Aluminum Angle or wood for structure?

[hockeyfish]

hey i'm thinking of starting to rebuild my 14' aluminum boat and i was just wondering what would be better to make all the flooring and what not, should i use aluminum angle for all the structure and bracings? ive read over many boat conversions and i see both used, is aluminum angle better because you dont have to worry about sealing it as you would need to for the wood?

any responses would be great,
thanks a bunch

 

[Dragonman]

Aluminum is lighter, stronger, and does not need to be coated.

 

[mmf]

when you use aluminum, you never do it again, go aluminum and always use stainless fasteners in a boat. Do NOT use regular or galvanized steel on anything in a boat, if you use wood and your boat gets wet on the interior, you will be doing it all over again in about 5 years. I'm all for doing it once and not worrying about it again!

 

[shawnfish]

i would use square stock if i was you instead of angle.

 

[Captain Ahab]

when you use aluminum, you never do it again, go aluminum and always use stainless fasteners in a boat. Do NOT use regular or galvanized steel on anything in a boat, if you use wood and your boat gets wet on the interior, you will be doing it all over again in about 5 years. I'm all for doing it once and not worrying about it again!

X2

 

[bcbouy]

aluminum if only to save weight.if i'd have used wood on mine it would be rediculously heavy,that means more gas,more motor less freeboard,plus aluminum is really solid.i used angle and square tube.

 

[atuck593]

I think aluminum is the better way to go as well. I used it on my build and it was easy to work with. The only down side is that it can be expensive. I went to Lowe's and Home Depot first to start pricing and almost cried when I saw the price. After some research I found a scrap/ surplus yard about an hour away from where I lived that sold the aluminum by the pound. It was like a $1 a pound wayyyy cheaper than any retail place. I would check in your area for a place like that even if it is a drive you will still save money in the long run.

 

[BassBlaster]

Not to hijack this fellas thread or anything but I have another question on the same subject. I am also getting ready to start my decking in the next couple weeks and will be doing an all aluminum build. I see where someone said to only use SS fasteners. I did use stainless for my transom as I know thats best but is the same true for the aluminum frame work? The local Ace hardware store is going out of business and everything in the store is half price so I went and purchased a bunch of supplies. I purchased every pack of aluminum rivots they had. Should I be looking to use stainless rivots and if so why are the alumnum not ok? Are they just not strong enough maybe?

 

[Brine]

Not to hijack this fellas thread or anything but I have another question on the same subject. I am also getting ready to start my decking in the next couple weeks and will be doing an all aluminum build. I see where someone said to only use SS fasteners. I did use stainless for my transom as I know thats best but is the same true for the aluminum frame work? The local Ace hardware store is going out of business and everything in the store is half price so I went and purchased a bunch of supplies. I purchased every pack of aluminum rivots they had. Should I be looking to use stainless rivots and if so why are the alumnum not ok? Are they just not strong enough maybe?

Aluminum are fine. Just engineer it so the rivets aren't placed in sheer whenever possilbe. Even the SS should be done that way.

 

[architorture]

Not to hijack this fellas thread or anything but I have another question on the same subject. I am also getting ready to start my decking in the next couple weeks and will be doing an all aluminum build. I see where someone said to only use SS fasteners. I did use stainless for my transom as I know thats best but is the same true for the aluminum frame work? The local Ace hardware store is going out of business and everything in the store is half price so I went and purchased a bunch of supplies. I purchased every pack of aluminum rivots they had. Should I be looking to use stainless rivots and if so why are the alumnum not ok? Are they just not strong enough maybe?

You'll be fine with aluminum rivets as long as they are at least 1/8". 3/16 would be quite a bit stronger and if you have some of those I would use those. If you have an area with high shear stress, I would only use 3/16 aluminum or stainless. You'll probably have to order the stainless. I ordered some 3/16 aluminum sealing blind rivets from mcmaster carr that had a steel mandrel, which makes them a lot stronger. Stainless are about 5x the cost of those, so I didn't see them as worth it. Here's a link to the site I order mine off of, which gives a chart for their strength. Hope this helps, -Tucker

 

[hockeyfish]

ya i was leaning towards aluminum anyways just wanted to make sure it would be the best way to go. and as for the aluminum what size should i use? i want to save as much money as i can but at the same time i want my structure to be strong to hold me and whoever i will have with me.

also when im planning on securing the structure to the boat, I’ve seen both people screwing into the ribs of the boat and riveting to the boat. should i do both? as in screw into the ribs and then rivet to the boat above the water line?

this is going to be my first time rebuilding my boat so i just want to make sure i do it right

 

[shawnfish]

sheer stress?????

 

[atuck593]

ya i was leaning towards aluminum anyways just wanted to make sure it would be the best way to go. and as for the aluminum what size should i use? i want to save as much money as i can but at the same time i want my structure to be strong to hold me and whoever i will have with me.

also when im planning on securing the structure to the boat, I’ve seen both people screwing into the ribs of the boat and riveting to the boat. should i do both? as in screw into the ribs and then rivet to the boat above the water line?

this is going to be my first time rebuilding my boat so i just want to make sure i do it right

I just rivited the aluminum frame right to the ribs. I didn't use screws for anything except to screw the wood decking to the aluminum framework for the final step.

sheer stress?????

Sheer stress I believe would be the rivet being cut in half by the two pieces of metal it is holding together. It should say on the package what the limit for each rivet would be. I think the rivets I used had a sheer stress of 200 - 300 lbs per rivet. I can't remember the specific weight.

 

[bcbouy]

when i was in doubt, i doubled up on the rivets where i could (3/16) and screwed as well. on the bright side,my wife is the office manager of a machine/fab shop,so my build was really cheap.fyi, i used way more s/s screws than i thought i would,all told around 150 or so.

 

[Brine]

sheer stress?????

Yes, but I mispelled it. Shear stress, as it pertains to most framing mods, is the perpendicular (usually downward) force applied to the rivet. If you plan out your framing, you can dictate how much "stress" is put on the rivets. I don't think I have any that were placed "in shear" (meaning that the rivet is solely responsible for bearing the force) in my build. Instead, I tried to have the rivet simply be a fastener of the two pieces and let the material itself bear the stress.

Hope that makes sense. There are pics in my build that should show this. I'll see if I can dig some up.

 

[Brine]

Here are a few pics showing the different types of stress.

Pic #1 (albeit not perpindicular stress) shows how the rivet heads used to attach the cross members are bearing all of the weight if you were to stand on them.

This pic shows some of the uprights (namely the center one just forward of the pedestal base) has the top rivets placed in shear

And here is a topic I dug up when I was asking about the same thing with said pics. Of course I didn't find it until I had posted the 2 pics above #-o :LOL2:

https://www.tinboats.net/forum/viewtopic.php?f=3&t=7027

 

[Ranchero50]

I'm pretty sure shear stress is the scissors action of your two plates moving against each other. Example being using a set of wire strippers to shorten a 8/32" machine screw. Thread them in the stripper and shear the bolt off by squeezing the handle.

Forgot the other term for the plates pulling apart but that's what the top picture shows. The seat brace section in particular is a poor design. Those angles should be on top of the angle running the width of the boat. As it is all the vertical load stress is on those rivets and they will fail from the seat movement.

Jamie