The bimini top is canvas over a frame, so the form is about source geometry and evidence, not just the length of a roof. It has to be cut to the selected source view, the deployed frame, any storage cover and the optional passages, windows or shade pieces you ask for. The main canvas measurements are in centimetres; raw frame survey values and option details are kept as review evidence.
Before you put a tape on anything
Before measuring, choose the source view that matches the canvas and identify any grey feature in fitter evidence before using it. Photograph the frame fully deployed, the old canvas on both faces, every sleeve, zip and fastener, and the tape square-on with centreline marks visible. Keep over-frame and straight-line survey values in the review area with their declared unit; the form says they are not mapped to production geometry. For a storage cover, window, backstay passage or side shade, supply fitted evidence or a full-size reference and leave unsupported details empty.
The coded measurements
| Code | What to measure |
|---|---|
| P | Full illustrated upper span for the selected source view |
| L | Full illustrated lower span for the selected source view |
| S | Full illustrated vertical extent for the selected source view |
| A | One feature: feature to right; two: second feature to right |
| B | One feature: left to feature; two: between features |
| C | Two features only: left to first feature; blank for one feature |
| E | Full outside length |
| M | Complete outside height |
| F | Outside top to upper boundary of central opening |
| D | Right inner-opening shoulder to outer right end |
Why a bimini cannot be measured from a frame length
The bimini form is deliberately conservative because a live frame survey does not define every cutting bearing. It says the frame values are review only and lists missing production bearings such as end direction, tube reference surface, sleeve seam, fastener pattern, tension state and allowances. That is why existing canvas, full-size references and square-on photographs carry so much weight. Treat a raw frame span as the pattern and you have skipped the parts that make the canvas fit the frame.
The rule that runs through every form we print
If you aren’t sure of a bearing, leave it blank and tell us. A blank is a question we answer with one phone call. A guess is indistinguishable from a measurement, so it survives all the way to the cutting floor and comes back as a cover that doesn’t fit. Four honest numbers and a note beat five where one is fiction.
Not sure? Send a photo.
A few phone photos of your boom, frame or stowed sail answer half our questions. Send them with your enquiry and we’ll guide you through the rest — then confirm every dimension before we cut.