Littoral Steel Trawler Design

This is rather just a concept I would like to pursue. The whole world is filled with fishing trawlers that are in many cases used in local subsistence markets. The need for the long range is often not necessary and large reefer holds is minimal. So I have a small littoral version.


I have chosen a design that matches the size needs of these fishermen. One critical issue is the absolute need to supply composite outriggers. This is because they can cost stability hugely. No concern for scaling down their mass can make a non-self righting design. So the exporting system simply make these for shipment. A USA kit system is the intention. Give the steel and parts for local welding construction. Include the single engine diesel also.

So here is the critical description. Adopt a ten foot beam. Make U-sections on a weldament forge. These U's will self nest allowing novice level lap welding.

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crossection of U plates

A weldament is a steel welded form to hot press the U section. It has a male and female design. Real red steel making gas nozzles simply are mounted in the forms. A set of four inch hydraulic pistons can then force the flat raw plate to the form. The lack of high accuracy allows this production method.

Real nested four inch overlaps allow straighten for the novice. The combing is all misaligned but who cares if angle iron is run along it for flat plat decks and spaccer flat strips fill the void of the nesting effect.

The bow plate and stern plate are the hard parts. I forgot the welder must have a steel cable hull rolling system to make always downward lapping.

*****This is where I need advice.. how to prevent the 90 degree welding of the steel ends.****** Tabs of some kind?

The bow is supposed to then be continued with a fiberglass nose cone.

 

I hope this diagram works

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Hull crossection

 

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right half hull crossection


Four foot long u sections. length to allow the ten foot beam.

 

I really have no idea of what you are talking about. To start with, how did you determine the "need of those fishermen"? Each fishing ground has its own different conditions.

 

Did the FAO produce a design to fit similar uses ?

 

To: Gonzo:

Your concern is appreciated. I don't sound like a fisherman either. And I am not one.

The design is target for free distribution to poverty zones along the coasts. They in general have no refrigeration capacity in their houses. A daily trip to the market is for selection of chunks of meet off the bare table. It is a once a 30 hour procession of time limited meat. So it is just a fisherman's one day overnight trip out. This forms the basis for the small version of trawler.

As an aside. Using this system to construct UAV commercial ships is real future coming also. 10 beam and greater than 100 foot long. One diesel, no humans aboard. Four contianer cargo capacity. "microships"

 

Pretty well every coastal village on the planet uses their own design of fishing boat perfected over centuries to suit local requirements.

 

To: Mr Efficiency

Thanks for the reference. I searched with google and came up with this design:
https://archive.org/details/fishingboatdesig034823mbp

It is for a FAO steel trawler.

I can not critique their design, but submit the concept of novice welding only design.

My press can make uniform U-plate sections. There are no compound curves. And no full welder skills necessary. It is a compromise but allows self righting ability. I am not using a box barge system. It is full dynamically stable curved.

I was thinking about how to setup the hull end plates. I guess my only out is to press steel straps to buildup a thickness at the end plate to U-plate joint. Building up this way prevents novice burn-thrus at the joint.

Thanks Doug

 

All I see are lines of *****. What is the design? Also, why focus on trawlers? They are the main cause of destruction of the ecosystem where fish live. Trawlers drag chains in the bottom. Also, how are villagers going to weld if they have no electricity, welding equipment or are trained welders?

 

To: whitepointer23

They certainly are using the local ship/boat-making systems. The problem is insufficient size and strength. Local wood boats are in general wow-fully poorly built. My design is obviously only functional where diesel fuel is found.

For an example of how poor, the Chesapeake deadrise design wood work boats are a study example. A frame every two feet means what? The Bay has only small waves at the worst is the only saving grace.

 

The Chesapeake deadrise design is an example of a really good design. What faults can you find on them? Have you ever been working on the bay on a rough day? You should study traditional designs and spend time on the water working, before criticizing vessels that are the result of centuries of refinement.

 

What does 'UAV' stand for?

 

Unmanned aerial vehicle. I thinks he autonomous ships.

 

To : Clarkey and Whitepointer

Yes I used the wrong use of UAV. Autonomous ship is the right intention. My ship is small and not a hazard to shipping. I figure a 14 foot crushable bow will make it harmless to small craft even. A 15 knot speed is expected. A 1/4 inch plate version could allow a 300 foot hull length.

A novel steel U-plate press system allows trivial costs. The four inch lapping means the strongest hull ever built.

In my world you are suppost to be communicating with people needing education. So unannounced intelligence versions are allowable. Jakarta and oslo need educating.

 

I don't see the advantage of unmanned container ships. Look at the biggest ships now. They have a very small crew anyway. Where do your unmanned ships end up if there is a malfunction and no one on board to repair it.