AMC Liftboats
Date: 31 July 2001 Revised 6 November 2001 Subject: MR. ALAN RSI Hull #18 O.N. 1040047 75’ x 56’ x 8’ Liftboat with 127' legs The owners of the MR. ALAN wish to replace the existing sponsons with new sponsons of a different configuration that will improve stability characteristics. The files on this site constitute the submittal for approval. Subsequent to the incline of the MR. ALAN, the stern pad was replaced with a pad of the same size but 6" deeper and a stern sponson was added. The owners performed a preliminary deadweight survey prior to removing the stern sponson and after the replacement of the stern pad. In the lightship calculation, we used the results of AMC's deadweight survey and the original incline to arrive at lightship values before adding the calculated weight of the new sponsons and removing the calculated weight of the existing side sponsons. Because the two calculations yielded different numbers, we used the least conservative of each (displacement, LCG, TCG, and VCG) for the new lightship values. All the modifications are at a VCG below the main deck. All of the modifications increase the bouyancy and/or the waterplane area. The calculated increase in lightship displacement is 1.2% of the inclined lightship displacement. Since the calculated lightship values are both conservative and minor, the owners respectfully request a waiver of the requirement to incline and/or conduct a deadweight survey on the vessel. The changes in the Operating Manual will be submitted after the tonnage admeasurement survey. Stability was run assuming the engine room ventilation would be moved outboard 7 ft. in case the owner chooses to at a later date. RIGHT CLICK to download the following:
File Link		Format and Size		Description
Lines		Autocad - 86KB		Lines drawing of MR. ALAN with new sponsons
Dwg. SP100		Autocad - 297KB		General Arrangement with new side sponsons
Dwg. SP101		Autocad - 83KB		Main Deck Plan
Dwg. SP102		Autocad - 93KB		Sideshell Plan
Dwg. SP103		Autocad - 100KB		Bottom Plate Plan
Dwg. SP104		Autocad - 101KB		Miscellaneous and Watertight Bulkheads
Dwg. SP105		Autocad - 159KB		Frames & Brackets
Sponson weight		Excel - 108KB		Calculated weight of new sponsons
Structural		pdf - 620KB - 7 pages		Structural calculations for scantlings and design of proposed sponsons
leg weights and VCG's		Excel - 23KB		Derivation of leg weights/VCG's since change of pads (added 11/06/01)
new lightship		Excel - 37KB		Calculated weight of new lightship after removal of existing sponsons, addition of new sponsons, and modification of stern pad revised 11/06/01 per corrections to leg VCG's
hull		pdf - 169KB		Computer model of hull with new sponsons
full model		pdf - 979KB		Computer model with wind areas
wind areas		pdf -6KB		List of wind areas and coefficients
downflooding points		pdf - 5KB		List and coordinates of downflooding point used in damage stability
intact draft 4'-6" intact draft 4'-9" intact draft 5'-0" intact draft 5'-3" intact draft 5'-6" intact draft 5'-9" intact draft 6'-0" intact draft 6'-3"		pdf - 332KB - 40 pages pdf - 334KB - 40 pages pdf - 335KB - 40 pages pdf - 337KB - 40 pages pdf - 341KB - 40 pages pdf - 342KB - 40 pages pdf - 341KB - 40 pages pdf - 342KB - 40 pages		Intact stability analysis 70 knot wind legs raised Wind direction from bow to stern in 15º increments
worst compartment		Excel - 27KB		Comparison of RA/HA results for all damaged compartments
damage comp.#01 damage comp.#02 damage comp.#03 damage comp.#04 damage comp.#05 damage comp.#06 damage comp.#07 damage comp.#08 damage comp.#12 damage comp.#18 damage comp.#19 damage comp.#20 damage comp.#21 damage comp.#22 damage comp.#23		pdf - 327KB - 40 pages pdf - 326KB - 40 pages pdf - 320KB - 40 pages pdf - 315KB - 40 pages pdf - 297KB - 40 pages pdf - 289KB - 40 pages pdf - 307KB - 40 pages pdf - 300KB - 40 pages pdf - 321KB - 40 pages pdf - 325KB - 40 pages pdf - 329KB - 40 pages pdf - 329KB - 40 pages pdf - 329KB - 40 pages pdf - 327KB - 40 pages pdf - 325KB - 40 pages		Each compartment subject to damage was run at a 6' draft, KG = 24.60', for wind directions from -180º to +180º in 30º increments to determine the worst compartment.
sample loading conditions		Excel - 957KB		This spreadsheet contains a graph of the allowable KG curves, sample conditions afloat and preloaded, table of hydrostatic properties, and tank capacity tables. Revised 11/6/01 per corrections to leg VCG's. Loading condition #9 added at maximum total variable load of 150 ST.
The MR. ALAN was analyzed with the environmental loads at the worst heading to determine the maximum working water depth and minimum required air gaps for a range of wave heights at which the vessel can operate and meet the criteria consistent with a: · 30 knot imposed wind (calm conditions and/or short periods of elevated operations), · 50 knot imposed wind (normal elevated operations), · 70 knot imposed wind (extended and/or storm operations), and · 100 knot storm elevated with the maximum deck load onboard (survival/safe harbor). The results are presented in graphical form in an Excel spreadsheet (24KB). Each individual run is available in an Excel spreadsheet (approx. 220KB each). The analysis draws on the ABS shallow water wave theory curves which have been digitized and are included below. Be sure to open the ABS Chart first or the individual runs will show errors. RIGHT CLICK on the links below and then SAVE FILE AS… to download. Graphical Results ABS Charts
100 knot wind	35 ft. WD		40 ft. WD		45 ft. WD	50 ft. WD	55 ft. WD
70 knot wind	55 ft. WD		60 ft. WD		65 ft. WD	70 ft. WD
50 knot wind	65 ft. WD		70 ft. WD		75 ft. WD	80 ft. WD	85 ft. WD
30 knot wind	75 ft. WD		80 ft. WD		85 ft. WD	90 ft. WD	95 ft. WD