By TR Mayer
We publish six issues of Ships in Scale a year, full of build logs, techniques, history, and reviews. Every so often we take one article out from behind the subscription and share it in full – so you can see exactly the kind of work that fills every issue. Here is TR Mayer’s tour of his scratch-built Coast Guard utility boat, reprinted complete from the May/June 2026 issue. If you enjoy it, there is a subscription link at the end.
I’m sure a few old-timers looking at this Coast Guard boat will ask, “Where’s the racing stripe?” One or two may even question the hull number. The first question is fair – I built this boat to represent what I knew in 1963. The diagonal red stripe didn’t appear until April 1967, so this version predates it. (You’ll also notice the “gumball” on the mast is still red rather than the current blue.) As for the hull number: there was a CG 40534 and a CG 40536, but CG 40535 was never built – so I thought I’d fill in the gap. The rest of this build is as accurate as I know how to make it.
This 1:12 scale USCG 40-foot Utility Boat, Mark IV, is scratch-built from actual Coast Guard engineering drawings, which I expanded to 1:12 scale to eliminate potential measuring errors during parts construction. She’s radio controlled and has seen a lot of hours on the water, so she looks a little worn – just like the prototype. A bit rough around the edges, some water stains, a little grunge here and there. Scale.
A lot of parts were scrounged from the junk drawer, and several repurposed items were pressed into service they were never intended for.
Window Gaskets
At 1:12 scale, the window gaskets were one of the first details to address. I traced all the window openings to ensure each “gasket” would be correct for its location. After discussing ideas with a friend, we decided to mill a 1/16-inch deep by 1/8-inch wide channel – exactly matching the tracings – into a piece of aluminum. We then mixed a batch of automotive body putty and filled the waxed channels. Once cured, the gaskets were sanded flush with the aluminum plate, carefully worked out, smoothed at the edges, and painted matte black. Glued into their respective openings, they look just like the rubber gaskets on the real boats.
Foredeck Details
Hanging on the foredeck safety lines are the boat hook and sounding pole. A real boat hook is designed to float vertically if lost overboard – high enough to be retrievable. With the decorative fancy work applied to this one (port side), it probably wouldn’t float, but it adds visual interest. Most boat hooks have a groove or painted line along the shaft to give the user a reference for the hook’s orientation when it’s out of sight underwater. On the 535, the raised portion of the cockscombing serves the same purpose.
The sounding pole is marked in one-foot increments to determine water depth or clearance under the keel. The red band indicates the boat’s draft.
Grab Rails and Instrument Panel
Moving aft, the grab rails have a French spiral worked onto them for a surer grip.
The instrument panel gauges are cutouts from an automotive parts catalog, fitted with jewelry jump rings as bezels. Once each “gauge” was set in place, I applied a drop of clear polyurethane and let it dry, repeating the process until the lenses had sufficient depth.
Engine Hatch Covers
The engine hatch covers were fabricated from household roof flashing. I initially tried plastic sheeting, but the material’s hysteresis prevented it from holding its shape. The flashing works well, and as a bonus, I could JB Weld small tubing to the edges and run spring steel wire through the tubing to create properly scaled hinges.
Crew Figures
The crew are heavily modified 1:12 scale figures sourced on eBay – both started as “Jesse Pinkman” from the TV show Breaking Bad. The original figure stands with arms down, wearing a hooded coverall with the hood lowered. Some plastic surgery created the arm positions, and I used Squadron Putty to sculpt the old-style blouses and bell-bottom trousers. The hats began with a nylon stocking base; I wrapped damp poster board (cut to length and height) around each head, shaped it – including the correct diagonal seam in the back – allowed it to dry, then painted.
Engine Compartment
Moving aft, we see the fireman (junior engineer) fiddling with something on the port 6-71 Detroit Diesel. When I knew this boat, the water expansion tank still had the GM logo cast into its face.
Further aft, the fuel tank inspection cover and deck plating shapes are visible. The non-skid surface is a rattle-can product from a big-box store. The “bolt heads” were punched from thin plastic sheet using a die designed for the model railroad industry. I used a pounce wheel for equal spacing, placed each bolt head where required, then painted the deck.
Five-Gallon Gas Can
The five-gallon gas can started life as an inhaler refill. I cut the top and bottom off, glued the bottom to the top (convex side out), created a new bottom from thin plastic, and used a very small scale porthole for the spout neck. The hand-pull guard is brass strip; the hand-pull itself is thick wire. This can serves the gas-driven P-60 fire pump that lives under the faded canvas cover nearby.
The protective cage was built directly on the can after wrapping it with several turns of household plastic wrap to prevent sticking. Once built, I removed the can, discarded the wrap, “bolted” the cage to the deck, and replaced the can.
Aft Deck
Further aft are the ready boxes, which would carry items such as mooring lines, shackles, a spare towing hawser, an emergency tiller, and perhaps a gallon of 9250 oil. A Stokes litter stands ready to transfer an injured person from an accident or recover someone from a tragedy.
Propulsion System
On a conventional RC build like this, the propulsion motors would be mounted inline with the propeller shafts and connected with universal joints. I wanted to place the 6-71 “engines” in the engine spaces for visual interest – simple enough on a static build, but RC presented challenges.
One idea was to mount the boat’s propulsion motors under the coxswain platform with a shaft running through the engines to the propeller shafts. That would have required pillar bearings to maintain alignment and might have proven unreliable.
The solution was to mount the motors facing forward, adjacent to the shafts, and connect them with timing belts and pulleys. The space under the deck is tight; I used a “span stick” laid temporarily across the deck flanges athwartships to confirm the motors and belts would clear the deck when it was replaced.
Electronics and Sound
In the engine compartment, from lower left to upper right: individual speakers (one for each engine), with sound modules in the cabin replicating the 6-71 sounds – starting, running (speed increasing with throttle input), and shutdown. The sound was sourced from a YouTube video of a Baltimore city bus powered by the same Detroit Diesel 6-71 engine; I sent the clip to Harbor Models in California, who produced custom sound modules for this build.
The engines themselves haven’t been fully detailed yet, even though the boat is several years old. Aft of the engines are the propulsion motors, turning the shafts inboard through cogged belts. With the deck installed and engine cover mounted, only the forward face of the pulleys is visible. Painting them bilge color or flat black would reduce their visibility further.
Just outboard of the motors are two 12V, 6-amp auto-reset breakers. Many builders insert a fuse to protect the electronics – a good idea, but with a downside: if your boat snags some weeds on the far side of the pond and creates a momentary amp spike, the fuse may blow, leaving you dead in the water. With auto-reset breakers, you wait a few moments for the unit to reset and can work the boat out of trouble – even if it takes several cycles.
Bilge Management
The hull frame immediately aft of the motors is solid, with no limber holes. Though not high, it could trap water entering through the rudder post housings. Against the keel on either side, I installed small pieces of brass tubing with surgical tubing attached. These tubes lead forward and are accessible through the engine housing. After a lengthy run, I use a squeeze bulb to check for accumulated water. So far, those compartments have remained dry.
Tucked into the corners of the hull are a couple of ounces of ballast on each side – lead cubes wrapped in blue tape, held in place by small pieces of rigid foam wedged between the ballast and the propeller shaft strut mounting plates.
On the Water
The final result on the water was exceptional. The prototype’s original design was intended to create a good sea-keeping boat for various Coast Guard missions, and that pedigree carries over to the 1:12 version. She creates a realistic wake, turns like the prototype, and maneuvers using the throttles just as she should. It’s very satisfying to run this outfit.
This build was off and on over a couple of years as time permitted, with some breaks to work on other projects and prevent burnout. I’ve learned that if I force work on a particular phase just to “get it done,” I invariably end up redoing it later because it wasn’t up to the standard of the rest of the build.
Enjoyed this? There is more where it came from.
This article appeared in the May/June 2026 issue of Ships in Scale, alongside seven other features and a full slate of departments. Six issues a year, written by modelers for modelers. Subscribe to print + digital for $44.95/year ($54.95 Canada, $64.95 international) at http://www.shipsinscale.com.