HOST > S.O.P.'s > Minimum Under-Keel Clearance in Commercial Ports

Safe Operating Practice 4-97
Minimum Under-Keel Clearance in Commercial Ports
Approved October 30, 1997

Issue. Presently, deepdraft vessels arriving and departing Hawaiian commercial ports, with the exception of non-double hull tankships, have no Federal requirements regarding Minimum Under-Keel Clearance (MUK). The State of Hawaii has established guidelines for maximum drafts and MUK for all of its major deep water ports and harbors, which are set forth in State Harbor Master Notices.

Vessel groundings occur in Hawaii's ports for many reasons. Vessels with maximized cargo loads that are barely within draft and MUK limitations, are at a much greater risk of grounding. Several "soft groundings" have occurred due to continual sediment shift and deposition in many harbors. Additionally, vessels without, or which have not shifted to high sea chests have experienced clogging of the main engine(s) cooling water intake strainer.

Discussion. There have been reports of vessels touching bottom during cargo operations while pier side, soft groundings in Honolulu Harbor and Barge Harbor, and vessels with deeper drafts than projected due to rain soaked cargoes. These are just a few incidents which are a direct result of too little MUK. As vessel agents and pilots feel greater pressures to facilitate commerce, vessels more frequently transit ports and harbors with drafts and MUKs that are just within or outside the prescribed limitations. Having readily available squat tables for shallow water conditions would be very beneficial to all pilots and vessel masters.

Making ports and harbors deeper through dredging would decrease the risk of grounding for the present fleet of deep draft vessels calling on Hawaiian ports. However, this would only bring bigger and deeper draft vessels to Hawaiian ports and harbors. Establishing a standard 2 foot MUK to parallel what may become future Federal legislation would further limit tonnages on the deepdraft vessels that routinely trade in Hawaiian waters.

Recommendations of HOST.

1. Fabricate and install a Tide Gauge at the entrance to Barge Harbor at Barbers Point.

2. Acquire squat tables for shallow water conditions on any type or class of vessel, as specified by Pilot's, entering Hawaiian ports and harbors. Tables should be maintained and kept on file with Pilots.

3. Tug vessel subcommittee should include in their agenda, required tugs for vessel's which are beyond the maximum draft or MUK limitations.

Resolution. Representatives from industry, the USCG, State DOT Harbors, and Hawaii Pilots Association have determined that MUK must remain a continual consideration for each vessel arriving and departing Hawaiian ports and harbors. The above recommendations have been approved by HOST.