The aluminum list
Aluminum is what it is all about. Before you get caught up in the details let me first outline the aluminum alloys that I regard as suitable for building a sea going vessel. Plate alloys 5083 & 5086 are the most suitable hull material. There is little to choose between them, although 5083 perhaps has the edge with respect to mechanical properties. Both alloys are an excellent choice. Extrusions like angle and pipe are available in both grades, although 5086 is much more readily available in the USA, and 5083 is more common in Europe.
There is also a slightly cheaper alternative 6063 or the ubiquitous 6061, which are a little cheaper, rather stiffer but they are not marine alloys (they contain some copper to give them added strength). Copper in aluminum is bad news in salt water. Just look at any unprotected aluminum mast after a couple of years. It corrodes rather nicely with some salt spray. One can however use these alloys in the interior of the vessel for stiffening the deck etc. where you are quite sure they will never be wet for any length of time. I personally think that if you are going too all the trouble of building a boat then use 5083 or 5086 extrusions. It didn't add more than 6% to the material costs for my boat.
Then there is the subject of tempers. This is usually defined as H32 or H321 or H116 or H111 etc. I have only the following reliable information to contribute.
Generally for plate below the waterline - H321 or H116 is best. It has the required mechanical and corrosion properties. The difference between H321 and H116, is that the H116 temper has an additional acidic accelerated corrosion test in its specification which checks that the material is predominantly free from continuous grain, boundary networks which are implicated in some types of corrosion (exfoliation and pitting). A reference I have is Aluminum-magnesium alloys 5086 and 5456 H116 by Brooks C.L. Naval Engineers Journal, August 1970. Otherwise H116 is equivalent to H321 in every way mechanically as I understand it. I don't want to get more technical than that, so if you have more questions read the journal reference. I am quite certain that H321 is as good, but as H116 costs no more, why settle for less (well plate sizes may be a more important consideration, so don't lose sleep over it). H32 is adequate mechanically but by may have a hidden potential for corrosion problems both above and below the water line unless painted, as a result of the 'as manufactured', crystal structure of the plate.
Suitable extrusions tempers in the 5086 & 5083 alloys are H32 & H111. For some reason H 112 is not to be used? I don't have more information about this.
One last point deals with pipe. The most suitable pipe for any application below the waterline is schedule 80. It has a much thicker wall than the equivalent schedule 40, and thus should last longer with respect to corrosion. This pipe is seriously expensive though, and normally comes only in 20ft. lengths, so check that your design uses one or two sizes only, if possible. Another anomaly is that schedule 80 pipe is differently specified compared to any other old pipe. A 3/4 inch sched. 80 pipe has an outside diameter (OD) of 1.050 inches and a wall thickness of 0.154 inches. A 3 1/2" has an OD of 4" and so on. My advice is to ask for a catalog.
The following are a list of mainly East Coast USA distributors that actually stock marine grades of aluminum (5083 and 5086).
Production supply Company
Pioneer aluminum
Renolds Aluminum (large orders of plate only?)
Kent, WA. 253-872-7060 fax : 253-395-0579
A&M non-Ferrous metals
The Aluminum Group (imported stuff)
Keep in mind when quoting.
I suggest that you make up your own mind who you would like to deal with. Remember that until you have aluminum in your paws and it's paid for in full, the dealing is not over. Verbal quotes over the phone are tenuous at best. Fax quotes are a little better, but not set in stone. Just keep your wits about you and good luck. As you can surmise haggling is not my most favored past time. I take things far to personally - not good.
I have included the table below to give you an idea of what goes into a 34ft. multi-chine Van de Stadt and how much it all costs - as specified by the designer - and cut to size. With a little hard negotiation you can do a lot better than the first quote. The prices per pound that I was first quoted are included, so that you can compare them with what you are quoted in your area.
One note here for the amateur builder - the alloy sales people, with some exceptions no doubt, are really bad at coming up with written quotes for the quantities you will need. I have had this experience on two continents. They are used to dealing with big company's corporate accounts. Your 5000 lbs. one-off sale doesn't seem to figure. My experience is once they know exactly what you want they loose all interest. The answer is don't give them any information until you have the information you want w.r.t. sheet sizes, thicknesses and pricing etc.. This is not true of all sales staff though by any means. There are a few individuals who just try harder. They are good to find! I must confess though that on the whole, the lack of professionalism/integrity of sales staff here in the USA has left me shocked. Perhaps I expected to much? Certainly the fast buck rules!
List of Aluminum together with the prices I was initially quoted by Pierce Aluminum, Canton MA
The calculations were done using a density of 2.67g/cm3 (feel free to check my calculations)
| alloy | number | dimensions | volume | quote | weight | $/pound | cost | |||
| plate | thickness | width | length | |||||||
| 5083 H321 | 7 | 0.236 | 40 | 240 | 2265.6 | $ 536.00 | 1529.78 | $ 2.45 | $3,752.00 | |
| 5083 H321 | 4 | 0.236 | 60 | 240 | 3398.4 | $1,070.00 | 1311.24 | $ 3.26 | $4,280.00 | |
| 5083 H321 | 1 | 0.236 | 60 | 120 | 1699.2 | $ 536.00 | 163.90 | $ 3.27 | $ 536.00 | |
| 5083 H321 | 3 | 0.156 | 80 | 240 | 2995.2 | $ 739.00 | 866.75 | $ 2.56 | $2,217.00 | |
| 5083 H321 | 1 | 0.156 | 60 | 120 | 1123.2 | $ 368.95 | 108.34 | $ 3.41 | $ 368.95 | |
| 5083 H321 | 1 | 0.5 | 6 | 20 | 60 | $ 24.50 | 5.79 | $ 4.23 | $ 24.50 | |
| 5083 H321 | 1 | 1 | 2.5 | 83 | 207.5 | $ 102.00 | 20.02 | $ 5.10 | $ 102.00 | |
| 5083 H321 | 1 | 1 | 8 | 69 | 552 | $ 221.00 | 53.25 | $ 4.15 | $ 221.00 | |
| 5083 H321 | 1 | 1 | 8 | 20 | 160 | $ 63.00 | 15.43 | $ 4.08 | $ 63.00 | |
| 5083 H321 | 1 | 2 | 3.25 | 6 | 39 | $ 21.00 | 3.76 | $ 5.58 | $ 21.00 | |
| 5083 H321 | 2 | 0.625 | 3.25 | 144 | 292.5 | $ 67.00 | 56.43 | $ 2.37 | $ 134.00 | |
| 5083 H321 | 16 | 0.25 | 2.25 | 144 | 81 | $ 20.50 | 125.01 | $ 2.62 | $ 328.00 | |
| 5083 H321 | 8 | 0.25 | 2 | 144 | 72 | $ 18.90 | 55.56 | $ 2.72 | $ 151.20 | |
| 5083 H321 | 8 | 0.625 | 1.25 | 144 | 112.5 | $ 35.50 | 86.81 | $ 3.27 | $ 284.00 | |
| 5083 H321 | 1 | 0.25 | 3.75 | 144 | 135 | $ 60.00 | 13.02 | $ 4.61 | $ 60.00 | |
| 5083 H321 | 1 | 1.5 | 1.5 | 72 | 162 | $ 94.50 | 15.63 | $ 6.05 | $ 94.50 | |
| alloy | number | dimensions | volume | quote | weight | $/pound | cost | |||
| thickness | length | |||||||||
| angles | arm 1 | arm 2 | ||||||||
| 5086 H111 | 2 | 0.25 | 3 | 2 | 300 | 375.00 | $ 92.50 | 72.34 | $ 2.56 | $ 185.00 |
| 5086 H111 | 4 | 0.375 | 2 | 2 | 300 | 450.00 | $ 103.00 | 173.63 | $ 2.37 | $ 412.00 |
| 5086 H111 | 4 | 0.25 | 1.75 | 1.75 | 300 | 262.50 | $ 60.00 | 101.28 | $ 2.37 | $ 240.00 |
| 5086 H111 | 5 | 0.25 | 1.25 | 1.25 | 300 | 187.50 | $ 43.00 | 90.43 | $ 2.38 | $ 215.00 |
| pipe | OD | ID | ||||||||
| 5086 H32 | 1 | 0.38 | 4 | 3.25 | 240 | 565.4867 | $ 603.00 | 54.55 | $ 11.05 | $ 603.00 |
| 5086 H32 | 1 | 0.3 | 3 | 2.4 | 240 | 452.3893 | $ 213.00 | 43.64 | $ 4.88 | $ 213.00 |
| 5086 H32 | 1 | 0.154 | 2 | 1.692 | 240 | 232.2265 | $ 209.00 | 22.40 | $ 9.33 | $ 209.00 |
| 5086 H111 | 1 | 2.75 | 72 | 1710.597 | $ 210.00 | 165.00 | $ 1.27 | $ 210.00 | ||
| 5086 H111 | 1 | 1.25 | 72 | 353.4292 | $ 42.50 | 34.09 | $ 1.25 | $ 42.50 | ||
| 5086 H111 | 1 | 0.5 | 144 | 113.0973 | $ 18.00 | 10.91 | $ 1.65 | $ 18.00 | ||
| 5199.00 | ||||||||||
| Totals | $ 14,714.15 |
Last Updated on 20 April 1998