Aluminum Frame Question

[x25xquinton]

I'm looking into buying a 14 foot flat bottom jon boat. I've been watching and looking around for everything related to jon boat builds that i can. Was looking into framing in a sub floor, then moving up and framing a deck with the hatches and all. Im looking at using coosa board along with a tad of plywood if need be.

However my question mainly comes from the frame itself. The measuring and all that stuff i have no issues with, or even figuring out where i want it all and the layout and what not, that ill go and do what i want. But my concern is the support from the frame. Im a 6 foor 4, 235 lb guy and my buddy who goes with me is slightly smaller, so overall around 400ish lbs. I want to make sure the frame can hold that (Tbh it may just be me the majority of the time but just for safe purposes).

Ive been looking at doing the 1/16 1 inch angle all the way down either side. Then sort of build off of that. I was thinking about running 2-3 cross beams between these 2, then sort of figuring where i want my hatches and all to go. Then underneath these crossbeams put multiple supports vertically spread evenly through out, such as corners on hatches and etc.

My question mainly occurs here. For these crossbeams should i just use flat bar? angle combined with channel(square)? What about just square? Then what about the vertical supports underneath these cross beams? Should i do an angle combined with a square channel, or just an angle, or just a square? If its an angle would 1/16 be thick enough, or should i just go ahead and increase to the 1/8?

Weight isnt a huge concern because itll be 95% aluminum, and itll be on a trailer and what not. Money isnt the biggest concern either in a way because i just want it done correctly. I just want to make sure the frame is going to be strong enough without any slack and be durable. But i also dont want to over spend on doing to many support beams in general, and with the wrong material.

I was thinking about doing square for the vertical supports, and for the crossbeams use 2, 1/8th angles butted together so i have a nice edge on either side to work off of, along with enough room on either side for hatches and everything to sit on. Then that would leave me room underneath to use square for vertical support that run every so many feet or inches underneath these crossbeams? (wasnt sure if this was overkill, not enough, perfect? Dont want to use 2 1/8th inch angle for the crossbeams if 1 angle would be enough or 1 square, etc.)

(I.E.) 2 4 foot 1/8th inch angle butted together across 2 difference sections in the center. Then every 1 foot underneath these have a 1/4 square channel vertical beam connected to the crossbeam down to the subfloor?

If this isnt enough information or is confusing please let me know. Just trying to figure out the best way to use aluminum to frame the boat, making sure its strong enough but keeping it within reason when it does come to money and weight, just making dang sure its strong enough to stand on and all. Any info would be awesome!

 

[BigTerp]

I used 1" x 1" x 1/4" angle to frame the floor and front deck extension on my 1648. The floor and deck are .125" sheet. All plenty sturdy with the proper support between the framing. I added extra support around my captains seat and bow deck pin mount base using angle for the captains seat and square stock for the pin mount base. All is nice and sturdy. I'm 6'8" 240#'s, was over 280#'s at one point, an no issues with support.

 

[jethro]

I've never done a build like this but in my mind, heavy angle would be strong enough for what you want to do like Big Terp said. I would definitely bump to 1/4" over 1/8", huge difference in strength. Buy once, cry once.

 

[CedarRiverScooter]

1/4 is overkill IMO. 1/8 is pretty strong - it is the end connections that will fail if anything does. I notched & folded the flanges over to have double thickness at those points. Look at how bridges & other structures are built. Another consideration is how much flex you are willing to have.

 

[x25xquinton]

So you only used the 1/4 thickness angle for the main frame of the boat and built off that? What did you use for the "extra support" ? Like what sort of vertical support did you use if you used the 1/4 angle? And for the floor and deck? Did you do coosa or plywood over the sheet? Im doing a sub floor with aluminum and and a sheet of metal. Then framing the deck from that and using coosa board.

I used 1" x 1" x 1/4" angle to frame the floor and front deck extension on my 1648. The floor and deck are .125" sheet. All plenty sturdy with the proper support between the framing. I added extra support around my captains seat and bow deck pin mount base using angle for the captains seat and square stock for the pin mount base. All is nice and sturdy. I'm 6'8" 240#'s, was over 280#'s at one point, an no issues with support.

 

[x25xquinton]

Trying to understand 110% on this 1. I was thinking of using 1/8 aluminum angle. So you think just that alone for cross beams around the inner of the boat is enough? Then on the rivets fold them on the side of the cross beam and rivvet to the outer edge?

1/4 is overkill IMO. 1/8 is pretty strong - it is the end connections that will fail if anything does. I notched & folded the flanges over to have double thickness at those points. Look at how bridges & other structures are built. Another consideration is how much flex you are willing to have.

 

[BigTerp]

So you only used the 1/4 thickness angle for the main frame of the boat and built off that? What did you use for the "extra support" ? Like what sort of vertical support did you use if you used the 1/4 angle? And for the floor and deck? Did you do coosa or plywood over the sheet? Im doing a sub floor with aluminum and and a sheet of metal. Then framing the deck from that and using coosa board.

Yes, 1" x 1" x 1/4" angle to frame out my floor and deck extension. The floor didn't require much framing though. The existing ribs provided plenty of support. For my deck extension it was framed out with the same angle. The vertical framing was angle attached through the side of the hull with solid rivets. This framing was done for custom aluminum hatches that I had a board sponsor make. The hatches dropped right into my framing and were riveted down with closed end blind rivets. For the extra support of my captains seat I double the aluminum sheet underneath the seat base and attached the seat base through both pieces of sheet. I then made a frame out of angle that was recessed below the boat ribs by 1/8" and matched the square dimensions of the extra sheet used for my seat support. With the floor in place this framing supported the extra piece of sheet that I attached my seat base to. I then riveted this down to the recessed framing with closed end blind rivets. My pin mount seat base on the deck I simply took square aluminum stock from starboard to port under the deck and ran the seat base bolts through the seat base, deck and square stock. This was the only place I used square stock. Everything else was the 1" x 1" x 1/4" angle. My floor is just 1/8" aluminum sheet painted with Parkers duck boat paint and asper grit (traction additive).

Here is how I framed things out. Photobucket sucks, but you might be able to get an idea by the crappy pictures.
https://www.tinboats.net/forum/viewtopic.php?f=21&t=26774&start=180

 

[wmk0002]

As mentioned angle is the way to go. Its easy to work with since you can access the faces for connections and much lighter than square tub, channel, etc while plenty strong. I think 1/8" is plenty beefy as long as you have vertical supports where appropriate. As mentioned, the locations immediately around a joint are most likely where it will fail. Also keep in mind rivets are typically not intended to carry tension, only shear, so try to avoid that if you use them.

 

[x25xquinton]

So rivetting the vertical supports wouldnt be a good idea? Like if i use a 1/8th angle for vetical support, rivvetting the top and bottom wouldnt be good to secure it?

As mentioned angle is the way to go. Its easy to work with since you can access the faces for connections and much lighter than square tub, channel, etc while plenty strong. I think 1/8" is plenty beefy as long as you have vertical supports where appropriate. As mentioned, the locations immediately around a joint are most likely where it will fail. Also keep in mind rivets are typically not intended to carry tension, only shear, so try to avoid that if you use them.

 

[x25xquinton]

iM THINKING that i will be using 1/8th angle for all the frame when it comes to support, crossbeams and vertical support. Everything else where i can, such as hatch frames and all will be 1/16 attacthed to 1/8th angle.

 

[BigTerp]

So rivetting the vertical supports wouldnt be a good idea? Like if i use a 1/8th angle for vetical support, rivvetting the top and bottom wouldnt be good to secure it?

All of my supports/frame is riveted together with closed end blind rivets. My floor and deck extension are riveted to the supports/frame using closed end blind rivets. The vertical supports on the starboard and port side of my deck extension is riveted to the hull using solid rivets. Only place I used solid versus blind (pop) rivets. No issues in nearly 7 years.

 

[wmk0002]

That would be ok. I was just referencing to avoid tension in pop rivets when possible but that is kind of broad as every deck is framed different. I imagine it would be pretty unlikely any of your joints ended up loading them in tension.

So rivetting the vertical supports wouldnt be a good idea? Like if i use a 1/8th angle for vetical support, rivvetting the top and bottom wouldnt be good to secure it?

As mentioned angle is the way to go. Its easy to work with since you can access the faces for connections and much lighter than square tub, channel, etc while plenty strong. I think 1/8" is plenty beefy as long as you have vertical supports where appropriate. As mentioned, the locations immediately around a joint are most likely where it will fail. Also keep in mind rivets are typically not intended to carry tension, only shear, so try to avoid that if you use them.