Hvor lang er en fot?

[Lars Hansen]

Hei,

 

Ser av en nettside at en fot er 30,48cm. Er det den samme foten som vi regner båtfot med?

 

Har kjøpt en Bavaria 38, 03 modell.

 

Denne er 12,3m som total lengde. Dette gir jo 40,35fot???

Skroglengden er 11,83m, som gir 38,8fot

 

Er det ikke total lengde som er vanlig å oppgi nå til dags?

 

Ser også at nye 38foteren er 58cm kortere i tot lengde, og 38cm kortere i skroglengde.

[roaldbj]

Til mer du graver i dette spørsmålet - til flere svar får du. Særlig for båter under 55 fot.

[baatsman]

Denne er 12,3m som total lengde. Dette gir jo 40,35fot???

Skroglengden er 11,83m, som gir 38,8fot

 

Helt korrekt oppfattet. Din 38 er like stor som den nye 40. Bavaria har hatt romslige føtter som nå har krympet litt. Men fortsatt i bransjen er de store.

 

Ellers gratulerer med en flott båt. Den 38 er veldig bra,

[Seiljåtten]

Jeg tror de fleste er enige i at en fot er 30,48cm, de er bare ikke helt enige i om det er skroget som skal måles, vannlinjen, skrog inklusive alt som er laminert fast i skroget, skrudd fast i skroget, eller rett og slett bare kalle den noe. feks 3500 (kan jo være noen da tror den er 35 fot).

 

Bavaria har så vidt jeg vet kun 38 AC fra 02-05 der de har lagt til en fot på lengden. Ellers har de holdt seg ganske greit til at 1 fot er 30,48cm som måles i skroglengde. Flere konkurrenter måler fot i båtens totallengde, og oppgir med noe mindre skrift skroglengde i fot. Har selv en 38AC, og vil gjerne gratulere deg med et bra valg. Båten er 39 fot, men ettersom det står 38 på siden blir det vel alltid en 38 foter for de fleste. Imidlertid artig å se at den er like lang som 40 fots konkurrenter(seilbåtkatalogen).

[Lars Hansen]

Bavaria har så vidt jeg vet kun 38 AC fra 02-05

Ja, det er AC, er bare jeg som har blitt "vant" til å se og lese om Cruisere...

[roaldbj]

Hvor lang er en Scand Baltic fra Scand Boats?

[Baatlaus]

Hvor lang er en Scand Baltic fra Scand Boats?

 

Er ikke den oppgitt til 9,65 omtrent, eller 31,5 fot???

Det må jo være inkl. baugspyd og badeplattform med davitere? :=)

 

Kjenner ihvertfall til mange måter å måle båt på og synes vel faktisk den mest ærlige av de er den Bayliner og andre US båter oppgir, fra innside, -til innside av skroget.

Det betyr at min 3258 oppgis til å være 32 realistiske fot, selv om den LOA er 10.91 meter.

Redigert 20.Juni.2008 av Thelina (see edit history)

[Seiljåtten]

Ja, det er AC, er bare jeg som har blitt "vant" til å se og lese om Cruisere...

 

38AC ble omdøpt til Cruiser etter at Match båtene kom på markedet, så det er vel igrunnen riktig. Da båten kom på markedet hadde bavaria kun AC, men etter at de lanserte Match serien ble det splittet opp i Cruiser og Match. 38AC er nesten like lang som 39 og 40 cruiser (mangler 1/3 fot på 39, og 1/2 fot på 40). Seilarealet på 38AC er også temmelig likt. Sammenligner man nye 40Cruiser, 39 cruiser, og 38AC, ser man at 38AC har mer til felles designemessig med 40Cruiser enn med 39 Cruiser. Tegningene av nye 43 minner også mer om AC serien igjen. Kanskje fordi de ikke lenger har noen Match serie. 38AC er kanskje bare 1/3 fot kortere enn 39 Cruiser, men 39 foteren har endel mer volum under dekk enn 38 foteren. Var på messa og kikket på 40 foteren, men satt igjen med inntrykk av at det ikke skilte så mye på størrelsen i forhold til 38AC. Har rett og slett 40 blitt mindre enn 39 målt i volum under dekk? Ikke egentlig, men de har senket båtens høyde, og det gjør mye med volum følelsen (og får den til å likne på AC igjen).

[Fru Charente]

 

Kanskje vi blir klokere av å lese dette:

 

 

SHIP HYDROSTATICS - dimensions and measurements

 

The Basics

 

 

 

Principal Dimensions

The shapes shown in a lines plan delineate what is called the molded form of the vessel. The principal dimensions of a ship are length between perpendiculars, beam, draft, and depth. These quantities are shown in Figure 5 and Figure 6 and are defined as:

 

Length Between Perpendiculars (LBP or L):

The horizontal distance between the forward and aft perpendiculars is called the length between perpendiculars. It is constant for a given ship and does not depend on the loading condition of the ship.

Beam (B):

The breadth of the ship at the broadest point is called the beam. Molded beam is measured amidships or at the widest section from the inside surface of the shell plating. Maximum beam or extreme breadth is the breadth at the widest part of the ship, and is equal to the molded breadth plus twice the plating thickness plus the width of fenders, overhanging decks, or other solid projections.

Draft (T):

The vertical distance between the waterline and the deepest part of the ship at any point along the length is the draft. Drafts are

usually measured to the keel and are given as draft forward (Tf ), draft aft (Ta ) and mean draft (T or Tm ). A ship�s forward and after draft marks are seldom at the perpendiculars and mean draft is not necessarily amidships; the slight errors introduced by using drafts at these points can be discounted if trim is not extreme. Molded drafts are measured from the molded baseline, while keel drafts are measured from a horizontal line though the lowest point on the bottom of the keel extended to intersect the forward and after perpendiculars. Navigational or extreme drafts indicate the extreme depth of sonar domes, propellers, pit swords, or other appendages which extend below the keel, and are therefore not used to calculate hydrostatic properties. Draft scales for keel drafts are usually placed on both sides of the ship at each end as near as practical to the respective perpendiculars. The external draft marks are generally Arabic numerals, with height and spacing arranged so that the vertical projection on the vessel of the numeral heights and vertical spacing between numerals are both six inches. The draft figures are placed so that the bottom of the figure

indicates the keel draft. Drafts can thus be read to the nearest quarter-foot (3 inches) in relatively calm waters.

Depth (D).

Depth is the vertical distance between the baseline and the uppermost watertight deck and is the sum of freeboard and draft. Molded depth is measured from the top of the outer keel to the underside of the main or freeboard deck at the side. Depending on hull form and ship�s attitude, both freeboard and depth can vary along the length of the ship. Unless otherwise specified, tabulated values for depth and freeboard are usually taken at midships or at the point of minimum freeboard.

 

Other Measurements

 

In addition to the principal dimensions, the following, also shown in Figure 5, and in Figure 7 are also used in describing ships:

 

Length Overall (LOA):

The extreme length of the ship along the centerline is called the length overall.

Length on Waterline (LWL):

This is the length along the centerline at the waterline in the ship's design loaded condition.

Freeboard (F):

This is the distance between the waterline and the uppermost watertight deck at any location along the ship.

Displacement Volume (V):

The displacement volume is the total volume of the underwater hull at any given waterline.

Displacement (W):

The displacement is the weight of the water of the displaced volume of the ship; for static equilibrium it is the same as the weight of the ship and all cargo on board. Therefore, displacement is directly related to displacement volume and it can be found by multiplying the volume with the specific gravity of the water in any set of consistent units. For example if the volume is in cubic feet, we may divide it by 35 to get the displacement in long tons in seawater, or by 36 in fresh water.

Buoyancy:

Any ship partially or wholly imersed in water will experience an upward push called buoyancy. The force of buoyancy is equal to the weight of the volume of water the ship displaces.

Reserve Buoyancy:

The watertight volume between the waterline and the uppermost continuous watertight deck is the reserve buoyancy of the ship. It enables the ship to take on additional weight, and it is closely related to the ability of the ship to survive a damage.

Moment of Inertia (I):

For hydrostatic calculations we will always refer to the moment of inertia as the second moment of area unless specified otherwise. It is a measurement of a plane surface's resistance to rotation about an axis in the same plane. The magnitude of the moment of inertia depends upon the shape of the area and the location and orientation of the axis of rotation. The moment of inertia is measured in the fourth power of a linear unit, such as ft4, in4, or a combination.

Tonnage:

Tonnage is a description of the cargo capacity of a merchant ship. It is a volume measurement and does not directly indicate displacement

Sheer:

The rise of a deck above the horizontal measured as the height of the deck above a line parallel to the baseline tangent to the deck at its lowest point. In older ships, the deck side line often followed a parabolic profile and sheer was given as its value at the forward and after perpendiculars. Standard sheer was given by:

sheer forward = 0.2L +20

sheer aft = 0.1L +10

where sheer is measured in inches and L is the length between perpendiculars in feet. Actual sheer often varied considerably from sheer

these standard values; the deck side profile was not always parabolic, the lowest point of the upper deck was usually at about 0.6L, and the values of sheer forward and aft were varied to suit the particular design. Many modern ships are built without sheer; in some, the decks are flat for some distance fore and aft of midships and then rise in a straight line towards the ends. Sheer increases the height of the weather decks above water, particularly at the bow, and helps keep the vessel from shipping water as

she moves through rough seas. Some small craft and racing yachts are given a reverse or hogged sheer to give headroom amidships without excessive depth at bow and stern.

Camber:

The convex upwards curve of a deck. Also called round up, round down,orround of beam. In section, the camber shape may be parabolic or consist of several straight line segments. Camber is usually given as the height of the deck on the centerline amidships above a horizontal line connecting port and starboard deck edges. Standard camber is about one-fiftieth of the beam. Camber diminishes towards the ends of the ship as the beam decreases. The principal use of camber is to ensure good drainage in calm seas or in port, although camber does slightly increase righting arms at large angles of inclination (after the deck edge is immersed). Not all ships have cambered decks; ships with cambered weather decks and flat internal decks are not uncommon.

Tumblehome:

The slant inward from the vertical of a transverse section of a hull above the design waterline. Tumblehome is the opposite of flare. Tumblehome was a usual feature in sailing ships and many ships built before 1940. Because it is more expensive to construct a hull with tumblehome, this feature is not usually incorporated in modern merchant ship design, unless required by operating conditions or service (tugs and icebreaking vessels, for example). Destroyers and other high-speed combatants are often built with some tumblehome in their mid and after sections to save topside weight. Recently, tumblehome is seen as a viable alternative to reducing radar cross sections.

Flare:

The outward curvature of the hull surface above the waterline, i.e., the opposite of tumblehome. Flared sections cause a commensurately larger increase in local buoyancy than unflared sections when immersed. Flaring bows are often fitted to help keep the forward decks dry and to prevent "nose-diving" in head seas.

Deadrise:

The departure of the bottom from a transverse horizontal line measured from the baseline at the molded breadth line. Deadrise is also called rise of floor or rise of bottom. Deadrise is an indicator of the ship�s form; full-bodied ships, such as cargo ships and tankers, have little or no deadrise, while fine-lined ships have much greater deadrise along with a large bilge radius. Where there is rise of floor, the line of the bottom commonly intersects the baseline some distance from the centerline, producing a small horizontal portion of the bottom on each side of the keel. The horizontal region of the bottom is called flat of keel,orflat of bottom. While any section of the ship can have deadrise, tabulated deadrise is normally taken at the midships section.

Rake:

A departure from the vertical or horizontal of any conspicuous line in profile, defined by a rake angle or by the distance between the profile line and a reference line at a convenient point. Rake of stem, for example, can be expressed as the angle between the stem bar and a vertical line for ships with straight stems. For curved stems, a number of ordinates measured from

the forward perpendicular are required to define the stem shape. Ships designed so that the keel is not parallel to the baseline and DWL when floating at their designed drafts are said to have raked keels, or to have drag by the keel.

Cut-up:

When a keel departs from a straight line at a sharp bend, or knuckle, the sloping portion is called a cut-up. High-speed combatants usually have a long cut-up aft (extending 13 to 17 percent of LWL) to enhance propeller performance and maneuverability. Ice-breaking vessels often have a cut-up forward to allow the ship to ride up on the ice.

 

Flotation Characteristics

 

The following terms are used with regards to ship flotation:

 

Trim:

Trim is the difference between the drafts forward and aft. Typicallu, we assign positive and negative values to trim to indicate trim (down) by the stern or trim (down) by the bow respectively.

List, Heel, and Roll:

Angular transverse inclinations of ships are described as list, heel, or roll, depending on the nature of the situation. List describes a definite attitude of transverse inclination of a static nature. Heel describes a temporary inclination generally involving motion, while roll indicates periodic inclination from side to side. For example, a ship rolls in a seaway, lists due to a side damage, and heels in a turn.

 

Centers

 

Certain point in the ship are described as centers and they are fundamental for ship behavior at sea. The most important of these centers are:

 

Center of Gravity (G).

Though the weight of the ship is distributed throughout the ship, it can be considered to act through a single point called the center of gravity. If the ship were to be suspended from a single thread, that thread would be connected at the center of gravity for the

ship to remain upright and on an even keel. The weight always acts vertically downward through the center of gravity. The location of the center of gravity of a ship is solely a function of weight distribution within the ship. The center of gravity is in a fixed position for each condition of loading of the ship, but moves whenever there is a weight addition, removal or movement within the ship.

Center of Buoyancy (B).

The center of buoyancy is the geometric center of the submerged hull. The force of buoyancy acts vertically upward through the center of buoyancy. When the ship is at rest, with or without a list, the center of buoyancy is usually directly below the center of gravity. As the ship is disturbed, the center of buoyancy moves to the new center of the submerged hull. The force of buoyancy then acts vertically upward through the new center of buoyancy. When the centers of gravity and buoyancy are not aligned vertically, the forces of gravity and buoyancy acting through their respective centers tend to rotate the ship.

Metacenter (M).

The metacenter is an imaginary point that is of prime importance in stability. When the ship is inclined to small angles, the intersection of the line or action of the buoyant force acting vertically through the new center of buoyancy and the now inclined centerline of the ship is the metacenter. In a stable ship, the metacenter lies above the center of gravity. Figure 8 shows the relationship between the metacenter, the center of buoyancy and the center of gravity as the ship inclines. For purposes of illustration, the angles of inclination are exaggerated.

Center of Flotation (F).

The center of flotation is the geometric center of the waterline plane. The center of flotation is important in longitudinal stability because it is the point about which the ship inclines or trims in the fore-and-aft direction.

 

 

Her kan dere se mere bl.a de figurer som er nevnt i teksten. Ships Hydrostatics

 

mvh

fru Charente

Redigert 20.Juni.2008 av Fru Charente (see edit history)

[27 knop]

Og enda litt mer info... Hvorfor 30.48cm? 1 yard= 0.9144 m = 36 tommer (0.0254m)

 

- En fot er en tredjedels yard

 

- Det er 12 tommer i en fot

 

 

 

[Krimart]

De tallene som brukes er ikke nødvendigvis det samme som LOA i fot. det er strengt tatt bare en modellbetegnelse. Nå er det jo sympatisk at de ligger på "undersiden " av LOA, ikke oversiden.

 

En kuriositet: husker for noen år siden jeg skulle kjøpe påhengsmotor; jeg skaffet meg da mange brosjyrer og alle hadde oppgitt effekt etter en eller annen felles standard i kW bakerst i brosjyrene, der tekniske data var listet opp. Da var det overraskende å se at Mercury, Evinrude og Johhnson konsekvent "jukset" seg til flere Hk, mens f.eks. Yamaha var det ofte motsatt. Mercury 55 (?) hadde f.eks. bare 45 Hk. Det var selvsagt fordi det bare var en MODELL betegnelse og ikke hadde noe med Hk å gjøre :-). Jeg kjøpte Yamaha.

[Jawik]

Skandinavia

 

Fra Skandinavia kjenner vi til at det gikk 20 tommer på et alen til å begynne med. Vi vet også at det senere gikk 12 tommer på en fot og 2 fot på et alen, den gang tommen utgjorde 2,37 cm, så i fordums tid har altså foten en gang utgjort 28,44 cm i Norge (trolig også i Danmark). På denne tiden ble imidlertid målesystemet regulert av alnets lengde, som har variert mye gjennom historien. Både fra land til land og sted til sted. Det betydde i praksis at også fot og tommer varierte tilsvarende.

 

I 1541 ble sjællandsk alen innført i Danmark-Norge. Det utgjorde 63,26 cm da det innført og gjorde foten til 31,63 cm. I 1683 ble det innført et nytt mål- og vektsystem basert på rhinsk fot. Samtidig ble det dansk-norske alensystemet avløst av et nytt fotsystem. En fot ble satt til å utgjøre 31,402 cm. Imidlertid viste det seg at den danske astronomen Ole Christensen Rømer (1644–1710), som hadde hatt ansvaret for det nye systemet, hadde gjort en feilanalyse den rhinske foten. Den dansk-norske foten ble derfor justert til 31,38535 cm fra den 10. januar 1698. Denne lengden holdt seg slik til i 1820 i Danmark, da foten med forordning ble satt til 31,375 cm. På denne tiden var Norge komet i union med Sverige, så den norske foten var fortsatt 31,38535 cm. I lov av 28. juli 1824 ble imidlertid også den norske foten konvertert til 31,375 cm. Dette målet gjalt fram til fotsystemet ble avviklet til fordel for metersystemet i Norge. I Danmark ble imidlertid forordningen opphevet i 1835 og foten justert til 31, 385 cm. Denne holdt seg slik til danskene gikk over til metersystemet (i praksis fra 1907). Både Danmark og Norge undertegnet meterkonvensjonen i 1875, men landene tok altså ikke i bruk metersystemt før mange år senere. Gamle alen, fot og tommer ble imidlertid etter dette satt i sammenheng med det nye målesystemet.

 

I Sverige gikk man over til fotsystem fra den 31. januar 1855. En svensk fot utgjorde da 29,6904 cm. Fram til dette var den svenske foten preget av det svenske alensystemet. I hovedsak har en svensk fot utgjort 0,94607 av den dansk-norske, prøyssiske og rhinske foten. Sverige undertegnet også meterkonvensjonen i 1875, men som i Danmark og Norge tok det mange år før svenskne tok i bruk metersystmet i praksis.

 

Internasjonal fot

 

I tillegg til den nåværende standarden imperial foot (30,48 cm) finnes det en litt annen U.S. survey foot, som brukes av U.S. Coast and Geodetic Survey. Denne er definert som nøyaktig 12 U.S. survey inches, som er omtrent 30,48006 cm.

[Marwin]

RIPAMÅL er en annen betegnelse, brukt av bl.a. Mørebas i sin tid...