel out of a single strip of wood. Start by squaring up the part of the stem that meets the keel. Then trim back the sternpost to be level with the ridge of the hull where the keel will go.
If necessary, prep the hull to be flat in this area. Glue down the keel in the same manner described with the stem earlier. Leave it long, over shooting the sternpost at the stern. When permanently mounted and glue has cured, trim back according to the ship plans.
It is time to do the final sanding of the hull. You should be familiar with the basic process by now - sanding and fitting the templates. Remember to go easy and gradually use finer grit sandpaper. Start with 80 grit and work through 150, and finish with 240 grit.
If you took off too much at any point, your efforts may still be salvageable. The missing material can be restored by building up it back up with putty.
There are many kinds of putty - my favorite is the epoxy version that comes as a bar with one part as a core inside the other. All you do is cut a slice and start kneading. The two parts have different colors, so when the mixture no longer is marbelized you're done and ready to use it. After letting the putty cure, start over the template fitting process.
In this article I'll limit the discussion to static rudders, i.e. they will be attached in a fixed position. The best way to attach the rudder is to make sure the rudder post is extended and glued into a hole drilled in the hull.
It may not be totally "scale" but a lot stronger than relying on the joint between rudder and skeg. If trying to hang the rudder from the skeg you have two options:
Non-working gudgeons and pintles (or "hinges" in layman's terms) can be created with brass strips cut to size. On small scale models a brass wire can be carefully flattened into strips using a hammer against a hard, flat surface. By bending and soldering bent strips and wires a simulated hinge can be created.
The metal strips hinges can be attached to the hull and rudder with epoxy or CA glue.