So after the wrap the floor framing is next on my plan. Being a novice when it comes to metal, this raised a number of questions. Which grade aluminium? What size aluminium? Where to buy?
I started with which aluminium to use. Researching the net I found the usual swamp of conflicting opinions. Some people, including someone from a boat work shop, told me you can use any aluminium. My gut told me there is more to it than this and I headed up to the local Bunnings to ask what grade their aluminium is. They told me with no reservation that the Bunnings aluminium is not marine grade. I figured if a company this big is recommending I do not to use their product there must be more to it.
After doing some further investigation I came across The Australian Aluminium Council (AAC). The AAC is the peak industry association representing the Australian aluminium industry. The AAC website has heaps of information (almost too much for the novice) but after some digging I discovered their recommendation for marine grade aluminium is the 5000 & 6000 range. The AAC website specifically states “What alloys does the term ‘marine grade’ refer to? Originally it referred to the 5000 series alloys particularly 5052 and 5251 used in the small boat market. The 5000 series are essentially sheet and plate alloys and the extrusions used in conjunction with these products for the marine industry are the 6000 series alloys. Whilst not originally given the ‘marine grade’ title the 6000 series have been used in the marine industry for over 50 years”
Some conversations I had with aluminium manufacturers reflected the AAC website information. From what I could work out, while 5052 is great for marine it is generally supplied in sheet and plates while 6060 aluminium is supplied for extrusions. After talking to the guys at Action Aluminium they recommended 6060 grade angle for my job (5052 was not available in angle).
After inspecting the aluminium and considering the balance between weight and strength, I decided to go for 32mmx32mmx3mm 6060 T5 angle for my floor supports. This came in at 0.49kg per meter and is supplied in 3.25 or 6.5 meter lengths. In the end I bought 6 x 6.5 lengths (39 meters) for a total weight of 19kg. After off cuts I’m expecting the weight to drop by probably 20% which will make it around 15Kg of frame weight added to the boat for the middle, casting platform and rear frames.
The total cost of the aluminium came to around $180 which I was happy to pay knowing it was coming from a reputable supplier.
Next stage: floor frame construction.