BellBoard

(3241658709E)   1   7   18  19
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 3142                   s               |
 1234               -   s   -           |
 1423                   -        |      | B
 435261             -   -        | A    |
 324165             -   -   -    |      |
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 1234657890E           (a)
 3241                   A
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 32416578E90    -       B
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 324165789E0    s       B
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Repeat, adding a bob at 1 to opening course of second half, and at end.

(a) = s1.s2.7.s9.s13.15.16.19

Start at backstroke with rounds as the fifth row of a slow six.