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Solid hull centerline

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I saw a thread here once but can't find it now.  So, starting over, how do you find the center line of a preformed solid hull.  Any help would be appreciated. Merry Christmas.


15 Feb 2016

There's a lot of great ideas posted here from other members.  I used some ideas, and added my own.

Now, toward the end of page one I posted a series of pics describing how I did it.  I hope this helps future modelers.


Cheers.  Hal

Edited by halbaby7
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This is my method for building a model with solid hull.

The first step is cutting slices of the hull in accordance with

 the contour of the waterlines, Material in this model is HDF board with thickness appropriate to distance between the waterlines.

Next this waterlines was sanded preliminary and glued into the hull bloc

for final shaping.









Happy modeling in New Year.



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If you use Tadeusz method - each layer could be made from two pieces using the join seam as the centerline.

One point - I think the USN requirements for submission to their museum include a solid hull be hollowed out - more shell than solid apparently.

I think the take home message is that for them to require this - they probably experienced stability problems with hulls that were totally solid.  Made up of two pieces - except for the lowest layer - the inside could be cut out before the join.


In the situation that Mark addresses -  try this:   At the level of the shear line at the bow and stern - mark the point that you determine is the exact center.  Drill a small hole.   Into each hole - push in a cut off large (carpet) eyelet needle - the eyelet close to the surface and centered,  Use mono filament line pulled tight.  tape it down along the way  to keep it from lateral movement and score the line with a #11 - then ink it or 6B pencil lead.  hould work for keel line and deck line.

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Thanks guys for your replies. First let me apologize for not proof reading before posting. How embarassing!


Mark has it right. This is a Model Shipways model kit of the Elsie,  1:96 scale. I bought the kit in 1968 and it has languished on a dark shelf ever since.  The hull is a machine pre-carved solid body requiring accurate light carving and much sanding to the final shape as per the plans. What I need is to locate and mark on the preshaped hull a centerline on the deck from stem to stern, and again along the keel from stem to sternpost.  These two lines must be exactly in line with each other on the vertical plane as all other lines relate to this center plane. If I can figure out how to upload a pic I will.  Is this any help, I hope?  Thanks.  Hal

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Think I would use a flat surface and secure the hull to it with the deck perpendicular to the flat surface. At the stem and stern post measure up from the flat surface to the C/L at each end, adjust until equal and secure the hull at that point, making sure that the angle from the flat surface to the athwart ship deck line near amidships was still at a 90° angle.
Then use a sliding marker set at the measured C/L at the bow and run her around the hull marking as you go, until reaching the starting point. That will show any adjustments needed to obtain a uniform C/L mark around the hull and revealing any adjustments needed before permanently marking the hull Center line.


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Good morning everyone and many thanks for the replies with info and ideas. I think I have formulated a plan using the information gained to build a jig to secure the roughed-out hull and transfer lines. I will describe what I come up with and supply some pics in the near future for the benefit of others down the line. I'm sure this question will pop up at some distant date.  Thanks again. Hal

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I don't see the pics :)

Finsing the centerline is a problem, certainly for those rough carved hulls. Is the keelslot also carved into the hull?, that may complicate things in vase that slot isn't straight, or out of center. (I once had such a hull, i gave up on symmetry...)

I have seen pics of people using a table saw to split the hull in havles, using the keel slot as a guideline. Rather drastic, and it requires adding an additional layer, to compensate for the width of the sawblade. It results in a nice visible line however, that is straight in alldirectiins. The simple option is the one suggested above with a paper template (and hoping the precaved hull is reasonably correct)



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What is your problem?

There are two ways of showing them

Either you upload them to something like picasa or photostream and use a link in your post placed between [img ] and after the link, aain between square brackets: /img

The orher option is to attach your pics to the post itself, by using the full editor to edit your pist, and use the option attacht file. The last one has the advantage that your pic will remain visible as it is stored together with the post itself.



Edited by amateur
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You will find pictures and helpful hints re working with solid hulls at my Brigantine "Newsboy" 1853 build log here at MSW.








Edited by Pete Jaquith
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Well fellas, there's the three pics. I had to have the wife help. Some things just take a womans touch I guess. LOL

I am going to try Shiloh's suggestion as I have come up with a plan.  Ya all heard that one before!  I will post a 'how to with pics'  in a few days. Thanks everyone! 


Happy Holidays. Hal

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  • 3 weeks later...

Machine carved hulls have enough extra to allow a little carving as needed.  The method I use is to pick two points, one at the stem and one at the stern as reference points.  Stretch a string between the points or use a straight batten to establish the center line.  Smooth up the bottom of the keel being sure to keep it level.  Mark the station lines on the keel.  Using the station templates, the established center line and the station  marks start working the hull into shape a little at a time.  Remark the station lines as necessary.  As long as the center line stays consistent you should be fine. 

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As above, the important thing is to get the centerline correct on the extreme ends, the Bow and the Stern. Connect the dots via the use of a flexible ruler or piece of cardboard pressed down onto and following the contours of the hull-  draw your line.  You will wind up having to re-draw any pencil lines you put onto the hull over and over again as you work on the hull and remove material. Be careful to not remove your crucial Bow and Stern landmarks as you proceed.

Cutting a piece of paper the exact distance between two points on the hull, then folding the piece of paper in half gives you the center point between two locations quicker than using a calculator.

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  • 4 weeks later...

Hello everyone.  I had earlier posed the question as how to find the center line on a pre carved machined wooden hull.  I used the comments from several members and came up with a plan as to how to do this.  As promised, here are some pics and text as to how I confronted this question.




This is the working platform, a smooth plastic coated 12" x 24" shelf board.




Here is the carved hull with the hold down tabs.  Made from 3/4" x 1/8" aluminum bar stock,  with a slight "S" bend and screw hole centered.  Here you can see the two pins, centered 'by eye' at the bow and stern.  Also note the two thin wood wedges which I used to 'jam' under the hull from the back side to hold it in place, as seen in the next pic.





The hull is attached to the work board using the tabs and screws.  I placed a pin at the bow and stern at a visual center point.  The hull is then 'balanced' on its resting point, keeping the two pins equal distance above the board .




Here is the marking tool I fabricated using a pencil compass (modified), wood block, tall machine bolt with nuts, brass tube with inside diameter matching the bolt, and several small screws to hold it together.  A wrap around strip of brass was soldered to the tube, and this was then bolted to the cut-off pointer section of the compass.  This allowed the assembly to be adjusted vertically in the bolt and also providing an angle range to aid in reaching over-under areas.




The hull now has a "center line" marked; bow to stern along the keel-son, and bow to stern on the deck.




The hull is shown here with the marking tool and the 90 degree triangle amidships.




Detail close-up of the hold down tabs with the hull securely held in place.

Edited by halbaby7
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Well I managed to re-arrange the pics and text properly.  Sometimes I simply amaze myself.  I hope this helps future shipwright/modelers.


I thank all the input from other members as I worked on this 'how to' project.


Cheers to all. Hal

Edited by halbaby7
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