TITANIUM CATARMARAN

[Morgali]

If I had the ridiculous money required to build a boat from scratch, from titanium, I wouldn't. I'd build it from Monel 400, or Hastelloy, or Inconel 625. Would almost certainly never rust, wouldnt need to be painted, and would last essentially forever.

[Cherod]

Originally Posted by RoadRacer

Really pretty easy to create the purge zone. Plastic bags work great, of course taped away from the heat zone. Flow argon into the bag through a diffuser and have at it. Just remember to not over pressurize the back purge area or the molten material will soon meet the tungsten!

ha ha,, sounds like you know what you are doing,,, how often have you forgot to release the purge before you seal the butt ????

[Dave_S]

I'd be concerned the titanium would work harden and crack. I also wonder if you could make a lighter / stronger / more flexible boat from thinner high tensile steel.

[a64pilot]

I don’t believe Ti work hardens, in most uses, it does in machining of course, about like SS does.
Now I don’t think it’s the best material choice here either, probably aluminum is for many reasons, Ti isn’t magic material, you’ll never see a Ti crankshaft for instance unless it has steel shells on the bearing surfaces.
Ti wins in a strength to weight and size ratio, and is very good for high stressed parts that are normally subjected to high cycle fatigue.
I’d expect to see it in rigging fittings, but here it’s just a cool factor I believe, sort of like gold plated things.
Aluminum due to it’s lighter weight could possibly be stiffer and maybe even lighter.
An aluminum sheet of the same weight is thicker.

[NorthernMac]

That's got to be crazy money, when something random happens? I could just imagine catching a rock or something and asking around a remote dock, or even lots of stateside docks, "hey do you know anyone who works on Ti?"

[Compass790]

I havent done any titanium welding but we used to do dual welding on ss tanks where you have tig torches on both sides of the weld seam but just one guy with the filler rod. Maybe that can work. You can get adhesive ceramic backing now that would be purgeable too.
Suspect it would be a fine boatbuilding material for a billionaire.

[a64pilot]

Ti can be welded very successfully with no filler rod if there is enough parent material.
What little Ti welding I’ve seen done was in a cabinet, looked like a bead blasting cabinet and was of course for smallish parts.

[yeloya]

Titanium – This naturally occurring metal has the highest tensile strength to density ratio of any metal, which makes it, pound-for-pound, stronger than tungsten. It scores lower on the Mohs scale of hardness, though. Titanium alloys are strong and lightweight and are often used in the aerospace industry.

If this is true, Ti is not a bad choice; "highest tensile strangth to density ratio"..
Obviously, there are other parameters to consider such as price, hardness, handling costs vs. traditional materiels, etc..

Cheers

Yeloya

[a64pilot]

Originally Posted by yeloya

Titanium – This naturally occurring metal has the highest tensile strength to density ratio of any metal, which makes it, pound-for-pound, stronger than tungsten. It scores lower on the Mohs scale of hardness, though. Titanium alloys are strong and lightweight and are often used in the aerospace industry.



If this is true, Ti is not a bad choice; "highest tensile strangth to density ratio"..

Obviously, there are other parameters to consider such as price, hardness, handling costs vs. traditional materiels, etc..



Cheers



Yeloya

Your other parameters are what makes it a bad choice.
While your building a Ti boat, be sure to insulate the engine room with gold while your at it, cause gold is the best reflector, it’s why it’s used on spaceships.

There is best, and then there is good enough.

[ranchero76]

It's so funny to see all opinions of Professors in materials science and titanium welding in particular.
But anyway:

1.Titanium is expensive but not CRAZY expensive
2. Titanium can be welded by qualified professional. Somewhere "far-far away" it will be equally hard to find qualified professional of any trade - fiberglass, steel or aluminum work. For boat of this price range there will be no problem to keep minimum equipment and materials on board and simply buy air ticket for qualified professional to fly in and do necessary repairs if ever needed.
3. There is at least one 50' titanium catamaran was made in Russia many years ago, home built, without naval architects or any other professionals involved. It successfully circumnavigated for 5 years, and still in use today. There's story somewhere on Internet.

It's definitely not for everyone, only for these who can afford it.

[Matt Johnson]

They seem to be a yard that specializes in high end composites. With an open and endless wallet, is there a combinations of high end fabrics/resins with the toughness and hardness of Titanium?

Matt

[ranchero76]

(Mark Schlocker, Satellite structural analyst with a masters in Mechanical Engineering and an MBA)


Titanium is stronger than carbon fiber polymer composite. There are many varieties of carbon fiber. Some are stiff, some are strong, others conduct heat very well. Some names are T300, IM7, M55J, K13D2U. Using one of the strongest fibers (IM7) in a fully uni-directional layup you would be able to almost match the strength of Titanium 6AL-4V which is about 120,000 PSI (120 KSI). I am looking at a datasheet of IM7/epoxy now, obtained by googling IM7. But, in a unidirectional layup all of the fibers are oriented the same direction. This is not a woven product like you are used to seeing. In this case the other direction is very weak so in the end, this material is still not as strong as Ti. Carbon fiber composites are much weaker in compression than in tension so you have to assume the lower compression strength which is what I did here.
Now, realize that carbon fiber composite is almost 1/3 the density of Ti so you can use almost 3 times as much of it to get a part of the same part mass. It is strength to weight ratio you are really concerned with. Otherwise the obvious choice is steel. Titanium has a legendary strength to weight ratio and in a more traditional fiber layup IM7 may match but not surpass that.
What carbon fiber composites excel at is not strength at all but stiffness to weight. What is interesting is that aluminum and titanium and steel all have about the same stiffness to weight ratios but carbon fiber composite can far exceed them depending on the fiber used and the layup. Even for a non-oriented layup you can get 2–3x the stiffness to weight of Ti. Orient the layup and you can double that again, or more.
Manufacturing methods are also vastly different so that can dictate the best product used for a given situation. Composites are draped like a fabric and cooked. They are great for thin and curved surfaces. I don’t think anybody would try and make a bolt out of them because for that metals are perfect.
If you are comparing products it is best to compare specs instead of materials. You can’t know all of the engineering decisions that went into a product but you can know the weight and if they have a reputation for reliability or not.
Edit to add: For composite structures often the weak point is not the fiber at all but the joints which are typically bonded with epoxy.

----------------------
To add - carbon fiber is by far not easy material to repair somewhere "far-far away" in order to keep it's original strength.

[a64pilot]

First Ti boat that I’m aware of was built or maybe launched 50 yrs ago.
https://en.m.wikipedia.org/wiki/Alfa-class_submarine

As was said Ti really isn’t that expensive now that a continuous refining method has been achieved, I believe.
However matching it and or welding it is exceedingly difficult, and that makes it expensive.
I would expect to see Ti to begin to replace many fixtures that are currently SS.

[yeloya]

Originally Posted by a64pilot

Your other parameters are what makes it a bad choice.
While your building a Ti boat, be sure to insulate the engine room with gold while your at it, cause gold is the best reflector, it’s why it’s used on spaceships.

There is best, and then there is good enough.

İnsulating the engine room with gold is not a good idea, gold is a best reflector but has very high thermal conductivity. If you want something exotic try platinum , it has much less conductivity

Cheers

Yeloya

[Training Wheels]

It’s a catamaran, gold would be too heavy!