liveaboard flat hull design disadvantages

Discussion in 'Boat Design' started by robint777, Sep 17, 2010.

  1. robint777
    Joined: Mar 2004
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    robint777 New Member

    Hey fellows

    What would the pros and cons be of a 26ft beam 80' long flat hull with a house structure 12' high.

    Fibreglassed sips(structural insulated panels) as hull structure and fibreglass panels for house structure.

    Powered by a gardner with a CPP

    hoping to cruise extensively with same. considering cat hulls for support but would prefer just flat if possible.

    Looking for 8 to 10 knots cruise only.
     
  2. WestVanHan
    Joined: Aug 2009
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    WestVanHan Not a Senior Member

    Sounds like a barge,scow,or houseboat to me.....

    I wouldn't set foot on a boat with its hull made of sips
     
  3. apex1

    apex1 Guest

    I donĀ“t see more disadvantages than these, you named them all!:)
     
  4. srimes
    Joined: Sep 2008
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    srimes Senior Member

    do you know questor?
     
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  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The concept out of hand isn't unreasonable, but you will have some (okay considerable) issues. The first one is SIP's are static load only, so you'd have to develop scantlings to address this issue. I think you'll want to revise your beam a tad, if only for reasonable maneuvering and dockage limitations, let alone efficient, cost effective cruising.

    You cruising speed is well within reasonable limits and if the craft is shaped appropriately (reduced beam of course) could be quite economical to operate.

    Not for nothing, but this is a vessel that needs to be professionally designed. A flat bottom would be perfectly suitable for near shore, coastal cruising. I see no reason to need two hulls and in fact one would probably serve better.

    I have riverboat designs that are easy to build and offer houseboat accommodations with the ability to cruise (most large houseboats are designed to remain parked).

    Attached is one of my 50' designs (16' beam). Scaled up to 80' the beam would only be 18'. This is RYD-47.
     

    Attached Files:

  6. robint777
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    robint777 New Member

    Do you have a website that would show some of your thoughts on riverboat designs?

    If the beam were reduced to 20 ft and the length stayed at 80. And the gunwhales were decently high.

    Does that translate into a reasonably stable and decent handling craft at those speeds?

    speaking of rougher days on the coast that is.

    I understand the extreme rough ride of a flat bottom boat trying to pound along, but what happens in rough water with a slow moving boat such as this?
     
  7. PAR
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    PAR Yacht Designer/Builder

    An 80' long flat bottom boat isn't going to pound. It will be longer then any wave train it encounters, for the most part. If you do get into conditions where the wave train can challenge the boat, you've got bigger problems then pounding to look forward to.

    80' boats generally are going to feel like cruise ships in most situations. The precise beam would need to be worked out, as would all the other possible variables on the yacht, but yes, you could expect exceptional stability.

    Again, you need a professional to design you a boat. No, I don't have a web site. My designs are generally custom and suit specific client needs. In fact, most of my stock plans end up being semi custom, when all is said and done.

    I suspect by your questions, you are quite new to the prospect of an 80' houseboat or yacht. Sit down with a pro and work up a design brief, establishing the goals you'd like this craft to achieve and a reasonable budget. Most things are doable, given the proper engineering.
     
  8. Riverrat1969
    Joined: Aug 2008
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    Riverrat1969 Junior Member

    The size boat you are considering is almost identical in size to a LCM-8.....21' X 73'. I don't see how to post images here, but if you'll E-mail me (put LCM-8 on subject line), I'll send a photo of one of these boats being hoisted out for new screws, so you can see the bottom profile.

    These boats are designed to land in surf. Despite what PAR has to say, a flat bottom boat this size Will pound.....just a four foot chop is all it takes. The pounding won't be tooth rattling, but it will be felt.
     
  9. Riverrat1969
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    Riverrat1969 Junior Member

    Robint777, I put a photo up on my profile. (link) This is boat 34 from the US Army 1099th Medium Boat Company, in Vietnam, in 1970.

    I agree with the other folks about building materials. I would look hard at the military surplus websites, and get a sectional barge. The pieces can be transported by truck, assembled where you want it, then build your crew quarters/house on it as you prefer......or you could buy a landing craft, or regular barge. Some of these vessels are disposed of at extraordinarily low prices.....a lot less money than a new build.

    http://www.drms.dla.mil/

    You can subscribe to regular E-mails that notify you of any watercraft up for bid.
     
  10. dskira

    dskira Previous Member

    And think about the "forgotten factor" that make dream disappearing fast:
    MONEY
    With the $ everything is possible and achievable.
    80' will pass the million dollars with full houseboat accommodation what ever you start with.
    This size is on the large size, your maintenance fees, insurance and dry docking will be around 50 to 100 thousand dollars a years,
    And the need to have a crew, since houseboat are very difficult to steer in close quarter due the the high windage and shoal draft on the size you mention.
    I love houseboat, but you have to understand the whole concept. It is not just a big flat hull with a structure on top, it is not a house, it is a boat with some very particulars engineering problems due to the shape. Hogging and twisting are the main problem. The high superstructures are difficult to built properly to be part structuraly of the whole vessel.
    I am talking of course of the size your intend to have, 80'.
    Perhaps consider a smaller size since the houseboat by definition contain twice the amount of accommodation that a blue water vessel.
    Daniel
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Riverrat1969, you have obviously never been on a large flat bottomed boat, nor understand the dynamics of vessel of this size. Most every large commercial vessels are flat bottom, cruise ships are flat bottomed, this 80' proposed vessel easily could keep it's forefoot "engaged" at all the speeds it will be driven at or that the sea will attack at, assuming it's driven in the environment it's intended for. There is no wave train that will "uncover" any portion of a vessel this size, to create a "pounding" in the traditional sense of the term.
     
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  12. Riverrat1969
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    Riverrat1969 Junior Member

    PAR, I've lived on board a mikeboat for a year, 24/7, as well as two years operating flat bottom boats in the USA.......how hours many do you have at the helm of a flat bottom boat the size we're discussing here?

    The requirement spelled out specifically shallow draft, and a flat bottom, shallow draft boat in the 70'-80' range will pound, because I've been aboard them in those circumstances numerous times. Ride aboard a US Army mikeboat (LCM-8) on the James River at Fort Eustis with a 20-25 knot wind blowing from the north, and see for yourself.......the boats pound in a chop of four feet or more...........not conjecture, but a cold fact.

    Would you like to read the same remarks from several other coxswains that also operated LCM-8's in Vietnam? Whether you are a designer or not, my comment comes from firsthand experience in the military. I cannot design a LCM-8, but I certainly do know how to operate them, and know from firsthand experience how they perform in shallow water, surf, heavy chop, and on the beach. You sir, very obviously do not have such operational experience. For you to comment otherwise shows your lack of genuine experience operating a vessel of this type. You might be able to design them, but I can operate them and make valid comments about their real world performance.

    I've noticed some of your posts to other folks in the past, and your general "uppity" demeanor.......you tend to take great pleasure posting demeaning remarks to folks that disagree with you. I suggest you comment about what you really know, and not comment based on what you think you know.

    Any ordinary person, not a knowledgeable designer like yourself, can see for themselves any large flat bottom, shallow draft boat in a seaway, with bluff bow throwing spray, pounding. Look at all of the commercial offshore barges routinely damaged in heavy weather, despite being prepped by seamen with internal shoring in advance..........or have you never been a deckhand involved in towing larger flat bottom vessels like that? I'm not in a pissing contest with you PAR, but when you make assinine statements that are pure bull pucky, someone will let you know you're wrong.
     
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  13. dskira

    dskira Previous Member

    Please keep your voice down.
    Par is very respected member and naval architect, his knowledge is fantastic and he share it with abundance.
    Just discuss with him and if you disagree tell him in a nice way.
    And read carefully his post, very carefully, and you will understand what he is talking about.
    Daniel
     
  14. Boston

    Boston Previous Member

    Ya I'm going to have to second that

    Let's keep it clean and stick to the issues

    Deal is I don't know spit about this particular issue but I do know I enjoy both your input
    So please
    Disagree all you want
    It does make for some great reading but
    Play nice people

    Except maybe for Guillermo
    Feel free
    I know I will
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'm not even going to comment on someone that thinks a LCM-8 is a reasonable example of the flat bottom breed. This is a pig of a boat, it's over driven, over weight (except the aluminum version, which is just slightly over weight) and generally only good for one thing, which incidentally happened to meet it's bid criteria. I've actually been on them and they truly suck at everything, unless you plan to be of dropping 50 tons of whatever on a beach.

    I was in the same war as you Riverrat, though didn't have the joy of riding a LCM-8 in any of its versions. I do have a 100 ton masters ticket though and considerable experience in craft of every shape and size, including an unlimited sail endorsement and considerable time in flat bottom boats. I'm sorry your experience with this hull form has caused you some discomfort, but clearly, your exposure to LCM-8's wasn't helpful. Hell, the current cruise ships working the waters in the USA are flat bottomed hull forms, as is every single container ship too. I guess they all suck too?

    Again, an 80' houseboat, used within it's design envelope will not pound, if done properly. Phil Bolger's larger box designs all prove this handily. I'm sorry you can't understand this, but your rant is mis-informed and ill advised. I'm also sorry you've apparently mis-understood my previous posts or at least take away a negative response from them, maybe my weird sense of humor. Could it be possible that I'm talking with someone whom I have previous history, that you haven't been privy to and my "general "uppity" demeanor" is something that has developed in time with a particularly difficult member? In other words, I think you'll find you are the exception to the rule, in regard to your observation and opinion of my "demeanor". I can only imagine what you think of Richard . . .
     
    Last edited: Sep 28, 2010
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