BODY 1 BODY 1
2. FISHINC IOAT
2 . 1 ' @ .
2.1. 1. !91:s1!i9a9!l!!:!s-!99!.
T h e f i s h l n g b o a l 1 B d e f l u e d b y S 0 1 , A S (I n t e r n a t i o n a l C o n v e n t i o n o f t h e S a f e t y o f L l f e a t S e a ) as a vessel used for catchlng flsh, whales, 6 e s 1 s , w a l r u s o r o t h e r l i v l u g r e s o u r c e s o f l h e s e a , b u t t h e r e 1 s n o c l e e r d € f i n i t i o n . A c c o l d i f l g t o t h e F l s h i n g v e s s e l L a l r o f J a p a n , t h e
f i s h i n g b o a t i s d e f i n e d a s a v e s s e l il) exclusively and directly u s e d f o r f i s h i n g , ( 2 ) exclusively used for fishing elth facilities f o r p r e s e r v i n g o r p r o c e s s i n g f i s h c s t c h , ( 3 ) e x c l u s i v e l y u s e d for carrying flsh catch o r i t s p r o d u c r s f r o n t h e f i s h l n g g r o u n d , e n d ( 4 ) e x c l u s i v e l y u s e d f o r e x p e r l m e n t , r e s e a r c h , i n s t r u c t l o n , t r a i n i n g , o r i n s p e c t i o n r e l a t e d t o f i s h i n g , w i t h f i s h t n g Aear.
2 . 1 , 2 . c h a r a c t e r t s t i c s o f f t s h l n g b o s t s .
A f i s h i n g b o a t u n l i k e v e s s e l s f o r p a s s e n g e r o r f r e t g h t t r a n s p o r t a t i o n s h o u l d h a v e t h e f o l l o w i n g c h a r a c t e r i s t i c s : h i g h s p € e d , g o o d naneuverabi 11ty, seaworthine6s, wide range of cruising, t o u g h c o n s t r u c t i o n , a p p r o p r i a l e m a c h i n e r y , r e f r i g e r a t i n g f a c i l l t i e s , f l s h i n g
99!t!!9I!, etc.
2. 1.3. !:1i9!.Pe!-!is9!:i9!:-3!@.
T h e p r i n c i p a l d i r n e n s l o n s of a ftshing vessel are the length, b r e a d t h , e n d d e p t h o f t h e v e s s e l , w h i c h a l e u s u a l l y expressed es L,B.D.
T h e s e I - . B . D . a n d p a r t i c u l a r l y t h e r a t i o of L.B.D. are very lmportant e l e B e n l s f o r d e t e r m i n i n g t h e v e 6 a e 1 ' s c e p a c i t y a n d p e r f o r n a l r c e ablllty.
L l B , L / D , a n d B / D a r e c l o s e l y related lrith the propulsion efficiency, s t r e n g t h , a n d s r a b i l i t y o f t h e vessel, r€speclively.
2 . 1 . 3 . 1 . P l i n c i p a l d i m e n s l o n s . 1 ) L e n g t h , L ( F i 9 . 2 . 1 . 1 . . ) .
' s )
L e n g t h o v e r a l l , L O A : T h i s i s t h € h o r l z o n t a l d i s t e n c e b e t w e e n t h e fore end and the aft €nd of rhe boat- b ) l e n g t h b e t w e e n p e r p e n d lculars, Lpp: This is th€
h o r i z o u t a l d i s t a n c e b e t w e e n t h e f o r e p e l p e n d l c u l a r ( F P ) a n d lhe aft perpendicular (AP) et the designed
w a t e r l i n e ( l , W L ) .
c ) R e g i s t e r e d length: T h i s l e n g t h v a r i e s a c c o r d i o g t o the r e g u l a t i o n s of each country.
3 ) D e p t h , D t F i g . 2 . 1 . 2 . \ .
This is the vertical distence from ihe base lln€ to the upper surface of the upper deck bearn on the shtp'8 stde.
2 . 1 . 3 . 2 . F { n e n e s s c o e f f i c i e n t s ,
S o m e v e s s e l s a r e f e t l n s h e p e w h i l . e o t h e r s a r e t h l [ ; S h i p r s
shepe ls compared by l!9!glgl*ll:gg!€. The flneness coefficlentg
c o n p r l s e b l o c k c o e f f i c i e n t , p r i s n e t l c c o e f f l c l e n t , l l i d s h i F c o e f f i c l e n t a n d nacer pl6ne coefficlent, ( - F I g e , 2,r.,3, (e) - fd)),
1 ) B l o c k c o e f f i c i e n t . C h )
W h e r e , V, L, B the breadth (n) and the
2) Prt!:natic
@
c o e f f i c L e n r C )
and d are the dl8plecenent C r a f t ( l l ) , r e s p e c t i v e l y .
( . 3 ) , tt. length h),
' F I
A x L
€)
ls the oidshtp s€ctlon erea (m')
3)
M l d s h t o c o e f f l c i e n t ( C ^ ).@ .B
27
4 ) W a t e r p l a n e c o e f f i c l e n t ( C ! r ) .
l x B
nh€re, Aw ls the I'ater plane area {.2)
5 ) R e l a t l o n b e t w e e n r h e c o e f f l c i e n t s . Cb - cp t c@ and Cb< Cp<
% 6 ) F l n e n e s s coefficl.ents of fishing boat3
T h e f i n e n e s s c o e f f i c i e n t o f a f i s h i n g b o e t v e r l e s rrith the t y p e o f f l F h e r i e s . ( T a b l e 2 . 1 . 1 ) .
7 . 1 . 1 . 3 . T o n n a g e .
1 ) c r o s s t o n n e g e ( c . T . ) .
T h e s i z e of a flshing boat is usually expreased in terms of c.T. The oethod of tonnage n€asuresent diffets con- s i d e : a b l y f r o n c o u n t r y to country. f o r t e t g e s i z e f i s h t n g boats, horrever, the itrEernatlonal method for tonnag€
measulement ls coming lnto force (Ilrt€fnatlonal Convention o n T o n n e g e M e e s u r e m e n t of Ships, 1970).
a) Internatlonal fofinule for cT measurenent of fishlng
bost more than _?1gb_E!gl!\.
G I ' ( V
where, V ls the totel vohrlte of ell enclosed spaces of b o a t ( m 3 ) a n d K = 0 . 2 + O . O 2 l o e t o v ( T a b l e 2 . 1 . 2 . ) .
b) Curren! foftula fcir cT n6a6urenent of snall fl8hhg boetB, The follostng fon rle ls ueed only in Vietnar0 aad Thellsnd.
cr =(s+-3) x rxc
rihere, P ls lhe periphery neasured around the rnidshlp s e c t i o n o f l h e h u l 1 . I n v i e t n a m , P i s d i r e c l l y
m e e s u r e d , t r ' h i l e i n T h e i l a n d , ? i s d € r i v e d f r o r D l h e f o l l o w l n g f o r n u l a :
p _ ( B + 2 D ) x C r
l r h e r e , C L i s 0 . 8 5 f o r d l s p l a c e n e n t h o 1 l , a n d 0 . 9 0 f o r f l a c b o l e o n h u l l c o u s t r u c t i o n . C i s d e f i n e d a s f o l l o r , r s i i n V i e t n a m , 0 . 0 6 0 f o r s w o o d e n b o a t a n d 0 . 0 6 4 f o r a s t e e l - b o a t , w h i l e t n T h a i l a n d 0.058 for a lrooden boat and 0.070 f o r a s t e e l b o a t .
2 ) N e t t o n n a g e ( N . T . ) .
By lhe net tonnage ls shown lhe v61une of a boat which is d l r € c t 1 y u s e d f o r t h e p u r p o s e o f t h e o p e r a t l o n o f t h e b o a t , r r h e r e a s by CI is sho&m the total volune of the bost herself.
T h e r e f o r e , l . { T is o b t a l n e d b y s r b t x a c t i n g t h e y o l u l l l e of the f o l l o l r i n g s p a c e s f r o l n t h e t o t a l v o 1 u r c o f t h e b o a t ( n J ) : a c c o r d o d a t i o o , c h a r t r o o n , s t e e r i n g g e a r r o o m , e n g i . n e r o o m , e t c .
3 ) D l s p l a c e m e n t t o n n a g e ( A ) .
D i s p l a c e n r e n t t o n n e g e i m p l l e s t h e weight of a boar and varies r r i t h t h e q u a n t i t i e s o f f u e 1 , \rater, crew, flsh catch, etc.
l o s d e d a b o a r d t h e boat. T h e t e f , o r e , d i s p l a c e r n e o t a o n n a g e shouLd b e d i s c u s s e d c o n s t d e r i n g t h e loadtllg condj tions such as lighr o r f u l 1 l o e d € d .
4 ) D e a d w e i e h t t o n n a s e ( D W ) .
D e a d w e i g h t t o n n a g e i s t h e n a x i n u n , \ r e i g h t o f f r l e l , $ a t e r , c r e l r , f i s h c a t c h , e r c . c a p a b l e t o b e loaded on bosrd; I n o t h e r words, t h e d € a d \relght tonnage is the difference behreen lhe dis-
p l a c e h e n t tonnages at ltght and ful1 load condilIon.
z . r , 4 . r e r m l n o r o g y .
L i s t e d b e l o w i s t h e e s s e n t l a l t e r d i n o l o g y used for fishing
1) !I99I: Sh€er refers to the upnard curvature of both fore end s f t d e c k ( t i g . 2 . 1 , 1 . ) .
2 9
2 ) B e a n c a n b e r : T h e arc-shaped curvature of a vessel deck i s c a l l e d b e a m c a n b € r ( F i g . 2 . 1 . 2 . ) .
3 ) R i s e d f f l o o r : R i s e o f f l o o r r e f e i s t o t h e d i s t a n c e b e t w e e n t h e b a s e l i n e a n d t h e i n t € r s e c t i o n o f t h e s i d e p l a t e a u d l h e b o t t o n f l a r e ( F i g . 2 . 1 . 2 . ) ,
6 ) 5 )
7 )
9 )
t D )
8 \ i i a t c h a a d c o m p a n i o n : H a t c h e s a r e t h e o p e n l n g s o n t h e d e c k r j A h t a b o v e t h e h o l d s . C o r n p a n i o n s a r € t h e s t a i r w a y s t h r o u g h w h l c h c r e ! , m e n b e r s p a s s d i r e c t l y f r o n a l o w e r d e c k t o t h e w e a t h e r d e c k , d o o r s a r e p r o v i d e d f o r i t .
B J l g e c i r c l e : A t t h e n i d s e c t i o n o f a v e s s e l , a p a r t o f a c i r c l e i s u s e d a s t h e c u r v e a s s h o r ^ r n r : n F i s . 2 . 1 . 2 a n d i s c a l l e d t h e b i l g e c i r c l e .
A . P . a n d I . ? . : A . P . r e f e r s t o t h e a f t e r - p e r p e n d i c u l s r a n d f . P . t h e fore-perpendicular a t t h e ends of the designed l ' a t e r i l i n e o f t h e b o a r . ( F i g . 2 . 1 . 1 , ) .
S u p e r s t r u c t u r e end deckhouse: Supersttucture and d e c k h o u s e a r e b u i l t o n t h e m a i n d e c k , the forner s t r e n g t h e n s the vessel and exrends from porr to s l a r b o a r d , f o r n i n g a continuous floor deck. the l a t l e r i s a l s o butlt on the deck but does no! touch
€ i t h e r s i d e o f t h e v e s s e l .
s u l w a r k a n d h a n d .ai1: B u l l ' a . k i s a ferce-like s t r u c t u r e b u i l t o n t h e u e a l b e r d e c k a l o n g the vessel side, lrhich has s t a y s a n d o u t e r p l a c e . Hand rails a r : e nade up of metal bars
D r a f t a n d f r e e b o a r d : D r a f t i s t h e v e r t i c a l d i s t a n c e r n e a s u r e d b e t w e e n t h e \ r a t e r s u t f a c e a n d t h e d e e p e s t Fart of the hul1
l y i n g , r n d e r w a t e r . T h e d r i a f t n a y b e m e a s d r e d a t a n ) . s p e c i f i e d p o s i t i o n s n c l r a s t h e f o r e , a f t o r m i d s h i p . F r e e b o a f d n e a n s t h e v e r t i c a l d i s t a n c e n e a s u r e d b e t w e e n l h e u p p e r d e c k g u n r ! ' a 1 e a n d t h e v a c e r s u r f a ( e a r h i d s h i p
D e e p t a n k s a p d t ' a l l a s t t a n k s : D e e J , t a n k s a r e t h e e x t r e m e l y / e e T c a n i s i ' r i l t . j n a < a n i n L a g r a l p a r r o r r l e h r l l . I l a l l a s ( t a n k s a r e t l o s € i n r \ i c l \ s e a J a t e r o r f . r e l o i l i s l o a d e d t o a d j u s t t h e v e s s e l r s c e n t e i o f e r a v i t y .
2 . 2 . I n s t a l l a t i o n s o n F i s h i n g B o a l s . 2 . 2 . 1 . E q u i p m e n r a n d i n s t a l l a t i o n s .
G e n e r a l a r r a n g e m e n t s o f f i s h i n g b o a t s a r e s h o $ n i n F i 8 . 2 . 2 . 1 . M a j o r e q u i p m e n t a n d i r s ! a l l a t i o n s f i x e d a b o a r d a f i s h i n g v e s s e l a r e :
1 ) S t e e r i n g g e a r ; r u d d e r , s t e e r i n g t n a c h l n e s ' steering
€ n g 1 n e s ,
2 ) l 4 o o r i n g a r r a n g e n e n t s , a n c h o r , c h a i n , w i n d l a s s , f a i r l e a d e r , m o o r i n g p i p e , b i t l , b o l l a r d , c a p s t a n ,
3 ) l , i f e s a v i n g a p p l i a n c e s : l l f e j a c k e t , l i f e b u o y , 1 l f e r a f l , I ; f e b u o y f l a r e , l i f e b o a t , b o a t d a v i t ,
4 ) C a r g o g e a r ; d e r r i c k , c a l g o w i n c h ,
5 ) ? i p i n g a r r a n g e r n e n t s ; b i 1 g e , b a l l a s t , a i r r s a n i t a r y w a t e r , f r e s h $ a t e r , s o u n d i n g , s c u p p e r , h y d r a n t ,
6 ) F i r e e x i s t i n g L r i s h i n g a p p l i a n c e s ; f i r e a l a r n , f i r e e x i s t i n g u i s h e r ,
7 ) V e n t i l a t i o n a n d l i g h t i n g a r r a n g e n e n t s ; n a t u r a l v e n t i l a t i o n , m e c h a n i c a l v e n t r l a t i o n , l i g h t i n g , a i r c o n d i t i o n i n g ,
8 ) E n g i n e r o o m a n i a n g e n e n L s ; n a i n e n g i n e s , a u x i l i a r y € n g i n e s , 6 , p r r l n p s , s h a f t i n g , p r o P e l l e r , e t c . 9 ) E l e c t r i c i n s t a l l a t i o n s ; n o t o r : s , s w i t c h b o a r d s ,
1 0 ) R a d i o i n s t a l l a t i o n s ; \ r i r e l e s s t e l e g r a p h , i , T i r e l e s s t e l e p h o n e , d i r e c t i o n f i n d e r , r a d e r , 1 o r a n , f a c s i f l i l e , r a d i o b u o y , e t c . 1 1 ) N a v i g a l i o n i n s t r u m e n t s ; g y r o c o n p a s s , n a g n e t i c c o n p a s s ,
t r a c k r e c o r d e r , d r : a f t g a u g e , p r e s s u r e l o g r e l e c t r i c t h e r m o n e t e r , c l e a r v l e w s c r e e n , h e l l n i n d i c a t o r , e t c . 1 2 ) F i s h i n g g e a r ; t r a \ r l w i n c h , n e t h a u l e r , l i n e h a u l e r , e l c .
2.2. 2. !!q9l:9si9-!99i.Pr94.
S i n c e l h e f i r s ! u s e o f a r a d i o d i r e c l i o n f i n d e r a t c h e
b e g i n n i n g o f r h € 2 0 t h c e n t u r y , o t h e r i m p o r t a n t r a d i o e q u i p n e n l h a s b e e n d e v e l o p e d . T h i s i n c l u d e s R a d a r , L o r a n , D e c c a , o n e g a , e t c . , a l l o f w h i c h a r e w i d e l y u s e d i n f i s h i n g b o a t s t o - d a y t o e n s u r e s a f e n a v i g a t i o n a n d t o c o n t r i b u t e t o L h e e f f i c i e n c y o f f i s h i n g o p e r a c j o n s .
3 1
F i s h f i n d i n g t e c h n l q r e s b y m e a n s o f e s f l s h f i n d e r r s o r l a r , n e t m o n i to r i n g d e v i c e s a n d a r e e l d e l y u s e d t h r : o u g h o u t t h e l r o r 1 d . 2 . 2 . 2 . 1 R a d t o d i r e c t i o n f i n d e r .
1 . W a t c h i n g t h e s e i l i n g r o u t e o f or{r ship and Chose of other B h i D s .
a c o u s t i c d e v i c e s s u c h a r € a l s o r a p i d l y d e v e l o t i n g
A r a d i o d i r e c l i o n f i n d e r ( R D F ) c o n s i s t s o f a ! o o p a n t e n n a a n d e r a d i o r e c e l v e r . A l m o s t a n y r a d i o s i t h a l o o p a n t e n r a c a n b e u s e d a s e R D F . F o r € x a m p l e , w h e n e l o o p - e q u l p p e d t a b l e n o d e l o r p o r t a b l e r s d i o i s r o t a t e d 3 6 0 d e g r e e s , t h e s i g n a l p i c k € d u p r i l l b e ninimun at l q r o p o i n t s . T h i s i s d u e t o t h e d i r e c t i o n a l c h a r i a c t e r i s t j cs of loop a n t e n n a . B y t a k i n A t b e b e e r i n g f r o m t \ r o o r t h l e e r a d i o s t a t i o n s l o c a t e d a t knor.m positions we cen provld€ a polnt inlersection o n t h e s e a c h a r t .
A ship or a radlo buoy transniltlng radio slgnala can be l o c a t e d b y u s l n g a R D F , T h l s i s v e r y u s e f u l i n r e s c u e n o r k b e c a u s e the 3 h 1 p i n d i s t r e s s whlch is sendlnS emergency or distreEs signals can be l o c e t e d . o c e e n g o t n g s h i p s l e r g e r t h a n 1 6 0 0 G . T . n u s ! 1 n s t a l 1 R D F e c c o r d i n g t o s n I n t e r n a t i o n a l C o i w e a t i o n , r ' S o L A S r r .
O n t h e o t h e t h a n d , R D f i s r s e d n o t o n l y a s n a v r : g a t i o n e q u i p n e n t b u t e l s o f o r f i n d l n g f i s h i n g Srounds because the fisheffren can knor the d i r € c t i o n o f o t h e r b o a t s l r h i c h a r e s e n d l n c j n f o n n a t i o n a b o , l t f i s h c a t c h
2 . 2 . 2 . 2 R a d a r ,
T h e t e r m M D A R i s d e r i v e d f r o n R a d i o D e t e c t i n g A n d R a n a i n g . B y t h l s , i t i s p o s s i b l e t o d e t e c r t h e p r e s e n c e o f o b l e c t E a n d t o d e t e r n i n e C h e l r v e l o c l t y , d i r e c t i o n , a n c l r a n g e ( d i s t a c e ) . I o a d d i t l o n , r o u g h
a n a l y s i s i s p o s s t b l y n a d e b y s o n e t y F e s of radar systens on the compo- s l t l o n o f the detected obiect, R a d a r a i . l s a n u r n b e r o f s h i p s t o n a v i g a t e l n an area of poor visibility, b e c a , r s e n ' i t h r a d a r t h e ob.jects can be seen o n t h e s c r e e n t h E o u g h t h e dark, as sell as through rajn and fog.
M a i n u s e s o f R a d a r :
2 . C o n f l r n a t i o n o f s h i p ' s p o s i t i o n . P r e v e n t i o n o f c o l l i s i o n s .
3 .
I f t h e t i m e T s e c , is required for radio lraves to reach and b o u n c e b a c k from such an objec! as a mountein, the round trip distance t r a v e l e d would be T x ( 3 x lob) n, because the speed of a radio rave
t h o u g h t h e a i r i s 3 x r a d a r a n d t h e o b j e c t
2 . 2 . 2 . 3 L o r a n .
n / s e c . T h e n t h e d i s t a n c e D b e t w e e n t h e b e c a l c u l a t e d b y t h e f o l l o i r t n g f o r m u l a ; 1 0 "
Th€ Decca navlgetion ayatem rrae lntroduced fot ptacticel uge In 1948. Thts aystem con3lsta of three to four 6hore rsdio atatioDs a:rranged to folo e chei[. lhe fir3t chain of stations ,aa established ilr England ln 1948 and was fo11o!Ed by chsins ln other Europeen countrles s u c h e s G e l n a n y , F r a n c e , S r e d e n , Spein end ltely, I n t h e E a a t , [ o 8 t o f Japen ls alreedy covered rrlth Decce systed aervlce areaa. If the Decca chaln is s€t up in the Southeast Aslan aree, it r'ill be of Ireet help to every ahlp opeleting in the region.
D = r x ( 1 x r o b ( l n n e r e r )
Loran ls an abbrevlallon of long Renge Navigation end i3 c l a s s i f i e d i n t o t w o s y B t e m s ( I r r a a A a n d C s y s E e m s ) . T h e L o r a n s y s l e m is bssed on che princille that the radio eeve goes thtough the eir with a k n o n n c o n s t a n t s p e e d .
D e t e r m i n a t i o n o f p o s l t i o n b y L o l a n s y s t e n l
l. Fron the two knowfl Lotan stetlons loceted on ahore, s y n c h l o n l r e d c o n s t a n t r e p e t l t l o n r a t e p u l s e s i g n a l s a r e t r a n s m i t t e d with the sarne frequency.
2 . A s h i p i n s t a l l e d L o r a n f t c e i v e a : t h e e b o v e algnals ebd t h e t i m e d i f f e r e n c e b e t n e e n i n d i v J d u a l p u l B e B i g n a l 6 i s m e a s u r e d .
3. Fron the knorn positlons of the above land stetions end t h e i r s F c h r o n o u s relation, t h e l o c j o f FulEe arrivtng t i n e d i f f e r e n c e i s c a l c u l e t e d a n d e r e p r e p e r e d o n t h e L o r a n c h a r E o r l h e t a b l e f o r p r a c t i c e l u s e .
4 . B y o b t a t n l n g a r o t h e r m P ( l i n e o f p o s t t i o n ) B e p a r a t e l y - f r o m t h e llne obtained by estronorhlcal observation,
R D F , R a d a r , e t c . e r r l n t e r s e c t l o n ! r { t h t h e L O P g l v e n f r o m l - o r a n c a n b e p l o t t e d . T h l s i n l e r s e c t i o n p r o v i d e s t h e s h i p ' s p o s i t i o n .
T h e s e r v l c e b l e r a n g e of l.oren sy6tems for posltlon determinetlon i s n o r m a l l y $ithin 7 0 0 m i l e s i n d a y t i m e a n d 1 4 0 0 n t l e s a t n i g h t t i n e . 2 . 2 , 2 . 4 , D e c c a .
3 :
T h € p r i n c i p l e o f D e c c a n a v l g a t l o n s y s t e m i s o n e o f t h e h y p e r b o l a n a v i g a t i o n s y s l e m s l i k e t h e L o r a n A a n d c s y s t e m s . T h r e e c o l o r e d l O P l s p r i n t e d o n a c h a r t , c a l l e d t h e "Decca chartl. T h e Point o f i n t e r 6 e c t i o n w i l l b e g i v e n b y r e a d i n g t w o o r t h r e e f i S u r e s l n d i c a t e d o n t h e r e c e l v e r . T h i s g l v e 6 l h e s h i p ' s Position.
2 . 2 . 2 . 5 F l s h f i n d e ! .
A f l s h f i n d e r l s u s e d t o m e a s u r e t h e d e P t h o f t h € o c e a n s n d t o d e r e c t t h e f i s h s h o a l s . T h l s a p p a r a L u s i s d e s i g n e d t o r a d i a t e s o u n d w s v e s t h r o u g h t h e l r a t e r , a n d t h e r e f l e c t l o n s f r o n lhe bolton and fish
s h o a l s a r € g e n t b a c k t o a r e c o r d e r o r a n l n d i c a t o r . T h e r e t u r n t i m e i s p r o c e s s e d electrically a n d r e c o r d e d o n s Paper: or displeyed on CRT
( c a t h o d e - r e y tube). T h e p r i n c i p l e o f e c h o i s a d o p l e d t h e s a m e a s i n R a d a r .
T h e t e l l n S O N A R s t a n d s f o r S o u n d N a v i S a t i o n a n d R a n g i n g , a n d i t i n c l u d e s a l l u n d e r r a t e x a c o u s t l c s y s t e m B u s e d f o r d e t e c t i o n a n d l o c a t i o n o f u n d e r - l r a t e r o b j e c r s , t h o ' r g h , r e c e n l l y t h € t e r m S o n a r h a s b e e n u s e d s s e n echo sounder for holizonlal d e t e c t i o n i n a n a r r o r r r s e n s e .
T h e S o n a r r e c o r d s o r d i s p l a y s t h e r e f l e c t e d w a v e f t o m a n o b j e c t u n d e r t h e w a t e r o n e r e c o r d l n g p a p e r o r a c a t h o d e - r a y t u b e ( C R T ) b y B c a n n i n g t h e t r a n s d u c e r h o r i z o n l a l l v . R e c e n t l y , m o s ! S o n a ! h a s b e e n d e s i g n e d t o u s e l n e i t h e r l r a y , h o r i z o n t a l o r vertlcal.
2 . 2 . 2 , 7 N e t n o n i t o r i n g s y s ! € m .
F o r s u c c e s s f u l t r a w l i n g , i t l s i m p o r t a n t ! o l . . n o u lh e n e t m o u t h p e r f o r d a n c e under towing. T h t s s y s t e m g i v e s i n f o r m a c i o n c o n c e r n i n g b o t h t h e n e t n o u t h h e i g h t a n d t h e f i s h s h o a l s e n t e r i n g t h e n e t a n d r e c o r d s t t o n a r € c o r d i n g p a p e r o r d i s p l a y s i t o n a C R T .
2 . 2 . 2 . 8 O t h € r e q u l g n e n t ( o m e g a , F a c s i m i l e , S a l e I l t e N a v l g a t i o n s y s l e n ) , T h e s e p i e c e s o f e q u i p m e n t h a v e a l r e a d y b e e n a d o p t e d i n s o m e d e e p - B e a f l s h l n g b o a t s .
A v a r l e t y o f e l e c t r o n i c e q u i F n e n t h a s b e e n a d o p t e d i n m a n y k i n d s o f f l s h l n g b o a t s . H o r r e v € r , l h e m o s t s u i t a b l e e q u l p m e l r t s h o u l d b e c h o s e n l n a p r o p e ! i n a n n e r c o n s i d e r l n g t h e p u r p o s e o f u s e s n d e c o n o m i c a l i n v e s t m e n t , o t h e r r i s e t h e equiFnen! will b e a u s e l e s s p o s s e s s i o n .
2 . 2 . 3 @ '
T h e t e r r n r r k n o t | l s u s e d a s t h e u n i t s p e e d o f a v e s s e l . o n e k n o t i s t h e 6 p e e d t r a v e l l i n 8 l n a u t i c a l m i l e p e r h o u r , e n d i s 1 , 8 5 2 m / h r
i l l the metrlc systen.
A n o n g e x i s t i n g v e s s e l s , d e s l r o y e r a c a n r e a c h a s h l g h a s p e e d as 40 knots (appror.imately 74 tun/hr) and ocean liners 33 knots (approximate- 1 y 5 1 K r n / h r s ) . T h e f a s t e e t f l s h i n g b o a t h a s a s p e e d o f r d o r e t h a n 2 0 k n o t s , w h i l e m o s t f i s h i n g b o a t s h a v e m a x i m u m s p e e d s i n t h e r a n g e o f 8 t o 1 2 k n o t 8 .
T h e s p e e d o f v e s s e l s c a n n o t b e c o m p a r e d i n a b s o l u t e v a l u e b e c a u s € t h e p r o b l e n o f w h e t h € l a v e s s e l i s f a s t e r o r s l o r e r h a s t o b e d i 6 c u s s e d i n c o n p a r i s o n t o v e s s e l s i z € . I l e r e , t h e s p e e d l e n g t h r a l i o
( Y , vhere v is the speed in knots, and I the length in n. or feet) is
, l L v v
u 6 e d . T h e v e 1 L r e o f _ - s h o w s t h a t $ h e n 3 = 1 , 4 4 a , ( 0 , 8 l n f t . u n i t )
,'L ,ll-
t h e s p e e d l s b e l o w t h e a v e r a g e ( s l o v ) , e h e n i = 1.811, (1.0 in ft. unit) t h e a v € r a g e ( n o r n a l ) , a n d w l e n
, i - 2 . 1 7 3 , ( 1 . 2 i n f r . u n i t ) a b o v e t h e a v e r a g e { h i g h ) .
t h e r e i s a l i n i ! t o t h e s p e e d to be obtsined. I t E s y be attahed p r o b e b l y up to 2.7 x JT, (rtr) in knot if care is taken of boa! shape and a h i g h p o r d e r e d e n g l n e i B u s e d . llolrever, il is almost impossible !o ge!
t h e s p e e d o f 3.6 x {-r, ( m ) ln knot. T h e l e n g t h s r e q u i r e d f o r a b o a t c a l c u l a t e d f o r d i f f e r e n r s p e e d s u s i n g V l ,/ L = l.O are tabulaled belo\rl
s p e e d ( k n o t ) l e n B t h r e q u i r e d f o r b o a t ( f r . ) 6
7 8 9 1 0 1 1 6
7 8 9 10 1 1
6 x 7 x 8 x 9 x 1 0 x 1 1 x
= 3 6
= 4 9
= 8 1
= 100 - I2r
F o r i n c r e a s l n g t h e 6 p e e d o f a b o a ! , lt ls deslrable to increase the length of the boat rather then the po\rer of the engine. llere let us c o n a i d e r t h e f o l l o \ . l n g e x a m p l e u s i n g M . V . Queen !1ary (U.K. Ocean ltner), C i v e n c o n d i t l o n s a r € g r o s s t o n n a g e : 80,000 tons length: 975 ft,, a n d s p e e d : 3 1 . 6 k n o l s . T h e v a l u e o f V : 3 1 . 6 3 1 .6
'[ 975 31
T h e r e f o r e , 3 1 . 6 k n o t s i s a n e c o n o m i c a l s p e e d f o r s u c h a huge length of b o a t .
A l t h o u g h the absolute speed velues of a fishing boa! seems to b e lorr, the speed ls relatively h i g h b e c a u s e the length is smal1. Table
2 . 2 . 1 s h o w s t h l s r e l a t i o n s h i p .
35
2 . 2 . 4 . @ .
the relatlon belweed horaepoeer end speed cen be 8lvan by lhe followlng equatiodi
A f v '
IHP =
IltP x C
The appllcetion of
aI
rhere IHP, A , V and C are the lndlcated hors€power, the dlsplacenent ln ton, the speed ln knot, the adnlralty coefflclent (nearly 80) r e a p e c t i v e l y .
T h e a d d t r a l t y c o e f f i c l e n t i s a n lnportant constant used ln esthreting the horgeporderwhen planning a nerd vessel, 4nd Is uauelly obtainable fron the data of slnllar exlstlnc v€ssels ln ehlch are lnatalled alDilgr engines.
lfith increase of Bpeed, horsepotrer increaaes proportionally t o t h e c u b e o f , t h e B p e e d . T h l s r e l e t i o o l s w e l l p : i e s e n t e d b y a h o r s e p o t r e r c u r v e a g a l n s t s p e e d t n F i g . 2 . 2 . 2 , h e r e t h e s l o p e o f l t ? becmes steeper and ateeper rlth increaalng speed. It 16 understood that ther€ exists a Daximrrm speed lleit for the slze of vessel, atrd that ftnelly speed does not increase et sll even thouSh the horsepower 1 n c ! € a s e a .
fo lncreeae horsepo*er to nor€ than the usuel leve1 leads trot odly to overload of the englne, but also to exc€Bllve cotrgiioptioa of fuel oll nlthout eny eppreclable galn of Epeed. lherefore, 1t is ell'ays necesgary to bea! ifl mlnd the reletton between reaso$able hor6epower and speed.
tP V curve, glveo by table 2.2.2 (o.) a \ y L
lB very uaeful f,or poser, length, etld thls calculatlon ss
lmredlste ftnding of the relatlon of speed, hors€- di3plac€ment. Aeble 2.2,2 (b) can be applled for
n e l 1 .
2 , 3 . V a r i o u s T y p e s o f F i e h i n g Boats.
2 . 3 . 1 , T r a I J l b o a t s . -;--
T r a w 1 b o a l s h a v e l o n g L, sllghtly l l a r r o n B, and deep D.
T h e b l o c k c o e f f i c l e n t C I . s h o u l d b e a s small as posslble, and the aft d r s f t a s d e e p as possible. L n g e r L s l g n i f i e s a n advdntage for k e e p t n g h i g h speed and so does the narrow B, though this r.esulls 1n u n e a s l n e g a i l l stabllity. D e e p D glves enough power to drag lhe net a n d g o o d steblliiy. T h e c e n t e r o f g t a v i t y C is placed as 1ow es p o s s l b l e ln any case. When dragging a trslrl net, rhe resistance due t o n e t increases. T h e r e f o r e the propeller should be large in slze to g i v e enough thrust for dregglng the ner. C o n s l d e r i n g the above, a ]olr-speed engine !'llh controllsble pltch propeller ls recorfirend€d.
C h a r a c t e r i s l l c s r e a u i r e d for Trawler: T h e v a t u e o f CTl(L x B x D)
f f i s r a b J t l r y , t h e c e n i e r o f g r s v t r y
s h o u l d b e located as 1o!r es po6slble, and dlaft should be as deeF as p o s s l b l e . S o m e other cherabterlsltcs a r e g i v e n tn Tables 2.3.1. and 2 . 3 . 2 .
Machlnes and apparatus for fishlng tncluite trawl I'lnch, 8 a 1 1 o w s r o l l e r ( c e n t e r and stde), gallolls top roller, f l s h tackle.
Palr trawlers a n d n e d l u m s i z e tlawlets.
lhese trawlers are gtven in Tebles 2.3.3. and 2 J:T.
The palr trawler and lhe nedtum slze trewler have developed fron the traditionat snlell slzed trardlers lrhich have fished by sailing o r r o w l n g a n d haullng nets manually for hundredB of yeats. p a i r trewlers o p e r a t l n g in the East China Sea are mostly of 75, 95 and 130 gross Eo$s.
O n t h e olher hand, rdediur size trawlers ere s1lghtly snaller than rhe f o r m e r and range fron 15 lo 100 gross tons. c e n e r a l l y s p e a k i n g , l h i s t y p e of boat hss compsratlvely narlow breadth and large draft
e s p e c t a l l y aft to assure pouerful drag. T h e p r o p e l l e r , t h e r e f o r e t s h o u l d b e lalge in dianeter and the rolation mtnber should be smeller. T h t s t y p e of boat has a sna11 flneness coefficlent. T h e c h a r a c t e r i s t l c s o f
Theae t\do types of trawler sometines encounter gea accldents
b e c s u s . of rough \reather, poor stebtllty a n d o v e l l o a d l n g of flsh. M o r e o v e r , fishidg gear and flsh storaSe boxes are placed on the upper aleck and rhis m a k e s lhe position of c hlghe!. N a v i g q t l o n a l tnsttuments euch as
d i r e c t l o r f l n d e r , l o r a n , r a d a ! , etc. are tostalled a b o v e d€ck 1eve1. By r e g u l a l i o n , J a p a n € s e r r a e l ftshtng boats are required ro fulfill t h e c o n d l t i o n that the metacenter height cM should be larger than the two q u a n t l t i e s , d e f l D e d as follows:
OU>B x -:_ + 12 (In cD)
cM>L x -L + 12 (tn cn) r50
( 1 )
( 2 )
Th€ abov€ rclatlon ls sppltcable to other types of ftshtng boet €r.cludlng lrurse sel.Ders atrd bonito engling boets.
tror the bosl whose breadth B is nore than 7 neters, the follontrg are epplled:
GX>(B - 7OO) |( : + 40 (tn cm) (3) t2
ou>(L - 4200) r( a + 40 (h cn) (4) 7 2
Freeboard ahould be greeter then (D x ! + 15) ln centlmeter 2 5
for steel boats, and should b€ greeter than (n x I ' 1 5 t 20) in centlmetet for lrood€n boats.
2.3.2. PrirEe seloers.
The slre of purs€ aeLnera renge! ftom 5 to 250 tons, thouSh Dat of theo a!€ less than 100 tona. In order to keep good naDeuverablllty
It ls d€sLrable that the length of the boet ls not too long. During fiBhing operetlona the stsblllly of the boe! 16 pertLculerly ftnportsnt because nost fiahereen asseoble on one slde of the deck.end Doteover purslng ls done on thc aee€ aide. fherefor€, the breadth of the boat 6hould be large enouSh, tho depth should not be very deep, beceuse shellow free board ls plefereble
for the purse s€tne oDeratlon. Thls shallotr freeboard sen/es !o ke€p the posltlon of C (center of gravity) lor.er.
Characteristlc6 requlred for purse selner: Charecterlstlcs requlred for purse 6er.ners are given in Fig. 2.3.1.
+ 27 (tn d
^ - - B
cM > -l- + 27 (1n cE) L20
( 5 )
( 6 )
turning circle cspaclty 19 nost lecedasry and some e:€mp1es ate shoBn i n l a b l e 2 . 3 . 5 .
2 . 3 . 3 . @ '
These boats raBge in size from about 20 tons for small boata to abou.t 800 tons for 1a!ge steel boets, They are compaiatlvely large t n l e n g t h a n d d e p t h . t h e p l l n c i p e l d l m e n s l o n 6 a n d c h a r a c t e r l s t l c 6 e l e 1 l 6 t e d i r l T a b l e 2 . 3 . 6 . a n d 2 , 3 . 7 .