What kind of tabernacle are you referring to? The hinged tabernacle or the stationary one?

The hinged one by Le Fiell is cast. I do not know if it is sandcast, or investment cast. I believe investment cast is better, that is because I specialize in molds for those castings. They produce a clean casting as with sand casting as there can be grains of sand falling into the melt as it is poured in. Investment castings are used in parts that are lighter, yet require break resistance. Die cast is superstrong because the filling pressure of the die has the same effect as forging a part, but not applicable here. The tabernacle material is most likely 50 series aluminum, a grade that is more corrosion resistant. Do not use 20, 60 or 70 series aluminum and have that fabricated from smaller pieces. I tried to make a halyard base plate, and a year later it looked like an old telephone book as the corrosion soaked into the grain of the aluminum piece and made it look like the pages spreading.  If the tabernacle of whatever material starts to look as if it has serious cancerous oxydation growth, get a new one. I am certain Bud Taplin can supply one.

Happy sailing to you,

Mike