[QUOTE=lfgd521rc;34749]Something as simple as a spring loaded calibrated wheel that could ride along the drill pipe could measure the length of the string. Height of hook from drill floor data strem also has possibilities of being used to feed data. Don’y know how far down they are calibrated. Plus or minus one foot should be close enough to determine the tool joint location. Thereafter use the weight indicator… that’s the old school way and proven way.
If we can use an ROV to cut riser in 5000 feet of water the drill string calculator display should be a breeze.[/QUOTE]
We’ve looked at this, and most agree, the best place is in the lmrp, a mass indicator. The dwks motor(s) has an encoder, the cyberbase knows it’s posiiton, the mass indicator would see the tooljoint…the rest is programming.
That takes away stretch, heave, tides etc. This is my 3rd rig with AHD’s and when you throw it into active heave and see the line spooling in, and your not moving the blocks, it’s very decieving. It’s better if they cant see the drawworks.