. Cassier's magazine . , knowing the height ofcentral buoyancy above bottom of keel,a curve may be constructed showingthe height of metacentre above bot-tom of keel. The position of thecentre of gravity of the vessel andits load for the several assumed waterlines is estimated and marked on thediagram, so that the value of G Mfor the several conditions are at oncedetermined. This is the metacentricdiagram, an example of which isshown in Fig. 6 for a cross Channelhigh-speed paddle steamer. Since the height of metacentre abovecentre of buoyancy is determined bydividing the transverse moment of in
. Cassier's magazine . , knowing the height ofcentral buoyancy above bottom of keel,a curve may be constructed showingthe height of metacentre above bot-tom of keel. The position of thecentre of gravity of the vessel andits load for the several assumed waterlines is estimated and marked on thediagram, so that the value of G Mfor the several conditions are at oncedetermined. This is the metacentricdiagram, an example of which isshown in Fig. 6 for a cross Channelhigh-speed paddle steamer. Since the height of metacentre abovecentre of buoyancy is determined bydividing the transverse moment of in-ertia of water plane area by the vol-urhe of displacement, it mav be repre-B2 sented by C , where C is a co- Defficient, depending on the type ofship, B the breadth or beam and Dthe draught. Also the height of cen-tre of buoyancy above the bottom ofkeel may be similarly represented byk D, where k is a coefficient, andcombining these two expressions intoone formula we may approximatelydetermine the height of metacentre. FIG. 5. ACTION OF ARMOUR AND GUNS above the bottom of keel amidshipfrom the expression: B2 36D2 + 5B2C YkD — or D 64D 5 B- 9= —D + 16 64 D This expression, where the meta-centric diagram is not immediately tohand, is useful in estimating roughlythe initial stability of a vessel whenthe position of the centre of gravityis known. It is evident that draught and beamare important factors governing theposition of the metacentre. For agiven draught the height of meta-centre is increased with increase ofbeam, and vice versa, and if thebreadth of vessel be preserved theheight of metacentre will increaseor decrease with a variation ofdraught, according to the relative va-riation of the two terms in the ex-pression. Generally in beamy vessels an in-crease of draught would bring themetacentre down, whereas in narrowvessels the height of metacentrewould increase. It is for this reason that where thedesigner is restricted to a limiteddraught he has to fall back upon amod
Size: 1719px × 1454px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyork, booksubjec
