Flipper Delta® anchor
Major advantages of this anchor:
- Proven superior high holding power capacity
- Excellent efficiency (weight / holding power)
- Open construction for smooth and good penetration in different kinds of soil
- No rotation, which means no decrease of holding capacity and no dragging
of the anchor
- Easy dismantling for transport purposes
Dimensions are not binding
Weight (in Dimensions W (in Dimensions F (in Dimensions H (in Dimensions TL (in
kgs) mm) mm) mm) mm)
500 1500 1200 570 1800
1000 1960 1560 740 2305
2000 2470 2000 930 2960
3000 2830 2285 1070 3380
5000 3330 2660 1260 3945
7000 3750 2995 1405 4440
7500 3850 3080 1435 4565
9000 4130 3320 1550 4925
10000 4270 3400 1600 5040
12000 4530 3600 1705 5335
15000 4845 3875 1830 5735
22500 5490 4360 2060 6905
400000 6650 5290 2480 7850
500000 7150 5690 2670 8440
600000 7600 6040 2830 9000
75000 8200 6560 3100 9430
What is essential for good behaviour and high holding
power?
Opening of the flukes > Large tripping palm area and a well
situated hingepoint.
Penetration > Bevelled shank, flukes, tripping palms and
stabilizers.
No balling-up and jumping out > Holes in the flukes and open
head structure.
Stability > Four plate-stabilizers.
Handling and safety > No protruding bars, high structural strength
by frame construction.
1. Flipper Delta anchors® dropped on soft bottom might sink with their flukes pointing upwards.
2. As soon as a horizontal pull is exerted on the anchor, it slides up on the flukes.
3. While the congested soil runs off through the open head, the large wide tripping palms - situated
behind the pivot - ensure that the flukes turn around.
4. The Flipper Delta anchor® digs in and the four stabilizers ensure that it stays in this optimum position,
while giving high holding power in soft soil as well.
5. A Danforth anchor falls into soft soil and, as a result of its heavy head, sinks with its flukes pointing
upwards.
6. As soon as a horizontal pull is excerted on the anchor, it slides up on the flukes.
7. While the soft soil bulges under the flukes, the relatively small tripping area - situated in front of the
pivot - cannot ensure that the flukes turn around.
8. Result is soft soil: holding power = 2 x weight of anchor.
How to set an anchor?
If possible, avoid to drop anchors. They might land on the anchor wire and
damage it. The anchor should be lowered in this way. Keep on heading away
from the rig while lowering the anchor. Do not stop until you have paid out
more length of pendant wire than the water depth.
Kinks in wires occur as a result of:
Anchors hanging on the anchor wire with a slack pendant wire.
Anchors hanging on the pendant wire with a slack anchor wire.
You can avoid kinks by always keeping some tension on both wires.
Never lower the anchor in this way
A swivel in the anchor cable is not the right solution. Due to the difference in lay length, the outer strands
are longer than the steel inner 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.
Due to the weight of the anchor, the pendant wire will untwist and the anchor will start spinning. This
causes kinks in the anchor wire
How to break out an anchor?
If an anchor in soft clay has been subjected to 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 centimetres. If these high load jerks are
repeated many times, the anchor can penetrate an extra 1 to 5 metres. This
is the reason why it is so hard to break out anchors after stormy weather.
When the pendant line is too long, the rear side of the lower tripping palm
might bite and obstruct an easy pull out.
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.
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 unsuccessful then you must try the
PETER KLAREN method. This method has three advantages:
You do not need to drag the embedded anchor cable through the soil
The tension in the anchor cable reduces the suction of the clay on
the rear sides of flukes and palms.
The rear side of the head will not be filled with clay.
Sequence of this break out action:
Ask rig to reduce tension in anchor cable just above minimum (no
slack).
Manoeuvre stern above anchor with bow in direction of rig.
While heaving in the pendant wire as much as you can.
Look out for too much tension in the pendant in rough seas.
Then slack 5-6 metres of pendant wire (not more).
Head in the direction of the rig under full power.
And ask the rig to tension up the anchor cable to 40-80 tons (see
sketch)
As soon as the rig reports that the tension drops, the anchor is loose.
Anchor handler must change course 180 degree, stop engines and
haul in sufficient pendant wire until the anchor is well clear off the
bottom.
Let the rig winch now haul in the anchor cable, pulling anchor and
anchor handler towards itself.
Drawing
Fluke Angle
Fluke Angle is the angle between the centre lines of shank and flukes.
If you 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. The anchor is not going that deep. What actuallly happens, is that
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-degree position 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.
1. 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.
2. For very soft clay and mud, the angle must be increased to 50 degrees by cutting out the marked and
pre-cut pieces of the tripping palms. 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 side.
3. 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.
