stumbled across this video tonight...
https://www.youtube.com/watch?v=qnhhsDwBEkQ
thoughts?
welded vs riveted?
-
kmorin
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- Location: Kenai, Alaska
Re: welded vs riveted?
slug,
as a long term welded hull designer, builder, welder, user, and having repaired both welded and riveted hulls I'd make a few remarks. Basically we're not talking apples to apples, these are my thoughts.
The video has some good points in regard both methods of building but....
The Dialog is very deficient in actual real world facts. The fact is you can’t reasonably rivet a scantling the same size as can be welded- with any affordable cost- image the riveting scheme for 1/4” plate to 1/4” or 3/16” plate or a comparable chine extrusion that would join those two plates? Also, the narrative concept that a pounding riveted hull will distribute the impact forces uniformly is not accurate. Why then do OLD riveted seams ‘wear’ out? Well, the loading ‘wallows’ the riveting holes and the seams open up- just a matter of time in the described pounding scenario. Also compression of the rivets can loosen and then the hull leaks.
If used in a tiny pond lake with 1/4 mile fetch, the riveted boat may last forever? Great use of highly machined thin sheet aluminum. But there are no off-soundings 26-40’ riveted hulls with a marine survey comparable to a welded hull of the same size and displacement.
Note that only small, and light scantling boats, are riveted. And the economics are to make hundreds of hulls the same as one another? While welding can afford a one-off design and still last for longer than press-formed hull panels riveted in rubber strip sealed hulls. All said; I found the discussion was very tailored to misrepresent the overall performance of the two classes of boats.
Welded boats- properly designed and built will weigh much more than riveted hulls but the idea they crack from pounding is to focus on the poorly designed or improperly built hulls. Lots of examples in the conversation shared in the video try to compare welded hulls to riveted structures in other vehicles and those comparisons aren’t valid for many reasons.
For example the skin of a truck cab and riveted boats are very thin. Welding very thin material without distortion is extremely difficult to do for the average welder (this may change with laser or laser robotic welding?) But cold joining those seams in paper thin aluminum, with calk in the joints to seal them in lieu of welding, will keep the original material looking good and therefore less work to prepare a saleable product.
However, those super thin riveted structures aren’t in impact with waves at 30 mph where the parent material needs to be 0.25” thick compared to 0.060” thick.
What is Lloyd’s of London’s Highest AAA insurance category for marine hulls? I don’t think it includes riveted 200’ yachts?
Since the video is an ad for a product.... it naturally tries to ‘sell’ the product over others.
Just my few cents, I find each product series has a place in the boating marketplace. Contrary to most wives and some fishermen; a man needs a boat for each type of water he'll float or fish. One for the ocean and that maybe both inshore and off-soundings (2 boats), one for narrow, shallow creeks, and one for any other specific conditions of water that will be enjoyed, like river boats, or speed boats.
Cheers,
Kevin Morin
Kenai, AK
as a long term welded hull designer, builder, welder, user, and having repaired both welded and riveted hulls I'd make a few remarks. Basically we're not talking apples to apples, these are my thoughts.
The video has some good points in regard both methods of building but....
The Dialog is very deficient in actual real world facts. The fact is you can’t reasonably rivet a scantling the same size as can be welded- with any affordable cost- image the riveting scheme for 1/4” plate to 1/4” or 3/16” plate or a comparable chine extrusion that would join those two plates? Also, the narrative concept that a pounding riveted hull will distribute the impact forces uniformly is not accurate. Why then do OLD riveted seams ‘wear’ out? Well, the loading ‘wallows’ the riveting holes and the seams open up- just a matter of time in the described pounding scenario. Also compression of the rivets can loosen and then the hull leaks.
If used in a tiny pond lake with 1/4 mile fetch, the riveted boat may last forever? Great use of highly machined thin sheet aluminum. But there are no off-soundings 26-40’ riveted hulls with a marine survey comparable to a welded hull of the same size and displacement.
Note that only small, and light scantling boats, are riveted. And the economics are to make hundreds of hulls the same as one another? While welding can afford a one-off design and still last for longer than press-formed hull panels riveted in rubber strip sealed hulls. All said; I found the discussion was very tailored to misrepresent the overall performance of the two classes of boats.
Welded boats- properly designed and built will weigh much more than riveted hulls but the idea they crack from pounding is to focus on the poorly designed or improperly built hulls. Lots of examples in the conversation shared in the video try to compare welded hulls to riveted structures in other vehicles and those comparisons aren’t valid for many reasons.
For example the skin of a truck cab and riveted boats are very thin. Welding very thin material without distortion is extremely difficult to do for the average welder (this may change with laser or laser robotic welding?) But cold joining those seams in paper thin aluminum, with calk in the joints to seal them in lieu of welding, will keep the original material looking good and therefore less work to prepare a saleable product.
However, those super thin riveted structures aren’t in impact with waves at 30 mph where the parent material needs to be 0.25” thick compared to 0.060” thick.
What is Lloyd’s of London’s Highest AAA insurance category for marine hulls? I don’t think it includes riveted 200’ yachts?
Since the video is an ad for a product.... it naturally tries to ‘sell’ the product over others.
Just my few cents, I find each product series has a place in the boating marketplace. Contrary to most wives and some fishermen; a man needs a boat for each type of water he'll float or fish. One for the ocean and that maybe both inshore and off-soundings (2 boats), one for narrow, shallow creeks, and one for any other specific conditions of water that will be enjoyed, like river boats, or speed boats.
Cheers,
Kevin Morin
Kenai, AK
kmorin