A lobster gauge with both measurements
One gauge that shows the minimum and the maximum size, with your name and permit number embossed on the handle.
The problem
The gauges in the shops show the minimum only. In parts of the country there is a maximum size as well, and you end up in the boat with a lobster in one hand and a gauge that does not answer the question. The numbers change, so they have to be checked against the current regulations before anything is printed.
The fix
The gauge has a U-shaped opening at each end, cut to whatever the current regulation says and marked so it can be read rather than just engraved. The slots print with compensation: a slot off an FDM printer typically comes out 0.1 to 0.3 mm tight, and the first few layers spread outwards against the bed, so the edge gets a half-millimetre chamfer. Every gauge is checked with calipers against a steel rule before it is bagged. The material is ASA, which stands up to sun and salt water better than PETG over a couple of seasons.
The handle is hollow and printed with five walls so the gauge floats if it goes over the side. That is not a given. Water wicks in between the layers of a printed part, and once the infill has flooded it sinks and stays down. Each revision therefore spends a day in a bucket of sea water and is weighed before and after. Name and permit number go in as raised text at print time, one gauge at a time. It is a tool for the boat, not an approval — the regulations set the numbers, and you have to check them yourself.
This is an aid on board, not a calibrated measuring instrument, and it is not approved by anyone. Minimum and maximum sizes change and vary along the coast — check what applies where you fish before you go out.
More ideas
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