Building
Time to start bulding. My design would be made out of three layers of foam.
Bottom Layer would be the three hulls
Middle Layer would hold most of the electronics and bait release mechanism
Top Layer would contain the Hoppers, Handle etc..
The foam cut quite easily with a jig saw and was easy to trim with a knife. Once I had the shape about right I got the sandpaper out and found this stuff very easy to smooth off. Once smoothed off I gave each piece 3 coats of weatherproof pva to seal it.
Before and after. Raw foam and after sanding.
Next came the central hull which needed to house the jet drive system and motor. Clearly I couldn't put the motor directly into the foam so I found a plastic hobby box in Homebase (about £3) and decided to make the central hull out of plastic (box) and foam.
Images of the cut out for the Jet Drive and the motor and jet drive unit offered into place. Note: The resisters on the back of the motor suppress interference...also my soldering is awful.
Starting to look the part. Just need to cut out foam to take the motor and Jet Drive ready for glueing
Three Hulls complete! Gorilla Glue is amazing, waterproof and doesn't melt foam or plastic. Don't get this stuff on your hands though as you won't get it off for a week. Had to fill a few lumps and bumps with general purpose filler.
Then sanded everything followed by three coats of weatherproof pva to seal.
Shaping Central Hull nearing completion
Time To Build Middle Level
The middle level of the boat is really where all of the electronics and mechanisms reside. It took a good deal of time to get it right but I found cutting out the foam quite easy and I glued in the Servo (for rudder control) and the Retracts (for bait release) using Gorilla Glue. They're rock solid now.
Mock up of how the rudder system would work....hopefully
Middle tier with central cut out to house battery and electronics. Left and right cut outs are for bait to fall through and will house the flaps that will hold and release the bait.
Servo offered into place ready for glueing.
Double thickness of thin ply glued in for strengthening in order to take the screws from the rudder mechanism
Hole cut out ready for Retract (shown). The Retract will drop and lift the bait release hatch
Hatches being put in place.
I made these out of 'L' shaped aluminium bought from Homebase. I also bought some aluminium bar and some brass hinges.
I took the hinges apart, drilled them out so the Ali bar was a good tight fit and threaded them on. I formed supports at each end using the 'L' stuff and finally used rivets to attach the hatches to the hinges.
You may notice that the far support is open at the top so as to allow maintenance or replacement as required.
The near end of the hinge has a brass connector which I salvaged from some old electrical connector strips I had lying around. A sturdy bit of bent wire completes the hatch meachism.
Cut out at rear of hatch (below) to allow rig tube to be snag free.
Video showing bait release mechanism in action. The flaps fall naturally and they are lifted by the action of the Retracts
Once I had the bottom two layer pretty much done I glued them together to form the overall base of the boat. Again I used Gorilla Glue for this and did some smoothing and filling along the way. This gave me my hull, complete with the main systems like the Motor, Jet Drive, Bait Release and Rudder all pretty much done in what was now a single unit. Pics below show the almost finished base unit.
Anywhere that I was going to put screws or I felt I needed more strength, I glued strips of ply either on the surface or cut into the foam. I did this for the rudder mechanism (above), the internal compartment (as the foam was quite thin there) and also the sides so that I could attach clips that would hold the boat lid on.
There was more strengthening to do as well. Foam coated with PVA was not going to stand up to the rigors of fishing and would soon be dented and scratched. I needed a hard coating to achieve this. I could have used fibreglass resin but I hate the smell and find it difficult to work with.
After protecting surfaces with waterproof PVA I next put a hard layer of P38 Car Body Filler on. This goes rock hard and hopefully will protect the soft foam inside. Once this was sanded (not easy by the way) I then coated the outside with plastic resin.
After some research I found this Black Fast Cast Resin (Ebay). This is tough stuff and if you build up enough coats it should give you a nice finish. However, at room temperature is starts to harden after just 2 minutes (as it's designed for casting moulds). I wanted to paint this on so had to reduce the setting time. I did this by leaving the bottles in the fridge which extended the setting time to well over 5 minutes.
Top Layer undergoing coating with resin.
Notice stips of ply on the side and also plastic skirt to keep water out an ensure seating correctly on the base.
There's a hatch at the front. This is for changing the battery. I made this out of a small electronics box that I found in the shed and it's perfect for the job as it has a water resistant lid which screws down. I cut the bottom of the box off anf glued what was left onto my moat (Gorilla Glue again). Sadly I can't find these online but know doubt you'll find something similar.
A Few other things to sort out. Firstly the ariel. I'm not entirely convinced that this needs to stick out of the boat but after some research, it certainly needs to be upright otherwise the signal reception is poor. I wanted to keep water out so didn't want a hole in the top of my boat...hmmmm
Then I found an old glow stick (the kind you get at kids parties where they wear them as bracelets) in a drawer and used that. The good thing about these is that the tube is sealed at the ends and there's a nice little connector so allow seating into the boat.
Glow stick ariel in place. Also water resitant on off switch (Maplins). Sadly this doesn't light up and I think this is due to the fact that it is rated at 12v and I only have 7.2v.
It's not a problem for me as Ihave since installed some LED lights on the front and back so I can use the boat in the dark!
Finally, I got a handle from Homebase and used long screws and big washers so it couldn't get ripped from the boat. I'm not sure I'll ever be completely satified with the overall finish but I reckon it's 90% there. I did give it a final couple of coats with a satin black spray paint and have since added some lights. Overall I am very pleased.