Next Generation of Z-Tech Tugs Arrive

Maritime Activity Reports, Inc.

February 8, 2019

  • Photo: Robert Allan Ltd.
  • Photo: Robert Allan Ltd.
  • Photo: Robert Allan Ltd. Photo: Robert Allan Ltd.
  • Photo: Robert Allan Ltd. Photo: Robert Allan Ltd.

At the end of 2018, Gulf Island Shipyards completed the first of ten Z-Tech 30-80 tugs, five of which were ordered by Bay Houston Towing Company through its operator G & H Towing Company in Galveston, Texas. 

The Z-Tech 30-80 tug Mark E. Kuebler evolved from the previous Z-Tech 7500 design for the same owner. Once again, the design team and client worked seamlessly addressing operational challenges the vessel will face. A main feature of this latest Z-Tech is incorporating Robert Allan Ltd.’s unique RAstar series sponsoned hull form into the existing Z-Tech design. Computer simulations conducted by Robert Allan Ltd.’s in house CFD team demonstrate escort performance of the new tug will be significantly increased by generating more than 100 mt steering force at 10 knots which is particularly important for escorting large vessels.

Particulars of Mark E. Kuebler are:

  • Length Overall: 98’-6”
  • Beam, moulded: 42’-8”
  • Depth, moulded: 16’-5”
  • Gross Tonnage:
  • ITC: 411
  • US Regulatory: 297


The tugs were designed and constructed to comply with all applicable Rules and Regulations of:

ABS ✠A1 Towing Service, ✠ AMS, Escort Service, Fire Fighting Vessel Class 1 and all applicable U.S. Coast Guard regulations

Tank capacities are as follows:

  • Fuel oil: 42620 GAL
  • Potable water: 6700 GAL
  • Sea trial results showed Mark E. Kuebler met all requirements to the design:
  • Bollard pull, ahead: 81.5 MT
  • Free running speed, ahead: 13 knots

Customized general layout of the tug represents more than a decade of cooperation by Robert Allan Ltd. naval architects and the owners. The Master and Chief Engineer’s cabin along with galley and mess are located on the main deck while two cabins for four crew members are located on the lower deck.

Main propulsion for the tug comprises a pair of Caterpillar 3516E, EPA Tier 4 certified diesel engines, each rated 3386 bHP at 1800 rpm, and driving a Schottel SRP 510FP Z-drive unit with Ø2800 propeller. The tug is fitted with a Fire Fighting 1 system with two FFS 6200 gpm pumps driven by two Caterpillar engine C18 respectively.

The electrical plant consists of two identical John Deere 6068AFM85 diesel gen-sets, each with a power output of 125 eKw 480V, 3-Ph, 60 Hz.

Ship-handling fenders at the bow consist of one tier of 36” OD x 18” ID cylindrical fender at the main deck level with 16” thick double loop soft fenders between the main deck and the knuckle at bow and along the sheer lines of main deck. 16” OD x 8” ID cylindrical fendering is used at the stern.

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