B737-800 captain reported he is unsure if he complied with MEL restrictions of remaining within 50 N...

Narrative:

Just prior to gate departure; maintenance informed me we had an inoperative left main tank fuel quantity indicator. I had not noticed this MEL item when doing preflight paperwork earlier; as weather was the main concern at the time; and we were rushed to get to the outbound aircraft due to being late inbound and having to clear customs.we departed soon after checking the MEL and speaking with dispatch via phone. Our dispatcher assured us we could comply with the MEL requirement to remain within 50 NM of land on our filed route. We were certainly legal; but in retrospect I wouldn't have taken the aircraft on this route knowing the full extent of the issue.after takeoff; we took extended vectors and deviations due to weather. We were also unable to climb due to other traffic deviating in our area. We had no way of knowing where we were in relation to a shoreline when we are in IMC and deviating around thunderstorms. I'm not sure if we remained within 50 NM of shore; thus I am filing this as soon as possible.do not dispatch an aircraft with an inoperative main tank fuel quantity indication on an overwater route and expect that the crew can comply with the 50 NM requirement while maintaining clearance from thunderstorms. This aircraft routing should have been switched to an over land domestic operation.

Original NASA ASRS Text

Title: B737-800 Captain reported he is unsure if he complied with MEL restrictions of remaining within 50 NM of land when he was dispatched with an inoperative main fuel tank gauge.

Narrative: Just prior to gate departure; maintenance informed me we had an inoperative left main tank fuel quantity indicator. I had not noticed this MEL item when doing preflight paperwork earlier; as weather was the main concern at the time; and we were rushed to get to the outbound aircraft due to being late inbound and having to clear customs.We departed soon after checking the MEL and speaking with dispatch via phone. Our dispatcher assured us we could comply with the MEL requirement to remain within 50 NM of land on our filed route. We were certainly legal; but in retrospect I wouldn't have taken the aircraft on this route knowing the full extent of the issue.After takeoff; we took extended vectors and deviations due to weather. We were also unable to climb due to other traffic deviating in our area. We had no way of knowing where we were in relation to a shoreline when we are in IMC and deviating around thunderstorms. I'm not sure if we remained within 50 NM of shore; thus I am filing this ASAP.Do not dispatch an aircraft with an inoperative main tank fuel quantity indication on an overwater route and expect that the crew can comply with the 50 NM requirement while maintaining clearance from thunderstorms. This aircraft routing should have been switched to an over land domestic operation.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1291215
Time
Date	201508
Local Time Of Day	0601-1200
Place
Locale Reference	ZMA.ARTCC
State Reference	FL
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Total 13000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural MEL Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Inflight Event / Encounter Weather / Turbulence

B737-800 captain reported he is unsure if he complied with MEL restrictions of remaining within 50 NM of land when he was dispatched with an inoperative main fuel tank gauge.