Down to business

So, making a start on the hull, firstly removing the moulding flash and finishing with 400 grit wet and dry paper for a smooth finish.

Next, moving to the bow thruster; using the template supplied on the plans, layout lines are transferred to the hull and holes for the bow-thruster tubes cut with the aid of a high speed drill fitted with a straight cutting burr bit. After installation of the bow thruster tubes, the excess is then cut flush with the hull sides. 

Moving to the Stern; mark holes for the propeller shafts, skegs and rudder tubes in the hull and cut out with care, using a high speed burr and drill bits as required.The author likes to lay down masking tape on the hull prior to marking out; this makes for easy marking out and helps to stop drill bits and cutters from damaging the hull. Assemble the keel and keel extensions from the CNC cut parts in the kit and fix to the hull with epoxy. Assemble the rudder tubes and propeller shafts and fix in place with ample amounts of epoxy adhesive; any excess adhesive should be removed and the hull sanded smooth.

The rudders are assembled from pre-built units and the three-bladed propellers shown in the picture will be replaced with the correct five-bladed type later in the build.

So back to the inside of the hull: with the propeller shafts fixed to the hull, extra bracing is included adjacent to the couplings to firm up the shafts. This is fixed to the hull bottom with epoxy.

Next comes the rudder servo box; made up from plywood, and fixed to the hull after adjusting the height, making sure the rudder comtrol arms are level with the servo operating arm. The servo box is finally fixed to the hull with epoxy cement.

Now we move to an important area - the motor installation. It was decided from the outset that brushless motors would be employed on this job for the main propulsion. Two "Tornado Thumper" power units are installed on custom built wooden mounts; these mounts are fixed to the hull bottom with glass reinforced Resin (copious amounts) after carefull alignment with the propeller shafts via flexable couplings.

The plans do not show any specific mounting arrangements - this is left to the individual modeller to design and fit appropriate mountings to suit the motors and couplings employed. It is of course important to try to keep an appropriate weight balance and keep overall weight to a minimum.

So on to the next job; putting on the water line.

A temporary waterline is marked on the hull using a scribing block equipped with a pencil. Taking measurements from the plan, the hull is secured firmly in the cradle and a check is made to confirm it is level and square. A flat clear surface is required, and here the kitchen worktop is ideal! A pencil is secured to a scribing block in place of the metal scriber; with the correct height set, the block is run round the hull, leaving a clear pencil line.

Now it's off to the bathroom for a balast test; first up it's weighing all the items still to be fitted to the model and substituting this result with items equally spaced in the hull. Next, we add extra weight until the hull displacment reaches the water line, then it's back to the scales with these extra weights, and we have the figure needed for correct balast.

While still in the bathroom, a check for leaks - and in this case we were lucky; the hull and fittings were watertight!

This compartment is an optional fitment and the builder should consider at this point if fitting is going to take place.

Parts for the build are located on the CNC precut sheets CNC2 and 3 and PPS sheet 1.

After carefully cutting out the required parts the cut edges are finished with 60 & 150 grit wet and dry paper for a precision fit. Parts 9 &10 of PPS1 also require holes to be drilled as an aid to bonding with the deck.

To aid construction and keep the job square, it was found that the use of heavy Gauge Blocks to  stabilise the glue-up and line up the individual pieces was found to be a distinct advantage.

This sub-assembly build is finished off with a 6x3 poly strip around the lower edge, that supports the removable floor section. This is left unglued, allowing access to the rudder servo and couplings.

Suitable platforms need to be installed in the lower section of the hull to carry the electronics and batteries.

These are not shown on the plans and can be designed to individual taste. In the case of this build two platforms were installed, one below the rear deck to accommodate the radio and servo battery  (6V 4 Amp gel rechargable).

The other platform (forward of the motors) to accommodate the receiver, servo mixer and main motor driver PCB's, also the speed controller for the bow thruster and switch gear.

The main Li poly battery packs are also supported on this structure with good access for quick replacment.

A coat of grey primer (Halfords) finishes the job and keeps things tidy.

Before we leave below decks there is one last job; to install the deck support strip along the top edge of the hull.

It comprises two pieces of 6x3 strip material and needs to be positioned carefully and strengthened with fiberglass filler along its lower edge. The author found it helped to glue only short sections of the whole strip at any one time, using copious quantities of clamps as required until the glue sets up.

We can now begin to prepare the hull for paint; first a coat of white plastic primer (Halfords) is sprayed on over the whole surface.

The picture shows a typical problem; minor surface blemishes around joint seams - so more work needed here.

The author's favourite fix is to make up a filler using a few drops of Nitrate Sanding Sealer and the cheapest talcum powder you can buy! Mix to a paste, and this can be painted over the problem area and left to dry, before sanding to a smooth finish.

The hull, having been already painted in plastic primer, is now ready for preparation to add the final colour:

First, the anti fouling coat.

There are various ways in which this can be simulated, but the author's favourite is to use red oxide primer - again, Halfords paints provide a good choice.

The first picture shows the lower hull masked ready for paint - perhaps a few points are useful here:

 The waterline needs to be re-drawn onto the hull and then marked with Lining tape. This tape gives a far superior line to that which can be obtained from standard masking tape - it can be purchased in various widths and the 6mm width is fine for this job. The most useful thing about this tape is that it can be removed and reapplied many times without losing the effectiveness of the tape. Pressed down firmly, it gives a clean line with no creep and when the paint is touch dry it should be removed swiftly and in one operation.

The picture shows the first of several coats of paint.

 Masking the whole hull is important and it's worth spending time to get this right. Remember to have plenty of ventilation while doing this job and allow at least half an hour between coats. Flating down with 1000 grit wet and dry paper between coats gives a good even finish.

Now, with three coats of paint applied, it's time to remove the masking tape on this first operation.

A crisp clear waterline is revealed and can be easily seen in the picture. It's worth leaving the hull to dry and harden completely before masking up to paint the upperhalf of the hull; in a warm, dry atmosphere a couple of days should do the job.

Keen eyed readers may well have noticed the accompanying picture seems to have changed from the image on the previous page!

After a visit to see RNLB Lester at Cromer a minor problem has developed. RNLB Lester has been away at RNLI HQ for the last 10 months being refitted and upgraded, and is now back at Cromer;  while undergoing a refit the red anti-fouling previously applied to the hull has been replaced with white anti-fouling!

A minor point, you may say, but one the author thinks changes the character of the boat completely - and certainly needs attention before we progress any further.

So it was out with the 400 grit wet and dry paper and plenty of water to cut down the red primer, then a coat of grey primer to cover the red and several coats of white primer to cover the grey! With a light sanding of 1000 grit between coats and finally three coats of white gloss, we were back where we started - a completely white hull!

If I had waited one more week before applying the red primer I could have saved a whole lot of work!

So, after a gap of some six months(!!) in which a lot has happened, it's back to work - and just to make sure we keep our minds on the job we have a deadline to keep. Late May 2015 is the date for the Midlands meeting of the Lifeboat Enthusiast's Society, and RNLB Lester is going to make an appearance (or at least that is the idea).

There is nothing like a deadline to focus the mind and to this end a new model making area has been created, in the hope of speeding up the build.

So an easy job to start, fitting the correct 5 bladed propellers and final alignment of the twin rudder assembly. This completes most of the lower hull work and a move to the deck area now calls.

Preparation of the deck commences with the cutting of the cabin aperture to allow access to the electronics, and also the fitting of the Y boat compartment.

Before the deck can be fitted the electronics and motors must be fitted and tested; after some initial trials a four channel outfit was installed with independent motor controls, rudder and bow thruster.

Programming of the speed controllers was straightforward with the use of a programming adaptor, and bench test runs were satisfactory. 

The picture shows the final fit with the wiring harness laced where required to keep cables away from the outrunner motors!