Recreational MLB 40' range

Discussion in 'Boat Design' started by Maverick510, Mar 12, 2008.

  1. Maverick510
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    Maverick510 Junior Member

    First post on this forum so excuse my newbie questions. I am a life long boater and avid waterman. I currently own a military spec. 6 meter rib and I am looking to move up in size. After extensive research of recreational boats I don't seem to be finding anything I like, my ultimate goal would be a 42' recreational version of a Coast Guard MLB in aluminum. I do quite a bit of business in China and have access to an aluminum boatyard in Southern China. Of course I would like to have all the attributes like self bailing and self righting.

    My question is does anyone have experience with this sort of project, any suggestions of where to start. I have seen some posts on this subject, so it appears to have come up.
     
  2. charmc
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    charmc Senior Member

    If you Goole search terms like MLB, motor lifeboats, etc, you'll find some good sites. There is a member here, USCGRET/E8, who, if I remember correctly, is himself or knows some experts on the subject.
     
  3. Maverick510
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    Maverick510 Junior Member

    Hey Charlie, thanks for your reply, I have done some searches on the subject but none of the info. I have found has much detail. I was looking to see if anyone has taken on a project like this or even if it is cost prohibitive. Or possibly if there are some line drawings that I can take a look at.
     
  4. charmc
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    charmc Senior Member

    Maverick,

    This site has some good info and better links.
    http://en.wikipedia.org/wiki/Motor_lifeboat

    Just what sort of MLB are you wanting to have built? The earlier displacement models, or the planing types, like the 44 and 47? Those are very sophisticated - translation: expensive, and I'm not certain you can get the designs, as they might be the property of the USCG.

    If you are willing to do without self righting, there are many options for seaworthy self-bailing smaller patrol boats.
     
  5. Maverick510
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    Maverick510 Junior Member

    Hey Charlie, thanks for the link I will check it out, I am shooting for the 47' I don't want an exact copy just a facsimile with some of the same attributes. Self righting would be optimal but we all have to compromise in life.
     
  6. Pericles
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    Pericles Senior Member

  7. Tad
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    Tad Boat Designer

    The Textron 47' MLB design has been adopted by various nations (including Canada) as the CG boat of the day.

    The design is very specialized and becoming somewhat outdated as the project began in 1984. The boats are awkward to get around, clumsy in the hands of young guys from the prairies, and ridiculously heavy and complex to build and operate. They are of very deep-vee form, overweight for their bottom (planing) area, and foolishly inefficient underway. In short they are what you get when designing by various committees and corporations, a mess.

    Vast improvements could be made if you eliminate the primary mission. There is a very good 1990 SNAME published paper on the design authored by Steven Cohen, Debabrata Ghosh, and David Shepard.
     
  8. charmc
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    charmc Senior Member

    Tad,

    I agree with all you've said about the 47' MLB except the word "mess". The design is extremely poor in many aspects, but all was driven by, as you noted correctly, the primary mission.

    The 47' MLB is built to operate continuously in the steep, fast-moving, and breaking waves of the littoral ocean, constantly drenched with salt water, thrown into extremes of angle and acceleration of pitch, yaw, and roll, including frequent capsizings. Everything in the boat is overengineered and overbuilt, so it's much too heavy and it's a pig when cruising. Personally, I would never want to own something like that. But it and other MLB designs are built to survive in waters that destroy nearly all boats. That primary mission defines the boat. It's a bit like a fire truck: heavy, awkward to maneuver, not fast on the open highway, but very good at it's primary mission of bringing a trained crew and equipment to fight fire and rescue those caught in it.

    Maverick now says he's looking for a good boat with some of the attributes of the 47' MLB. I interpret that to mean a 40'+ boat for personal use, but designed to handle rough water. Once you remove the self righting and extreme surf handling, there are many designs of good, rugged, small craft. SeaArk, which builds patrol boats for government work, also builds commercial boats incorporating some of the same hulls and design factors. This cruiser, by a designer who's done some good work on other boats I've admired, might be a good boat for someone who wants a 40' - 50' cruiser able to handle rough water while still providing some amenities: http://www.tadroberts.ca/about/pdf/pacific-yachting-review-of-express47.pdf .
     
  9. Maverick510
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    Maverick510 Junior Member

    Hey Tad, Thanks for the breakdown I realized the prototype went back to 1990 but I didn't know it stretched back to 84'. So given the advancements in the last 20 years it appears you feel it would be easy to improve upon the design. Just last week there was a video of a 47' MLB taking a rollover in a 25' set in Morro Bay, I have been surfing for over 20 years and have a healthy respect for the ocean and conditions like that, any boat that could survive a wave of that magnitude and continue to run is remarkable. I do get what you mean about the design being a little clumsy, it would be nice to refine it make it a little more user friendly, is it possible to keep the boat light and fuel efficient but still maintain the best attributes such as self righting and self bailing? I realize that might be unrealistic or as you referred "eliminating the primary misssion".
     
  10. Maverick510
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    Maverick510 Junior Member

    Charmc, beautiful boat, in my search I have been looking at some of the lobster styles, on the West Coast they are not that common but the format seems very sensible. I am getting the feeling some of my goals may be a little unrealistic, what goals do you guys think might be obtainable? maybe everything with the exception of self righting.
     
  11. Tad
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    Tad Boat Designer

    Self-righting of itself is not difficult, but it has certain implications for the design. The freeboard becomes somewhat low to promote instability when inverted. And the deckhouse must be fairly high to add to the inverted instability. The contents of the vessel must remain in place and the windows stay intact. Air intakes get complex. Some of this adds weight/windage which is not required if self-righting is ignored.

    For progress from the Textron boat look at the Swedish Sea Rescue Society SSRS-1200 (40') and 2000 (65') designed by Rolf Eliasson and first built about 1995. These are foam cored composite vessels with waterjets. Service speed is over 30 knots and range is 350 miles at full speed (10+ hours). The Textron boat has a service speed of 20-25 knots and 200 mile range. It weighs about twice that of the Swedish 40'. There is some info on the Swedish boat in Principals of Yacht Design, also a Professional Boatbuilder article here........
    http://www.proboat-digital.com/proboat/200612/
     
  12. Maverick510
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    Maverick510 Junior Member

    The Swedish boat is very cool and it fits the requirements very well. Problem is where to start with something like this to get an idea of cost. I work with a fiberglass manufacturer in China but the process of production for this type of vessel is realitively complex and specific when it comes to material and technique. What would be a sensible approach? Would aluminum be easier? The cost to produce a mold like this would be quite high and not that sensible for a one off.
     
  13. Tad
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    Tad Boat Designer

    Maverick,

    It is always advantageous to the customer if the builder is working with materials and methods he understands and is used to. I tell clients to pick a builder who allready works with your chosen material. I always create designs with a specific builder in mind, usually with materials and methods stipulated by the builder.

    I would say yes, aluminum will be easier for a builder experienced in aluminum construction. But good aluminum work will be time consuming for a first time build. Let your builder work with what he knows, and then he can do a great job.

    The Swedish boats are all developable surfaces, thus simple throw away molds can be built of MDF on CNC cut forms. Or the fiberglass sandwich panels can be laid up on a table, trimmed to shape, and taped together. The rubber donut collar is part of the hull form.
     
  14. Maverick510
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    Maverick510 Junior Member

    What do you think a good start would be, possibly some line drawings with rough specs to quote out? From past experience on custom builds do you have any cost ranges from 38 to 40'? I understand it can vary quite a bit like anything else.
     

  15. Tad
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    Tad Boat Designer

    Quoting accurately (or not) will depend on the experience of your builder. Most always want more information rather than less. An experienced builder should be able to quote a project quite accurately from a GA drawing, midship construction section, and a written specification outlining equipment, materials, and finish level. Some will quote from less than this, watch out....they are probably hungry. This may not be a bad thing, but it often is. In the end deciding if a quote is believable depends on trust....if you don't trust the builder, don't get involved.

    Costing boats is difficult because of the vast differences in overhead and labour in various countries. Right now I have a 48' design under way in South Africa with a yard rate of about $20 per hour. There is no way a North American or European yard could compete with this. But you get (more or less) what you pay for, ie semi or unskilled people working in marginal facilities who don't produce a great deal per hour. I usually urge people to go to established yards with experience and a track record. This usually means you've made a better long term investment in your boat. If the yard stays around for a few years a market value for their products is established.

    As a ballpark guesstimate I look at man hours and double it to cover materials. Today in expensive yards the labour is often more than materials, but we are just ball parking here. If you are building 20,000 pounds of boat good people will do something between 2.5 and 3.5 pounds of boat per man hour. Thats something between 8000 and 5700 man hours. I'll take the high number because I'm a pessimist. In SA your labour cost will be 160k USD. In North America the lowest yard rate will be $50 so labour will be $400k. Double that for materials and equipment. So you have a range of between $320k and $800k, top European or NA yards will be more.
     
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