Fixing compass and instruments to bulkhead

[ContessaBob]

Can anyone tell me the correct procedure for cutting fixing holes for instruments and compass in a bulkhead with as double skin. Does this need to be drilled and filled before cutting. This is on a Contessa 26 bulkhead? Thanks Bob

 

[captainslarty]

Hi Bob, depends what you mean by a double skin.. if, for instance, balsa cored, then drill the hole, stick a small allen key in a drill and writh out the balsa back about 3/8th of an inch.. then fill the edges of the hole with polyester filler or preferably epoxy filler.. clean up and fit.

 

[Chrissie]

You will probably find that the CO26 bulkhead, although double skinned isnt balsa cored. The slight angle makes it harder but not impossible. Drill the corners first, I used an electric saw, then after breaking several blades, resorted to a hand pad saw.
Best of luck, I have an extra instrument hole to cut into my CO26 this week as well!

 

[ContessaBob]

Thanks Joe and Chrisse, Thinking aloud would it help to drill and introduce epanding form to bind and make cutting easier? just a thought, it might help stop the second skin vibrating, or am I talking out the back of my head? Bob

 

[oldsaltoz]

You must prevent any moisture entering between the skins.

This means drilling and filling over sized holes, then re drilling to the required size, adding a small amount of sealant under the head of the screw / bolt.

If a cut out is required then the edge of the cut out must be treated by filling and fairing to get a neat fit, again using a small amount of sealant to prevent moisture inside the cabin.

Also don't forget to twist the power cable for the internal light, this prevents it creating a magnetic field that can throw the compass out by several degrees.

I would use an epoxy resin mixed with Micro-fibres as Micro balloons may get crushed and cause a leak.

Hope this helps.

Avagoodweekend......