Aluminum Cross Beams on a Wooden Catamaran - What Think Ye?

[noelex 77]

Originally Posted by DaveOnCudjoe

G2L,
In the case of the Mac 36 the ends of the tubes are open and the corrosion was evident in the bottom of the tubes. I have seen corrosion in 6061 T6 which is a recommended alloy if not annodized. Dave

Sorry Dave I did not mean to cast doubt on what you have seen, but I think there will be some cause, such as stray current from an anchor winch etc.
Saltwater on its own will not corrode marine grade alumium (even 6061 which is less corrosion resistant than the 5 series, but can be extruded), but a cat beam is typically attached to a large amount of ss from the rigging, galvanized steel from the anchor chain and has the potential for electrical problems from anchor winch wiring etc. It is a relatively small and light structure compared to these other dissimilar metals.
Despite this it seems common to use this on fiberglass cats and I cannot see any great additional problems on a wooden structure, but I would look at it carefully.

[beiland]

Originally Posted by bangkaboat

I see that the bow tube is capped.

Were there some pics posted? I didn't see any?

[DavidO1]

Use of aluminium cross beams on a wooden surface is a good idea indeed because aluminium is much stronger that wooden. We can put more load on aluminium cross beams according to above members which is exactly that information for which i am looking for. Great work keep it up !

[DavidO1]

Originally Posted by DavidO1

Use of aluminium cross beams on a wooden surface is a good idea indeed because aluminium is much stronger that wooden. We can put more load on aluminium cross beams according to above members which is exactly that information for which i am looking for. Great work keep it up !

It's good to take part cross beam related discussion and i am much interested in it .