The Trust have been working for some time on a new locomotive style boiler design for Consuta. Those who have worked as firemen on the existing boiler will know it does have some issues but these are manageable with training and good coal. One major problem, for which there is no solution except replacement, is that the present boiler is too heavy. This is an important consideration for Consuta because a key feature required of any fast displacement boat is to keep things as light as possible.
Sam Saunders knew this and his monocoque construction using Consuta plywood meant that Consuta, when built, was much lighter than other umpire launches of that period, and therefore created much less wash.
The pictures above were generated from a Computer Aided Design Solid Model. Rather than draw the boiler in the same traditional way as the original it is possible to machine and fabricate the design within the computer program and then generate drawings automatically. The software can also calculate the weight of the design. This shows that a new boiler could be made lighter than the present one by about 850lbs (this includes 100lbs for less water content). To give an idea of the scale of this extra weight it is equivalent to carrying 19 bags of coal or 5 people.
There are other advantages to the new design such as much drier steam and a larger usable operating water range.
The modified crown stay arrangement has been incorporated into the CAD design and discussed with a boiler maker to ensure the design can be made.
The current drawing can be viewed as a pdf by clicking on the image below.
Some detailed design analyses
The proposed design uses thinner plate than the original and has more steam space above the fire box crown. We have taken the opportunity to perform a lot of engineering simulation using a Finite Element Modelling system which has proved to be very interesting.
The analysis helped design a modified crown stay arrangement which significantly reduced the distortion and stress in the boiler wrapper.
Go to the Finite Element Modelling page