Originally Posted by johnw
Originally Posted by EthanEdwards
Originally Posted by Idaho_Shooter
Originally Posted by boatboy
Following this

Keep in-mind not all welded boats are created equal

The blanket statement welded better is not really true
I can be, but not always

Hank

There's welding, and then there's welding.

More importantly, there's Aluminum, and then there's Aluminum.

Aluminum alloys come in various grades. Some hard, some soft, some brittle, some ductile.

Just as an example, the first boat I bought to take the G-kids fishing in was a little 14 foot Shasta with an 18 hp Merc. When I started drilling holes in the hull to mount rod holders and such, the Aluminum cut like butter. When we took the boat out on Brownlee Res and the wind came up in the morning at sunrise, the floor would visibly flex with impact of every wave. Within a half dozen outings, the floor had cracked at each flex point and water was coming in.

Brownlee is the first dam at the head of Hells Canyon. The lake averages maybe 1/4 to 1/2 mile across. But it is about 40 miles long. Each morning at Sunrise the breeze kicks up and produces six to eight inch chop.

We fished from the Shasta for two years, and periodically hit the switch on the bilge pump to remove the water.

Then I bought a 16 foot Lund hull. I built a console into it and put my little Merc 18 on it. Drilling holes in the Lund was night and day difference from the Shasta. The wall thickness was very similar, but the Aluminum in the Lund was much harder.

In the same lake, under the same conditions, there was no flex in the Lund hull.

You will find the same to be true of welded boats. Some are constructed of superior, expensive Aluminum alloys. Some are made of less expensive alloys, and are more prone to stress cracks or heat damage along weld lines.

Most of the better built boats will tout their alloys in their advertising copy. It pays to become familiar with the alloys, or at least know how examples of the boat model has performed for others before investing a large sum of hard earned money.
Or to sum it up, welds can crack and leak too.


Proper alloy selection combined with correct welding process can give some incredibly durable metal joints. HAZ in the weld joint can be reduced through lazer or cold metal pulsed welding, but base metal thickness is limited to around .100 IIRC.

Most fab shops won't be set up for these welding processes and I'd guess that most of the semi custom boats rely on heavier section metal and a spool gun.

I'd wager that .100 of 5083 alloy, welded with a low HAZ process would suffice for almost any use that didn't involve regular violent contact or extreme abrasion. If I were going to boat in extreme conditions, I'd feel better about heavier section metal and archaic welding process. Repair as needed.

If one could only predict violent contact with a rock or something..... LAFFIN...am I the only one that eats MRES....?

Last edited by johnn; 04/03/20.

For those without thumbs, it's s Garden fookin Island, not Hawaii