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  1. pauljohn

    Look what they got away with

    I believe Jaguar did something similar with their inline 6 engine in the sixties when they enlarged it from 3.8 to 4.2. Although they left the head unchanged so the new spacing of the bores in the block left the combustion chambers and cylinders out of alignment.
  2. pauljohn

    arneson drives

    I have driven a couple of boats with arnesons and neither of them had sea water intakes for the drives just the regular intakes for the engines. However the props themselves were very susceptible to any marine growth and needed to be cleaned regularly or boat speed would suffer badly.
  3. pauljohn

    3412 Cats

    Hi trainwreck I haven't had any experience with 3412's but have with other Caterpillar engines and my advise would be to contact Cat themselves and ask them. In my experience they are quite proud of their engines and are one of the best companies to deal with. We had an overheat problem with...
  4. pauljohn

    Looking for description of ferrys unloading

    There is a roll-on/roll-off ferry that runs in the Upper Peninsula of Michigan that regularly does this, in fact I have never seen it tie up unless they are on a break! Ferry capacity is about 30 cars or maybe a couple of semi trucks and a few cars. The ferry dock is L-shaped and has an...
  5. pauljohn

    Print-Through

    ...here is what I understand is going on. Print-through caused by the curing process is done, it is unlikely that heating the laminate up now past 170* will do anything. What is causing the print through now is simply the different rates of expansion that happen when the laminate is heated by...
  6. pauljohn

    Print-Through

    Thanks for input. I will try and raise the temp to see if that does anything, is it possible that laminate a year old could still benfit from this or has the curing process done at this time? What would you use as a 'gel-coat' on epoxy? Do you think building up the polyester primer (duratec)...
  7. pauljohn

    Print-Through

    I am having a print through problem on a laminate that only shows itself when it is warmed by the sun. The laminate was post-cured to about 170* and has been taken up to that same temp on a regular basis by the sun but still shows print-through above about 120*. The epoxy laminate is hand-laid...
  8. pauljohn

    Beam Perforation Program.

    Thank you for replies. Appreciate your time Greg on running the analysis. I am happy with only losing 10 or even 20% of stiffness. I think I will try and keep the holes down to about 60 or 70% of wall height. Not really following you on what a 'doubler' is and yes I knew from the beginning it...
  9. pauljohn

    Anodised aluminum corroding out when in contact with stainless steel.

    A few other things to check. The stainless fasteners should be tapped into stainless backing plates under the deck or held by nuts. I have seen regular steel a few times moulded into the deck (ugh! lost a mast this way) Also make sure someone hasn't run wires onto the metal to bond all metal on...
  10. pauljohn

    Beam Perforation Program.

    I shall give a little more info, if only to calm the fears of the ‘responsible’ engineers on this forum and show them that I am not one of those ‘irresponsible’ engineers trying to deceive his boss/customer (both myself btw)! ; ) I am working on a small boat (50’) where the builder thought it...
  11. pauljohn

    Anodised aluminum corroding out when in contact with stainless steel.

    Berkshire "A fiberglass tape impregnated with corrosion inhibitors that is applied to the underside of the sail-track, this material is designed to stop corrosion and stainless in the joint interface." Not quite sure how that is going to stop the contact between the threads of the fastener...
  12. pauljohn

    Beam Perforation Program.

    Hi Ed thanks for the reply. I think I might of oversimplified my question.(But if you still think it is easy I will return to my textbooks for help!) Once I get a feel for the weakening process as I enlarge the holes I want to try and strengthen the beam by welding tube into the hole. I would...
  13. pauljohn

    Beam Perforation Program.

    Hi I am trying to get a 'feel' for how much a beam (rectangle tube steel) is weakened by drilling holes in it and have been looking for free software on the web that might show me this with no luck. I do not wish to solve complex problems but just want to get some idea if I drill a beam to run...
  14. pauljohn

    Anodised aluminum corroding out when in contact with stainless steel.

    When I was working in a rigging shop in the caribbean we tried many things to isolate, from primer too pieces of plastic that I would carefully cut up hoping that if we isolated some of the fitting, it would slow down the corrosion but it never worked very well. As long as the stainless...
  15. pauljohn

    Anodised aluminum corroding out when in contact with stainless steel.

    Hi Berkshire Yes 4200 is good although not quite as aggresive as 5200. That is why I like it on sail/car tracks and other spar fittings that don't come off very often because it is so difficult to remove. There is a product that is supposed to remove it but I have had limited success with it...
  16. pauljohn

    Anodised aluminum corroding out when in contact with stainless steel.

    Very common what you are experiencing. Problem is not so much stainless touching alum. but really salt water laying in contact with both of them when they are in contact with each other. I see it much less on fresh water boats. Yes monel would definately be better but has less strength although...
  17. pauljohn

    Heat transfer question - ice on windshield

    I feel like a student posting amongt professors. While I can't offer any theoretical explanations or numbers, thermodynamics was not one of my strong points, I have a few observations I would like to run by you to see what you think (By coincidence I was thinking about this same problem a few...
  18. pauljohn

    Round Tube/Pipe with Tension Cable Core

    This sounds similar to the in-mast roller furling you see on sailboats. Consists of a central wire or rod (rod works better - less deflection at centre) suspended between one or two turnbuckles for tension inside the mast. A series of aluminum foils cover the whole length of the outside of the...
  19. pauljohn

    Submersible Barge Ballasting

    Ken Try searching for 'Dockwise yacht transport systems'. They use semi-submersible barge technology to transport cargo. (Used to be called dockexpress.) I don't know anything about the ballast technology but they use manual labour for loading and unloading. Float on/Float off.
  20. pauljohn

    Berthing orientation based on initial wind direction

    ozziz Go to google maps and type in 'cedar island, michigan 49726' and hit the search button. Switch to satellite mode and move the map north of the area until you pass over the US/Canadian border. You will see a very uniform wave pattern interacting with some islands. You can see how the waves...

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