I've now cut the jet mount plate, base plate, and transom. The base plate will be rebated into the bottom and the jet mount plate will be glued to that. The jet plate will protrude below the hull 3mm to try and get the intake as low as possible. The boat has a fairly flat bottom, and the jets need water to at least shaft level to get started, or you just get cavitation.

I found some right angle bends at the hardware store (garden irrigation pieces) which will help with fitting the reverse system. It's going to be fun fitting all this in and getting everything connected properly, Getting it all watertight is going to be the main problem.

Did some initial hacking out today to fit the base plate into the hull. The plate will be eventually glued into the rebate round the edge of the hole, and the back end glued to the transom plate which will be glued on first. Also epoxied the jet plate to the base plate. I'll have to have a look for some foam safe glue, as I think I might need a bit. PVA works well, or bathroom sealer, but there will be something better out there. Might have a look at Gorilla glue again, although tried some years ago and hated it.

HK used to sell a brilliant polypropylene glue for foam planes, (there was no branding on the tubes, just an umbrella,- apparently was the stuff manufacturers of foam planes etc used.) but the 'safety restrictions stopped them shipping it years ago,- shame, as it was by far the best for polystyrene - or anything really, (never went completely hard).

Might rebate in some side plates at the rear to strengthen the foam for the reversing ducts as well. Once the glassing is done, I'll be able to hack out a lot more if necessary. Good thing about the foam, is if you need a space for a battery etc, you just cut one out.

Most of the foam was cut using a 100+ year old Beardshaw & sons' (Sheffield UK) keyhole saw which was my grandfathers. He was a carpenter (NZ) from around 1909 till he died at 83 in 1972 while still doing odd jobs and building a bathroom cabinet for a church member. Saw is about half its' original depth from years of sharpening.

At the moment, with the jet, valve box, base plate and transom, the hull weighs just 700g.

The bottom of the hull has now been covered with PVA glue and heavy model tissue (left over from a Graupner plane kit in 1978 - used Solarfilm instead) The PVA is trowelled on with a piece of thin ply (could use the small sponge paint rollers) to make sure all the holes in the foam are full, then the tissue is applied, smoothed out, and another layer of PVA trowelled on and finally smoothed out with the fingers. Once dry, any high spots will be sanded, and another coat of PVA applied. The glass should be able to then be laid on top with no melting of the polystyrene.

It doesn't matter what the finish is like, as the majority of the inside of the hull will never be seen. Once the glass is on, sanded and faired, you'll never know. Had a look in the big hardware store for Polystyrene safe glues, but most safe ones are PVA based. There was a Gorilla construction adhesive in a caulking gun tube which was safe for polystyrene, but a bit awkward to use a caulking gun on a model. I tried a sample of ply stuck to the foam with bathroom sealer (non silicone) and it stuck 100% (as can be seen in the sample below the tube) -probably as good as anything for wood to foam, and sets fast.

The other PVA glues are Parfix (Aust) craft glue (china) Weldbond (Canada and Elmers Glue All (US). I bought the Weldbond hoping it would be something fantastic (cost $14 for 260ml) but it's just another type of PVA (ripped off by the Canadians 😁) - probably like Elmers which supposedly has an elastisizer added. The Parfix is 500ml for $10, and is fine for this job. I'll try the Weldbond on balsa when I get back to the Stiletto.

The transom plate has also been glued on using generous amounts of PVA.

Finished covering the hull with tissue and PVA and have added reinforcing plates to the rear for the reversing jet ducts. Have also had a play with the superstructure. It's an ugly boat whichever way you look at it, not made for looks, purely functional. Very low freeboard and tall cabin. If I can find a decent side on view of the boat, I could make it a bit more accurately. Hull could be longer thinner and lower, but I needed some room inside for the diverter box piping.

Cabin pattern will need a bit more work, and more searching the net for a better photo. I got the basic shape by measuring the photo, and found the wheelhouse is roughly twice the height of the hull.

Have now attached the base plate to the hull using bathroom sealer (non silicone, perfect for foam, and waterproof) will fill around and smooth when set before glassing over . Re-modelled the superstructure template and window positions and sizes as well. Space for the diverter box and piping will be cut out after glassing, as well as the 'rudder' box recess, (pic 1)

Pic 2 shows the stbd reversing duct/flap set-up, (the jet unit bolts to the front,- pic 3)

Drilled the rear ply reinforcement for the reversing ducts, and modified a garden irrigation elbow
to try for the actual duct. I can't do a lot of the cutting out inside till the hull is glassed, as it would be too soft to work on. Once fully glassed, the foam will be cut back to the transom and tunnelled out for the internal ducting. Going to be fun getting all the piping together inside the hull.

The ideal piping would be a flexible ball type (as used for coolant on lathes etc) but with a 20mm ID, as it would be able to be bent to any shape. Might have to have a look around.

Managed to glass the outside yesterday (6oz cloth) and made some better angled reverse tubes, by cutting and grinding a 90deg socket to hopefully better match the angle of the black ducts.

Managed to get the reverse ducts into the hull with a lot of cutting, tunnelling, fitting and re-fitting, plus one small notch to allow the end of the stbd tube to go through the deck I was trying to fit it in without going outside the black lines, as that's where the cabin will sit. Haven't made the system permanent yet, but it's almost ready to fix in place once all the sealing and deck glassing etc is done. There are 4 screws which hold it in place on the ply base plate, using the glued on saddles.

The outer ducts will be fitted from the outside last, the plan being, to use a ring of silicone around the inner ends and then push them into the fittings inside. They will have no real pressure on them, so only need to seal nicely. They will be resin faired on the outside to seal them in. Once everything is eventually in place and I know it works, the cavities around the tubes will be filled with expanding foam to hold them tight. The jet unit slides into the front tube of the diverter box and is a tight fit in the tapered bore of the tube. It will eventually be finally fitted with silicone to seal it fully, and then screwed to its pre drilled position on the bottom plate.

Still have another resin coat to do on the hull, and glass to do on the deck and transom. Rudder box set-up also has to be made for twin built in rudders.

Second coat of resin on the hull and deck now, and most of the foam inside, resin sealed. I've made a thicker Perspex lid ( 5mm) for the diverter box and sealed it (hopefully) with a firm silicone. The previous 2mm lid was far too flexible and lifted too much under pressure. As long as one of the valves is always open, there shouldn't be too much pressure anyhow. The valve shaft holes are counter bored to accept O-rings under the collars.

Have sanded the hull, so all it needs is a wipe of resin with fairing powder, another sand, and it should be good to paint. Not going to be a luxury yacht, just a bashed around work boat. These things were very basic when they were new. I'll be assembling and testing it all before painting, as this being an experiment, has no guarantee of success, and may need modifications.

Made a start on the rudder box for the ahead steering. It will unfortunately protrude from the transom slightly due to the position of the diverter box. Would have moved the box and jet intake 200 forward if I was clairvoyant, but things can be a bit off when trying to build from a photo. The section protruding will be cut off on the line, so won't be too horrible.

There are 2 rudders which have to go inside the box, either side of the orange jet pipe (which will go into the back of the box and be shortened to about half its' length). The fun part will be getting the assembled rudders with shafts, into the box and into the shaft tubes once it's in the boat.😐 May have to drill large holes in the top, feed the rudder shafts with tubes through, straighten them up, slide another pre drilled ply top piece over them, and glue that to the box top. Not a lot of room to play with

The rudder tubes could then be glued in place, and rudders held up with collars. Once they are in, they will be there for life, so they had better work!. Rudders would have to be the right height to rotate to vertical from an angle as they were inserted. This thing is straining my brain, - so many things to think ahead about, so something doesn't go horribly wrong, necessitating chainsaw work😁