@Sandcrab
I am under the impression that Sunreef started as an all aluminum shipyard and later added composite superstructure, to finally add a carbon line of a very different gunboatish design.
They, on purpose, do not detail their construction method, but some of the hulls called "composite " on their web site is actually alu hull and cored
fiberglass superstructure, a direction also taken by many one-off builders.
Here is their take on aluminum :
"Aluminum materials
For the production of aluminum hulls, superstructures and other yacht
equipment, we use widely known and highly appreciated types of aluminum alloy such as Sealium® and Alustar® among others which have become the international industry standard for large cruising yachts. These types of alloy optimise the overall performance of vessels in general as they make them more robust, safer, and user-friendly.
Sealium® and/or Alustar® alloy advantages:
- Higher welded yield strength than standard 5083 alloy
- Proven improved
corrosion resistance
- Increased fatigue strength
- Same usage proprieties (formability and welding) than 5083 alloy
The characteristics of aluminium provide the best
safety guarantee for the yacht:
- Rigidity : an aluminium hull is an extremely rigid object that does not suffer from
distortion caused by the ballast, the
rigging or the sea state. This is the ultimate
guarantee of
safety for your yacht and the durability of your hull and of its
interior
fittings.
- The capacity of aluminium to absorb shocks without rupturing is one of the biggest
advantages of aluminium hulls in encounters with containers, tree trunks, etc.
- The density of aluminium (2.7) is low and offers the benefits of the other advantages
of aluminium without increasing the weight of the boat."
This being said, they have produced more than 60 large cats and are now at a stage where they have enough demand to justify moulds, in which case aluminum loses the economic war and you are very right to point out at an increasing number of full composite boats.
For a quick reference to the past this link
http://www.catamarans.com/news/2008/...nstruction.asp
points to the construction of their 102 in 2009, all aluminum.
So you were right to point out that the right formulation is probably that " a large number of past boats built by Sunreef and most of their present custom boats are built in aluminum "
Cheers
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