concept report. palm island frond c – tip lot. private ...yachtworld.webplus.net/palm marina...

Patrick Keating 1 of 9 16 November 2009

Concept report.

Palm Island Frond C – Tip Lot.

Private marina jetty.

This report is prepared for Sheikh Ibrahim Sharbatly, the owner of the above property (hereinafter referred to as the owner). It is prepared for his use and may be copied and distributed for the purpose of designing, constructing and gaining regulatory approvals for the construction of a private marina jetty on the Palm Jumeirah Tip lot C for the berthing of private non commercial pleasure craft. Definitions used in this report. Palm – Palm jumeriah island Tip Lot – The construction plot at the very end of frond C of the palm. Boundary- The demarcated boundary of the tip lot. Beach – The area between the boundary and the water line. HAT – Highest astronomical tide LAT – Lowest astronomical tide MHWS – Mean high water springs MHWN – Mean high water neaps

MWL – Mean water level MLWN – Mean low water neaps MLWS – Mean low water springs CD – Chart datum taken as the datum mentioned on sea navigation charts. DMD – Dubai municipality datum Plot Level – The proposed finished plot ground level. Freeboard – Distance from the water line to the working deck level.

1. Aim of report. To advise on the best location for a private marina jetty at the owners

property on Palm Island taking into account all environmental and operational issues.

2. Location. Palm Jumeirah Island, Dubai, UAE. Frond C tip lot. The area considered in this report is bounded by the following coordinates/control points and the water area up to 100 metres around the tip lot outside these points.

Serial Nakheel control points WSG84 lat and long 1 N2780271.78 E481145.42 N25 07.696 E55 08.783

N

E

S

W

YACHTING WORLDWIDE LTDYacht and marina consultancy


2 N2780279.82 E481179.7 N25 07.699 E55 08.806 3 N2780248.17 E481229.88 N25 07.682 E55 08.832 4 N2780197.99 E481198.23 N25 07.655 E55 08.819 5 N2780190.18 E481164.93 N25 07.651 E55 08.795

When looking out from the tip towards the crescent the tip centre line is orientated at 80 degrees magnetic. Attached drawing at appendix A is the affection plan issued by Nakheel for this plot. Appendix B shows the whole site in relation to other fronds and the crescent with dimensions and orientation.

3. Purpose of marina jetty. The jetty is to be constructed to enable the berthing of the owners private pleasure craft, including a motor yacht, open fishing boats, enclosed fishing boats and other small powered and non powered leisure vessels. The jetty has been designed and sized to take vessels up to 50 metres and 300 tonnes GRT.

4. Climatic conditions. For the purpose of this report the only significant climatic factors are wind direction, wind speed and frequency of direction. Precipitation, temperature and pressure are not significant in the purpose of this report. An evaluation of the wind based factors has been carried out and the following conclusions have arisen:

a. The climatic data used for this report was derived from the following sources: i. US Government Atlas of Pilot charts for the Indian ocean area, Third

edition 1991.

ii. British Admiralty Sailing directions – Persian Gulf Pilot NP63 – 12th edition.

iii. Meteorological station of Dubai civil aviation department.

b. The data from the above sources was collated and is shown in the table

below. This was then analysed and has been summarised in the wind rose charts shown at appendix C “Wind rose by month for the Gulf region” which is attached. This data shows that the prevailing winds are predominantly from the North West quadrant. The highest wind speeds have also been recorded from this direction. The table clearly shows that the winds from the North West quadrant will have the most effect on any floating structure built on the palm. The effect of this wind data is shown graphically applied to a palm overview at Appendix D where it can be clearly seen which areas are protected and which are at risk for the prevailing wind conditions.


Key

Wind direction = The direction from which the wind is blowing % = The percentage of time the wind is blowing from this direction

Mean wind speed = Averaged wind speeds from this direction Max wind speed = The maximum sustained wind speed (not maximum gust strength)

January February March April May June

Win

d di

rect

ion

% Mea

n sp

eed

Kts

Max

spee

d kt

s % M

ean

spee

d Kt

s

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

N 18% 9 9 10% 13 13 10% 13 13 10% 9 9 10% 13 13 6% 9 9 NE 7% 9 5% 9 6% 9 6% 9 4% 9 4% 9 E 6% 9 8% 9 7% 9 8% 9 5% 5 4% 8 SE 7% 9 10% 9 7% 9 7% 9 5% 5 3% 8 S 4% 9 5% 9 4% 9 4% 9 3% 5 3% 8 SW 4% 9 5% 9 3% 9 5% 9 5% 9 5% 9 W 12% 9 9 14% 13 13 20% 13 19 20% 9 19 25% 9 15 25% 9 9 NW 34% 13 30 36% 13 30 33% 13 37 30% 13 30 33% 13 30 40% 13 30 calm 8% 7% 10% 10% 10% 10%

July August September October November December

Win

d di

rect

ion

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s % Mea

n sp

eed

Kts

Max

spee

d kt

s

% Mea

n sp

eed

Kts

Max

spee

d kt

s

N 7% 9 9 9% 9 9 10% 9 9 10% 9 9 15% 9 9 5% 9 9 NE 4% 5 6% 5 6% 5 7% 9 7% 9 10% 5 E 7% 9 9% 5 7% 5 7% 5 10% 9 5% 9 SE 5% 4 7% 5 7% 5 6% 5 8% 9 5% 9 S 4% 4 5% 5 4% 5 4% 5 2% 5 10% 5 SW 7% 9 7% 5 5% 5 4% 5 2% 5 15% 5 W 22% 9 19 20% 9 19 20% 9 9 19% 9 9 13% 9 9 6% 5 5 NW 31% 9 37 26% 9 37 32% 9 30 31% 9 24 33% 13 24 27% 13 24 calm 13% 11% 9% 12% 10% 17%

c. The highest recorded wind data (maximum gust strength) for the period 1997 to 2005 is reproduced in the table below. This data was recorded at the meteorological station at Dubai Airport and therefore could be 10% lower than actual wind speeds across sea areas. The highest wind speed during this period was recorded at 71 knots (116 kmh) with winds in excess of 50 knots on a number of occasions.


Year/month 1997 1998 1999 2000 2001 2002 2003 2004 2005Jan 34 34 30 28 29 32 35 29 26Feb 36 44 41 30 28 30 40 30 33Mar 34 29 32 31 35 44 41 32 32Apr 29 38 31 27 28 33 71 32 35May 27 32 31 28 27 32 33 34 35Jun 29 31 31 25 27 32 29 31 36Jul 28 55 33 29 32 31 33 31 37Aug 39 34 32 31 27 36 32 29 32Sep 30 31 26 28 24 30 30 31 33Oct 58 28 28 56 28 31 29 28 34Nov 35 27 31 48 30 32 31 48 30Dec 28 25 26 27 28 33 35 31 27

d. Conclusion based on wind data. Due to the predominance of wind from the

North West quadrant and the fact that it can reach significant force at times (Force 11) it is prudent to locate any marina jetty where possible in a location that provides maximum protection from this wind direction.

5. Sea Conditions/wave data. The palm structure is a new development and there is no historical wave data for inside the breakwater to base any decision on. However in looking at this aspect of the location the following has been taken into account.

a. The area inside the breakwater is protected and is not subject to major sea conditions. However due to the fact that many of the structures to be built on both the crescent and fronds are not yet complete, the effects of wind on water inside the breakwater have not been sufficiently documented at present.

b. Although protected from the open sea there is a considerable fetch from some angles that could impact on any marine structures that are built and this should be taken into consideration when deciding on the location of such structures. The fetch from the north is of prime concern as winds from the North west have historically been the strongest and this is the prevailing direction. As the wind does veer to the north frequently this has a significant effect.

c. The most exposed area of the plot is the extreme tip and this area should be

avoided if possible. The south side of the plot offers the best protection from any water generated forces from the prevailing wind.

d. Conclusion. To protect any vessels and jetties from wave effect the best

location is to the south side of the plot.


6. Operational aspects. The design and location of the jetty on this plot was approved in 2006 by Nakheels design team. The approved location was on the south side of the plot in the position shown in the drawings at appendix B, C and D. The owner has therefore proceeded with construction of the property on this basis. Prior to selecting the south side of the plot the following was taken into consideration:

a. Nakheels operational plan for the water area allows the use of power vessels outside an arc formed by the tips of each frond and the crescent. Many vessels transiting around the inside of the palm area will tend to take the shortest route which will mean going close to each tip lot. Therefore it is prudent to locate any jetty to the side of the plot and not on the end to minimise risks to navigation. Any jetty protruding directly from the tip centre line is a potential hazard to navigation.

b. Asthetics. During 2005 and 2006 the jetty location was discussed with a number of Nakheel managers and technical advisors and the consensus was that Nakheel did not want anything protruding beyond the tip plot limit. The owner took this into account when planning his jetty on the south side of the plot. This would give a clean visual look to the palm for any craft transiting the waterway.

7. Water depth. Attached at Appendix J is a bathymetric survey carried out on 17 Nov

2009 of the area out to 200 metres from the plot limit. The survey indicates that there no major differences in siltation rates between the North and East sides of the plot. However the south side shows a different profile to the other sides (see water depth profiles at Appendix J). The south side appears to be shoaling more gently than the other two sides and has more depth of water in the area suitable for the jetty. The critical area for the jetty is 70 to 90 metres from the plot limit and the South side is the only area that exhibits the correct characteristics for the vessels requirements. The graph below gives a summary of average water depth below DMD at significant points for the jetty location. The vessel shape is based on a yacht with a draft of 2.5 metres and how it relates to the water depth profile at LAT. The coloured lines indicate the water depth relating to distance from the boundary at each side of the plot.

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

North side

East side

South side

50 55 60 65 70 75 80 85 90

Zero = DMD

Metres from boundary

Vessel shape 2.5 draft at LAT


The conclusion from the water depth analysis is that the tip centreline (East side) location has the worst water depth profile for placing a jetty. The best location to allow plenty of water depth and a margin of safety is the South side of the plot.

8. Proposed Jetty structure. The original design and approval of the jetty is based on a system provided by Walcon Marine of UK. Walcon is the UKs largest marina construction company and has built many marinas world wide including the DIMC marina at Mina Seyahi and the marinas used every year for the Dubai International Boat show.

a. The jetty proposed by Walcon, is their system 2000 which consists of:

i. Loading: 0.75kN/m2 live load with 25% reserve.

ii. Freeboard: 700mm

iii. Draft: 300mm

iv. Structure: Welded aluminium braced frame from marine grade aluminium alloy to international designation 6082 or 6061.

v. Decking: Hardwood decking from audited and sustainable forestry

which ensure a long service life. Boards will be planed and grooved to provide a non slip surface and fixed with stainless self tapping screws.

vi. Floatation. Expanded Polystyrene floats encased in fibre reinforced concrete. The benefit of these floats are that they are extremely durable and even if the fibre concrete case is punctured there is no loss of floatation.

vii. Piles: Jetty to be fixed on steel piles 503 mm diameter by 16 mm wall

thickness. Piles to be driven to a suitable depth to provide secure mooring. Each pile will be placed to ensure sufficient height to retain jetties in position during maximum storm surge conditions. Each will be covered with a white fibreglass pile cap.

viii. The jetty has been designed to take the berthing loads of a 40 metre

motor yacht of 300 tonnes GRT plus a variety of smaller craft.

b. Jetty access. The jetty will be accessed across the beach via a wooden decked structure designed to blend into the environment. This will extend from the beach area to the MWL line leaving sufficient gap at the beach end for the passage of beach cleaning and replenishment vehicles. From there an aluminium alloy bridge will be fixed to land on the floating jetty as shown in appendix A.


c. Jetty services. The jetty will be equipped with service equipment supplied by ROLEC of UK. ROLEC is a provider of service equipment to the international marina industry. The services proposed for this jetty are housed in a number of separate weatherproof service bollards all with self contained illumination as follows:

i. 1 Main service bollard with 250Amp 3 phase supply with 200 Amp 4 pole MCCB and 200 Amp 4 pole RCD. Also containing TV and Telephone connection points. 1 x water point with inline anti contamination valve.

ii. 1 secondary service bollard containing 2 x 16 Amp and 2 x 32 Amp single phase supplies with double pole MCBs for each and 1 x 100Amp double pole RCD. Also includes telephone and TV connections plus water point with inline anti contamination valves.

iii. 1 x self contained sewage pump out station. With all associated

pumps, pipe work and controls to pump out the holding tanks of any moored vessels and discharge into the main shore based sewage system.

iv. 1 x fire hydrant cabinet with 25 metres of hose, fire extinguisher and

life buoy.

v. 2 x SOS bollards with illumination and containing fire extinguisher, first aid kit and life buoy.

vi. 2 x Emergency ladders for escape from the water will be provided by

Walcon.


Bea

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By:

Pat

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Kea

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Dat

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pre

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Pile

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E

S

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9. Summary. The data available can be summarised in the following table. It clearly

indicates the east side of the plot (extreme tip) is the most dangerous location for any jetty and boats. The north side provides better protection, especially from navigation hazards. However the best location is the south side of the plot, where there is complete protection from prevailing winds, fetch and navigation hazards.


This applies to the palm in general in that the south side of all the fronds is the safest place to locate a jetty. In this location 80% of the fronds would be sheltering the location and in the remaining cases the vessels would be berthed head to the prevailing wind, minimising wind cross section and forces.

Location Prevailing

wind Wave

conditions Navigation operations Water Depth

North side Exposed Acceptable Protected Acceptable

East side Very exposed

Very exposed

Very Exposed Poor

South side Protected Protected Protected Good

10. Conclusion. Having studied all the data available the jetty should be located on the south side of the plot as the safest location. The owner has already designed and completed significant works based on this location. The tip centreline of the lot (east side) should be avoided as a jetty location.

Appendices. Appendix A –Affection plan issued by Nakheel. Appendix B - First group drawing 001 Jetty details. Appendix C – Distances and orientation to principle structures. Appendix D– Wind rose for the Gulf Area. Appendix E – Effects of wind on the proposed location. Appendix F – Area of impact for wind driven waves/fetch. Appendix G –Walcon jetty information. Appendix H - Datum Chart of water depths, tides and datums. Appendix J – Bathymetric survey drawing. Appendix K – Rolec jetty service equipment specification and drawings.

491 metres from MHW to crescent

335 m MHW to

MHW302 m MLW to

MLW

303 m MHW to

MHW276 m MLW to

MLW

40 M

JETTY LOCATION

24.3

226.5

9

26.28

451 metre

s fro

m M

HW to

jetty

build

ing

NORTH

Drawn by: Date:

Palm Jumeriah

Principal dimensions

Patrick Keating 10 Nov 2009 Approved Yes/No

Scale: Not to scale

N

E

S

W

11

4.6

5

Plo

t

Cle

ar b

ea

ch

Are

a

188.97

349.6094.49 56.69

28.35

28

3.4

6

Plo

t

Detail as per development plan

Section through plot A-A showing jetty and 40 meter yacht position in relative scale.

A

A

Blue = % of

time wind is

blowing

from this

direction.

Green =

Mean wind

speed in

knots from

direction

Red =

Maximum

wind speed

from direction

Wind Rose by month the Gulf region.

Data derived from the USA Atlas of pilot charts for the Indian Ocean, Third edition 1991. Prepared by P Keating, 10 Nov 2009

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

January

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

February

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

March

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

April

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

May

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

June

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

July

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

August

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

September

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

October

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

November

0

10

20

30

40N

NE

E

SE

S

SW

W

NW

December

Appendix D

40 M

Annual averaged prevailing

wind direction. Also equates to

the direction of the strongest

annual wind forces

Palm Tip .Wind effect analysis

Red shading shows

maximum wind force

area.

JETTY LOCATIONUn shaded area shows

area of maximum wind

protection

Red shading shows

maximum wind force

area.

NORTH

Drawn by: Date:

Palm Jumeriah

Wind effects on site


Scale: Not to scale

-10

-

10

20

30

40 N

NE

E

SE

S

SW

W

NW

Annual average of windspeed and direction

%

Mean speed Kts

Max speed kts

N

E

S

W

Appendix F

1.2

6km

2 k

m

Palm Tip Showing main area of wind driven fetch.

The fetch from the north is 1.26 km.

With a wind direction from the North

East quadrant it is possible for a

significant fetch to build up in the area

of Tip that could potentially damage

small boats tied to any jetting in the

shaded area.

Proposed

jetty

location

The location proposed for the jetty is the

most sheltered available for known wind and

sea conditions

Drawn by: Date:

Palm Jumeriah Frond

Wave effect on site


Scale: Not to scale

N

E

S

W

concept report. palm island frond c – tip lot. private ...yachtworld.webplus.net/palm marina...

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