How big should the aluminum pieces be that you put down?

[Jeffrey]

Put down for decking that is.

I found a guy that can weld aluminum for a good price. I am thinking of cutting the aluminum and using enough rivets to hold it in place and then let this guy weld it.

If I put down the largest sheets that I can manage, it would result in a clean look, but would have fewer exposed ribs to weld to. Less welding to do. Might give a bit of bounce to the floor

If I cut the aluminum into smaller pieces, could weld to every rib but might not be as clean of a look overall. Would also result in quite a bit more welding. Would be more solid.

How many ribs can you span to make it just right?

 

[johnnybassboat]

Jeffrey your welder could probably button hole weld on the ribs even with a big sheet. A button hole weld is where a hole is drilled through the sheet on top to expose the metal underneath then the hole is welded shut with penetration into the lower metal, in this case the ribs. Holes in top sheet are usually about quarter inch in diameter. My opinion is that bigger sheets are better, but just mho. Only reason to use small sheets is because you got them cheap, in which the labor to join them would offset the cost savings,or to allow access to what ever is underneath. sorry for the rambling reply hope it helps.

 

[Jeffrey]

Your reply is spot on. Thanks! I am starting to get a good idea as to the direction I want this project to go. I have gotten quite a bit of direction from the more experienced tin boaters on this site, so I owe a word of thanks to several people, yourself included.

 

[cva34]

only problem i see with welding floor down is if you ever need to get under it for repairs or mods..My boat is john its hull is all welded.With that being said.the bow deck/platform is welded in..and a seat is welded in across back,so it could be a tiller motor if wanted..and or seat for C Console..That leaves a 5' wide X 7' area midship ..I recently removed the 1 piece 1/8 sheet that was pop rivited in place from factory..Drilled out the alu pop rivets (lots) and removed by myself..It wasn't that bad...That gave me access for needed repairs.Then put it back Pop rivited it in ..Just last week I sprayed Total interior with TuffCoat..Once tht dries I will set the C Console in and rivit it in...The boat is a 93 mod and lots use and abuse..Never found a rivet that held down floor or console that had failed when I was takeing it apart..jus my 2C ...cva34

 

[Jeffrey]

The welder that looked at my transom said that he would not recommend welding the deck down. He liked the idea of welding the structural support that would be beneath the decking, but he said it wouldn't be bad to screw it either. He liked those rivet nuts.

 

[cva34]

Rivet nuts are OK But once you put the bolts/screws in, and there there for years they refuse to come out...Pop rivets alu on the other hand, take drill with proper size bit and in a few sec its over(that center dimple centers bit too)..The bolt or screw in the other hand require minutes of drilling and centering is a problem ..Of course you can twist them off.Then you still get stump out..Alu/Alu pop rivets are Cheap and fast...Not sure of price on rivit nuts but stainless and or alu screws and or bolts aint cheap My 2c worth...cva34

 

[Jeffrey]

In your collective experience, do aluminum rivets stay tight over time or do they stretch out and become loose?

I guess it depends on various factors, but what can I expect?

 

[muskiemike12]

If you get some loose rivets you can drill them out and pop new ones back in. I would rivet the whole deck if it were mine.

 

[cva34]

Lets put it this way the 5x7 sheet I removed had 3/16 alu/alu pop rivets .Ribs were spaced 12" and rivet spaced every 6" down length of ribs...This was factory installed and never been removed The boat is 93 and used in salt bays(Big) its entire life..And no loose or broken rivets...Yes over the years on diff boats I see broke or stretched or loose rivets...But like muskiemike said just drill them out and pop a new one in..cva34

 

[Windman7]

Some good points on temporary fastening for maintenance. As a thought on large sheet verses small sheets. Small sheets creates what is called a simple span. In other words, it is only supported by the ends. When you use a large sheet, you create what is called a multi-span. The outside spans are still a simple span on the outside edge, but the middle is supported by each rib as it stretches over multiple ribs. It is much stronger to be a multi-span.

 

[BarHum]

Put down for decking that is.

I found a guy that can weld aluminum for a good price. I am thinking of cutting the aluminum and using enough rivets to hold it in place and then let this guy weld it.

If I put down the largest sheets that I can manage, it would result in a clean look, but would have fewer exposed ribs to weld to. Less welding to do. Might give a bit of bounce to the floor

If I cut the aluminum into smaller pieces, could weld to every rib but might not be as clean of a look overall. Would also result in quite a bit more welding. Would be more solid.

How many ribs can you span to make it just right?

Saw this post and couldn't help but chime in... This would be my opinion from an aluminum boat builder's perspective.

- Generally plug welding (drilling holes in the sheet and welding through the holes to the ribs) will usually crack out over time unless you're using substantial material. Welding hardens the aluminum around the spot weld and then the expansion/contraction of the sheet over time generally cracks the weld on FLAT sheets that tend to bubble, such as the floor. (your welder was correct)

- Cutting small pieces and welding in between the ribs will result most likely in a bubbled floor. The heat from the welding, which will have to be stitched, not solid will usually warp the sheet.

- Most boat builders use aluminum rivets, as they do provide some "play" for the natural expansion/contraction of aluminum and the wavy-ness of flat sheet that is repeatedly walked upon. Plug welds do not provide this, and coupled with the hardening will crack on thinner flooring (usually).

- You could use Stainless steel self drilling screws instead of rivets, but with time they will cause some corrode the aluminum they're in and you'd have a fun time getting them out. Also if they break off, you can't drill them out easily like rivets. They're also pricey.

- Make sure your rivets are Aluminum WITH aluminum mandrels. Steel mandrels will rust and discolor any carpeting you put over it.

- The flooring isn't a structural component of most boats, so I wouldn't be too concerned about loose rivets over time other than for cosmetic reasons. Properly fastened rivets (with an pneumatic gun) on reasonable-thick floors with proper support (10-12" spaced ribs) shouldn't loosen too much over time.

Hope that might help.