Aluminium boat with no welds?

Probably several million aluminum canoes and boats up to 20' or so have been built for 65 years or so in the US and Canada with riveted joints. A flexible sealer is used in the joints.

 

5052 perfect for marin use?
I am not sure but isn´t this a low alloy manganese aluminium. I always thought I have to use at least 5754 for salt water. Ialso know Norwegians wants to use 6082 silical alloy alu possible to harden.
Am I totaly out of track?

 

3

3m has a marine dept. About 4 years ago I e-mailed them to find if they had an adhesive to bind a whole 24' fishing boat together with just some bolts and perhaps some counter sunk screws All aluminum of course to hold together 5052 and 5086 plate.
I was using angle for side frames and angle for borrom frames. They highly recommended 2 of their products and even called me to explain everything. I no longer have the names but contact 3M marine to get data. It was the Glen-L Cuddy sport 24' by 8'-6" comes with wood or aluminum plans and materials list which you can read on their web site. It is an outboard. There are adhesives today that are far stronger than welds or rivits. The idea though of a few bolts here and there made me comfortable. They even told me in detail how to prep the aluminum before the adhesve was applied--Very helpful people.
http://www.glen-l.com/designs/hankinson/cuddysport-al-bom.html 5052 is fairly soft and dents, I would not use it for bottom plate, I would go with 5086 on the bottom. and 5086 for the frames.

 

If you get a proper cert, with an Asset test. It is also listed in the DNV tables shown here:
http://www.boatdesign.net/forums/boat-design/aluminium-boat-no-welds-38520-2.html#post469676

I am not familiar with 5052, I don’t use it. If you look at the tables I posted, you can see that 5052 has roughly half thre strength of the commonly used 5083 when welded. So, not sure why you’d select 5052 really? However, most of the 5000 series have relatively “high” levels of magnesium, nominally below 6%. Or are you confusing this with a low manganese, usually less than 1%?

But this needs to be put into context since Magnesium is important in the 5000 series. The 5000 series non-heat treatable alloy derives most of its strength from the solution hardening of magnesium. The Al-Mg phase at room temperature, it is shown that aluminium can dissolve up to 1.8 wt% Magnesium at equilibrium. In practice the Al-Mg alloys can contain as much as 5.5 wt% Mg in solid solution at room temperature - a supersaturation solution.

The 6082 is a heat-treatable alloy, very different from the 5000 series. The 6000 series you can use extrusions shaped to pretty much what you like. It also has a high un-welded yield stress too, pretty much twice that of the 5000 series. But you have to be careful in selecting the correct grade and temper for use, others it’ll go wrong. Especially in terms of corrosion; avoid those with a high copper content, and note the differences in the ‘as-welded’ strengths.

 

Thanks Ad Hoc!
Yes I was definately mixing up the mangenese with Mengnesium.
Else I still think I am on track.
Still I think salt water will eat the 5052 before 5754.
The heat treatable 6000 serie can be very good but as Ad Hoc noted the more strength of theat treat will also make it easier to breake and get cracks in dynamic parts.