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Double Plating Question

Discussion in 'Chris Craft Roamer Yacht' started by 545x, Nov 21, 2009.

  1. 545x

    545x New Member

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    Hello All,
    I recently began restoring a 1958 Roamer 25 Express Cruiser, I chose to sandblast so I could be as thorough as possible and what I discovered was some rust cancer spots and a couple pinholes. My question is; the fabricator wants to plate on the exterior with 1/8 steel plate on top of the freshly sandblasted rust cancer / pinholes. I am concerned about just plating over the freshly sandblasted rust areas, does anyone know if this is the proper way to double plate or should I try to primer the trapped metal/rust before plating and if not how much time do I have in these areas before rust over powers the weld and new plate?
    ~Billy
    Roamer named “Ice Breaker”
    :confused:

    Attached Files:

  2. Oneiros

    Oneiros New Member

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    Hi no way you must cut away all bad plates weld in to gather in the proper way.
    have replaced 20m2 of the botton of our boat shall put some pic of my project so you can see how to do it the right way
    bestregards Erik
  3. wrenches74

    wrenches74 New Member

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    WOW! are you sure you want to undertake a project like this?????maybe the hull isn't as bad as it looks in the pics, but WOW!!!...i agree...cutting out the bad is the only way to go...otherwise, rust will just fester under the patch like cancer...Tim
  4. 545x

    545x New Member

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    Thanks for the replies,
    The rust you see in the last picture is all surface rust, the person I bought It from prepped the boat for primer then parked it outside for 6 months so all that rust just dusted off with no pits. The main damage towards the front keel of the boat where so bilge water had sat inside for a few months. What I was thinking of doing was grinding out as much rust as I can or possibly cutting the infection out then welding a piece of 1/8 steel on top of good metal. Below I have attached a picture he solid black line is the new plate and the dotted line is where I am thinking I need to cut or grind down. Please let me know if this is the best way I don’t want to be to destructive unless necessary.
    Thanks ~Billy

    Attached Files:

  5. Oneiros

    Oneiros New Member

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    Hi Yes that the way you should do it we veld first on the inside then on the outside.Im gong to put in some pic from my job so you can see more my english is not so good.
    Erik
  6. Marmot

    Marmot Senior Member

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    Please size them so they don't screw up the whole thread!
  7. YachtForums

    YachtForums Publisher/Admin

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    That image was ridiculous. Do we really need a 2400 pixel wide image? The image has been reduced. Please keep images under 640 pixels in width.
  8. 545x

    545x New Member

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    Sorry about the picture, i was having problems resizing after the text overlay, Thanks for the correction. ~Billy
  9. K1W1

    K1W1 Senior Member

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    Hi,

    Is the hull rotten on both sides here or just the one and is this all of the holes you have or just a sample?
  10. 545x

    545x New Member

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    It is rusted inside also but only seems to be near the front keel for about 24" long and 8" high on both sides, i'm thinking that the steel could have of been weakin by the loading and unloading from trailer over the years or pulling ashore to sand and rock "maybe now i know why they named the boat Ice Breaker". Their is a pinhole below the gastank and two bad welds that left holes around the prop, everything alse looks pretty good. i taped the areas for the welder and put my first coat of primer on yesterday. ~Billy

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  11. Henning

    Henning Senior Member

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    I guess your idea of "looks pretty good" and mine are different. IMO you have a good bit of metal to remove and replace. You'd be wise to invest in a plasma cutter and a magnetic straight edge to run it against. Not that big of a job really if you have the right tools. Weld from the inside first, grind the weld in the seam even from the outside and then weld the outside. If you have the right equipment you're looking at 4 days work to do it right. Remember, no corners where plate meets patch, always use as large of a radius as you can fit.
  12. K1W1

    K1W1 Senior Member

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    Hi,

    Henning - The original poster has already stated that he has a fabricator ready to to the metal work, do you think it makes better sense to buy some tools and carry out a procedure the poster might have no experience of at all?

    You could also do with refreshing your Class rules welding techniques a bit, the mega radius is not the current practice (in GL and LROS anyway).

    I discovered this point when arguing about the way an insert plate was installed in a new build.
  13. Henning

    Henning Senior Member

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    Hmmm... I guess the new way will make it down to the Lloyds office here in Aus in a couple of years, because they just made me do radiuses on some plate patches...:( BTW, it sounded to me like he had somebody lined up who would weld fresh metal over his rotten stuff hence the "Double plating" question. I'd hesitate to call them a fabricator much less a shipwright.....

    And yeah, I think taking on a boat like this is a perfect time to learn to weld and fabricate metal.:D It's fun, it's not rocket surgery either. With a MIG welder most people can learn to run a structurally sound and sealed weld in under a couple of hours. I enjoy it anyway...for a bit... then it's like work:rolleyes: That boat will see plenty of need for welding.
    Last edited: Nov 23, 2009
  14. 545x

    545x New Member

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    Thanks for the info,
    I went to my fabricator this morning and we discussed the different repair options, it left me a little concerned about where to start and finish.

    I thought of a different approach to the problem, I was wondering if anyone has try this or could see any problems with this option. I own a general engineering company in southern California and in the past we have been contracted by the state to line rusted water pipes and tanks. We used a special designer epoxy that can withstand up to 15,000 psi and flex without breaking it is also resistant to acids, petroleum everything but UV. I contacted the chemist and he said “he has a mixture is sells that is suitable for underwater marine use and will serve as structure strength and has been applied directly over rust which will stop the spread” so he says. What I know is that I have seen this epoxy work on lining a rusted 12 inch water pipe with numerous holes some even 1inch in diameter, from no pressure to 150 PSI in 5 hours.

    If I went this direction, I was thinking of sandblasting both sides again, grinding the rust spots, trow on the epoxy 1/8 inch thick on the inside then about 1/8 inch on the outside were needed, then let sit overnight grind then sand outside to smooth finish then start the epoxy paint process

    My question is has anyone done this before? And am I crazy for looking at epoxy instead of cutting my boat apart
    ~Billy
  15. Savasa

    Savasa Senior Member

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    Greetings,
    My opinion is: Go with a proper repair (cut and replace) rather than band-aid solutions.
    Peter
  16. Henning

    Henning Senior Member

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    Crazy? No, there's a bunch of ways to take care of this, but the right way is to cut away the rotten metal back to good (from your pictures I'd cut it up to that first seam) and insert a new plate and flush weld it in. That is the proper way of replacing metal. Heck, you could just get a tub of Belzona and trowl it on and fair it. It would most likely last several years with no issues. It wouldn't be right though. At the end of the day, it's your boat. I've fixed this kind of stuff various different ways, as long as the boat isn't in class, there's nobody to object to it. If it were in class, the surveyor would tell you to cut it back and put in a new plate. I have also seen people sand blast the pits, fill them with a Mig welder, grind them flush and paint before the surveyor shows up. It's up to you to decide how you want this project to go.
  17. 545x

    545x New Member

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    Reality as kicked in and it looks like I am going to be cutting some rust out. I’m sure I will be asking for more help Thanks for the info ~Billy
  18. PropBet

    PropBet Senior Member

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    Is Everything!
    To anyone who is familiar with metal fabrication, it should be a pretty straightforward task. Cut out the bad (plasma preferably, and hopefully not a torch) and replace with new. (MIG or TIG ideally) Cut back far enough into good material, and replace.

    There are always many ways to do something. On that same note, there is always the right way to do it.

    For the time and effort, you have the comfort knowing it was done right at the end of the day.
  19. Henning

    Henning Senior Member

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    That's good, it really isn't as big of a deal to do right as you think, You can rent plasma cutters, and long magnetic straight edges are available at most industrial and machine supply shops. You just set the straight edge so when you run the torch end along it it cuts just about 1mm proud of where yo want it. That will put the rough pits in the cut on the line and when you grind smooth it'll be on the line. You need a 4" angle grinder with an assortment of cut off and grinding discs. (buy a box of thin ones) Get the flapper wheel discs for sanding stuff, they last way longer than flat ones. Your plates look pretty flat with no compound curves, so forming them into place should be straight forward. Then just Mig it together. Like I said before, with the right equipment, you've got a 4 day job. A pro crew could do it in a day and a half.
  20. chriscraft4me

    chriscraft4me New Member

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    Looking for information on obtaining ultrasonic tester for steel hull

    Hello YachtForums community,

    I am very new to this community and this is my first post. I have an opportunity to get 57' Roamer. It is located in an offbeat location where the nearest capable surveyor is mile$ (and hundred$) away.

    I am very familiar with "frozen snot" hulls, having owned a few for a couple of decades, but steel hull is a totally new material for me.

    I'd like to get some information on obtaining (buying, or renting) an ultrasonic hull tester and would love to get any advise on checking a hull condition on 1965 vintage (other than sounding).

    Thank you for reading my post,

    Traveler.

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