3238 RFI 44 .pdf
PDF 71 KB Posted
- Attached to
- 3238 CELRE TUG REPLACEMENTS Federal contract opportunity
- Solicitation number
- W912BU21R0050
About this file
This document contains a request for information and answers related to a solicitation for the procurement of two new tugboats for the U.S. Army Corps of Engineers Detroit District. The tugboats must be self-propelled with a minimum of 1600 BHP, between 65 to 80 feet in length and 24 to 30 feet in breadth. Each vessel is required to be capable of breaking first-year ice up to 12 inches thick in the St. Mary's Falls Canal between late December and late January and mid-March to early April each season, as well as scraping ice from the canal lock chamber and miter gates during the same periods. Additional requirements include an ABS classification as a Maltese Cross A-1 Towing Vessel, Ice Class C0, Great Lakes Service with Maltese Cross AMS and compliance with USCG subchapter M. Each tugboat must include crew quarters for six, pilothouse, machinery and engine spaces, and be supported by two generators, with barge winches and crane/towing winch options. Delivery of the completed tugboats will be at the St. Mary's Falls Canal in Sault Sainte Marie, Michigan.
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Other files for this federal contract opportunity
| File | Type | Posted |
|---|---|---|
| W912BU21R0050 0005.pdf | ||
| 3238 RFI 45-46.pdf | ||
| W912BU21R0050 0004.pdf | ||
| 3238 RFI 30-43.pdf | ||
| W912BU21R0050 0003.pdf | ||
| W912BU21R0050 0002.pdf | ||
| 3238 RFI 1-29.pdf | ||
| W912BU21R0050 0001.pdf | ||
| W912BU21R0050.pdf | ||
| Drawings.zip | ZIP file | |
| 877-B601-01 PIPE MARKING GUIDE.pdf | ||
| 877-B406-01 MDC STANDARD FLOATING PLANT PAINT SCHEDULE.pdf |
Show all 12
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Text version
ANSWERS TO RFI 44 AS OF NOVEMBER 30TH, 2021
44. Background on Question - “The answer to RFI 30 and 31 states that bollard pull shall be a minimum of 25 tons, and also that during Phase II Engineering propeller options would be reviewed to see what options there are for maximizing bollard pull beyond 25 tons. The industry standard for a vessel of this size and type is that for every 100 BHP installed, 1 ton of bollard pull can be expected for open wheels. Nozzles would improve this to 80 BHP per 1 ton of bollard pull, but per C606 open wheels are required. Section C602 discusses that for two engines, each engine would be rated for 800-BPH, which is 1,600-BHP total.
With the BHP rule-of-thumb in mind we would expect an estimated 16 tons of bollard pull available. A design risk exists, in reaching the 25 tons of bollard pull, without increasing the installed power to larger tier IV engines above the stated 800-BPH. Further, based on section C003 the expected barge handling (170’ length, 50’ breadth, and 4’ draft) we estimate a bollard pull required of approximately 12-15 tons. Question – Would the
USACE consider reducing the 25 ton requirement to 12-15 tons minimum, with a maximum bollard pull being considered during Phase II Engineering? If not, would larger engines be permitted?
ANSWER: Bollard pull shall be a minimum of 30,000 lbs with a goal of over 40,000 lbs.. Light ship open lake transit speed shall be a minimum of 10 knots. During Phase II Engineering, three propeller options shall be developed, one maximizing bollard pull potential, one providing the minimum 30,000 lbs bollard pull, and one with a mean bollard pull value (between the minimum
30,000 lbs and maximum potential). Calculated light vessel transit speeds and towing speeds
(based on C002 “Excavator barge with dimensions of 170’ of length, 50’ breadth, and an approximate draft of 4’ with up to one (1) deck or hopper badge (150’ x 35’ x 4’ draft).”) shall be provided. The COR will select the propellor to be used based on the three options.
Specification Section C606 will be modified to:
“The propellers shall be designed per ABS Rules and shall be classed for ABS Ice Class C0. The
Contractor shall design the propellers for a minimum 30,000 lbs bollard pull and a minimum light boat open lake transit speed of 10 knots.
The propeller shall be open wheel type and shall have a propeller tip clearance to the hull of at least 10% of the propeller diameter.
Kort nozzles may be used at the Contractor’s discretion. If used, the propeller tip clearance from the nozzle inner diameter shall be a minimum of 0.5 inches. The nozzles shall be designed and constructed to be integral with the hull structure. No part of the nozzle shall extend below the vessel baseline.
The propellors shall rotate outboard at the top when looking forward.
The propellers shall be CF-3 Stainless Steel. The propellers shall have anti-singing trailing edges.
The propellers shall not exceed 10% back cavitation on the Burrell chart.
During Phase II Engineering, the Contractor shall develop three propeller options: one maximizing bollard pull potential, one providing the minimum 30,000 lbs bollard pull, and one with a mean bollard pull value (between the minimum 30,000 lbs and maximum potential). Calculated light vessel transit speeds and towing speeds (based on C002 “Excavator barge with dimensions of 170’ of length, 50’ breadth, and an approximate draft of 4’ with up to one (1) deck or hopper badge
(150’ x 35’ x 4’ draft).”) shall be provided for each option. The COR will select the propellor to be used based on the three options.
After the COR has selected the propeller based on the options, the Contractor shall develop drawing 877-C606-01 PROPELLERS and 877-C606-02 PROPELLER CALCULATIONS for submittal to the COR and ABS during Phase II of the Contract.
The Contractor shall provide an ABS Statement of Fact that each propeller meets all ISO R484, Class I fabrication, finish, and balance requirements. ABS certificates shall be provided to the
COR for each propeller.”
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