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Boat Forum / Building / December 2007Aluminum Designs
Anybody know of any all aluminum designs (no wood composite or sandwich) available for sale for a shallow draft semi tunnel for river running? I can modify if need be, but I ain't gonna put no wood in it if I build it. Well, maybe for totally non structural stuff, but I doubt it. I'm trying to talk Mrs Santa into getting me a 60% duty cycle MIG w/ spool gun for Christmas.  SignatureBob La Londe Fishing Arizona & The Colorado River Fishing Forums & Contests http://www.YumaBassMan.com -- Posted via a free Usenet account from http://www.teranews.com >Anybody know of any all aluminum designs (no wood composite or sandwich) >available for sale for a shallow draft semi tunnel for river running? I can [quoted text clipped - 3 lines] >I'm trying to talk Mrs Santa into getting me a 60% duty cycle MIG w/ spool >gun for Christmas. Uh-oh: you said "aluminum boat" and "MIG welder" really, really, casually. Tell me you have MIG welded aluminum before - that you have the right mask screen, that you can not only stitch thick aluminum castings together, but you have seamed sheet as well..... Brian W >Uh-oh: you said "aluminum boat" and "MIG welder" really, really, >casually. >Tell me you have MIG welded aluminum before - that you have the right >mask screen, that you can not only stitch thick aluminum castings >together, but you have seamed sheet as well.... Place I do my boating has lots of fifty year old aluminum boats, none of which have ever had paint or maintainance of any kind. All are riveted. Grumman canoes are riveted and they get bounced off the rocks regularly, if they are used in white water. I don't think welding is really suitable for anything under forty feet. Metal is too thin. Note that all those airliners are riveted. Casady >>Anybody know of any all aluminum designs (no wood composite or sandwich) >>available for sale for a shallow draft semi tunnel for river running? I [quoted text clipped - 8 lines] > Uh-oh: you said "aluminum boat" and "MIG welder" really, really, > casually. There are some things about mig aluminum welding that a lot of people don't realize... 1st - Its really hard to do a good job with a cheap welder like the 120V 20amp 10/20% duty cycle things with only two heat ranges like they sell at Harbor Freight. I'm looking at a Hobart Ironman 250. I already got one of those cheap ones. Figured I'ld use the push feed gun for steel and a spool gun for aluminum so I wouldn't ever have to worry about gun/tip contamination. 2nd - You have to burn some metal to get it dialed in just right. I got scrap laying around from some other things I can burn up. 3rd - Use a clean stainless brush on all surfaces just before welding to break up and remove the oxidation. Never use your brushes for aluminum on ANYTHING else. Brushes are cheap insurance. USE THEM EVERYTIME even if you brushed it yesterday. 4th - A spool gun is the way to go, but even with a push feed gun its possible to push aluminum if you swap out the V groove feed wheel for a U groove feed wheel. The V groove wheels shave the soft aluminum wire causing it to plug up the feed tube and your gun. 5th - There is no 5th item. 6th - if for ANY REASON the wire doesn't feed STOP. Otherwise you will you will have a wad of crammed up aluminum wire someplace in your rig. 7th - Practice and warm up for a few minutes on some scrap EVERYTIME before you start on your cut pieces. (Thats a good idea on steel too.) > Tell me you have MIG welded aluminum before - that you have the right > mask screen, that you can not only stitch thick aluminum castings > together, but you have seamed sheet as well..... Nope, I'm not super experienced, but I got a pile of scrap aircraft aluminum to practice on. I've played some with aluminum, and I don't plan on using a cheap rig. I've used some of the torch alloy stuff too, but its really only suitable for small work. I have a variable shade autodarkening mask, and I use it for everything. I even use it for cutting. I just lighten the shade up. And worse comes to worse... I can alway learn to install blind rivets. LOL. SignatureBob La Londe Fishing Arizona & The Colorado River Fishing Forums & Contests http://www.YumaBassMan.com -- Posted via a free Usenet account from http://www.teranews.com ... >> Uh-oh: you said "aluminum boat" and "MIG welder" really, really, >> casually. [quoted text clipped - 9 lines] >possible to push aluminum if you swap out the V groove feed wheel for a U >groove feed wheel.... >5th - There is no 5th item >Bob La Londe This seems like a plan to me: the story I hear quite often is that the hot puddle will drop out given half a chance on thin stock. A particular optical filter is said to be a big help in visualizing the puddle's state. Good luck! Brian W >... >>> Uh-oh: you said "aluminum boat" and "MIG welder" really, really, [quoted text clipped - 20 lines] >A particular optical filter is said to be a big help in visualizing >the puddle's state. THere have been at least a million aluminum airplanes produced. All were riveted. Wonder why? Casady >>... >>>> Uh-oh: you said "aluminum boat" and "MIG welder" really, really, [quoted text clipped - 23 lines] >THere have been at least a million aluminum airplanes produced. All >were riveted. Wonder why? Lowest bidder? >>>... >>> [quoted text clipped - 26 lines] > > Lowest bidder? not hardly. Best fastner for the material. >>>THere have been at least a million aluminum airplanes produced. All >>>were riveted. Wonder why? [quoted text clipped - 4 lines] > >Best fastener for the material. Rivets were the best fastener for ships until they started welding plates (then a few Liberty ships sank before the subs got 'em.) Brian W >>>>THere have been at least a million aluminum airplanes produced. All >>>>were riveted. Wonder why? [quoted text clipped - 9 lines] > >Brian W Most of the high strength aluminum alloys are not weldable. See Materials specification for 2024 - one of the more commonly used aircraft alloys: Welding Welding may be done by use of resistance welding or inert gas consumable electrode arc method. However it must be noted that, in general, welding by any means is NOT recommended for this alloy because of the degradation of corrosion resistance that occurs as a result of weld heat. A repeat heat treatment should be done if welded. Bruce-in-Bangkok (Note:remove underscores from address for reply) >>Rivets were the best fastener for ships until they started welding >>plates (then a few Liberty ships sank before the subs got 'em.) [quoted text clipped - 4 lines] > >See Materials specification for 2024 >Bruce-in-Bangkok I marvel that people thinking about aluminum sheet invariably think of 2024. There are stronger materials now available, but weaker materials are often useful. But one other factor mitigating against welding is the top coat of soft aluminum which helps the sheet resist corrosion. Brian W >>>Rivets were the best fastener for ships until they started welding >>>plates (then a few Liberty ships sank before the subs got 'em.) [quoted text clipped - 14 lines] > >Brian W The question was about why airplanes were riveted and I believe that 2024 is still used in the aircraft industry although I think it is all alclad, as you say. Bruce-in-Bangkok (Note:remove underscores from address for reply) >>>>>THere have been at least a million aluminum airplanes produced. All >>>>>were riveted. Wonder why? [quoted text clipped - 11 lines] > >Most of the high strength aluminum alloys are not weldable. Yes, of course. There are weldable alloys that make a very nice boat and they are easily weldable if the plates are thick enough. Rozema in Seattle makes a nice forty foot power boat. Yacht or oil skimmer, same fittings and workmanship. The same good cabinet latches are on the workboat. There are otters living under the building and you can watch them from the breakroom. Casady For boatbuilding, you will want to use the 5000 and 6000 series alloys. See Pollard's book, Boatbuilding with Aluminum http://www.amazon.com/Boatbuilding-Aluminum-Stephen-F-Pollard/dp/0070504261 . NEVER use aircraft or other alloys, especially for use in salt water. These alloys, down to about 3/16 thickness, can be welded. 1/8 is trickier, and lighter gauge requires very specialized knowledge, experience, and equipment, generally not appropriate for small-scale boatbuilding. > See Materials specification for 2024 - one of the more commonly used > aircraft alloys: >>>Anybody know of any all aluminum designs (no wood composite or sandwich) >>>available for sale for a shallow draft semi tunnel for river running? I [quoted text clipped - 54 lines] > And worse comes to worse... I can alway learn to install blind rivets. > LOL. Trust me, you can't really push aluminum well enough to weld a decent seam. I have the Ironman210, and even with the teflon liner, it balls and birdsnests easily unless the gun is straight out from the welder. Even then, it'll only skip once, and then you gotta get out the cutters. Spoolgun is the way to go. I don't care what they told you. Signature“TANSTAAFL” ____________________________________________________________________________ America: Ironically, the safest place to be anti-American. ____________________________________________________________________________ "A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3 Any plywood design can be modified for aluminum. You need a design that will be OK with some weight, as 1/8 aluminum weighs about the same as 3/4 ply. even 1/8 can be a bear to work with, I wouldn't be optimistic for the chances of success with any thing lighter, unless you have a LOT of experience. I'm not sure what you mean by "semi tunnel" but I built an Atkin Rescue Minor with fully protected prop and rudder. Or you can modify the transom of any skiff to give you a bit of a tunnel effect with an outboard - at the loss of some "lift". Can you provide a link to pictures of the kind of boat (in wood or glass) you are thinking of? Sal's Dad > Anybody know of any all aluminum designs (no wood composite or sandwich) > available for sale for a shallow draft semi tunnel for river running? I [quoted text clipped - 3 lines] > I'm trying to talk Mrs Santa into getting me a 60% duty cycle MIG w/ spool > gun for Christmas. >as 1/8 aluminum weighs about the same as 3/4 >ply. If you divide 2.7, the density of aluminum, by 6, you get .45. I thought plywood was heavier than that. Casady >>as 1/8 aluminum weighs about the same as 3/4 >>ply. [quoted text clipped - 3 lines] > > Casady plywood floats. Aluminum don't. What am I missing here? >>>as 1/8 aluminum weighs about the same as 3/4 >>>ply. [quoted text clipped - 9 lines] > >What am I missing here? A clue. Casady >>>>as 1/8 aluminum weighs about the same as 3/4 >>>>ply. [quoted text clipped - 13 lines] > > Casady I thought most aluminum alloys weighed in at .1 pound per cubic inch. Except 6061 which is only .09 lbs/cu.in. Ply was .025 to .033 lbs/cu.in. So clue me in. >>>>>as 1/8 aluminum weighs about the same as 3/4 >>>>>ply. [quoted text clipped - 20 lines] > >So clue me in. I simply questioned if aluminum was in fact exactly six times as dense as plywood. That is what you get with sheets six times as thick weighing the same. That would make the density of plywood .017.lb/cu. According to you it isn't. I simply opined that most plywood does not have that particular density. What don't you understand? And I am sorry about the cheap shot. It isn't really my style. I have the 'calculator that takes no prisoners',HP-48, and it isn't a problem but it is usual to express wood density as pounds per cubic foot, in the US, at least. Density figures in general are usually with reference to the density of water. Casady >>>>>>as 1/8 aluminum weighs about the same as 3/4 >>>>>>ply. [quoted text clipped - 33 lines] > > Casady Accepted, thanks. >>as 1/8 aluminum weighs about the same as 3/4 >>ply. [quoted text clipped - 3 lines] > >Casady It may be. Black ash 0.54 Birch 0.67 red cedar 0.38 (!!) see the table here... http://woodsgood.ca/woodDensity.htm Regards Brian W There are lots of sources of materials density out there. http://www.rfcafe.com/references/general/density_building_materials.htm shows: Aluminum at 171 lb/cu ft. Divide by (12*8) to get approx. 1.78 lb/SF for 0.125 aluminum. Plywood (5/8 thickness construction grade) is 1.77 lb/SF (or 34 lb/cu ft) So I stand corrected. 1/8 aluminum weighs about the same as 5/8 construction grade ply. Maybe, when I calculated this a few years ago, I used a different grade or species of plywood, or alloy of aluminum - I honestly don't recall. But either way, it gets you into the ballpark. There are relatively few elegant small boat designs using material this heavy. Sal's Dad >>as 1/8 aluminum weighs about the same as 3/4 >>ply. > > If you divide 2.7, the density of aluminum, by 6, you get .45. I > thought plywood was heavier than that. >Aluminum at 171 lb/cu ft. Divide by (12*8) to get approx. 1.78 lb/SF for >0.125 aluminum. >Plywood (5/8 thickness construction grade) is 1.77 lb/SF (or 34 lb/cu ft) > >So I stand corrected. 1/8 aluminum weighs about the same as 5/8 construction >grade ply I thought a figure was a bit high. It is, slightly, but had I known the difference was a small as it is[I will take your figures] I don't think I would have bother to post anything. It did smoke out some interesting figures. Plywood tends to be about as dense as the wood it is made from, it seems. The texts seem to give the density of woods in pounds per cubic foot but with a modern calculator[HP48] any and all units are convenient. Casady > I'm not sure what you mean by "semi tunnel" but I built an Atkin Rescue > Minor with fully protected prop and rudder. Or you can modify the transom > of any skiff to give you a bit of a tunnel effect with an outboard - at > the loss of some "lift". There are some "tunnel" designs for running an outboard a few inches higher that just have a small tunnel at the rear of the boat. When I was really reading a lot about boat building a few years ago I recall reading about some of them. SignatureBob La Londe Fishing Arizona & The Colorado River Fishing Forums & Contests http://www.YumaBassMan.com -- Posted via a free Usenet account from http://www.teranews.com I modified my Bolger Diablo along those lines - It had a 20" transom, and I wanted to run a "short shaft" outboard. It worked ok 90% of the time, but ventilated like h3!! when accelerating. So I cut a notch out of the bottom - maybe 2 or 3" high into the transom, 16 " forward into the bottom panel, and 8" wide. Sort of a mini-tunnel. I'm sure this causes a small degradation in performance, but gains me a few inches of draft. I'm sure you could take any skiff design, with a flat bottom, and play around with this. I would start with a really deep tunnel, and high transom. If that seems too much, just cut down the transom (and glue foam into the top of the tunnel) until you get the desired performance. You might be surprised. But, if you are going to cut a big notch in the bottom, make sure there is enough bottom left at the transom to provide lift. Maybe extend the panels out beyond the transom, on either side of the tunnel - you can always cut them off. If there is a good high-speed tunnel design for home-builders, I haven't seen it. Atkin had a bunch of low-speed tunnels, you might take a look at the Atkinboatplans.com website for ideas. Sal's Dad >> I'm not sure what you mean by "semi tunnel" but I built an Atkin Rescue >> Minor with fully protected prop and rudder. Or you can modify the [quoted text clipped - 5 lines] > really reading a lot about boat building a few years ago I recall reading > about some of them. >I modified my Bolger Diablo along those lines - It had a 20" transom, and I >wanted to run a "short shaft" outboard. It worked ok 90% of the time, but [quoted text clipped - 17 lines] > > Sal's Dad That's basically what I figured. What I am really looking for is a shallow water runner for an outboard. I suppose I could go with an air cooled mud motor, but I already have a couple regular outboards. I looked at converting one to jet, but there is no jet available for one, and the jet available for the other is pitched for a smaller motor. My motor over-revs with it. I'll look at the Atkin designs. I'm figuring if I get this the way I want a 28-35mph top speed is all I can expect. That's about what I get out of my current shallow water boat (16' flat bottom jon). 28 with one motor and 35-37 with the other. (gps speeds) >>> I'm not sure what you mean by "semi tunnel" but I built an Atkin Rescue >>> Minor with fully protected prop and rudder. Or you can modify the [quoted text clipped - 5 lines] >> really reading a lot about boat building a few years ago I recall reading >> about some of them. SignaturePosted via a free Usenet account from http://www.teranews.com |
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