Dive Report: Hydro Atlantic Date: Sunday Morning February 25, 2001 Boat: ReefCat Captain: Jim Mims By: Mike Rodriguez Three Association of Underwater Explorers (AUE) core divers showed up at the boat Sunday morning along with four others to dive the Hydro Atlantic, a 300 foot long "real" wreck that sank just outside the Boca Raton Inlet in 1987 in 170 feet of water. It was a nice day with the air temperature around 81F and seas around two to three feet. The water temperature was 75F at the surface and about 71F at the bottom. On the way out the Hillsboro Inlet we spotted a Spanish Dancer (Hexabranchus sanguineus) nudibranch in the water. We scooped it up in a bucket to take a closer look at the odd creature, then we let it go and continued on our way. At the dive site, we found a strong north current. The captain gauged the feel of the current to determine where to drop us as my buddy and I geared up. We held on at the stern and when the captain called out, I took the hook and dropped into the water. The drop was perfect and we were at the wreck before my bottom timer ticked off the first minute. The current was moving us south briskly, so I didn't waste any time and immediately found a handy-dandy railing to hook the line on. About five seconds after I set the hook, the current took up the remaining slack in the line which snapped taught. I waited by the hook for a minute to make sure it was going to stay put; on a recent dive on the Lowrance, the current was so strong it actually pulled the railing off the ship after I hooked it, and I wanted to make sure that wouldn't happen again. When I was satisfied that the hook wasn't going anywhere, I took off exploring. On this dive I breathed trimix 22/26/52 with 50% and 100% oxygen for decompression. The visibility on the wreck varied from as low as 30 feet up to about 50 feet. There seemed to be waves of dirty water flowing past like clouds in the sky. I swam to one of the openings into the engine room and dropped in. I took a brief look around, then exited and swam to the bow, my favorite place on the Hydro Atlantic, to watch the myriad of fish that always hang out there. I find fish are more interesting to watch in strong current and with the strong current we had on this dive I was in for a treat. At the bow several hundred jacks of all sizes schooled just forward of the ship. I held on with one hand and used my other hand to shine my bright HID light at the shiny jacks and brightly colored tropicals. As the current flowed past me, I followed individual particles and tried to make a firm mental image of their speed. Later on land, I'd use that memory to compare with movement of a known speed to improve the accuracy of my current speed estimates. I watched the particles for several minutes getting a feel for how long they took to travel the length of my body and once I was satisfied, I swam out over the sand off the starboard side of the ship and let the current carry me aft. At the stern I moved into the lee aft of the ship, then up to the deck where I meandered forward again. I met one of the other divers who'd followed us in after a few minutes. He had a 10 watt HID light and I wanted to compare it with my 18 watt. We took turns pointing at various objects and studying the color and brightness of the light. The 10 watt, while noticeably dimmer than the 18 watt, is more than 10/18 as bright. The color temperature seemed a touch warmer also, but considering the benefit of the longer burn time and smaller battery, the 10 watt seems to be a good compromise. After the light test, I swam forward to the bow one more time, then ascended to about 100 feet and drifted aft again over the wreck until I intersected the line. I grabbed it as I went by, then I started my decompression. The current near the surface was much stronger than at the bottom and I deployed my jon-line so I could relax hands-free. After about eight minutes, the line let go from the bottom very abruptly as the last divers freed us. It turned out they were unable to unhook and had to cut the line which explained the abrupt release. Usually during deco I stare at particles in the water-column for immediate feedback of my vertical speed. Used in combination with a depth gauge, the technique allows a diver to maintain accurate depth control throughout deco without 'chasing' the depth gauge which often lags the actual depth. For this to work, the diver has to be in undisturbed water (not over other divers' exhaust). On this dive, however, no matter where I positioned myself, the particles seemed to be in a perpetual state of swirl. Maybe the sharp current sheer of the surface and bottom layers was causing this. After deco, everyone boarded the boat and we headed home along the Intracoastal stopping briefly for some drinks at a popular waterfront restaurant. Everyone had a great time; I enjoyed diving again with several old friends and meeting a few new ones too.