Ships – Anchor – Fluke type
Patent
1997-07-15
1999-08-10
Swinehart, Ed L.
Ships
Anchor
Fluke type
114294, B63B 2138
Patent
active
059342196
DESCRIPTION:
BRIEF SUMMARY
Cross References to Related Application: French Patent No. 27 29 36
Statement as to rights to inventions made under Federally-sponsored research and development:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The anchor described is used to secure any type of vessel in harbours or anchorages.
2. Description of the Prior Art
Since ancient times, man has needed to anchor boats, this was first achieved by means of casting overboard heavy stones attached to the ship by a rope. Over a time, more sophisticated anchors made of iron or wood and ballasted with lead were developed. The traditional marine symbol, the fisherman anchor, is virtually no longer used today, due to it's heavy weight, it's dimensions and it's poor performance.
The common modern anchors, although offering an improvement of anchoring performances, have the disadvantage of not being well adapted to all types of sea bed and not giving a high holding resistance.
SUMMARY OF THE INVENTION
The Spearhead anchor was conceived to achieve the three most important characteristics of an anchor:
INSTANTANNEOUS SETTING
To dig in the sea bed, the pressure of the anchor's tip (Kilo/sq cm) must be higher than the seabed surface resistance. It is necessary: weight distribution on the anchor tip is obtained through it's geometry and it's weight distribution. Due to it's geometry and balance, the anchor automatically positions itself in the setting position: stands on three points (a) the extremity of the shank (b) one of the two ears of the fluke (c) the tip of the anchor (FIG. 5). The ballast position constituting the counter-tip with a "chvron" cross section shape (FIG. 7), is external to the "tip/ear" axis (b-c) and located outside of the support base (a-b--c) to balance the weight of the shank (FIG. 5). At this time, nearly all the anchor's weight is distributed only between the two contact points: the tip (c) and one of the two ears (b). As a result, the anchor's centre of gravity is located nearly on the "tip/ear" axis (b-c) and as close as possible to the tip (c), in order to distribute the highest part of the weight onto the anchor's tip.
As most of the weight distribution is on the anchor tip, it improves the performance of digging into the sea bed
BURIES IN ANY TYPE OF SEA BED
In general, the density of the surface layer of the ea bed is not very high but increases as you go deeper down through the layers. On a mud or sand sea bottom, the pressure exerted by the tip, would be in the majority of cases, higher than the sea bottom resistance and the anchor's tip will dig in immediately. The boat pulling on the anchor will contribute to the anchor digging in.
Sea bottoms covered by a layer of thick weed make anchor penetration more difficult: most other common anchors tend to slip over the sea weed, without penetrating the bottom and can not hold. The Spearhead anchor, in the normal anchoring position, presents a profile with an angle of about 20.degree. similar to a chisel (FIG. 7), this profile is applied to the sea bed at an angle of less than 90.degree., exactly like a chisel. Thus the anchor tends to penetrate beneath the weed, spreading it out, until it can reach solid bottom and dig in.
PROVIDE A HIGH HOLDING POWER
The density of the sea bed increases as you go deeper, therefore the anchor fluke must then be sharply pointed, with the tip down, so that the tip can provide the best penetration of the bottom. The widest part of the tip is connected to the lateral side of the quasi-elliptic shaped fluke. This provides the required surface area to ensure the holding power of the anchor even in the top layers of less density.
The geometry of the fluke is the second important factor in the anchor's holding power. A NACA profile (plane wing) has a holding resistance coefficient of 0.1, a "wedge" surface coefficient can range from 0.5 to 1 in relation to the wedge angle, a plane surface reaches a value of 1.20 and a concave surface coefficient will be 1.70. The working surface of the Spearhead anchor does have a concave shape which the
REFERENCES:
patent: 5188055 (1993-02-01), Kershner
patent: 5474015 (1995-12-01), Bruce
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