Coming  out of Ulsta  into yell sound  looking north  between  Bigga and Yell    tidal rates  up to changing  direction   twice a day            0 to  6 knots 

lh  photo Samphrey and  Bigga  ,  midchannel  Yell sound  between Yell and Bigga 

looking North   up Bluemull  SOund   from  Hoganess,   a hill  by  Belmont Unst

Looking west from Hoganess   across  BLuemull  SOund

Looking to Cullivoe where  there is a vertical   axis  propellor type  of  tidal generator  powering  a fish freezer plant at the north  end of  Blumull  sound  

Some photocopied   pages  from Admiral Days  survey   of tidal  directions and  rates around  the SHetland Isles   

Linga from  WInd dog  2013                                                             BGS  seabed   scoured of sediments in bluemull sound                                    

from the bus on yell  looking  towards Bigga in Yell sound

tidal race south of Sumburgh Head     photocopied   from Admiral Days  survey  50s,   lerwick reference library      sue me  it would have been  lost