Offer: true go anywhere Trawler to build "side by side"

Discussion in 'Metal Boat Building' started by apex1, Aug 4, 2009.

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  1. M-Sasha

    M-Sasha Guest

    Richard, I do not like to "rain on your parade" here, but when you did a more conventional boat, I mean not with a commercial look, I am sure you would easily find a partner to build. I know you hate to show up with your yachts, but with a classical look, could it be possible to achieve your goals too?
    One like this I have in mind (I know you will like the style).

    Sasha
     

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  2. dskira

    dskira Previous Member

    Sasha, the problem with your comment is we didn't see a picture of Richard's project. I am also very anxius to see a drawing, and after that we can start the discussion about the style.
    I think it will be reasonable.
    Daniel
     
  3. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    :D Thanks for the offer.. but got get my current projects (2) finished before even dreaming of new concepts.. well dreaming for sure but nothing else no no..
     
  4. apex1

    apex1 Guest

     
  5. MikeJohns
    Joined: Aug 2004
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    MikeJohns Senior Member

    Richard

    Be nice to see the lines, curves, coefficients. Weight distribution, GZ GM and a RM curve.

    Surprised if you had full RAO’s for this, transfer functions are expensive to produce. Presumably basic resistance testing for smooth water powering ?


    On extremes of cold, all our boat building steels here have a notch toughness guaranteed to -15 degC and the marine insurance companies are happy with this for 60 degrees south in winter. Cargo shipping is another story and cargo ships operating in high latitudes need considerable thought to the material toughness for sure. Most of the Korean Russian and Jap trawlers working the southern ocean are poorly built and maintained and work right up to the ice and they are not the tougher steels either.

    There are ways of using cheaper steels but implementing arrester strakes with a variety of tougher materials, austenitic stainless steels are good too. As is combined framing of topsides not just longitudinal or transverse, but this is getting extreme. In ships the girder is well stressed and I don't think it's really an issue with the size boat you propose.

    There's always the option of alloy deck superstructure and alloy bulkheads in a steel hull but everytime I have considered this used only alloy watertight doors and steel bulkheads. Alloy superstructure does make a difference particulalry if you have a lower D/L ratio vessel.

    My own opinion is that steel is actually a better material all things considered ( John will disagree) I really like alloys passive corrosion resistance in the marine air environment. I don't like it so active when immersed and it can be very problematic from unforseen sources.

    I have seen problems and advantages from both materials, I think steel will always have better longevity if properly built and maintained and it is the gift of materials when it comes to welding and repair. I’ve seen alloy patrol boats built to class and a high standard that have split bottom welds after a day in a storm. Driven too hard too much slamming and should have known better but not up to spec for required use, and class minimums being a little light at times and the fatigue life being reached early in the vessels use. I have posted phot's before of fractures in topside panels properly supported just from heavy weather on the topsides these often run to a adjacent frame and stop there fortunately.

    For coastal cruising long periods at anchor steel hull would be my choice. More vessels are damaged from coming off their mooring or dragging anchor than from collisions at sea and that one thing -Abrasion resistance means a lot. For example I have a lot more confidence emergency careening a steel hull on a coral beach knowing there will be minimal paint damage, while alloy is too soft to do this and corrodes too fast when the paint is breached.and emergency remote maintenance is everything to a wandering power vessel.

    Bulbous bows are one of those in vogue areas of development that often bite the designer and the owner, they are expensive to fabricate, need extensive RAO testing, tend to be easily damaged in collisions with very detrimental performance results and can cause a lot of resistance with medium and above fouling, I’d rather a boat rode up onto a reef it collided with at 12 knots than smashed in a bulbous bow and tore its engine mounts.

    In most instances you would be better off with an extra meter of waterline and slowing down (relative) than pushing a submerged vessel ahead to try and cancel out your bow wave. Some pitching characteristics can be increased some can be decreased which is where reasonable RAO testing is required. Sometimes something as simple bottom plate on a skeg rudder can have a similar effect.

    Seakeeper or similar will be indicative of the basic hull design but you need tank testing for the bulb.

    Active Stabilizers, what’s your radius of gyration and GM ? Are you going to add masts for sail or just derricks? Whats the hullform would static bilge keels be as good an option for a lot less drag ? Auto Rudder control for roll reduction strategies ? A little less beam perhaps?

    I've just rambled here as I guess any of us could all day on boat design but hard to assess a design this way :)
     
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  6. dskira

    dskira Previous Member

    Please don't be shy. Seriously I like it, it is a very good post, with a lot of very thorough informations. Like it very much, mostly when you will favor steel, and avoid bulbous bow. I am with you on these one :)
    Daniel
     
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  7. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Mike

    I wouldn't say i disagree with you "..My own opinion is that steel is actually a better material all things considered ( John will disagree)..". However, on the single topic of temperate, steel versus ally, ally wins hands down.

    BUT and this is a very big BUT, design is not about one single issue. The whole SOR of the boat must be satisfied, so many conflicting issues to be satisfied.

    When we design a boat we don't select everything from the outset and then just hope it works...we go through the SOR and then a "natural" convergence to the final solution occurs, all on their own merits.

    I am sure Richard is aware of this, hence this thread to kick these 'knowns' about to see if all bases have been covered.

    I agree and have stated previously, bulbous bows are limited to very exact requirements and if ones design does not fall into said "exact parameters", then i would not have one. Save on weight, cost, time etc...But in the absence of real hard tank test data, regarding seakeeping too, if any done...not so easy to fully conclude.
     
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  8. dskira

    dskira Previous Member

    Can't be better said.
     
  9. apex1

    apex1 Guest

    Well, here it is:the pro´s of you know already, (sorry Mike and Alik,I do not exclude you).

    And to end a debate about Steel vs Al.... I have had both, and Al for me is the superior material. period........but...
    I mentioned that in a previous post, I would NEVER and under NO condition, and at no price and terms build a Aluminium vessel for the average boater who leaves it unattended in a port, marina, or where so ever! Al has to be pampered or driven day by day, then (and only then), it is a favourable material. Leave it unattended for a moment and you know why your insurance claimed for extra rates!
     

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  10. apex1

    apex1 Guest

    And we can end the discussion by a simple fact, my yard has today stated* to be not able to build in Al/ Al so, steel Al is the way to go, or we leave the project.
    * as to GL standards

    Again I like to tell you (all of the contributors by so far) that I am very impressed how civilized we can treat each other when the topic is a clear one and the people involved are of such knowledge. You make me happy in destroying my plans! Well, you bring them further as you know.
    Richard
     
  11. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Richard
    "..Again I like to tell you (all of the contributors by so far) that I am very impressed how civilized we can treat each other when the topic is a clear one and the people involved are of such knowledge..."

    That is because there are no egos at play here and the contributors are professionals, and can debate the issue at hand and/or just simply provide quality advice from personal experience.

    Not a single PlayStation in sight!...bliss :)
     
  12. Guest62110524

    Guest62110524 Previous Member

    I have 16 larger alloy hull in the water, some of them are unnattended for months, and some of them are now quite old, one nearly 25 years, with no problems
    I think there is much hearsay bandied about with al al, and until you have built, owned and upkept such, there hearsay is all it is
    one yard that has won awards for best superyacht in Monaco, I think twice, who i used to have close connections with, put 300000 man hours into the engineering systems alone on a 150 footer(sailing) so there were many systemss your vessel will not have
    properly finished (yacht class) 60 footer, may take 20000 and thats not a fast build
    there is a crowd near you called Cobra yachts, they are doing a very big expedition yacht in steel, and do really big wooden Gulets, may be worth a look there
    http://www.cobrayachting.com/
     
  13. Guest62110524

    Guest62110524 Previous Member

    Daniel
    Are you familiar with work of Robert Clark? Carita etc?
    so you still draw the old way?cheers Stu
     
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  14. dskira

    dskira Previous Member

    Yes I know Carita, she still in good shape under the name I beleive "Flurtge" but I will not garentee nor the name nor the spelling. I have a flint for Robert Clark, brillant design. Who will not love him, so elegant.
    Yes I still designing the "old" way. Do you know an other way to draw:D
    Cheers
    Daniel
     

  15. apex1

    apex1 Guest

     
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