Aluminum Hull - How Thick is Too Thin?

I am deciding between some short (10’ - 12’) Jon boat options. Most of the hulls are either 0.08” (2.0 mm) or 0.063” (1.6 mm). One manufacturer, Marlon, builds boats out of 0.047” (1.2 mm).

The boat will not be used for anything rough, but I would like a long-lived boat. Is a worry that 0.047” is too thin well-founded?

 

...or, How Thin Is Too Thick?

Is any worry well founded?
I think not. A concern maybe.
Yes, I would be concerned with 0.047".

 

If you carry the boat on top of your truck and carry it, the lighter one would be my option. On a trailer, the thicker would be my choice.

 

The thinnest gauge Marlon boat is this one - I guess that this is the one that you are considering?
They mention that the dry weight is 105 lbs - easily manageable if there are two of you, but more difficult if you have to put it on or off your truck roof rack single handed.
Marlon Recreational Products - Marlon SP1049 Jon Boat https://marlonproducts.com/products/marlon-boats/marlon-aluminum-jon-boats/marlon-sp1049-jon-boat/

From the photos the hull bottom and sides appear to be corrugated (with the corrugations forming effective stiffening).
Even though the bottom thickness is 'only' 1.2 mm, I think that you would be hard pressed to puncture it in 'normal' usage - but if you slam it down hard on a pointy granite rock at speed then there is more chance of holing it.
Even so, it is probable that the ally shell might just be dented rather being torn - aluminium plate is strong stuff.

The cambered aft canopy of the cat in my avatar photo is made from 1.2 mm thick plate - the unsupported panel size of this roof is much larger than that of the Jon Boat in the link above, yet the crew of this boat can easily and safely walk on it (without it deflecting or buckling) from the flying bridge if they want to check what is behind them if they have to reverse.
And this roof still looks like new 25 years after it was built.

 

Are they all built from the same alloy, and internally braced equally?

Aluminum Yield Strength & Tensile Strength Chart https://amesweb.info/Materials/Aluminum-Yield-Tensile-Strength.aspx

 

That’s the Marlon in question. It is made in China, and has rivets on the seat to hull connections. The main rival is NEW 2025 MODEL — Lifetimer Boats https://www.lifetimerboats.com/new-page-2 a customizable, Canadian-made, all-welded boat. Weight is ~ 150 lbs. The Lifetimer is sold direct to consumer and is approximately the same price as the Marlon, which is sold through retailers.

If the Marlon’s hull was “too thin” the decision would be easy. So now, it comes down to the weight difference versus the build quality, etc., differences.

My current thinking is that, at some point when I am older, I will need a mechanical handling system either way, so the difference in weight will be less relevant.

 

The Lifetimer is 5052. I had formed the impression that the Marlon was 5052 as well, but there is no mention of the alloy in anything I could find.

Re-examining assumptions is often valuable - thank you.

 

If it is not stated in the information then it would be a reach to assume that it is 5052.

.047" is very thin. If you should happen to need a repair in the future the .047 will be a challenge
We had been asked many times to repair riveted boats but almost always had to refuse as we could not weld near the mastic that some boat builders used at the overlap joint.

If weight is not an issue, go to the Lifetimer.

 

Totally agree - an error on my part.

Lighter would be better, but the tradeoffs favour the Lifetimer.