Author Topic: Love the boat! Can I build it in ALUMINUM?  (Read 31 times)

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Brian.Dixon

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Love the boat! Can I build it in ALUMINUM?
« on: February 16, 2021, 07:17:09 AM »
    The question mentioned in the subject line gets asked often enough that I think I ought to post a short FAQ on the topic.

    NOTE that there are a lot of aluminum or fiberglass boats on the market already, they cost a lot, and they all get less than 1 or 2 miles per gallon.  The are the RIGHT solution for sum, but the Great Alaskan was designed for the rest of us - very seaworthy, BIG, custom-built to your requirements, tougher than commercial (polyester+gelcoat) fiberglass boats and not as tough as aluminum, and cheaper to operate.  End cost is 25-35% the cost of a commercially-built boat in its class, and gas mileage runs 3-5 miles per gallon (depending on size and accommodations/weight).  But there are trade-offs.  Noting that I do NOT design for aluminum and cannot answer aluminum-related questions in detail, the following are the trade-offs as I see them.

Aluminum Boat Pros
  • Tough, good for rough beaching (bad rock beaches)
  • Weatherproof
  • Can be stored without shelter - any weather conditions
  • MIG-welded (wire welded) boats are relatively fast to build

Aluminum Boat Cons
  • Expensive.  At $8-$10 per pound for marine aluminum, a 26-28 ft Great Alaskan weighing approximately 4900 lbs costs close to $50,000 in materials alone
  • Noisy and 'cold' on the water
  • For the Great Alaskan, you will need to seek out an aluminum boat building expert that can specify structure/construction details for an offshore boat of this size (or give up on the Great Alaskan and pick out a nice design at https://www.SpecMar.cm - Specialty Marine or equivalent)
  • The number one factor in terms of boat efficiency ('gas mileage') is boat weight (displacement) - Aluminum versions of wood/glass/epoxy boats generally weigh between 1-1/2 to 2 times MORE than the wood/glass/epoxy version - Aluminum is NOT lighter weight (aluminum is 160# per cubic foot, wood-glass-epoxy is 45# per cubic foot).  Aluminum boats BURN MORE fuel per hour and require HIGHER horsepower
  • Requires welding equipment, knowledge and skill (MIG/wire-welding, TIG)
  • If you hit a sharp rock or obstacle with an aluminum boat, it tears open a hole that stays open, maximizing in-flow of water
  • Aluminum is denser than water - aluminum boats sink unless significant flotation is added

Great Alaskan Pros
  • Tougher and more weatherproof than off-the-shelf fiberglass boats - Epoxy resin IS waterproof while polyester resin (commercially-built boats) is NOT waterproof.  Wood/glass/epoxy boats can be stored outdoor with minimal shelter
  • Lowest-cost construction of any boat in its class, finished cost generally running 25% to 35% of the cost to buy an equivalent commercially-made fiberglass boat, even cheaper when compared to equivalently-sized and capability aluminum boats
  • Quiet and 'warm' on the water, the construction materials naturally deaden noise (better for fishing!)
  • Lightweight, yet overly-strong for its size, and utilizing a monohedron/prismatic hull form, there is no other boat in its class that gets better fuel mileage
  • Compared to commercially-built fiberglass boats, the Great Alaskan has a LOT more interior room since 'hollow structural elements' necessary in fiberglass boats are NOT necessary in wood/glass/epoxy construction.  Aluminum boats are similar.
  • I've been helping builders build Great Alaskans for over 16 years and love doing so - I cannot offer any assistance on an aluminum build
  • If you hit a sharp rock or obstacle with a (plywood) wood/glass/epoxy boat, the wood tends to be self-closing, tending back towards its original shape and limiting the in-flow of water
  • Wood is less dense than water - There is enough wood in the Great Alaskan to keep the boat afloat, even if swamped or capsized

Great Alaskan Cons
  • You trade labor and hours for the discount on the price of a finished boat.  The total cost is the lowest that you can find for a boat in this class, but it does take time and effort to build versus welding aluminum or buying a commercially-built boat
  • While tough with a 3/4" thick bottom and heavy fiberglass, and able to be beached on sandy or rocky beaches without damage, wood/glass/epoxy is tougher than commercially-built polyester+gelcoat boats but not as tough as aluminum
  • Long term maintenance is minimized by at least keeping the boat out of hot sun typical of lower latitudes or heavy snow and ice typical in higher latitudes

There you go!  If anybody can think of more pros and cons on either of the above, let me know and I'll add them to the list!

Happy building!
https://www.GlacierBoats.com

Brian


The Great Alaskan - Professional performance - Easy to build! - https://www.glacierboats.com  ><((((> .`.><((((> .`.><((((> .`.><((((>