1.2.1.1 Shipyard - Building - Hull - Aluminium

Joohee R14 is designed in aluminium alloy. Despite the original scanting calls for 5086-H116/H32 alloy for plates and 6061-T6 for extrusions, we have opted for over 25% stronger, and more corrosion resistant 5059 Alustar alloy* for plates and generally stronger, but more importantly, more corrosion resistant 6082-T6 for most extrusions (tubes in Joohee R14 are from marine 5083 O/H111 alloy). The (almost complete) material list for R14 and basic assembly principle can be found here. Ultimate tensile strength AFTER welding of respective alloys is given in the table below:

 

5086-H116/H32	240MPa
6061-T6	165MPa
5083-0/H111	275MPa
5083-H321	275MPa
5059-0/H111 (alustar)	300MPa
5059-H321 (alustar)	300MPa
6082-T6	170MPa

Alustar (AA5059) is produced by Corus Aluminium Walzprodukte GmbH and distributed (for dwarfs like us anyhow) by Aluland, which, to our finding is possibly the most reasonable aluminium supplier within EU anyhow, price, stock and knowledge wise alike.

*(See also what Superyacht Business September 2006 issue has to say about Alustar and its use in the Royal Huisman Shipyard - RHS)

As to the question why aluminium, I would say, because the Titanium is simply not workable solution. There are numerous and endless discussions on benefits of aluminium over steel and vice versa, however the metal boat club is unified, convinced and undivided over benefits of metal over plastic 'supermarket' boats. The aluminium/steel topic is also discussed in numerous books, however, the final choice seems to be largely a personal matter... we simply prefer aluminium for its lighter (thus faster), does not rust and has its own silverish beauty.

Yes, the day had come when we ordered our four metric tons of aluminium, got it cut on a CNC plasma machine and started to assemble the boat, which seemed as easy as one... two... three .... four million two hundred thousands, five hundred and forty one... four million two hundred thousands, five hundred and forty two....

Fig. 1.1 Four tons of aluminium at the back of the truck (Date: 9.2.2004)

Fig. 1.2 Plasma cutting (Date 10.2.2004)