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Aluminum Hull Issues

Discussion in 'Chris Craft Roamer Yacht' started by YachtForums, Nov 29, 2004.

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  1. Mov-it!

    Mov-it! New Member

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    FML; the logical Aluminium replacement

    Aluminium remains a preferred shipbuilding material. Unfortunately it also has some minor downsides like the material's softness.

    At this moment I'm studying on the development of Fiber Metal Laminates (FML's) developed by Stork. For those not familiar with FML's, they are a composites made of thin metal layers (Alu or stainless steel foil) and a fiber reinforced matrix. The test are very impressive. Both the lightness of the materials and the enormous strengths are remarkable. FML's are widely used in the aviation industry. The Airbus A380 is built with an FML called glare.

    FML's are likely to be introduced in yachting in applications like floors, doors, hatches and inner walls. At this point it will probably take at least 3 years to make a yacht hull in FML. The formability is limited and complex, but the engineers will find a solution for that.
  2. Charlie D

    Charlie D New Member

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    I am more familiar with steels than aluminums. The steels came with CAPAC. I am surprised at how many Roamers are in salt water. I thought they would disolve instantly, like dropping an alka seltzer into water. Without scientific backing, I'm sure the CAPAC would be beneficial in salt water. CAPACS seem to have been standard equipment on Roamers, so it ought to be on there, unless someone removed it for some unknown reason. I consists of a couple of discs on the exterior of the boat bottom, about 8 - 10" diameter, (do not paint) a box of "electronic gizmos" hidden somewhere (probably by the fuse box) and a "control panel" near the helm. It is mostly a "leave it alone" piece of equipment. Also, sometime in the '70's or so Mercruiser was making a similar unit. If someone needs a complete set up, this is one route to check.
  3. alloyed2sea

    alloyed2sea Moderator

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  4. Mov-it!

    Mov-it! New Member

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    Eric,

    Ofcourse Aluminium isn't "soft". I meant it relatively compared to fml's.
    I prefer an aluminium boat over any piece of plastic.

    It only looks soft if you compare it to this.

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  5. alloyed2sea

    alloyed2sea Moderator

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    Hmmm,..., I can read; BUT, (like our president) CANNOT understand (that fine chart):
    "Skin"?
    "Core"??
    "Q layers"???
    Sheesh - sounds like everybody already uses diagonally layered, composite aluminum strips (FML?) to build ship hulls -- COOL!
    Point is: Aluminum > GRP, eh?
    PS - Check out the extruded aluminum "speedboat":
    http://www.speedspecboats.com/

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  6. Northern Lights

    Northern Lights New Member

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    capc and isolation

    The Capac systems are great. Like anything they need service. I have seen the anodes last 30 years. I have seen the reference electrode fail due to dive services using abrasive pads to clean the reference electrode. It has to be cleaned and over a period of years and the plated reference electrode is damaged. The damage is the base metal of the electrode is exposed. The system no longer has a proper reference and usually causes the system to over protect. The symptom is burned paint in a halo shape aroung the anodes. The manufacturer still exists and parts are still available. The system has a good history and has protected the boat for years. Wards marine electric is the official source of Engelhard Capac systems. Technically the boat is no better off than if you protect it with zinc. If this is the choice than it is smart to use a monitor only sytem. Electroguard makes a monitor only for aluminum. The nice thing electroguard monitor is that it is constant reading - no buttons to push. The reference is a small piece of mil-spec zinc. The thru-hull penetration is a 1/2" hole. The job can be done with a dive assist.
    The larger Roamers had isolation transformers. They need to periodically be tested to insure isolation. The transformers that were used did not have encapsulated cores. The windings are exposed to sea air, dust, and debris. The in service and harsh conditions can lead to transformer fires. Not much to burn except the dust and debris. For those who have the transformers take a flashlight and look through the cooling holes. You will be surprised how much debris is in there especially if the boat was painted and or had major carpentry done. I have replaced a few transformers and always replace them with an Acme transformer as the winding are encapsulated.
    The amazing thing about this subject is all the dock wisdom and self proclaimed experts.
  7. Mov-it!

    Mov-it! New Member

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    Eric,
    The projectmanager needed about two hours to get those figures cleared up for me.:D . It all looks like a bunch of hocus pocus but FML's are widely spread in the aviation industry and will soon be available for the construction of LNG tankers. Bottom line of the chart is that those numbers implicate the strength of the "sheets". Those numbers are an equivalent to 6mm thick Alustar (AA 5059 if i'm correct). You can imagine how much extra strength it has and how much weight can be saved. Effectively the target weight savings are 70% of a comparable aluminium hull. It's so stiff that buckling is virtually impossible.:cool:
  8. eloyex

    eloyex Member

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    hello to all ...

    new to the forum .
    i have a striker 44 aluminum boat.
    Its name is Aluminum by the way !!!!!!
    4 years restoring the boat. Too much job. But is getting great.

    As electrical engineer, i can tell you for sure the right and probably only failproof way to go, is to protect an aluminum boat (or any metalic boat) with isolation transformers installed in the boat. Isolation transformers allow to tranmsfer the elctrical power from dock to boat without ANY interaction or mess. Also , electrical problems at dock side remain at dock side, as well as interaction with other boats around you. Downside ?? heavy, expensive, some quality cabling work needed. Basically that. An isolation transformer gives you years of troublefree service. Also, a corrosion meter is a MUST in an aluminum boat. BAsically a simple meter with a reference point inside the water thru an appropiate thruhull plastic device. Last word: mixing metals others than aluminum with an aluminum boat is a source of problems. Try to avoid that mix of metals. An aluminum boat is great, but requiers more attention and expertise than a FG boat. i will post some pictures later or my rebuild process.

    eloy
  9. waterlover

    waterlover New Member

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    Thanks for the info

    Thanks for the info on isolation transformers. I have made a decision to put one in, the one I am looking at has a security response in case of need for repairs, etc. Charles industries seems to be the best, I think. If there are any better units someone please tell me. I'm like the other super boater, I,m into my 4th year of rebuilding my weird looking roamer. I want to protect her as much as possible. I am putting alot into extensive welding, and hull reworking, as well as up grading and refitting the cabin. I decided early in this project that if I was going to do this I would do it right. Its good to know that my decisions are good ones. It took me just about a year to find a good welder that knows boats, Ks doesn't rebuild anything they just throw things away. UGG!!
  10. Seventh Heaven

    Seventh Heaven New Member

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    green ground wire

    you will find a green ground wire in the breaker box on the dock.This
    ground wire connects your boat to every other boat on th dock.
    If you disconnect it from the dock and run your own ground wire to a
    coper ground rod on the bank you will eliminate any problems.
    As the owner of two aluminum Marinettes I know routine.
  11. homer1958

    homer1958 Member

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    Location:
    Annapolis MD
    Keep it simple...KISS

    Fresh water = Magnesium "Zincs"
    Brackish water = Aluminum "Zincs"
    Salt water = Zinc "Zincs"

    Capoc = 1960's Voodoo and running your batteries low and whatever else.
    Good 3 coat Interlux epoxy bottom after blasting.... 3 coats Pettit Alumacoat for aluminum. (they have 2 products for this, one with isolated cuprous, the other with no cuprous.... this stuff works!! BIGTIME

    (Trilux 2 is junk) Pettit really works ..... spray their gray zinc chromate primer on your props for 24 bucks... it works too for cheap.

    DRIVE SAVERS.... isolate your shaft from your transmission... no electric in or out... plus smoother ride and transmission safety.... careful with not over-torqing... 35lbs is right.

    Charles Isolation transformer KVA 3.6 for 30 amp... if you don't have the space or extra cash... Derryland makes the best galvanic isolator... (commercial grade.)

    Zinc on each rudder, 2 "Zincs" on each shaft.

    Stick one on your hull ladder-loop welded to the hull from factory.... it requires a 1.25 zinc... that one really gets hit there for some reason?

    Hang one tube zinc overboard hooked to the metal hull... for big Roamers... 46 and up, you may need two.... little roamers probably 1 is best. Call Bob at boatzincs.com


    DO NOT over Zinc as it can attract electric to your vessel... ouch!

    Get silver diode tip to hook to your volt meter.... test for around .9-.975 range.... this means you are perfect or close enough.... use isolation, proper sacrificial metal depending on water type.

    Keep water out of your bilge... PSS shaft seals.

    Check your hull every 75 years or so thereafter... :)

    Aluminum ROCKS!

    If you are a Libtard.... use copper instead of Zinc then get a Bayliner.

    HOMER