Click for MotorCheck Click for Delta Click for McKinna Click for Llebroc Click for Lurssen

Titanium in Yacht construction?

Discussion in 'Technical Discussion' started by Codger, Apr 22, 2006.

  1. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    Let me preface this by stating that I have not looked very far for information on this topic. Honestly, I just did a search for Titanium on Yachtforums and that's about it. :) Only mention is small pieces.

    Was playing with a beautifully engraved, solid titanium globe of the earth this morning and it just got me to thinking about this....

    Is there much use of titanium in yacht manufacture?
    It is a very interesting material with many of the attributes of steel with one major advantage, less weight. With the evolution of various alloys and surface preparation via the rather impressive advances in anodising technologies the applications are seemingly endless.
  2. YachtForums

    YachtForums Publisher/Admin

    Joined:
    Dec 22, 2002
    Messages:
    17,814
    Good subject Codger.

    I'm not overly familiar with titanium's properties, but a couple of things come to mind. The first and most obvious is... cost. A Google search turns up plenty of reading on the subject. Here's one link...

    http://www.janes.com/aerospace/military/news/jdi/jdi060228_1_n.shtml

    Given it's anti-corrosion properties, it could be ideal for marine applications, but I wonder what it is like to work with... i.e., forming, bending & welding. How pliable is it? Does it mate well to other alloys? And if you weld it, does it loose some of its properties.

    I didn't read much further into the subject, but maybe some of our members have first-hand experience?
  3. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    Certainly, cost could be a factor. Corrosion resistance is key strength of Titanium. Kiwi friend was talking about some of the harbours in the Pacific rim that have absolutely nasty ph levels.
  4. Ben

    Ben Senior Member

    Joined:
    Feb 9, 2005
    Messages:
    177
    Hi Codger, here is an extract from a link I posted earlier, refering specificaly to titanium and yachts.


    "Titanium
    With very high strength, extreme nobility on the galvanic scale, virtual immunity to corrosion in sea water and in the atmosphere, and about half the weight of steel, there is no reason Titanium should not be considered the "perfect" hull material.

    Among the higher strength Titanium alloys there is little spread between the yield point and the failure point. This reveals a limited plastic range. However, elongation before failure is fairly high compared to, say steel.

    Another characteristic is "stiffness" expressed through the modulus of elasticity. For steel, it is 29 million psi. For aluminum, it is 10 million psi. For Titanium, it is 15 million psi. This indicates behavior that is somewhat closer to aluminum in terms of material rigidity. In other words, before Ti is made to yield (the point at which a material is deformed to the point where it will not return to its original shape), it will flex about twice as much as steel, but about 50% less than aluminum. Interestingly, Ti has about the same stiffness as Silicon Bronze, but Ti has less stiffness than copper nickel, which has an elastic modulus of 22 million pounds.

    Yet another consideration is the ease of welding, which has to do with several properties.

    Titanium melting point is above that of steel (3,042 deg F, vs 2,500 deg F) and about a third that of aluminum (1,135 deg F). Titanium forms a very tough oxide on exposure to the air, so welding must be done only after thorough cleaning of the weld zone, and must assure a complete inert gas shroud of the weld zone as the weld is being made, both on the side being welded and on the opposite side. The weld must be shielded until the metal cools below 800 degrees. These characteristics are surmountable by thorough attention to detail, good technique, and aggressive measures to assure post weld shielding. These characteristics would however dramatically increase fabrication costs over those associated with, say, aluminum.

    Among the other material properties that contribute to ease of fabrication of any metal are the heat conductivity, and the thermal expansion rate of a material. Aluminum expands twice as much as steel, per degree of temperature change, and is three times as conductive thermally. The thermal conductivity of aluminum is a big help, but the expansion makes trouble. As a benefit however, an equivalent aluminum structure will have greater thickness and locally greater yield strength, so the score is more or less even between steel and aluminum, with aluminum having a slightly greater tendency toward distortion while welding.

    With Titanium, this latter consideration will be the overriding factor in determining the minimum practical thickness for plating. Thermal conductivity is given as 4.5 BTU / Sq Ft / Hr/ Deg F / Ft for Titanium. For steel, it is 31, for aluminum it is 90. Thermal expansion is given as .0000039 in / in / deg F for Titanium, about 50% the expansion of steel and about 30% that of aluminum. These figures seem to indicate that the material would be fairly stable while welding, but that welds would take a much longer time to cool. In other words, the heat would remain concentrated.

    Based on these factors, as a very rough guess, a thickness of around 3/32" may possibly be the smallest practical titanium hull thickness for a welded structure. As a comparison, the least thickness for other materials (mainly due to welding ease and distortion issues) is 10 gauge mild steel (.1345") and 3/16" aluminum.

    An interesting Titanium alloy is the experimental alloy 5111 (5% Al; 1% SN; 1% Zr; 1% V; 0.8% MO), described as "a near alpha alloy having excellent weldability, seawater stress corrosion cracking resistance and high dynamic toughness." It has a high elongation before failure, a "medium" overall strength of about twice that of mild steel, and has a slightly greater spread between its yield point and failure point than the "high" strength Titanium alloys.

    Although I believe Titanium would be an outstanding hull material, it would require extreme care during construction. Titanium is possibly the "ultimate" in terms of heirloom boat hull materials...! "


    The site also discusses other metal types and can be found here....

    http://www.kastenmarine.com/metalboats.htm#Which Metal
  5. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    Hi Ben
    Thank you very much. Most of the info that I was looking for.
    Very good link!
    The note on Monel is interesting as well.
  6. Ben

    Ben Senior Member

    Joined:
    Feb 9, 2005
    Messages:
    177
  7. Kevin

    Kevin YF Moderator

    Joined:
    Nov 25, 2004
    Messages:
    2,209
    The heat / welding issue would be the biggest deterant to large-scale use of titanium I would think. I know that when we've worked with the material, even low temperature treatments (under 1000 deg. F) were tedious.

    Like Ben mentioned:

    The titanium had to be thoroughly rinsed in acid, and then handled with sterile rubber gloves. Even the slightest bit of contaminant would seriously mar the surface when heat treated. And the heat treatment itself had to be done in an Argon atmosphere.
  8. SimonB

    SimonB New Member

    Joined:
    Mar 19, 2006
    Messages:
    13
    Wallypower gas turbine exhaust pipes were built in titanium.
    They look pretty nice, they're light (quite easy to handle in that packed ER) and did not get affected by the hi gas temperature. They obviously do not show any sign of corrosion due to marin enviroment.

    I'd rather go for zinced iron pipes. Maybe you'll have to change them every one or two years but the cheap price will allow you to do it.

    SimonB
  9. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    Anyone aware of any hulls, of any size, built out of Titanium alloys?
  10. absys

    absys New Member

    Joined:
    May 12, 2006
    Messages:
    12
    Titanium milling or lathe process can produce burning chips flying away, scarry for the operator machining, some people keep scares on face from burned chips landing on their faces....

    If you let it be machined inside your vessel you should be aware of that and take necessary precautions...
  11. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940

    :D Suppose that I ought not to be laughing. Having worked with magnesium I have the scars to prove that it burns like hades. Rather than finding out from personal experience with Titanium I'm going the cowardly route and trying to find out from the experience of others....

    So far it seems that despite what appear to be the strengths of Titanium as a medium for building boats, the difficulties of it's processing have not been accomodated.
  12. absys

    absys New Member

    Joined:
    May 12, 2006
    Messages:
    12
    I am manufacturing golf caddys in titanium and the material is very fine to work with it, just need proper tools,correct speeds...

    We have a CNC department and some machines have Thinner Inflammable liquids nearby, so when we will work Titanium we just make sure this is not around :eek:

    The bending of tubes is great and easy, the welding can be easy handled by some experienced stainless steel welder with Tungsten Inert Gas (TIG )

    Very interested to hear about some Titanium hull as well....:cool:
  13. nas130

    nas130 New Member

    Joined:
    Apr 15, 2005
    Messages:
    89
    Imagine an 80-120 foot open styled boat made of titanium. No paint, no fairing, just show off the the welds and beautiful color of the titanium.

    nas
  14. sailronin

    sailronin Senior Member

    Joined:
    Dec 7, 2005
    Messages:
    111
    I believe the largest hulls built of Ti would be the Russian Ballistic Missle Submarines. I forget the class name now but the pressure hull was titanium.
    You may be able to get a good deal on some scrap Ti from that fleet these days!

    Dave
  15. absys

    absys New Member

    Joined:
    May 12, 2006
    Messages:
    12
    Just make sure you have a GEIGER detector, as they can be a bit radioactive...
    :eek:
  16. Antonio Torres

    Antonio Torres Member

    Joined:
    Aug 28, 2004
    Messages:
    55
    Sailronin,

    I believe the russian subs class name is Typhoon.
  17. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    Seems that both Typhoon and Mike class Soviet submarines have titanium pressure vessels. Interesting, but military budgets and materials applications don't really relate to civilian surface vessel applications, unless you happen to own a country.;)
    So far it seems that there is no good technical reason that titanium has not been applied to the manufacturing of yachts.
  18. gja

    gja New Member

    Joined:
    Jun 25, 2006
    Messages:
    1
    titanium

    I repaired several part from a half tonner.the hull is carbon kevlar and all the hardware is titanium.I just got some rods and though I´d give it a try with my TIG.I mainly weld aluminium and found it quite easy to get used to.I asked a technician what would be the correct process and it´s true you need to clean the parts with acid (which I did not do,just brushed it with stainless steel brush).(not that I recommend this).Ti is a beautifull material,but it´s true that the excess material removed on a lathe for example is highly flamable.Anyone interested should buy small surplus parts on the web and try on small projects.I found once a website with the pictures and description of a russian runabout prototype made of titanium,powered by a small diesel engine and equipped with foils.It was said to speed to 40knts+.I´ll try and find the link if anyone is interested.

    gja
  19. Codger

    Codger YF Wisdom Dept.

    Joined:
    May 29, 2005
    Messages:
    940
    gja
    Yes please. I've only done cursory searches but have not come across the vessel that you mention.
  20. Loren Schweizer

    Loren Schweizer YF Associate Writer

    Joined:
    Apr 20, 2004
    Messages:
    1,269
    A titanium bicycle left out in the rain looks good over time and one would imagine that a Ti hull would do well, esp. as evidenced by posters noting the (previously) Evil Empire's subs.
    Interestingly, our new F22 will contain ~34% by weight Ti, the highest ever for a warplane.

    Sadly, there's no free lunch, just expensive hammers.

    The price of hot rolled plate steel is roughly $650 for a metric ton and about thirteen times that for Ti sponge... and this with Ti prices having been on the decline after 9/11.

Share This Page