Origami steel yacht construction

Discussion in 'Metal Boat Building' started by origamiboats, Nov 30, 2001.

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  1. Brent Swain
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    Brent Swain Member

     
  2. rugludallur
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    rugludallur Rugludallur

    Are you saying your paint job has lasted 26 years?

    You should immediately contact one of the major paint manufacturers and get into discussions with them on how to commercialize this paint system as it would be a major revolution in marine coating, with this kind of paint ships could be painted once when built and won't need the costly dry docking.

    On a more serious note, the primer on pre-primed plates is not a suitable primer for a marine coating systems, I still think using pre-primed plates is worth it since you don't have to deal with mill scale but any marine paint specialist will tell you to sandblast and use a proper dual component primer.

    Jarl
    http:/dallur.com
     
  3. rugludallur
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    rugludallur Rugludallur

    Rusty spots

    So the rust was showing back then to?

    :p

    Jarl
    http:/dallur.com
     
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  4. pdwiley
    Joined: Jun 2008
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    Location: Hobart

    pdwiley Senior Member

    I'm using blasted plate primed with a weld-through primer. The local Jotun rep is happy with it under the Jotun 2 part epoxy primer. I painted up some test pieces and I've tried to get the Jotun epoxy off. It's stuck well, a wire brush on an angle grinder doesn't really cut it and it certainly won't come away except by abrasion right under the wire wheel edge.

    PDW
     
  5. rugludallur
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    rugludallur Rugludallur

    If they are willing to guarantee the their paint scheme over the pre-primed plates that's great news for you, originally I intended not to sandblast and the responses/questions I got were:

    1. What kind of primer is currently on the plates, chemical composition, etc?
    2. What was the surface roughness of the plates before the primer was applied?
    3. How clean were the plates when the primer was applied?
    4. Was the environment where they were primed dust free as to not embed any hygroscopic particles?​

    Aside from that it also meant that I had to touch up any grinded/welded area within 4 hours and abrade it to the correct surface roughness, although this is made easier by using dual component spray cans so you won't have to mix a batch every 4 hours it's still tedious.

    Even though I had Lloyd's certificates for all my steel I still was unable to obtain the relevant data and having seen pre-primed steel with mill-scale still attached under the paint I decided to bite the bullet and buy/build a sandblasting rig and compressor.

    Jarl
    http://dallur.com
     
  6. pdwiley
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    Location: Hobart

    pdwiley Senior Member

    I'm sending my steel to a local place that specialises in blasting & priming steel. Hobart is a small city, the industrial area is even smaller, these guys all know each other. In my last job we used a lot of steel that went through these blasters without any problems so I'm pretty confident; they have enclosed premises for blasting & painting. The Jotun epoxy paint is a slow cure rust chelating type that binds well to light rust so the main game is to get all the mill scale off.

    I've bought a 120 cfm 3 phase Hydrovane compressor so I can do my own blasting but some things are better paid for IMO. It's a terrible job to do even with forced air breathing apparatus. I'll blast all the small stuff myself.

    PDW
     
  7. rugludallur
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    rugludallur Rugludallur

    I didn't realize that you were actually having the plates blasted and painted, I thought you were buying plates with the primer from the manufacturer in which case one usually has no way of knowing what kind of paint or surface preparation has been done. In your case you can be pretty sure that the quality of both is good so your in a much better position.

    I recently bought a 120cfm Hydrovane myself, (it's still in transit), planning to use it to blast with a 1/4" nozzle and garnet.

    I got a couple of local blasting outfits to give me a ballpark quote for blasting and priming, the quotes ranged from USD $10.000-50.000 for a 33ft boat, it wasn't a hard decision for me to do it myself, I spent around $3500 and bought/built a complete blasting rig with helmet, air feed, etc.

    You guys in OZ have an advantage when it comes to blasting, cheap garnet available locally must be nice, I had to get mine from India and I live in Iceland :p

    Jarl
    http://dallur.com
     
  8. apex1

    apex1 Guest

    Three times wishful thinking BS!
    Or let me say it in my unmistakeable frank and nice way:

    YOU LIE,
    and you know that you lie. But that doesn´t bother you as long as your lies support your income.


    No BS,

    don´t think that way, they are not longitudinally framed. Hence not as strong.

    A boat built to your method is either as heavy or as strong as a framed one. Never both! That is technically not possible.
     
  9. pdwiley
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    pdwiley Senior Member

    I tried to buy primed plate from the steel merchants. Hah. Doesn't exist. Pipe, RHS, sure. Flat baR & plate, no.

    My quotes for blasting & priming a complete hull after it was built were equally as outrageous as yours. It's going to cost me around $4K AUD to have the plate done instead - $22/m2 plus 10% GST. I was a bit hesitant to do it this way as someone observed that I was also blasting (expensively) my scrap pile but my recovery of steel from the keel deadwood plates has been so high that I think the wastage is going to be minimal. A plasma cutter makes a HUGE difference for the steel work.

    I bought my Hydrovane compressor off Ebay for $2K. No pot as yet but I can buy a 80 litre one for $300. I've got a machine shop so adding another expensive tool to it wasn't much of a consideration really and I can easily re-sell it if I wanted to.

    Copper slag is pretty popular as a blasting medium here as well as garnet.

    PDW
     
  10. welder/fitter
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    welder/fitter Senior Member

    Rugludallur,
    Just spent the past few hours viewing your excellent site! http://dallur.com/
    Nice job! Best of luck with the completion & launch!
    Mike
     
  11. rugludallur
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    rugludallur Rugludallur

    pre-primed plate

    Over here it's impossible to get shipbuilding steels without the primer and I would say about 80% of the mild steel is coated to, but then again I'm almost exactly on the other side of the planet.

    Because of shipping costs I ended up building my own sanblasting pot from a discarded air compressor tank, the other parts I ordered from the UK from the same guy that sells these, essentially the same kit except no tank:
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330351745024&ssPageName=STRK:MEWAX:IT

    I also bought my compressor on ebay, 500 pounds sterling but with shipping and VAT it's probably going to cost the same as yours.
    Most of the sandblasting guys here tend to use local sand which is essentially black volcanic sand, unfortunately it's weathered and relatively low hardness so even though they can clean a surface well enough they can't get the roughness up.

    The plasma cutter is a lifesaver for sure, have you considered getting the plates CNC cut? I ended up modelling my boat in Rhino3D and cut using a CNC Plasma table, it took about 3 days to cut everything for my boat and it saved me a ton of work.

    Jarl
    http://dallur.com
     
  12. rugludallur
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    rugludallur Rugludallur

    Thanks, I'm getting really close to blasting and painting, just a couple more days and some finishing touches. If everything works out I might be able to launch next summer.

    Hopefully I'll have more time to spend on the website once the boat is done, I've got tons of pictures and videos that I want to add including a time lapse from the webcam.

    Jarl
    http://dallur.com
     
  13. welder/fitter
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    welder/fitter Senior Member

    Jarl,
    Obviously, it depends where one lives but, in Western Canada, one can order wheel-abraded, pre-primed(Zinc coating) steel which will come with a MSDS sheet/details for the primer. As for the primer's ability to stick to wheel abraded steel, I've found no issues, though the wear on the abrading wheels is, obviously, of significance.
    Mike
     
  14. rugludallur
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    rugludallur Rugludallur

    In the end it probably all depends on what the paint manufacturer specifies. If they are OK with the primer then I would think that's all that matters.

    Someone told me a while back that most all of pre-primed steel was abraded with wheels, the same person also told me that this was the primary factor in causing locked in curvature since it heated the plates enough to cause them to deform.
    From what I have heard I would be a bit hesitant to use zinc primers below waterline but otherwise I agree.

    Jarl
    http://dallur.com
     

  15. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    Those were the subsidy for the average car in BC, published in the Vancouver province and on CBC radio a couple of years ago. Their math , not mine. It is the difference between gas taxes and other vehicle taxes and the cost of roads and highways.
    One of my clients, who was BC chief medical officer for several years told me that 80% of the cost of the health care system were inacitivity and smoking. So if you want to support health care , get of your asses and live more like me.
     
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