The hull is now ready for glassing but first I need to attach the keel, this is in three pieces which need gluing together first. Again relying on the accuracy of the laser cutting I’m confident I can glue these “off hull” as it were. This done, I then epoxied the length of the keel and then offered it into position, a very accurate piece of wood, lining up exactly as per drawing, I secure the keel by first having drilled some 0.5mm holes to take some brass pins and tapped them home to secure the keel. This was left to set overnight and then a light fettling to a condition ready to be glassed.

The balsa block seemed to be a fairly straight forward affair and so the fitting of the block using aliphatic wood glue was just that. However form this point onward it got a little more difficult, carving balsa to the precise shape that I wanted wasn’t that easy, as the grain of balsa is variable to say the least, as the shape was three dimensional the grain altered dependant on where you were trying to shape it. Balsa is also soft in places and harder in others (I wish I’d steamed the ply) making sanding difficult. Solution – use the wood hardener on the block, this helped and eventually I had what I was happy with using a template traced from the keel plan in order to glass the hull, (more on the block later)

This is a simple construction from ply which when the angle has been measured and the height/front face calculated is easy to cut and assemble.
I used a solid brass joint which is the same size as the flexible joint that will eventually be used to enable the motor to be suspended in the correct position whilst measurements were taken. These dimensions were transferred to the front face so the rest of the frame could be made to support the front face. Once the joints have set I made the cut out to match where the motor wires exit from the floor. Still with the brass joint in place I marked out the 3 securing bolts these were spotted through to the floor. These marks enable the holes to be drilled (hardened using wood hardener) and then tapped M4, now the studs can be screwed into the floor ready for the final mounting of the motor.

As with the side skins the first job is to make sure the formers are “in line” as before from one to another and on to the next doesn’t make the skin look as if it shows an undesirable bump in the profile. The bottom skins need to be fitted to the keel profile first so some minor trimming to accommodate the prop shaft curve. The bottom skin also needs some steaming to fit the curve just before the balsa block, this curve is at the discretion of the builder so a gentle filing against a pre-made template to ensure both sides are the same.
The sheet is then applied to the base and clamped in position, this allows the steaming to be done and to pencil around to show the excess that can be removed before gluing and the outline for the former lines can be marked to enable some pilot holes to be drilled
I then use the same location method as I did on the side skins using 3mm dowels to make alignment much easier and less trimming after the glue has set. The curve at the bow is rather difficult to hold whist gluing as pins into balsa don’t hold very firmly so I used a build-up of clamps just to apply enough pressure to maintain the curve whilst the glue sets as well as a few brass pins.
Left overnight to set I can now use the plane to lightly trim back to the side skins

I forgot to publish this operation at the correct build point so here it is slightly behind. The angle of the prop shaft is taken from the drawing so it can be transferred to the brass shaft whilst in situ; the hole created by the build leaves a square hole large enough to allow some vertical and lateral movement so I can now position the shaft with the aid of the angle gauge along the centre line and set using epoxy. The underwater part of the prop has a supporting ply quadrant which will be epoxied at the same time, I use some light wedges to position the shaft and hold it whilst the epoxy sets.

Fitting the skins is always an exciting part of the build for me as it starts to make the project start to look like a boat. the first job is to make sure the former's are “in line” by this I mean that the transition from one to another and on to the next doesn’t make the skin look as if you left something behind it and shows an undesirable bump in the profile. This is done with a piece of scrap flat wood with some say 120 grit abrasive glued flat to it, gently draw the block over the profile to remove any high spots, I sometimes mark the edges with a marker pen to show where the high spots are and in theory when a light rub remove or touches all areas you can assume the profile is ready for the skin.
Skins are provided well over size and also will benefit from a little heat treatment on the bow. I like to trim as close as possible before gluing so a minimum of planning and sanding is required after. I first lay the skin over the frame and then and clamp along the length, then at the bow I applied some heat along with a light spray of water which quickly turns to steam but allows the ply to become pliable this is then bent around the bow and clamped, I now leave this overnight to dry and cool, which will hopefully retain the bend.
I then drill 2 x 3mm holes on the bow into the pre-prepared reference blocks to take a 3mm bamboo dowel; I then do the same at the stern. This is followed by scribing around the skin with a pencil to indicate the excess and also mark the position of the formers so holes can be drilled for pins to be driven into the formers exactly in the middle I then remove the clamps and dowels and remove the excess ply close to the pencil marks, and then drill some 0.4mm holes in the former positions for later pinning. Next I prepare some epoxy, the frame is then “glued up” ready for the application of the skin. Using the dowels the bow is located first, closely followed by the stern dowel; this locates the skin exactly ready for all the clamps to be applied, I then work along the marked positions of the formers and use some 0.5mm brass pins to ensure contact along the length of the formers, a final check that all the skin is in contact with the frame this is left to cure overnight.
The other side is next but first some trimming at the bow is required so it doesn’t catch on the previously applied skin. I followed the same process on the second skin
The final operation on the side skins is to remove the excess ply, I prefer to use a jack plane for this job, which may sound OTT but I find its size an assistance in gauging the angle of the plane against the skins to get it level with the deck and the bottom chine, it’s also so easy to keep razor sharp and is easily adjustable to take minute cuts when required. It’s now ready for the bottom skins to be applied.

The bottom skin I think will need some additional support around the gaps between each of the lower formers so that the lower skin doesn’t sag between formers and is supported whist the adhesive is setting. I used some scrap pieces of balsa to fit the gaps making sure they were 1.5mm below the keel support.
The other preparatory thing I added was an additional block at the bow either side to use as reference points, the stern has two 12mm blocks which will also serve as reference point these will be used to position the skins when gluing.

Whilst the construction is still in skeleton form I thought it better to put in the holes for the rudder and the water pick-ups in because at this stage it’s easier to hold the frame in a vice on my drilling machine. The holes are marked out and then the top K6/6a are held in a toolmakers clamp which is subsequently held in the vice so the holes can be drilled centrally and square with K7, both holes are drilled one 6mm (water scoop) & 8mm (rudder housing).
The rudder is a commercial item, loosely described as a “Large Rudder” which requires a small modification of turning the blade through 90 degrees and re drilling and riveting and then soft soldered just to make sure of a secure joint. The blade is then shortened by about 10mm on the trailing end and 5mm on the leading end, then a final polish and it’s ready for installation at a later stage.
The water scoop is a different issue, it’s one of those items that can be purchased for a few pounds but what’s the fun in that. I would much rather take the long route and make my own. I’ve documented this process before but here we go again. Using a piece of 0.250” brass tubing at 3” long the first job is to fill it with soft solder, tinman’s solder is best as it’s not as expensive as the cored solder, so resting one end on a piece of wood the tube is fluxed and then heated externally and the solder fed in from the top until its full to the top, its then left to cool. Holding the tube in the machine vice with a 50mm round bar in the jaw the tube can be easily drawn around the 50mm bar to the desired degree (about 35 degrees in this case). The tube is then held in the machine vice and trimmed to the appropriate shape on the inlet end. I then made a collar to be soldered on the tube in the appropriate place giving a position in line with the top of the propeller this will be epoxied in place at a later stage.

There are a number of small details that need to be added to give the curvature of the deck and also the curvature of the stern these are best described by pictures, as a long winded description will only cause confusion these will need trimming after the glue has set. In addition to these supplied pieces there needs to be some provision for strengthening the area where the exhaust exit at the stern as any pressure from the exhaust fitting could cause the stern ply to dent. These additional pieces were tapered to align with the curve of the stern and applied both internally and externally. To ensure everything lined up, the 8mm hole was first put into the balsa sub structure and the 4 inserts prepared, then I used a piece of PTFE coated oven sheet rolled up and placed through the 8mm balsa hole, then, adhesive applied the inserts were pushed over the rolled up oven sheet until they settled on the balsa sheet in the correct alignment.

The chines are made from 3 pieces, which as with the keel, are very accurately laser cut, and can be laid on a flat surface with pieces of PTFE sheet under the joints and glued together with the aid of some pins to hold while the glue sets with confidence that they are the correct shape and will fit around the formers without any corrections.
Now they are set they can be offered to the formers and secured in position, F1 needs some trimming to accommodate the curve but that’s all. I added the two lower chines first securing with aliphatic glue closely followed by the upper chine then I applied some securing pins top and bottom and quickly before the glue sets some elastic bands are applied to ensure some tension to the joints, the whole assembly was then left to dry.
Hopefully the pictures will show the detail better than a description.