Aluminum hull & composite superstructure?

I think Oceanfast built several yachts like this already in the 1980:s.

http://www.oceanfast.com.au/go/history

I seem to recall the Delta-built 161’ Gallant Lady had an aluminum hull and composite superstructure...?

The advantages mostly would be a lack of maintanence on the superstructure in regards to paintwork and paint blisters. Better sound deadening (GRP) does not transmit as much noise. Possible weight savings. I worked on that Delta for a short period of time. You don't have to deal with the dissimilar metal issue in regards to having stainless bow rails and such with SS screws into aluminum.

aluminum and Composite construction

One issue is two totally different rates of expansion and contraction between the two, most major fastenings today through Alu. are sleeved and through bolted, with mylar separation between teak etc and alu. The beauty of welded alu. is it don't leak !!!!!
construction methods are critical with alu. to minimize oxidization at construction and during it's lifetime, continous welding is critical rather than spot.

Composite Superstructure on Metal Hulls

This has been done since the early 80's. Yachts and Ferries. It started as a way to take advantage of composites by traditional metal builders to mitigate risk. Today it is mostly used on very large vessels and some ferries.

Fexas and P-J's did one of the early ones - 80 ish feet as I recall. SSM and Bay Island transport just launch a new hybrid ferry.

For many years, the U.S. Navy, and at least a couple of U.S. boatbuilders, used DetaClad, a DuPont product, to join the Al superstructure to the steel decks.
No way for leaks to occur and no mechanical fastenings which reduced labor costs.

Used? It's still used a lot! Ask Derecktor much they used last year. We used a lot on a local project recently.