A description after receving question about outriggers. Feb. 19 2004

I am not totally familiar with when and why outriggers started to appear in the fleet (and so therefore I am not a good quotable reference). Although I am not positive, I think you will find that outriggers were introduced into the fleet as a more modern, faster and safer way to deliver fuel and cargo than the older boom system. They reduced the manpower requirements for the old hand tended lines (incidentally, the only hand tended line still in use is for personnel transfer that is rigged so that there is not a tensioned high line). The STREAM rigs allowed you to UNREP at a greater/safer distance (I might add it was hard to convince aggressive commodores of this in the destroyer force who were used to high speed narrow/seamanlike approaches in spite of the fact that to ride where the saddles were set required opening the distance after hook-up). The saddles are normally set up so the riding distance is 120-140 feet or so. I have no recollection of ever having experienced a transfer using booms except alongside the pier or during skin to skin CONREPS at sea and at anchor where palletized cargo was transferred over. My guess is that booms did not provide the static and dynamic requirements for wider transfers and could not handle the multiple points for tensioned transfer used in faster breakaways. Better check that one out though.

 By the time I joined the Navy (1968) STREAM rigs were already there. By the time I reported to Kawishiwi in 1975 they were on board both port and starboard. I do know this: there was a movement toward reduction of manpower required to do UNREPS at-sea as well as toward safety and speed of hook-up/disconnect as well as a movement toward increasing the distance between ships. The probe refueling rig started to appear in the 1960’s. I remember a change out was made of our refueling rigs on my first destroyer in the yard at Hunters Point in 1968. Probe rigs came about due to the Navy decision to shift from black oil to Navy Distillate (now DFM [diesel fuel marine]). Probes provided rapid disconnect and retrieval. Once you got away from the bolts required for Robb and NATO couplings, more rapid retrieval could be achieved. Part of that retrieval had to do with the tensioned span wire and retrieval line. Once the probe was unseated and the heave around signal was initiated the winch operator on the delivery ship could operate the in-haul rapidly from his winch. The span wire during this process stays tensioned through another winch that maintains tension through the Ram. Breaking the span only required slacking by detensioning the ram on the delivery ship and breaking the pelican hook/tending the outhaul line on the receiving ship. I think the design of the outrigger provides greater strength, keeps rigs swung away from the side when not deployed and provides a greater angle for distance, stability and weight support for transfer (STREAM for fuel/and STREAM with or without SURF for cargo). Once the rigs are attached there is not much requirement on the receiving ship when refueling. When transferring cargo, the riggers on the receiving ship will handle the drop line and or the cargo reel.

 I think you will find therefore that a ram tensioner is not employed with a boom and that modern STREAM transfer cannot be accomplished with standard booms. As to why they started to appear on the port side, my guess is that STREAM technology was first introduced as a priority on aircraft carriers followed by other combatants. Because of the angled decks (and position of the island) on almost all aircraft carriers of the 1960’s, cargo and liquid cargo transfer was done on the carrier starboard/delivery ship port side. If you take a look at any of the service force ships today, I think you will note that all are equipped with outrigger technology. They also have booms but those are primarily used for shore and skin to skin transfer of palletized cargo. Look at the AO-177 class layout and you’ll see what I am talking about.

All of this having been said, ironically, the Navy is now reviewing new ways to provide even more safety for fuel/cargo transfer. Virginia Tech University and Sandia National Labs have developed technologies to provide stabilized cranes (booms if you will) that sense the dynamic and static forces and operate on gimbals that accommodate ship motion. In the ship building projects I have been involved in for the last 8 years, my company has combined these crane technologies with our own 6 degrees of freedom ship motion physics based codes to determine the efficacy of these systems in tomorrow’s fleet. Unlike an outrigger, these cranes will sense ship motion and keep themselves vertical despite ship motion in up to state 5 seas. Static load requirements will be comparable to outriggers but dynamic loads will be reduced since you’ll be taking ship motion out of the equation. Probably more than you want to know but it is interesting to see where the Navy is headed 

All the best

Jim Barton   (1975-77)