US3134355A

US3134355A - Sea anchor

Info

Publication number: US3134355A
Application number: US223760A
Authority: US
Inventors: Jakosky John Jay; Jr John J Jakosky
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-09-14
Filing date: 1962-09-14
Publication date: 1964-05-26
Anticipated expiration: 1981-05-26

Description

y 26, 1964 J. J. JAKOSKY ETAL 3,

SEAANCHOR Filed Sept. 14, 1962 United States Patent 3,134,355 EA ANCHGR John Jay .lahoslry and John J. Jakosiry, 112, both of PD. Box 1791, Newport Beach, (Ialif. Filed Sept. 14, 1962, Ser. No. 223,760 3 Claims. (Cl. lid-20h) This invention relates to sea anchors or drogues, and more particularly to a drag-type anchor towed by a water craft: To slow down its forward motion; to give desired orientation for maintaining its bow in a seaway; to otherwise stabilize and hold it while drifting as when fishing, or under abnormal conditions of sea and weather and under distress conditions.

In accordance with this invention, a novel drag type anchor is provided, having a multiplicity of elements of special shape, suspended coaxially in-line along a cable.

It is therefore an object of the present invention to provide a novel drag type anchor of relatively small diameter and extended in-line length.

Another object of the invention is to provide a drag anchor which will not be dependent upon movement thru the water to open or activate it but which will be ready to function immediately upon being immersed in the water.

Another object is to provide a sea anchor which will remain open and without any tendency to collapse or close when slack occurs in the anchor rode connecting it with the water-craft.

Another object is to provide a sea anchor or drogue which will tow properly in a straight line behind the craft and not swing laterally in an irregular or erratic manner which may be dangerous by preventing proper steering and/or predictable forward movement which must be coordinated with the cadence of the seas.

A still further object is to provide a sea anchor having novel means for storing oil at a multitude of points, so it will slowly ooze to the surface to decrease the flying spray normally generated by a strong wind in a breaking or cycloidal sea.

Another object is to provide a drogue which will minimize the tendency to snag or tear when brushed against or dragged over debris or jagged rocks in shallow inlets or shoals.

A still further object is to provide a sea anchor that may be used repeatedly and which does not require drying and/ or rinsing with fresh water after each use to remove the salt and moisture that causes corrosion and rot in the metals and fabrics normally employed in the construction of conventional sea anchors.

Another important object is to provide a convenient sea-anchor assembly or package which may be placed in operation or layed with minimum hazard to personnel, and with minimum danger of fouling the propellor or rudder, in storm weather when high winds and rough seas prevail.

These and further objects and advantages of the present invention, including such as will become apparent or are incidental to the use of the structure described, are set forth in preferred embodiments of the invention in the accompanying drawings to illustrate the major features and improvements.

The sea anchor is defined by Bowditch in the American Practical Navigator as: An object towed by a vessel to keep it end-on to a heavy sea or surf, or to reduce the drift. When conditions get so bad offshore that a boat cannot make headway and begins to take too much punishment, the usual practice is a heave-to. This can be done by laying a sea anchor from the bow, so that the drag of the sea anchor will keep the bow headed into the waves. In use, the theory of the sea anchor is not to go to bottom and hold fast, as does the conventional Patented May 26, 1964 anchor, but merely to present sufiicient drag or resistance to keep the boats head within a few points of the wind as she drifts olf to leeward. Such anchors are sometimes equipped with an oil container which permits oil to ooze out slowly, to form a slick on the surface, thus preventing the seas from breaking.

The conventional type of sea anchor consists of a cone shaped canvas bag having an iron hoop at its throat or larger end, and normally with a diameter of about 3 feet. To this hoop is attached at least three equally spaced short bridle or lead lines, which terminate at a fitting attached to the anchor rode laid out from the bow of the boat. Occasionally a trip-line is attached to the small or after end of the canvas cone, to spill the bag and make it easier to haul it back aboard or when used as a drogue.

A second type of sea-anchor, having limited application, is an adaptation of the conventional parachute, which itself was intended originally for use in the air. This parachute type has the usual parachute shape and construction, and also is made of light cloth. The throat has a diameter of about 25 feet. The light cloth parachute is fastened to the tow line with light nylon suspension lines. To the after end of the parachute is fastened a trip line, so the parachute may be hauled aboard when desired.

The conventional cone and parachute sea anchors are fairly satisfactory except on days of strong winds and choppy seas. During these periods, considerable difficulty is encountered in properly laying them. Generally, the smaller cone type is satisfactory if proper precautions are exercised, but their holding power is insufiicient for the medium or larger size craft. The larger parachute-type sea anchors have somewhat greater holding power but their laying is usually a serious problem. They are a definite hazard in heavy winds, due to the danger of carrying a man overboard or becoming fouled with the ship or being caught in the propellor or rudder. Our research investigations have clearly indicated that the practical solution requires the use of a rigid, small sized drag element, with a multiplicity of these elements to give the desired holding power. In particular, it was found that a number of small area elements have proportionally a much greater holding power than the same total area incorporated into a single element or parachute. Studies were made to determine the most eflicient size and shape of these individual elements, and the results thereof form the subject matter of this patent application.

' Referring to the drawings:

FIGURE 1 is a generalized isometric view of a vessel laying to or secured to a sea anchor of the type described herein and in accordance with this invention.

FIGURE 2 is a diagram showing the flow past a plane disc when it is moved thru the water in a direction perpendicular to its plane, and at a speed greater than the very slow movement required to satisfy the conditions for theoretical laminar flow; i.e., when turbulent flow occurs on the after side of the disc.

"FIGURE 3 is a diagram showing the flow of water past an element having a cone or parachute shape, when moved thru the water at a speed comparable to that prevailing in FIGURE 2.

FIGURE 4 is a diagram showing the flow of water past an element having a shape embodying the principles of this invention, whereby an optimum deflection of water flow radially outward from the surface of the element is obtained from the positive pressure area forward of the element; and optimum turbulence is created in the nega tive pressure area aft of the element.

FIGURE 5 illustrates the general form for an absorbent member, useful for releasing oil.

FIGURE 6 depicts an assembled sea anchor having 3 a multiplicity of elements telescoped together, contained in a fiexible fabric bag. For illustrative purposes, the bag is shown in a partially opened position.

When a disc is drawn thru the water, as illustrated in FIGURE 2, with its plane perpendicular to the direction of movement, the drag is due largely to the pressures over the surface (a positive pressure build up forward of the disc and a negative pressure aft) and it is also dependent on the formation of the wake behind the object. In general, when the wake is large the profile drag is large, and when the wake is reduced by streamlining the profile drag is correspondingly reduced. At low velocities, the shape of the tail of the body determines the size of the wake and this is of primary importance in determining the profile drag. The drag coefficient of a fiat disc or plate is on the order of 1.9, and varies little with the Reynolds number while that of a streamlined disc or strut varies from about 0.10 at a Reynolds number of 20,000, to 0.06 at a Reynolds number of 110,000. The streamlined shapes, "because of their small turbulent wakes, possesses little profile drag. These values are typical of those resulting from tests of brusque, blunt and streamlined objects. For this reason, the conventional cone or parachute shape sea anchor as illustrated in FIGURE 3 is relatively ineificient because its wake is reduced and under some conditions completely cancelled by the streamlining effect of the cone or parachute tail.

Our investigations have established the fact that to obtain the maximum wake, the disc must be shaped; (1) To allowlaminar flow of water trapped forward of the disc in the positive pressure area, and to deflect it to flow radically outward from the edge of the disc, and (2) to inhibit streamlining or laminar flow aft of the disc and create maximum turbulence. By shaping the. disc in accordance with the general cross-section illustrated in FIGURE 4, and with the leading edge having an angle of 63 to 98 degrees with the axis, the water forward of the disc in the high or pressure area is directed radially outward. This outward flow serves to effectively increase the size of the disc. The faster the movement of the disc thru the water, the greater is this effective increase in size, thereby resulting in a much greater drag as the pull on the element increases. Secondly, by giving the rearward side of the element, where the low or pressure area prevails, a convex shape, optimum turbulence and cavitation is created. This combination of outward radial flow from the forward face of the element, and optimum turbulence at the rear of the element, results in an extremely high drag from a relatively small sized element. The shape which creates the desired turbine or defiective outward flow of water from the face of the element, also has sufficient lead to give the required stability. This lead should be not less than 0.35 the diameter of the disc. Each element therefore incorporates a coaxial stabilizing portion which extends forwardly of the drag portion. The cable line is fastened to this forward lead point, which is rigidly fixed in relation to the face of the element. As a result, the tendency of the elements to wobble is minimized. Wobble produces erratic motion, drag, and diving when a strong pull is exerted on the anchor line.

The elements are spaced along the cable at a suflicient distance to avoid interference between the turbulent flow occurring on the after side of a preceeding disc and the laminar flow on the leading side of a following disc. It has been found that a spacing greater than 0.6 the diameter of the disc, with a leading edge of 63 to 98 degrees, should always be employed.

The preferred embodiment of the sea anchor comprises a series of identical elements, each about 14 inches in overall diameter, threaded on and uniformly spaced along a steel cable. The greater the holding power desired, the larger the number of elements and the longer the overall length of cable,

Referring now to FTGURE 4, the element 1 is precision molded from non-breakable, impact-resisting plastic, which is practically unaffected by sea Water. A special bronze alloy rearwardly flared sleeve 2 is crimped securely to the flexible steel cable 3 to position each element at the proper spacing along the cable. The wall of sleeve 2 extends radially outwardly to form the drag portion thereof. The cable preferably is made from rust resisting material, such as stainless steel, and may be covered with a nylon sleeve. Referring to FIGURES 1, 4 and 6, the leading end of the cable 3 is made up with a thimble 4 so it may be shackled directly to the anchor rode, which comprises a flexible line 5 and a short length of chain 6. The after end of the cable 3 is terminated in a fitting 13 that is crimped to the cable and secures the fabric carrying bag, 7 and '7'. The complete assembly is designed for continuous and rugged off-shore use. Preferably, all components should be made from materials which are not adversely affected by sea water, mould, rot, rust etc. so that fresh water rinsing and drying after use in sea water is not required.

FIGURE 5 illustrates the preferred shape of an ab sorbent member which may be installed on the cable. The absorbent member 10 preferably is fashioned from an oil-insoluble porous plastic sponge-type material. Thru its center and extending longitudinally is a cored opening 11 having a diameter to fit the cable. A diagonal slit 12 is provided to allow the member to be slipped over the cable and into the inside of the leading portion of the element, as illustrated in FIGURE 4. The member 10 may be frictionably or mechanically held in position.

The carrying

bag

7 and 7 is a sturdy fabric bag, and is provided with two handles 3 and 8'. The bag preferably is made in two parts, with the joint extending longitudinally. The two parts may be joined together by use of a zipper 9 and 9, or other conveniently opened fastening means. The elements of the sea anchor are telescoped together, and contained in the bag. The entire unit is light in weight, compact, and easy to stow away and handle.

This form of sea anchor package is convenient and safe to use; it merely being necessary to shackle it to the anchor rode, then while holding the two handles 8 and 8' of the carrying bag with one hand, the fasteners 9 and W are released with the other hand. The entire unit may then be dropped or thrown overboard: The'bag opens and the elements automatically fall out of the carrying bag. A short lateral movement ofthe boat strings out the cable and its attached elements, with the bag trailing behind. Any movement of the sea anchor immediately causes it to function as intended.

The anchor rode may be the same as used for bottom anchoring. If the rode is a fibre anchor line, it normally is provided with a short length of chain, which in turn is shackled to the anchor. The short length of chain is necessary when using any type of sea anchor to keep it properly below the surface of the water. (See FIG. 1.)

The number of elements varies with the size of the boat, and its effective Wind and sea resistance. The following relationship has been found to be satisfactory for average small sail and power boats:

Length of boat: Number of elements 0 to 16 feet 3 17 to 26 feet 5 27 to 36 feet 8 37 to 46 feet 12 47 to 56 feet 17 57 to 66 feet 23 It will be understood that this invention shall not be limited to the specific embodiments shown and described herein, but may be incorporated in other forms without departure from its spirit or essential characteristics as defined by the following claims.

What is claimed is:

1. A sea anchor or drogue as described; having coaxial stabilizing and drag portions, said drag portion having a forwardly directed cavity and being dish-shaped, and said stabilizing portion being elongated and extending forwardly of said drag portion, said stabilizing portion being hollow and flared rearwardly, and being integral with said drag portion.

2. A sea anchor or drogue as described; having coaxial stabilizing and drag portions, said drag portion being dishshaped, and said stabilizing portion being elongated and extending forwardly of said drag portion, said stabilizing portion having a rearwardly directed cavity, and an oilinsoluble porous material in said cavity adapted to slowly release a quantity of oil from said cavity, the wall of said cavity being a continuation of the wall of said dishshaped portion.

3. A sea anchor or drogue as described; having coaxial stabilizing and drag portions, said drag portion being dish- 6 shaped, and said stabilizing portion being elongated 1101- low and extending forwardly of as a continuation of said drag portion, the cavity of said dish-shaped portion being forwardly directed, the rim of said dish-shaped portion being at an angle of between 63 and 98 degrees from the axis of the stabilizing and drag portions.

References Cited in the file of this patent UNITED STATES PATENTS 508,271 Boucher Nov. 7, 1893 1,133,154 Kahnweiler Mar. 23, 1915 1,299,186 Irnaizumi Apr. 1, 1919 1,675,606 Henry July 3, 1928 2,974,913 Steinthal Mar. 14, 1961 FOREIGN PATENTS 271,522 Italy Feb. 11, 1930 89,397 Netherlands Nov. 15, 1958