Tool to Take Measurement Inside of a Hull

[ChrisLBren]

Hey Group,

Just curious what most of you use to take accurate measurements for deck clamps etc on the inside of a hull.

Thanks

Chris

[Gaffrig]

Hello!

 

I find one of theese (or similar) handy for such measuring. Then measure the compass with a ruler or caliper.

 

Gaffrig

[Mike Y]

I assume you mean the vertical measurements? Then it is easier to think of it as a tool to transfer dimensions from the side plan to the hull, rather than a measurement tool.

You would need some kind of a sliding gantry with a fixed height (Hahn method makes that easy since you do not need a gantry, the jig is playing its role. But you will see all sorts of aluminum profile or wooden constructions in other logs!)

From that gantry you can clamp a vertical strip with pointy tip. Then I glued the side plan to some backing material, cut with an offset to match the gantry / base jig thickness.
Then you can transfer dimensions from plan to model without any calculations - but by putting that cross-slide directly on the plan, locking in position and then transferring to the model:

My first version was a friction fit one, just two perpendicular sticks, can't really make it any simpler:

 

The second version was slightly fancier, but I built it because I had a loong pause and forgot that I have the simple contraption 

They are functionally identical.

[tmj]

Dial, or 'digital' calipers are always your best friend! They can measure 'anything', almost. Sometimes you'll need a telescopic 'I.D' gauge for difficult to measure areas, but you'll also need the caliper to measure what the I'D. gauge fits into. 

 

Caliper is good for 'this'. Note the inside measuring jaws, the outside measuring jaws, and the 'depth Blade'! 

Telescopic 'I,D.' gauges look like this. You put them 'inside' whatever you're trying to measure, rotate a screw to extend or retract the ends, then put your calipers on the ends of the I.D. gauge to get an exact measurement. These are really handy when certain things get in the way of simply using your calipers alone. With these two gadgets in your toolbox... there are very few things that you'll ever struggle to successfully and accurately measure!

 

Edited 18 hours ago by tmj

[tmj]

Bonus Tip! If you need to duplicate complex geometric shapes, get one of 'these'! They're called 'contour-gauges'. Shove the needles into, or upon the said curious shape, lock it down, then trace that projected shape onto paper, with a pencil, and you have a template to replicate whatever complex geometry was measured. 😉 

Edited 18 hours ago by tmj

[Dziadeczek]

I found this somewhere in the abyss of my external drive.

(Unfortunately, I don't remember who the author is and where it was originally posted...)

Hope this helps,

Thomas

[ChrisLBren]

These are all great ideas - thank you so much - my construction site is built at the waterline so I have a reference point here.  That contour gauge is another great idea I can use when I get to planking the wales next year and I need to get the right bend at the bow.

[druxey]

If you need to measure inside the hull from a baseline (the building board) outside, the best way is a gantry style frame with an adjustable pointer from the cross-piece. Mine slides along the building board and the horizontal scale (if needed to) slides to zero adjust. The vertical scale and pointer are held by friction. Note that there are pointers to each side. Rigidity is provided by L-plates screwed to the sides away from the camera.

[mgdawson]

Another alternative would be a bar gauge, you could knock one up in a size to suit mostly from scrap. Similar function as the telescopic gauges shown by tmj.

 

An internet search will find a number of commercial & diy versions, too big for a model ship but different design ideas to make your own.

 

I found a take down rifle cleaning rod on one of the chinese websites with 90mm sections to make one for the workshop, that'll measure from about 100mm to 1m when I screw all the sections together but after reading this thread I might cut down a couple of the pieces and make a mini one for models.