Glen-L.com

Does anyone have a rough idea of what the material cost would be to build a large driftboat - maybe 18 footer out of marine grade aluminum, say 125thousand thick?

Well after a couple of months of research, so far it seems as if you can figure about $2 a pound for materials for a welded aluminum boat. So a 1,000 pound aluminum boat would cost around $2,000 + for just the raw materials. This is a guesstimation.

good lord you can buy a used boat for that amount

I have been wanting to build a 28' power catamaran for several years. Four years ago I estiamated the aluminum cost @ about $4,000.00. I wish I had bought then. Today the cost of the aluminum exceeds 15K.

Does anyone have current price estimates per lb

LOL if you have to ask, you can't afford it!! LOL

Bill

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Any day spent messing with boats, is a good day! me

Boat Building sometimes becomes a disease that costs you money! It's not about saving money!

SO very true!!!

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I just got a price yesterday for a drift boat, 5086 is $3.57 a lb and 6061 is $2.52 a lb.

I presume with a drift boat you are building a freshwater boat? Another option would be to use 5052. Usually about 30% cheaper than 5084 stuff. I have a pile of freshwater boats I have built using 5052 and have never had any issues as far as strength of hull, or corrosion.

mcm, jim, I'd like to make sure we don't exclude 5052 from consideration for salt water boats. There is nothing 'wrong' with 5052, yes its softer and not as strong as 5086 or 5083 but... its fine for pleasure boats in the salt.

For many years 1945 til 60's70's 5086 was pretty scarce material and '52 was the most available and it did the job. This alloy won't dissolve in salt water, it won't fail if you plan the scantlings and welds correctly; its just not as 'good' when compared to the other two alloys.

An end wrench from sears will work for a lifetime, yes, Snap-On (tm) is likely to be more precise and last longer and all that but the sears wrench will work and do the job well. But the one is just not as 'Cadillac' the other.

So too with marine alloys. 5052 is in the hulls of countless fine boats so it could be used for a salt water boat anytime without loss to the project.

I often complained online about 5052; until another builder pointed out I was splitting hairs and there was no reason to make my preference for the 5086 and 83 alloys into a complaint about '52. So I pass that on here. Lots of distribution in the US does NOT STOCK 5086 in alloys thinner than 0.125" and some don't stock anything but 5052. So finding decent pricing and sizes of '86 alloy stock is not always easy- a good reason to price out a boat in the less stiff and less expensive 5052 alloy.

Cheers,
Kevin Morin
Kenai, AK

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Kevin Morin

I see some drift boats built with 6061 and I know you lose strength around the weld on 6061, but I like the analogy between Craftsman and Snapon...how much is enough. Is there any merit to using 6061? Also a lot of the shapes used don't come in 5000 series.

Thanks Guys

jim,

6061 is brittle in sheet products and will crack where the 50's will all bend/deflect/distort but not crack under the same load. 6061 shapes/extrusions are fine with 5052/5086/5083 sheet/plate as long as you use 5356 filler and not 4043 which has so much silicone its very crack prone in the 50 series welds.

the comparison is tool steel to mild steel, the tool steel is stronger for some applications but will chip/crack/flake where mild will bend/twist/distort but not come apart. Each have their place.

you loose strength over the native material tensile ratings on all weldable alloys, 6061 the same as the 50 series- similar proportional loss not the same amount.

6061 T6 is the 'standard' marine extrusion; angles, T's, flat bars, pipes, and half pipes as well as the channel, I beam and wide flange of the steel world. 50 series extrusions are near and dear and not very widely available.

for a four to six place rowing dory (often called a 'drift boat) I'd go with 0.125" thick bottom panel up to 60" wide and move to 0.160" for the wider 6 and 6'+ bottom boats. I'd stay with 5086 if affordable and drop back to 5052 if not. All longs, ribs, gunwales, chines (if they're used) and other extrusions of 6061 T6 and welded with 5356 wire. If you can run a 0.030" wire then most of the thinner material will be less wrinkled by the smaller more proportional welds. If not, then run 0.035" wire and practice moving rapidly and using a small fillet at higher amperage and especially higher travel speeds to reduce the net heat of welding.

Don't weld the boat out until the ENTIRE shape is final and fair, otherwise the natural weld contraction can and will distort the dory's shape- radically.

cheers,
Kevin Morin

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Kevin Morin

Kevin,
Thanks so much. A buddy and I have built 3 Pygmy Kayaks with stitch and glue and want to build an aluminum driftboat. I am a general manager of a Steel fabrication shop and we want to do the driftboat as a learning experience.
Again, thanks for your help!

Jim

www.discountsteel.com is a pretty good supplier 5052 is actually cheaper than 6061 at least in the 0.1 size I priced about 3.50 a pound that was for a 4 x12 sheet