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「海と民衆知・個人知」英文要旨
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Navigational Skills and Collective Wisdom / Tacit Knowledge
HATTORI Hideo (Part 1) and KUSUNOSE Keita (Part 2) 
 In Part 1 (navigational skills and collective wisdom / tacit knowledge), I 
consider navigational skills based on information found in medieval 
literature(12th ~16th century).  First of all, I thought about the meaning of a 
phrase "Japanese do not voyage at night." in a report by a missionary called 
Almeida (a letter written on November 17, 1563).  Although this only means 
the same as 'they do not work during the nighttime,' in general, people who 
navigated ships actually avoided sailing at night.  If the occasion arises, 
they navigated waters during the night, but this carried a risk.  
 Secondly, I examined 'Takakurain Itsukushima Gyokoki" written in the 4th 
 year of Jisho (1180).  When a noble person was on board, night crossing 
 was avoided.  Leaving port at night involved risk.  They had to adjust a 
 departure time to a current making full use of their navigational skills.  If 
 you always leave port in the morning, it is likely to have an adverse current.  
 On these occasions, oarsmen worked to move a ship along a coastal current 
 (countercurrent), a weak current or a partial tide.  Oowada Shigekiyo 
 wrote a diary in the third year of Bunroku (1593).  He traveled by ship 
 from Nagoya(Hizen) to Nagasaki and wrote in his diary that they did not 
 get under way at night.  
 A voyage from Ise Bay was described in 'Tokitsugu-kyo Ki."   It said they 
 sailed for Shinojima and arrived there in the evening.  Considering the 
 breadth of the bay, it was impossible to sail within the time recorded in the 
 diary with the help of the current alone.  Wind power and manpower must 
 have been needed.  Especially in the case of north-south traffic in the bay, 
 it took a long time.  The current would turn from favorable to unfavorable 
 during the long voyage, so they must have relied on the oarsmen or wind.
 In the latter half of Part 1 and Part 2, we obtained geographical names for 
 tides and land features in the sea by interviewing with locals in two bay 
 areas, respectively.  They are from Kasuga, Hirado-shima in Nagasaki 
 prefecture and Itoshima peninsula in Fukuoka prefecture.  To be more 
 specifically, there are four features: (1) beach / rocky shore, (2) cape, (3) 
 seamount and (4) shoal.  Geographical names are not given to small shoals 
 which are always underwater and they are not shown on maps (some of 
 them appear on marine charts).  But the locals know all the shoals and 
 gave them  geographical names since they are important in fishing 
 operation using nets as shown in yamami and masuami (trawl fishing).  
  This information about the sea is integrated in collective wisdom (fishing 
 techniques).  But, in fact, it usually belong to each individual and is seldom 
 disclosed to others and shared with fellow workers