How to build a boat that lasts centuries?

Several very skilled glass blowers, all working the same bubble of molten silica, untill it's a boat shape.

 

Most boats built to those standards use unobtanium.

 

The people possessing the obscene amount of money probably needed for this project, would likely rather spend it on life extension for themselves, alas, billionaires fall off the perch pretty much as soon as the rest of us.

 

The material you seek is called Cupronickel...Read this:
Cupronickel: a Copper Nickel Alloy with Impressive Qualities https://www.thebalance.com/metal-profile-cupronickel-2340116?utm_term=copper+nickel+alloys&utm_content=p1-main-1-title&utm_medium=sem&utm_source=msn_s&utm_campaign=adid-06bcbffb-1977-4168-9205-756d987dd903-0-ab_mse_ocode-4604&ad=semD&an=msn_s&am=exact&q=copper+nickel+alloys&o=4604&qsrc=999&l=sem&askid=06bcbffb-1977-4168-9205-756d987dd903-0-ab_mse

 

I'm not a metallurgist, but cupro-nickel corrodes badly in a salt environment, if the coins made from it are any indicator. But those coins are from memory, 25% Nickel, 75% copper

 

Cupronickel is commonly known as Monel.

 

What happened to the ship made from Monel ?

 

The alloy used for bitcoins may be more suitable.

 

I'd say a decent writer does his/her research, like this, instead of expecting writers to already know stuff outside of their specialization. Unless you meant the part where you invent a new element, which is a possibillity depending on how "hard" the science is of your worldbuilding. I'd like to keep it as science-based as possible. Furthermore, I'm not a writer, but a game developer.

 

A lot of replies name a material type without any explanation, which is devastating for someone without proper knowledge of these materials. As for cupronickel here is a nice succes story and analysis: Copper-Nickel : Ship and Boat Hulls https://www.copper.org/applications/marine/cuni/applications/hulls/performance_corrosion.html

But with proper elaboration of your choices it would be quicker to pick. Like why silver? Right now I have not heard a good argument against picking something high-up on the galvanic series list (the most noble) for the hull, like graphite or gold.

Also do you think a sailboot would be more reliant?

 

Some metals like gold, tungsten, titanium and certain type of stainless steel do not corrode in seawater, but that doesn't mean they reject marine growth. After a century at rest in a bay such a hull may accumulate so much fouling it no longer floats but literally stands on the seabed.
Graphite is not suitable as a hull material because it needs a resin to provide strength. Silver reacts with sulfur compounds so is also unsuitable.
I already hinted at artificial shark skin, seen in a recent documentary of Midas Dekker. The very dense texture is such that marine life cannot attach to it. Very promising tests are made with an experimental adhesive foil applied to a sailing yacht.

 

They could have genetically engineered marine animals that feed on the growth. The crew would then harvest them for food.

 

Thanks for your reply. The first time you mentioned it, I thought you were pulling stuff out of the air without references. My bad. I just saw the documentary (dutch). The shark indeed has a great system for its skin. The foil they applied was based on sea urchin's spiky skin btw, which also should work. For anyone that's interested, I found the manufacterer that creates these films: Home http://www.micanti.com/

Right now they last 5 years, I can imagine that technology improves upon this over the years, so thanks again for the tip. Would it be smart to use this and a noble, non-corrosive metal as a hull? Because then I'm set for the hull.

I still think a sailing boat has a better chance at surviving than an engine right? Or is it impossible for a sailing boat to be stealth?

 

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Is this boat just abandoned for 200 years and then found and used, or is it part of a plan and it's been properly prepared and sealed etc so it will be ready to use in 200 years when people return?

Marine railways for all size boats are pretty common. If you had the boat stored in a boathouse or a bunker or cave, on a railway out of the water, it would last a long time no matter what it was made of. Regular steel would work.

If it's out of the water, there's no worry about any anchoring system lasting 200 years. There would not be 200 years of bottom growth.
There would probably be other advantages also.

A sailboats sails might not last 200 years.

Ropes might be a problem. As would be fuel.

 

Part of the plan, it should be usable when people return. Thanks for your answer, really helps.

Right now I'm thinking of:

• Stored inside ready to use.
  
• Radiation-absorbent material (anyone know of any that is usable for naval?)
  
• Engine instead of sail (will have to do research into an engine that is good to go after a long while).