Bubbletrubble
Contributor
RTee initially brought this up. I'll expand on it a little...I'm curious but what brand and model is that dive computer?
Your second dive profile was most conservative. I can't understand why the computer would prescribe a 5-minutes stop unless that's what the computer was automatically programmed to do - 5-minutes stop versus 3-minutes stop.
Suunto dive computers may convert the "recommended" shallow safety stop from 3 minutes to a "mandatory" safety stop of 3 minutes or longer (5 min.?) if the ascent rate exceeded the Suunto-specified "maximum" rate (39 ft/min) instantaneously or 33 ft/min "continuously." The duration of the shallow safety stop is determined by the severity of the ascent rate violation.
It's certainly possible that the OP is confusing "stop" terminology: "recommended" safety stop vs. "mandatory" safety stop vs. "deco" stop. The most likely explanation of what happened is that the OP accidentally caused an ascent rate violation which resulted in a 5 min. "mandatory" safety stop. This was caused by suboptimal buoyancy control or raising the computer through the water column too quickly to read it. With some computers, it's also possible to cause an ascent rate violation simply by moving a wrist-mounted computer too quickly, particularly if it's attached to an arm/wrist that's being used to lift and exhaust gas from the BCD corrugated hose.
When it comes to operating a dive computer, it's always advisable to read the manual before using it.
Hope this helps...