Hit the Deck Running

I was interested to learn that one of the first technical scheduling meetings that we’ve had with Gulf Island had to do with what we call the “UNOLS Standard Deck Bolts.”  Though I found that a somewhat odd place to start, this requirement could be a driver of the shipyard’s build strategy, and, because this feature has not ever been required by their commercial customers,  they needed to learn more about it up front.

The first example of the UNOLS standard bolt pattern can be traced back at least as far as the AGOR 3 Class of ships (Robert Conrad) that were built by the Navy in the early 1960s, a good 10 years before UNOLS was even chartered.  The first Thomas G. Thompson operated by University of Washington was one such vessel. The cold war of the 1960s marked huge growth in the Oceanographic ship community and researchers and operators recognized the need to standardize certain operational features so that researchers could easily work on different ships.  One such feature they devised was series of recessed threads in the back deck into which a 1″ bolt could mate–basically a grid on exactly 2′ centers of 1″ nuts welded in the deck.  This simple system vastly decreases the turn around times between cruises.  Mariners need only unbolt a winch and crane it off, bring on a new anchor system for the next cruise and bolt it down, sound one prolonged blast on the ship’s whistle, and they’re underway. No welding, no grinding.

The system caught on and was incorporated into RVs Knorr and Melville in the late 1960s, into the intermediate Oceanus Class in the early 1970s and the Cape class in the early 1980s, as well as subsequent AGORs.  This standard yet modest design feature has saved countless hours and makes our vessels very adaptable.  The RCRVs will have the 2′ x 2′ foot deck bolt pattern not only on the back deck, but also throughout the foc’sle area, on the O-1 level winch deck, and even up on the Flying Bridge (or Bridge top).  If a science party wants to attach something to an RCRV, we’ll be ready.

I mentioned bolting down winches.  Imagine if a winch was bolted down and the wire rope was very strong and it, say, caught on the ocean bottom.  Then imagine if the standard bolt pattern we’re so proud of was actually not welded in all that strongly. It’s not hard to see that those bolts holding the winch down could just rip the threads right out of the deck maybe taking a big chunk of it with it right overboard. That would indeed be bad.  To avoid such a catastrophe, Glosten and Gibbs and Cox very carefully calculate the shear and pull forces and how to construct our deck to meet those requirements.  In our case, our deck bolts will be rated at 6000 pounds force in both a vertical and 45˚ from vertical plane. If a winch/wire rope has a 20,000 safe working tension, then the winch will need to be bolted with a minimum of four deck bolts to accommodate the force.

Before we started designing the RCRVs, I and OSU’s Marine Superintendent Stewart Lamerdin visited a number of great research ships including several from our European colleagues.  I was a little surprised to learned that many European ships use wood decking material. In fact, the amazing German research vessel R/V Sonne uses Bongossi wood from Africa.  It’s so dense that it doesn’t float. They don’t, however, employ a standard deck bolt pattern as does the U.S. Academic research fleet.  I should add that neither, to my knowledge, does NOAA as they typically have less variety between cruises and don’t generally require the flexibility.  I should also add that this feature adds quite a bit of both cost and weight to our ships. Constructing them on exact 2′ centers with only 1/16″ of tolerance while still maintaining a 6000 pounds force rating has its trade offs.

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