M_M_I_2015_04_

http://www.marinemodelmagazine.com APRIL 201519

An odd thing; when the tug was being tested in its original

moulded orange colour, the lake’s resident male swan kept

displaying aggressively towards the boat and trying to drive it away.

When the hull had been painted black the swan subsequently left it

alone. Do male swans see an orange coloured object as a threat?

Goth XP and MX

I have now finished building my Goth XP from a plan from Frank

Russell Designs but I have only managed to sail it once and it

seems promising (if only I can become a better sailor). The hull is

an epoxy resin moulding from a split mould made by a fellow club

member. He also is planning on building a yacht from the mould

when I have proved whether mine works. I have managed to build

it to the minimum weight limit of 4000 g for the IOM class and

also made the ballast and fin weight close to the maximum allowed

weight of 2500 g. I’ll follow up in a later column when I have sailed

it some more but for the moment sailing is out of the question while

the lake is frozen over.

My fellow club member Richard Bailey has purchased an MX

from CM Yachts and this yacht is also based on the Goth XP so it

should be interesting to see how it compares with my home built

version. The MX14 is beautifully moulded and comes built to deck

level with ballast, fin and rudder also supplied. The winch tray which

slides into the fitting in front of the mast is set up to take an RMG

winch but it also has the same fixing holes to suit the British made

Titan winch. The accompanying photographs should make the

layout clear.

MakinG a Ballast WeiGht for an ioM

Yacht

I was reluctant to buy a finished ballast for my yacht (cheapskate!)

and thought it would be an interesting exercise to try and make

one. The plan for my Goth XP showed a scale layout of the new

type long (385 mm) ballast and gave drawings of its various cross

sections. I decided I would make a half section mould for the ballast

so that I could cast it in two halves and then join them together with

carbon fibre cloth between the halves to strengthen the moulded

lead. So I set to and made a pattern out of 6 mm MDF sheet with

infills between the cross sections of hard balsa wood. The finished

pattern was given a coating of epoxy resin and then rubbed down

in preparation for making the mould. I had been planning on making

a mould from casting sand but by the time I got around to it my

ideas had changed and I now wanted to make a mould that would

be reusable so that I could cast a reasonable number of ballasts

from it – a casting sand mould being usable only once. I was also

considering a ballast that was oval in shape rather than the round

one shown on the plan so this also caused me to alter my plans.

In the end I decided that I would make a mould from the existing

pattern and mould the two halves with less lead in each. I would

then cut a centre section from lead sheet to the reduced size of

the lead mouldings and join, with epoxy resin, the two carbon fibre

reinforced halves together with the centre section in between. This

would give me a slightly wider ballast but also would significantly

reduce its height, this means that the centre of gravity of my ballast

would be lower than that of the round one and this might give a

slight advantage.

My reusable mould was made from high temperature silicon

rubber obtained from MB fibre glass. This material is able to

withstand temperatures of 300 degrees Celsius for longish periods

so I hoped it would also be able to withstand molten lead for a

Goth XP One metre yacht

with club member Richard

Bailey modelling it

One metre ballast in course of construction

CM Yacht’s MX 14 One metre yacht hull

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