A few weeks ago, while looking after our 7 year old grandson for the day while his mum and dad were at work he asked (several times) if he could help me building my boats. As I'm not currently building anything, we had to find other things to do build (Lego) for the day. After he had gone home, I started to think about a boat he could help build.

I had come across HAkits in a couple of blogs on this site so found their website and decided that their Rescue Launch would make a nice model for a 7 year old. The kit was duly ordered and arrived a few days later.

Building from a kit like this is a bit of a departure for me as I usually scratch build my models. The kit was well packaged but there didn't seem to be much in the bag. Three sheets of laser cut ply, a few sticks (rubbing strakes), some plastic window frames, a sheet of clear acetate with a template for the windows and an instruction manual.

The instruction manual will look familiar to any 7 year old who is used to building Lego kits. It has numbered steps, each with a drawing of the assembly showing the next piece to be fitted. Each of the laser cut parts is identified with it's name etched into the surface. However I did notice that in some cases the name of the part used in the instructions is different to the name etched into it. For example assembly step 3 says 'glue the bow former .. in place'. The required piece is etched with 'bulkhead 1 support'. Guaranteed to confuse a 7 year old (and his grandad occasionally 😉).

The pieces need to be cut from the ply sheets with a Stanley knife. I didn't like the idea of sending my grandson home with bandaged fingers at the end of the day so decided to make a thin 'chisel' from a snap-off blade mounted in a dowel handle. This should allow the pieces to be freed from the ply sheet using a hammer with less risk to little fingers.

So now I'm ready, waiting for the return of Finley....

The first thing to do is "Read the Instructions" and study the parts to work out what goes where😉.

The micro chisel works well to release the laser cut parts from the plywood sheets. Less risk of cut fingers and somehow we managed to avoid any bruises.

The parts are accurate and easy to fit together with very little cleaning up required. The first challenge came when fitting the centre keel to the underside of the hull bottom. The keel is in two pieces which are spaced to leave a gap for the propshaft. There is no hole in the hull bottom for the propshaft to pass through so the keel pieces were used to work out where to cut the hole. A length of 7mm dia. brass tube was used to ensure that the hole was big enough and in the right place. The keel doublers were added to strengthen the area around the shaft tube. Additional keel doublers were needed to accommodate the 7mm tube. These were cut from scrap ply.

Having completed the basic hull framework, the next instruction in the manual is to fit the side skins. However doing that at this stage would make fitting and aligning the motor much more difficult. Better to sort out the motor mounting while there is access through the sides of the hull. It is a shame that there isn't a note in the instructions explaining this as an inexperienced builder would likely press on at this stage and then have the challenge of having to fit and align the motor through the restricted deck access hatch.

As I needed some time, (and peace and quiet 😁) to sort out the motor mount, 'we' decided to move on to assembling the cabin. Finley cut out the parts using the chisel, I held them in place while he applied the superglue. I didn't end up with too much on my fingers and managed to peel them off the model several times. 😊

The cabin is built in situ but needs to be removable to gain access to the inside of the hull. Masking tape was applied around the access hatch before the cabin pieces were glued in place to ensure that it didn't end up permanently attached, despite the liberal application of superglue!

By the end of the day we had made good progress. Finley went home and wouldn't stop telling his Mum and Dad about the boat. He wanted to come back the next day to carry on construction, but I need time to sort out the motor mount, and the rudder servo mount, before he returns.

Sorry there aren't so many photos, but I had my hands full!

Before Finley returns to continue with the construction. I need to install and align the motor and propshaft.

The instruction booklet suggests fitting a 1500kV brushless motor which surprised me as I was expecting it to call for a brushed motor, but I thought 'why not?' so a suitable motor and ESC were ordered.

First job once the motor arrived was to make a mounting bracket. I found an old domestic radiator mounting bracket in the scrap box. A short length cut from this gave a strong, lightweight right angled bracket. Four holes were drilled and tapped for the motor mount, and another four holes drilled and countersunk for screwing the bracket into the hull.

The motor has a 4mm dia. shaft and I'd already found a 30mm propeller, left over from Crash Tender commissioning, which had an M4 thread. Based on these part dimensions, I decided to use a 4mm propshaft and a 7mm dia. outer tube. With the tube in situ, but not glued, a hardwood wedge was made to match the angle of the tube. To align the motor shaft with the tube, an alignment tool was made. This is simply a length of steel which was turned to be a sliding fit in the propshaft tube, and with a 4mm hole to slip over the motor shaft. With this tool, it was a simple matter to adjust the heights of the wooden wedge to align the motor shaft with the propshaft tube. The wedge was then glued into position.

While the glue was drying, two phosphor bronze bushes were turned for the propshaft. With these fitted, and the alignment tool used to ensure everything was in line, the propshaft tube was epoxied into position.

Finally, the alignment tool was replaced with a universal coupling, and the other end of the shaft was threaded M4 so that the propeller could be attached. A quick check was carried out with the ESC attached and powered up. All seems to be OK so far. 🤞

Another part of the RC installation best completed before the skins are applied to the hull is the rudder and associated servo.

A simple rudder was first made from some thin brass sheet and a length of 3mm brass rod. I think it may be a bit on the large size, but better that than too small. I can always trim it down if it proves to be overly effective.

There is no information with the kit about locating the rudder. A laser etched marking for the recommended position would be helpful for a novice building the kit. I chose a position to give plenty of clearance behind the prop on the basis that 'if it looks right, it probably is'... time will tell.

A brass tube was installed through the bottom of the hull. A servo mount was cut from spare ply that came with the kit. The top of the rudder tube passes through this ply panel and is epoxied in place to provide plenty of support.

Now that the motor and rudder installation are complete, it is time to fit the side and bottom skins. I just need to wait for Finley's return....

The hull sides and bottom are skinned with 1mm ply. This is supplied laser cut to size.

I held the first side in place while Finley applied the superglue. I'd bought some superglue from the local pound store which came with a long flexible nozzle which was ideal as it allowed me to keep my fingers away from the liberal application of glue by Finley 😉. I'm amused by the wording on the package and haven't yet worked out how to 'reuse' the glue that didn't go in the right place! 😂🤣

Finley's younger sister decided she would like to be involved 🙄 Unfortunately her idea of helping was to grab anything she could in the workshop that was within reach, so we had to cut the session short.

I used my trusty block plane to trim the side to size, and then fitted the other side. Before fitting the bottom panels holes were drilled in the framework so that it would be possible to seal all the internal ply once the hull was complete. The bottom sheets were glued in place and held with masking tape while the glue set. These sheets were barely long enough or wide enough at the transom. A few more mm in length and width would have helped. The gaps were filled with epoxy and smoothed to shape.

I also made a simple stand for the completed model which Finley helped to paint with 'quick drying woodstain'. This is ideal for this application as it is water based and washes off little sticky fingers quite easily 👍

With the hull assembly complete, its time to get painting!

The hull was first coated with epoxy resin and fibreglass cloth.

Once set, the rubbing strips were shaped and fitted to the gunwales. A former to bend these strips was cut from some scrap MDF using the top deck outline left in the laser cut ply as a template. The rubbing strips were soaked in hot water, clamped in the former until dry and then glued in place.

Grey primer and knifing putty were used to prepare the hull for the finish coats of paint. The deck was been painted with a textured paint to give a non-slip appearance. The hull sides are dark blue (left over from the Gaff Cutter). Below the waterline is red primer.
A white pinstripe was added to separate the two colours.

The kit comes with 3D printed window frames. These were primed with an etch primer and then painted white. Windows are glazed with clear plastic sheet which was also supplied with the kit. The superstructure was painted grey and the completed windows glued in place.

Finally a few decals complete the overall effect.

Finley has been back at school so he hasn't seen the recent progress but it is half term this week. He's going to be a bit surprised when he sees it!

Now it's time to start adding the electronics..

Before fitting the motor, Finley added vinyl decals to each side of the hull. I'd sourced these from ebay and it was a simple task to position them and rub them down onto the hull before peeling off the protective film. The hull will be lacquered later to seal and protect the decals.

The motor was screwed into position on the previously installed mounting block. Small fingers are definitely an advantage when placing the screws into position 😉. The propshaft was coupled to the motor with a metal flexible joint. Connecting the ESC, battery and a servo tester allowed for a quick test of the installation. The noise was terrible !🙉 Despite the care taken earlier in the build to align the motor and propshaft, something was not right. Loosening the motor mount screws and wiggling the motor mount resulted in better alignment and slightly less noise 🤔.

Moving on to the rudder, the 9g servo was fitted to the mounting plate and a wire link connected between the rudder horn and servo. Again small fingers made this easier. A quick test showed the rudder works smoothly - and without any significant noise! 👍

Once Finley had gone home I decided to revisit the motor coupling issue. JBkiwi uses rubber tubing to link his motors to propshafts so a length of 3mm bore silicone vacuum hose was ordered to replace the metal coupling. This turned out to be a bargain. A 500mm length of silicone tube, 3mm bore with 2mm thick walls sent by First Class post for a total cost of 99p. There is enough tube for at least 10 couplings for less than 10p each 👍👍

Fitting the new coupling was straightforward. The motor shaft and propshaft are both 4mm dia so the silicone is a tight fit. I did have to shorten the propshaft tube by 5mm to give enough exposed shaft to slide the coupling onto as well as having enough room to fit a brass collar between the coupling and the propshaft. This collar is held in place with a grubscrew and ensures that the propshaft cannot slide out of the tube should there be any slippage of the coupling on the shaft.

I'm pleased to be able to report that there is now an acceptable level of noise when the motor is running. All of the noise is now the usual high pitched whine from the motor, with no sound from the coupling.😁

I want to add as many 'bells and whistles' to the boat as I reasonably can to give my grandson plenty of controls to operate. That should make it more interesting (and challenging) for him to operate.

First up is the radar. Martin recently posted in his blog an excellent write-up of how to build and motorise a radar:

blogs/96788#100486

wiki/101690

The navigation lights are simply red and green leds fitted through holes in the cabin roof. The leds are wired in series and connected to one port of a two port RCswitch.

A simple searchlight was built from bits of plastic tube and fitted with a 5mm white led. This is connected to the second port of the two port RCswitch.

The RCswitch is homemade based on a PIC microchip programmed to allow control of the two outputs from the Ch4 joystick on the Tx. From centre position, pushing the joystick to one side turns on the nav lights. Pushing it to the other side turns on the spotlight. Repeating these movements turns off the lights. The RCswitch, protected with green heatshrink, is attached to the underside of the cabin roof with velcro.

As Michael noticed in the last post, there is a blue Police light on the cabin roof. This is one half of the 'blues and twos' installation on the boat.

The light was bought on-line and simply plugs into a spare channel on the Rx. Using the corresponding switch channel on the Tx allows four different flashing patterns to be selected in sequence.

The two tone horn is provided by a small waterproof speaker mounted on the underside of the main cabin roof. This is driven by a two tone oscillator (yes, another PIC!) plugged into another Rx channel. To disguise the hole for the speaker in the cabin roof, a lifeboat is mounted on spacers above the hole. The lifeboat was bought as a 3D printed item and painted appropriately.

With all the bits and pieces fitted, time for a short video: