TECHNICAL INFORMATIONFlipper Delta Anchor

No need for a back-up anchorHow to set an anchor?

How to break out an anchor?The fluke angle

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No need for a back-up anchor!

With the numerous Flipper delta Anchor applications a back-up anchor (piggy back) has never been required. This means a considerable saving in time and material. We disapprove the use of these back-up anchors, because the holding power of the back-up anchor might pull the flukes of the main anchor parallel to the shank, thus redusing its holding power to its own weight only.

How to set an anchor?

If possible avoid to drop anchors. They might land on the anchor wire and damage it.

Never lower the anchor in this way!

If possible lower the anchor in this way (see above). Keep on heading away from the rig while lowering the anchor. Do not stop before you have paid out more lenght of pendant wire than the waterdepth.

Kinks inwires occur as a result of:A. anchors hanging on the anchor wire with a slack pendant wire.B. anchors hanging on the pendant wire with a slack anchor wire.Kinks can be avoided by always keeping some tension in both wires.

Due to the weight of the anchor the pendant wire will untwist and that is why the anchor starts spinning, making kinks in the anchor wire.

A swivel in the anchor cable would not be the right solution. Due to the diference in laylenght the outer strands are longer than the inner steel core. By untwisting the wire all the load will therefore be applied to the inner core, which will break and will damage the outer strands from the inside.

How to break out an anchor?

If an anchor in soft clay has been subjected to a high tension, there will be a vacuum behind the anchor head. When the tension is taken away, the anchor falls back into the vacuum and the effect of the falling anchor results in a deeper penetration of one or more centimeters. If these high load jerks are repeated many times, the anchor can penetrate an extra 1 to 5 metres. This is the reason why anchors are hard to break out after stormy weather. Do not try to break out an anchor with a vertical

pendant line in rough seas, because the pendant line will break by a shock load when the anchor handler rides the waves.

When the pendant line is too long, the rear side of the lower tripping palm might bite and obstruct an

easy pull out.

The good way and the "Peter Klaren" method

The good way

A good way to break out the anchor is pulling on the pendant at an angle of approximately 15 degrees to the vertical, away from the rig. Then there is some elasticity in the system. If this is unsuccesfull you must try the "PETER KLAREN" method. This method has 3 advantages:

a) You do not need to drag the embedded anchor cable through the soil.

b) The tension in the anchor cable reduces the suction of clay on the rear sides of the flukes and palms.

c) The rear side of the head will not be filled with clay.

The "PETER KLAREN" method

1) Ask rig to reduce tension in anchor cable just above minimum.2) Manoeuvre stern above anchor with bow in direction of rig.3) While heaving in the pendant wire as much as you can.4) Look out for too much tension in the pendant in rough seas.5) Then slack 5-6 metres of pendant wire (not more).7) Head in direction of the rig under full power.*) Ask the rig to tension up the anchor to 40-60 tons (see sketch above).8) As soon as the rig reports that the tension drops, the anchor is loose.9) Anchor Handler must change course 180 degrees, stop engines and haul in sufficient pendant wire until the anchor is well clear of the bottom.10) Let the rig winch now haul in the anchor cable, pulling anchor and Anchor Handler towards itself.

Do not use a pendant wire which is too long, because when the anchor is deeply embedded, it will be very hard to break out.

Fluke Angle is the angle between the centre lines of shank and flukes

If you should use a fluke angle of 36 degrees in soft clay, the anchor head will penetrate deeply, but the shackles, and eventually the chain will slide on top of the soft clay. Thus the shank will make an angle of about 30 degrees to the seabed, forcing the flukes into an almost horizontal position and consequently the anchor cannot penetrate deeper and it will drag at a low resistance. What happens in that case is that the pendant buoy is pulled under water. Do not believe that the anchor is going that deep. In reality the anchor tunnels through the clay and the pendant line follows its horizontal path.

With the fluke angle set to 50 degrees, the shank will go in the same 30-degrees prosition to the bottom, but there will be another 20 degrees left for the flukes to enable them to penetrate the soft clay deeper for more resistance.

A Flipper Delta anchor has standard the most universal angle for its design = 36 degrees. This angle can be used in 80% of worldwide soil conditions.

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For very soft clay and mud the fluke angle must be increased to 50 degrees by cutting out the marked and pre-cut pieces of the tripping palm. Weld these pieces somewhere inside the anchorhead and do not let them get lost, because for other soil conditions they MUST be welded in place again. Then weld sides only, not the sloped pre-cut outside.

For very hard bottom soils like rock, cemented sand or coral we recommend to reduce the fluke angle to 28 degrees to achieve a higher penetration force on the fluke tips. Be sure that the fluke tips are not blunt but sharp.