Reference_2-5_Pisces_ROV_Winch_Attachment_Calcs_-_REV_A.pdf

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NOAA Ship Pisces ROV Winch Attachment

Figure 1: Winch and Foundation Location Plan view

SMB

ROV Winch Attachment Temporary Install Winch Foundation Rev A 2/26/2024

RWJ

2/26/2024

Rev A - Figure 5 changed to represent as-built ship structure, transverse flanged member depicted in phantom lines.

The NOAAS Pisces is temporarily installing a winch on the aft main deck on the port side utilizing a newly fabricated foundation fastened into existing deck sockets. The intension for the winch is to tether an ROV to the vessel and retrieve the ROV if the ROV loses power, however a second winch will be utilized for hoisting the ROV out of the ocean and placing it on the deck.

Foundation design and construction drawings are shown in "PC-185-001_Rev -_Bolt-On Winch Foundation Assembly & Installation Details.pdf".

The winch will be fastened to the new foundation using a similar method as the manufacturer recommends in "HH84-000-01 Rev. 0 1313 Leopard Winch Assembly".

The foundation will be fastened to the deck using 3/4in Grade 8 (SAE J429) bolts, conforming with ASTM A490. These bolts will screw into M72 to 3/4in adapters as shown in the Figure 2.

Calculations for the deck sockets and their supporting structure have been performed using dimensions given in "SH-611-FH89-08 Deck Fittings & Tie Downs Key Plan & Details.pdf".

Cable breaking load provided by "rm0071.pdf" as 300kN (67,442.7lbf). These calculations are run at an absolute worst case scenario assuming two (2) times the breaking load of the umbilical cable , in accordance with ABS Rules (totaling 134,884 lbs). However, in normal operating conditions according to the manufacturer, the loading will not exceed 3,000 lbs for the ROV and supporting winch wire fully deployed.

Accelerations for the NOAAS Pisces are based on the motions study presented in this document. This document presents worst case accelerations calculated with GM based on arrival conditions. Sea state 5 and a roll constant of 0.49 sec/√(ft) were used at the clients request. While the winch is installed on the vessel, the vessel is not intended for operation above sea state 5.

Design Loads were calculated according to ABS Lifting_Appliances_Guide_dec21.pdf 2-6/19.7:

-Two (2) times the maximum reactions induced by the maximum tension in the rope in accordance with 2-4/3.1.

-The maximum reactions are to be calculated for the worst loading combination of line pull forces and inclinations of the wire rope, with the force applied on the outer layer of the drum. The calculated stresses are not to exceed the allowable stresses in 2-2/5.

Typical loads to be submitted and considered in the analysis of the cranes, as applicable, are:

i) Dead loads

ii) Live loads and dynamic loads, including the applicable vertical amplification factors, as per 2-2/7, 2-2/9, or 2-2/11

iii) Loads due to vessel’s or unit’s motions, as per 2-2/5.17

iv) Loads due to wind, as per 2-2/5.19

No miscellaneous loads were added.

Variable Unit

Winch Weight Ww lbs 14000.00 NOTE:

Weight of Foundation Wf lbs 1960.00 Input Total weight W lbs 15960.00 Calculated Total Mass Mt Slugs 496.05

Approximated Center of Gravity (Location on Vessel) Distance Aft From Midship Dx ft 76.33

Distance outboard from Centerline Dy ft 13.42 Height above Baseline Dz ft 32.42

Winch Vertical Center of Gravity Including Foundation Dvcg ft 4.00 Winch Horizontal Center of Gravity Dhcg ft 4.30 Vessel Deck Plate thickness tp in 0.50

Longitudinal Acceleration (x direction) Ax ft/s2 9.61

Transverse Acceleration (y direction) Ay ft/s2 10.28 Vertical Acceleration direction (z direction) *Winch Location Heaving Up In Addition to Gravity Az1 ft/s2 47.63 Vertical Acceleration direction (z direction) *Winch Location Going Down Following Gravity Az2 ft/s2 16.72

Longitudinal Force Fx1 lbf 4764.89 Transverse Force Fy1 lbf 5097.90 Vertical Force - Stern heaving up Fz1 lbf 23625.45 Vertical Force - Stern heaving down Fz2 lbf 8294.55

Weights (Loads)

Dvcg and Dhcg were conservatively estimated from "HH84-000-01 Rev. 0 1313 Leopard Winch Assembly.pdf"

Winch weight provided by manufacturer (Hydramec Offshore Hydraulic Systems)

Foundation weight is rounded up to be conservative.

Figure 2: Deck Socket Threaded Adapter

Forces From Vessel Accelerations

General Dimensions

Accelerations (Loading Factors)

Calculated on the final page of this document.

Cable Minimum Breaking Load as per "rm0071.pdf" Fc lbf 67442.70 Force Multiplier Constant applied in accordance with ABS Regulation Cabs 2.00 Foundation Height Dd ft 0.29 Winch Drum Height Dwdh ft 5.17 Winch Drum Height Above Deck (Dd+Dwdh) Dvf ft 5.46 Sheave Height above Deck Df ft 17.75 Sheave Height above winch drum height above deck Db ft 12.29 Longitudinal Sheave distance from Approximate Center of winch Da ft 45.00 Approximate Winch Wire Angle From Deck to Sheave θ ° (deg) 15.27 Cable breaking load x2 in horizontal direction Fa 130121.09 Cable breaking load x2 in vertical direction Fc 35532.70 Total Moment From Cable (CCW Rotation around tipping point) M1 ftlbs 863468.63 Moment from Weight of Winch (CW Rotation around tipping point) M2 ftlbs 35666.55 Moment from Horizontal Acceleration (CCW Rotation around tipping point) M3 ftlbs 19725.57 Distance to Bolt 1 (B1) from Tipping Edge Db1 ft 9.24 Distance to Bolt 2 (B2) from Tipping Edge Db2 ft 8.04 Distance to Bolt 3 (B3) from Tipping Edge Db3 ft 6.85 Distance to Bolt 4 (B4) from Tipping Edge Db4 ft 5.49 Distance to Bolt 5 (B5) from Tipping Edge Db5 ft 4.29 Distance to Bolt 6 (B6) from Tipping Edge Db6 ft 3.10 Force Ratio Bolt 1 Fratio1 0.250 Force Ratio Bolt 2 Fratio2 0.217 Force Ratio Bolt 3 Fratio3 0.185 Force Ratio Bolt 4 Fratio4 0.148 Force Ratio Bolt 5 Fratio5 0.116 Force Ratio Bolt 6 Fratio6 0.084

Force Coefficient Cf 122949.86

Moment on Bolt 1 Mb1 ftlbs 283661.66 Moment on Bolt 2 Mb2 ftlbs 214939.28 Moment on Bolt 3 Mb3 ftlbs 155734.35 Moment on Bolt 4 Mb4 ftlbs 100121.82 Moment on Bolt 5 Mb5 ftlbs 61224.97 Moment on Bolt 6 Mb6 ftlbs 31845.57

Tension Force Bolt 1 Fb1 lbf 30697.68 Tension Force Bolt 2 Fb2 lbf 26721.64

Figure 3: Tipping Edge to Bolt Distances

Operational: Bolt Tension From Winch Cable All calculations in this section are performed in a vertical plane along the winch wire from the center of the winch to the sheave.

Winch and Foundation Vertical Center of Gravity was found by adding the winch foundation height to the approximate CG of the Winch. The winch longitudinal and athwart Centers of Gravity are estimated at approximately the geometric center of gravity.

Winch Drum height was provided by the manufacturer.

The worst case scenario is applying the cable force as a moment about the tipping edge while the stern of the vessel is heaving down. This overturning moment applies maximum loading to the bolts. In this condition the self weight of the winch provides less counter moment to resist overturning due to the winch cable pull. Although these calculations are run at an absolute worst case scenario assuming two (2) times the breaking load of the winch cable, in accordance with ABS Rules -in normal operating conditions, according to the manufacturer, the loading will not exceed 3,000 lbs for the ROV and supporting winch cable fully deployed.

Designed utilizing SAE J429 Grade 8 (ASTM A490) 3/4in bolts with a proof load of 50,100 lbf.

Tipping point was placed vertically below the aft edge of the winch on the deck, however all other measurements are based on the foundation and winch being one unit.

Because the angle of the in-line winch wire pull relative to the centerline of the ship is a vector of the transverse and lognitudinal accelerations, an average of the two accelerations was used to better represent the actual acceleration of the winch in the configuration.

𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 =

𝐷𝐷𝑏𝑏𝑟

𝐷𝐷𝑏𝑏𝑟 + 𝐷𝐷𝑏𝑏𝑏 + 𝐷𝐷𝑏𝑏𝑏 + 𝐷𝐷𝑏𝑏𝑏 + 𝐷𝐷𝑏𝑏𝑏 + 𝐷𝐷𝑏𝑏𝑏

𝐶𝐶𝑓𝑓 =

𝑀𝑀𝑟 −𝑀𝑀𝑏 + 𝑀𝑀𝑏

𝐷𝐷𝑏𝑏𝑟 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 + 𝐷𝐷𝑏𝑏𝑏 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑏 + 𝐷𝐷𝑏𝑏𝑏 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑏 + 𝐷𝐷𝑏𝑏𝑏 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑏 + 𝐷𝐷𝑏𝑏𝑏 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑏 + 𝐷𝐷𝑏𝑏𝑏 ∗ 𝐹𝐹𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑏

Tension Force Bolt 3 Fb3 lbf 22745.61 Tension Force Bolt 4 Fb4 lbf 18237.68 Tension Force Bolt 5 Fb5 lbf 14261.64 Tension Force Bolt 6 Fb6 lbf 10285.60 Proof Load (maximum tensile force that can be applied to a bolt that will not result in plastic deformation) on a 3/4in Grade 8 Bolt lbf 50100 Maximum Load on a Single Bolt (Tension Force Bolt 1) lbf 30697.68 PASS

A36 Steel σy psi 36000.00 Bending (60% of σy): σall psi 21600.00 Shear (40% of τy): τall psi 14400.00 Bending Moment MOMmax lb-in 180315.00 Section Modulus (SMbot) SMmin in^3 8.78 Max Bending Stress σmax psi 20539.36 PASS Maximum Shear SHRmax lb-in 16010.50 Cross Sectional Area (Deck Socket Structure) Ads in^2 12.81 Max Shear Stress τmax psi 1250.33 PASS

Figure 4: Winch Free Body Diagram

Figure 5: Deck Socket Under Deck Structure

Deck Socket Structure Figure 5 shows the as built version of Detail 22-A which is a portion of drawing "SH-611-FH89-08 Deck Fittings & Tie Downs Key Plan & Details.pdf". The red hatched outline shows the intended 4"x0.5" flat bar rider to be installed at each deck socket underdeck structure. The flat bar increases the load capacity on the deck socket to a safe margin. Figure 5 shows the 3"x4"x0.25" rotated so the 4" side of the angle iron is vertical which is the as built condition. The flat bar is to be continuously welded to the structure.

Calculations for MOMmax and maximum shear were performed using Gobeam! Referenced calculations are available upon request.

Underdeck structure dead weight is not included. This was a conservative decision because the self weight would counteract the moment from the winch wire.

Approximate Winch Wire Angle From Winch alignment to Centerline α ° (deg) 18 Cable breaking load in horizontal direction (straight aft) Fa lbf 128283.64 Longitudinal Force From Vessel Motion Fx1 lbf 4764.89 Total Force Aft 133048.53 Cross Sectional Area of a 3/4 in Bolt per ASTM in^2 0.334 Shear Force Per Bolt lbf 14783.16965 Shear Stress Per Bolt psi 44260.98698 Shear Capability lbf 30060 Shear Load Percentage of Shear Capability 49% PASS

Force Applied at Bolt 1 lbf 15348.84 Force Applied at Bolt 2 lbf 13360.82 Force Applied at Bolt 3 lbf 11372.80 A36 Steel σy psi 36000.00 Bending (60% of σy): σall psi 21600.00 Shear (40% of τy): τall psi 14400.00 Bending Moment MOMmax lb-in 352159.00 Section Modulus (SMbot) SMmin in^3 39.05 Max Bending Stress σmax psi 9018.16 PASS Maximum Shear SHRmax lb-in 21512.20 Cross Sectional Area (Deck Socket Structure) Ads in^2 17.25 Max Shear Stress τmax psi 1247.30 PASS

Figure 6: Deck Socket Under Deck Structure Cross Section with Calculations

Deck Loading Deck loading calculations are based on using the member with the highest load which was determined by the tension on the deck socks calculated above. The tension on each of the three deck sockets is far greater than the weight of the winch.

The member used in the calculations is smaller than the member forward of it and is highlighted with the red line in Figure

8. The tension is divided by half because it is split between the member forward of deck sockets 1-3 and the member used in the calculations. The blue square in Figure 8 represents the location of the foundation of the winch.

The deck sockets are represented by point loads and the shell of the ship and longitudinals are represented by the supports in the beam analysis. The major longitudunals far exceed the strength of the transverse members.

Calculations for MOMmax and maximum shear were performed using Gobeam! Referenced calculations are available upon request.

As stated above the force applied by 2x the breaking load of the winch wire far exceeds the intended use. If the worst case scenario occurs, this system has been designed in a way that prioritize and maintains vessel integrity over winch attachment.

Shear Capacity is calculated from 60% of minimum ultimate strength (50,100lbf)

Operational: Bolt Shear From Winch Cable

Figure 7: Transverse Member Cross Section With calculations

Figure 8: Examined Transverse Member Location

Stowed: Transverse Loading from Vessel Motion

Wind Velocity Vk knots 100.00 Shape Coefficient (ABS Lifting Appliances Guide 2-2/5.19.2 TABLE 4 Isolated structural shapes (angles, channels, beams, etc.)) Cs 1.50 ABS Air Coefficient f 296.00 Area Aw sqft 16.00 Wind Pressure Pw lbf/ft^2 50.68 Horizontal Wind Force HLwind lbf 810.81 Transverse Force Fy1 lbf 5097.90 Average Bolt Distance From Tipping Edge 6.17

Dvcg 4.00 Moment from Vessel Accelerations and HLwind Mccw 23634.83 Moment from Weight of Winch Vessel Stern Heaving Down (CW Rotation around tipping point) Mcw 35666.55 PASS

Weld Leg Size ω in 0.31 Allowable Shear Stress on Throat of Weld (Blodgett's Fillet Weld A36 (7.4-8 Table 6) τ psi 13600.00 Allowable Force on Fillet Weld Per 1" weld (Blodgett's allowable force on fillet weld (7.4-3) f 3004.75 Total Length of Weld L in 8.00 Total Shear Force (2x Winch Wire Breaking Strength and Accelerations) lbf 134885.98 Total Allowable Shear Force on Welds (Includes all 24 Capture Tabs) lbf 576912.00 PASS

Weld Strength

Weld Arrangement can be seen in Figure 10 and in more detail in "PC-185-001_Rev -_Bolt-On Winch Foundation Assembly & Installation Details.pdf"

Figure 9: Transverse Loading from Wind and Vessel Accelerations

Figure 10: Capture Tabs

Side area was estimated from the renderings of the winch provided by the manufacturer. It was estimated that approximately half the winch is exposed to the wind above the bulwarks and winch structure occupies about half of the exposed portion.

Dhcg was used as an approximation for the transverse center of gravity because the winch is square as seen from above.

The moment created by the weight of the winch is greater than the moments from wind and vessel accelerations.

𝑃𝑃𝑤𝑤 =

𝑉𝑉𝑘𝑘𝑏𝐶𝐶𝑠𝑠

𝑓𝑓

𝐻𝐻𝐿𝐿𝑤𝑤𝑟𝑟𝑤𝑤𝑤𝑤 = 𝑃𝑃𝑤𝑤 𝐴𝐴𝑤𝑤

𝑓𝑓 = 0.707 × 𝜔𝜔 × 𝜏𝜏

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