Building the Fire Fighter 26 Gas Rigger
From Tom Moorhouse
Over the winter months we will be building a gas rigger
Part 1
After downloading the drawing from Tom (http://firefighterboats.com/main.php) you have the option to print out from Autocad or Deltacad,( having both Autocad and a A0 printer / plotter ) at the office plans were printed out to a 1: 1 scale, I checked with tom some sizes and found the 1:1 was perfect.
First thing was to cut out the templates from the plans. Next was to go and buy the materials, the plans call for ¼ marine 7 ply but this is not easy to find, I found a good supply of 2 mm marine 4 ply I decided to use the 2mm 4 ply and laminate it with 1 lay of 285 gram carbon fibre on the outside. The overall thickness should be about 8 mm just over half of the 2 X ¼ ply and much stronger showing a carbon fibre look to the tub sides. I had the option to build a 4 inch or 5 inch tub I chose the 5 inch.
First to cut out the parts
8 X 2 mm 4 ply side pieces which make the tub
7 X ¼ ply bulk heads for the Tub and radio box
2 X hard wood boom blocks
2 X ¼ ply doubler ends
I cut outside my template line and sand down all together to final size.
Tip. make a sanding plate, all you need is a piece of flat 25mm ply wood 40” X 4”, glue a piece of sanding paper down, perfect for sanding the bottom of the tub sides
Assembly
Before gluing the tub sides you need to sand all pieces together, a good disc sander is important as you need to keep all the pieces square and the same size, I use some double side sticky tape as it comes off without leaving any marks on the wood, take your time setting up the sander so the table 90 deg to the disc and 90 deg if you have a finger board.
First I glued up the tub sides with an epoxy glue ( the best I have found is Devcon 2 ton epoxy sets crystal clear) ,
I cut holes into the 2 inner sides to reduce weight making sure it was solid where the engine mounts would go, the most important thing at this time is a good heavy base to work from and it MUST be flat, I use 2 piece or 50 mm X 50 mm aluminium angle to clamp the tub sides down perfectly flat onto 25mm ply.
I left these overnight but you could leave them longer, it is essential to let the epoxy fully cure before unclamping, any twisting now will show up in the finished rigger. I thought carbon fibre would look nice on the finished rigger so I found some 10mm safety class which I could use to attach the carbon fibre,
I next made a Jig to set the bulk heads onto the tub I used 2 pieces of aluminium angle set square to each other, I did only 1 side of the tub allowing me to get them square to one tub side, make sure you have any drain holes and throttle tube holes in before fitting bulk heads as it is hard to drill holes when you have glued the bulk heads in, Tip if you are running plastic tubing through from the engine bay to the rear of the tub for water outlets test them with petrol not all plastic is petrol proof the last thing you need is a leak in the radio box. I used Devcon inst-n epoxy for gluing in the bulk heads this as this sets in 1 minute. I set 2 pieces of angle square to each other and clamped the bulk heads to the tub sides, you should check everything is square and the tub is flat on the jig, I left this for 2 days and kept on checking its flat, twisted frames will not work well on the finished rigger Avoid temptation to unclamp before the glue is set (at least 24 hours) Tip glue up some small pieces of ply so you can test if it is fully cured and bonded. In the areas where there are bulkheads that are enclosed I have filled them with blue foam, this will add some buoyancy to the finish tub with only 28 grams of weight.
Next time: Fitting the top bottom and doubler pieces to the engine and radio hatch, top and bottom skins and starting to glue the sponsons up