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Author Topic: The Station Method of Half-Hull Modelling  (Read 688 times)

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The Station Method of Half-Hull Modelling
« on: May 10, 2007, 01:05:37 AM »
The Station Method of Half-Hull Modelling
By Colin Sheehan

This method of carving a half-hull model does not use several pieces of timber as does the Lift Method, rather a solid block of wood is carved into the final shape. This is the method I
personally prefer for my own models as I have an abundance of beautiful timbers to choose from. If timber is scarce or if you have to buy it (shudder) then possibly the lift method may be more economical.

Templates
As mentioned in the Info page, the important part of a set of lines plan for this method are the stations. Once the scale of the model has been established and the lines plan reduced or enlarged to the appropriate size, a pattern is then made of each station as seen in the Body plan view either by tracing the plan or photocopying and gluing to a thin cardboard or hardboard to make a template. Also make templates for the Sheer and Half Breadth plans to enable you to accurately set out your work later. The thinner the template is without losing stiffness, the better. (Sheet aluminium or plastic card?)

You will notice that in the example here, there are eight station templates needed. If you don't have a fine blade on a bandsaw, a coping or a fret saw will do fine for cutting these out. Cut wide of the lines and finish the edges of each template carefully to the lines. Once the templates are all made, Choose your timber of a dimension to suit the overall size of the finished model with about 25mm left over each end. If you wish to use a different timber for the topsides, waterline and bottom, then cut your chosen wood to appropriate dimension to suit the size of the model. For a nice thin waterline or boot topping, as it is sometimes called, utilise veneers which are already cut to various thicknesses. This saves the often wasteful process of cutting your own on a tablesaw. I have been known to cut a 3mm kerf through the wood to get a 1mm thick piece of timber for a waterline! The waterline timber thickness should be deducted from the vertical dimension of the topsides piece as the painted waterline is usually above the actual surface of the water.Laminate the pieces together to form a rectangular block and when the glue is dry, square it up with a good sharp plane or jointer.

If you merely wish to produce only the waterline of a different colour to the rest of the model, then you can slice the block along the waterline and glue a veneer of timber back in between the two pieces. Again, the waterline veneer thickness should be deducted from the top side of the plan waterline drawn on the block.

Marking Out

Firstly, I would lay the half breadth template on the top of the block with the centreline flush against the back edge of the block and draw a line around the edge of it. Whilst it is in place, mark the location of the station lines on the top of the back surface. Remove the template and using a square, pencil in the station lines down the back, and across the top & bottom sides.

Now, using the sheer plan template, trace around the edge on the back side of the block, taking particular care to firstly line up the station lines on the block with those on the template and also to ensure that the sheer template is pointing the correct way (Check with the half breadth outline on the top.) N.B. Don't laugh, I have done it! The top of the block was going one way and the back was heading in the opposite direction. (Note: Numbering each station [and template] 1 - 9 (in the case of design above) from the bows to the aft sections will help avoid confusion.)

Cutting Out
Once you are satisfied that you have checked your marking out fifty times, it is then time to cut away the excess bulk timber from the block. A bandsaw is definitely an asset, but not necessary here. If you don't have one, for bigger models maybe something like a bowsaw would be fine or join the local woodworker's club and use their facilities. Cut slightly proud of the line with the sheer plan uppermost at first. I usually then re-attach the waste pieces with some masking tape, hot glue or small tacks to give me a level surface to slide back over the bandsaw table when I make the next cut. (Note: Take care when securing the offcuts back to the body of the model to realign the station marks before fixing.)

Next, cut around the edge of the half breadth plan view allowing, once again, a slight margin for finishing. The should leave you with a squarish block of wood which actually looks a bit like a boat. Don't throw away the excess timber you have just cut off as this can be used for keel/stem or rudder if you have allowed enough around the edges. This is important if you want the timber grain to match.

In order to hold the model whilst carving it, I attach a length of wood of about two thirds the length of the model to the back surface with two screws. To this I have attached a flat piece of wood at right angles to act as a handle or vice mounting. This allows me to clamp it securely in a vice or workmate-like device while it is being carved.

Carving The Hull Shape
Using a small gouge (approx. ½"), (My personal favourites here are a palm type carving gouge like the excellent Flex-cut brand) I start to cut a groove at right angles to the grain starting with say, station 5 amidships. After taking the corner off the block, start repeatedly checking your progress with the station 5 template, ensuring that the template is held at right angles to the centreline of the model (back surface of the block) and that the waterline on the template is kept in line with the waterline on the model. By noting the gaps under the template, you will be able to safely approach the correct shape for this section of the hull. Once you are content with the shape of this station, move to the next one and so on. It will quickly become self-evident what is required.

Take care not to cut any more wood away than is necessary as this will destroy the accuracy of the lines. NOTE: You can take off, but you cannot put it back on, so slowly, slowly. Final fairing of the hull can be done with a small block plane or spokeshave on the convex surfaces and careful application of a suitably sized and shaped gouge through the area under the tuck of the stern where a reverse sweep often takes place. A last check with all the station templates and sand with progressively finer abrasives down to 320 grit and now you have a very fair and lovely hull to finish as you choose.

If the vessel being reproduced has a seperate external keel and rudder, these can be made, fitted and added at this stage. Usually, I glue the keel/rudder assemblies to the backing board after I have mounted the hull with a couple of screws.

This is a fairly lean description of the process and I do recommend that any keen boat modeller refer to the boating press for lines plans. Some recommended reading appears on my Half-Hull Info Page.

Afterthoughts:
1    If you want to make another identical half-hull pointing in the opposite direction, you could glue the two together to make a complete hull.
2    If you are planning to paint the model in original colours, then any available timber can be used to save money.


« Last Edit: October 28, 2007, 11:14:38 AM by magus »
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