Aluminum build with RIVETS?

The old style Viking lapstrake hulls seem to be quite light and strong.

I'm wondering if todays high grade marine aluminum and sealants would lend it self to this style construction , riveted together?

A simple hull "should" be able to be digested on a computer , and all the parts Pre Cut ,
so assembly over a simple strong back would require a rivet gun , and not welding skills.
As a cruiser the lapstrake setup might be stiffer , and a single hull piece could be replaceable , if needed.

Comments ?

FF

 

Fred
I knew I would find one on the web if I looked around. I saw rivetted aluminium boats in the 1960s. I think some of the early deHavillands might have been rivetted.

All of the early steel ships were rivetted.

I don't know how they achieved such a tight seal in the aluminium but there is no need for sealants. Lots of well fitted rivets I suppose. It has the advantage of no heat distortion as well.

I have included a photo of one of my long aluminium hulls. It was only glued up on the underwater section to keep it smooth. The white powder looking material is where I did a bit of fairing across the seams with some filler. Without lazer cutting it is hard to get a perfect fit. The seams butt with a backing plate. There was one seam along the top that was screwed and glued. Loctite make a very impressive glue for light guage aluminium. A properly designed lap joint will fail at the metal before the adhesive lets go.

Overall I think welding is the best for plate 3mm above and for thinner you might find glue or rivets easier. I would be interested in others view on this because you see some really neat welding on small aluminium boats with maybe 1.6 to 2mm plate. Not something I am equipped to do. Would like to find someone who does it well.

Rick W.

 

http://www.azom.com/details.asp?ArticleID=2860 and searching

 

From that site,


Joint Design For Adhesive Bonding


It is also not adequate to simply use adhesive on a join that would otherwise be welded or mechanically fastened. Joint design for adhesive bonding should allow for maximum surface contact between the adhesive and the aluminium. The joint design should also consider the loading forces that the joint will endure. Adhesive bonding performs best when the forces are predominantly pure shear, tension or compression. The use of lap joints is common as they have a large joint surface area, load predominantly in tension and avoid cleaving or peeling forces.
Mechanical Joints

From small aluminium boats to aircraft, riveting is still used to make joins. Riveting, screwing and bolting can produce high strength joins without distortion or strength loss and requires less skill than for other joining methods.

Aluminium alloys used for rivets include 2017A, 2024, 5056, 5052, 5754, 6061, 6082 and 7075.

Sounds like the combination of adhesive and a serious number of rivets could produce a "one off ' with a simple method.

The welds in aluminum seem to be the weak points , unlike steel, so this construction should be reliable , although noisy and time consuming.

The Richardson line of boats were built in the 60's , anyone know if they had a reasonable service life , or ???

FF

 

aluminum has an critical oxide surface that must be prepared
before gluing and riviting away readup some more on bonding

 

I own a 1946, Grumman Aircraft built, aluminum Canoe. My Grandfather bought it brand new. It's 17.5ft. X 4ft., with a flat transom and sealed air pockets in both ends. Growing up on the Tennesee River, it was my main mode of transportation. I've had a 16H.P. Johnson on it, but it was a hell of a ride!
What I'm trying to say is, I abused this boat in many different ways. It's out here in the yard, waiting to get wet, right now! NO maintenence, ONE very small leak in ONE of the many seams, 61 years old!
I would say that's pretty good service life.

 

Yeah Rick, The early De Havillands were rivited, and close together too. They were very good, some still are.

there is a boat builder in Brisbane that uses a moulded alloy section as the chine and gunwale, and inserts flat sheet to join them together to make a boat. There is a custom plastic insert that holds it all together. I was going to buy his company from him about 15 years ago, move production to Fiji, but chickened out as there was too much "inside" information need to be known about build problems, and he was the sole source of info. He is still in business, well the boats are anyhow, and they seem to be very good. They can be purchased from Leisure Marine in Capalaba (Queensland), I forget the name of the product unfortunately.

 

The Russian s and italians and others made many hydrofoils this way
But they built like aircraft, they were/ are strong, and beautifully engineered not at all like a dingy
When you consider a Mig jet flys through the atmosphere at warp speeds without leaks, what challenge is a mere boat?
All rivets flush,
A skilled trade

 

lazeyjack,

All tradesmen are skilled, some more so than others, it is a shame that the do gooders of this world have advised our youth for the last 20 odd years to "get a university degree", and if you did not get one, you were basically the scum of the earth.

Now of course we have few skilled tradesmen left, the newer ones are unfortunately not being as well trained in all aspects of thier trades as they were in the past, however they will become so in a few short years.

Having a trade is something to be proud of, after all, it is the tradesmen that build every darn thing you see. 99% of the "things you see" can be built too without the university degree behind them. hey they made the pyramids, the old boats that traded the world, and so many other things before the university graduate came along, we seem to forget that.

Do not get me wrong, I have all the respect in the world for those uni graduates that are doing whatever it is they do, just that without the skilled tradesmen, all they design would be left on paper (or in their computers today of course) if it wasn't for the tradesmen that actually do the construction.

Long may they reign. Some of us too are finally being paid a decent wage in recognition of our abilities to "do things".

 

"Some of us too are finally being paid a decent wage in recognition of our abilities to "do things"."

My father's (a plumber) favorite cartoon was of a fellow with a suit and briefcase walking up to his house. And on seeing the Plumbing contractors truck in the drive , Exclaims ,

O God , I hope she is having an affair!

FF

 

Rick, if you need to do some really light weight aluminium for your pedal power boats, I noticed that at
http://www.azom.com/details.asp?ArticleID=2860

it says
"Brazing
Aluminium can be brazed by torch, dip or furnace processes as long as close temperature control is maintained."

There are specially designed brazing torches that can braze a beer can cut in half and leave it waterproof.

That might be of interest.

 

Ray
There is a fellow who has a stand at the Melbourne boat show where he demonstrates the brazing. He does patch a beer can.

I bought some of the brazing rod a couple of years ago and have used it sparingly since. I have brazed reasonably thick material with success. It gives an acceptable joint.

I tried to make a butt joint in 1mm thick sheet that had some mild stress and it distorted badly. It might be possible if the sheets were not stressed or had a solid backing but any stress and it relieves as soon as heat is supplied so buckles when cooled. It needs to get red hot to braze well.

With thin sheet I have had much greater success with Locktite glue. Even builders glue and rivets do a lasting job but I get concerned about the drag of the rivets.

I would like to try welding light gauge sheet but my welder is not suited to it. It is something I am working on. For now I am reliant on skilled craftsmen. My boilermaker nephew can MIG weld aluminium cans so maybe I need some advice from him.

Rick W.

 

Rick - that guy at the melbourne sells the brazing material, but for proper brazing of aluminium, you need a special torch - as I found out. The standard CIG torch does not have enough control.
There is a guy I was in contact with some years a go that was selling a US made torch that they claim gives much better results than even MIG. I cant locate his details at the moment, but you may be able to google the product. The torch was pretty expensive, but less than MIG.
Are you still building the pedal powered record breakers?

 

Ray
The pedal boats are a means to an end. The objective was to learn about efficient hulls and propulsion systems. You learn a lot about efficiency when you have 120W to play with. When I started out I thought it would be amazing to hit 12kph in a burst but I can now go close to sustaining that speed. So have learnt a lot. Will be ever grateful to Leo Lazauskas and Martin Hepplerle for making the mathematics usable. Stuff I never really mastered and long forgotten.

I always intended to have a yacht for retirement when I will have time to actually enjoy it. However I now see a lot of merit in an easily driven slender hull using electric power from solar and wind. Something light enough to bring home rather than worry about it sittiung at a marina - been there.

Hence my need to find a naval architect who can detail a concept design that is easy to build and lightweight. If it is done in aluminium I need a lot of it to be less than 3mm plate to achieve the weight target. I think this presents a challenge.

Rick W.

 

The "rivet guns" I have seen, shoot "pop" rivets, that leave a hole. Fast, but are you going to trust sealant on that many holes ?

The (home built) aircraft industry use a rivet "squeezer" or 2 people, one with an impact hammer and one with a "buck" to install solid rivets.