5 December, Saturday
This morning the wind appeared to be shifting from the southeast to the east and almost the northeast. A northerly wind is ideal for the work we want to do. It keeps the southerly swell down to a minimum. This was so encouraging that Meryck, the captain of Nimrod, took one of the small boats around to the outside of the reef to check whether we would be able to dive. The report came back….maybe!
On the swimline off Wreck Reefs
Anchor from HMS Porpoise on Wreck Reefs
The schedule of morning activities was quickly reorganized (to include a dive team) before breakfast. The briefing was done and the teams started putting their gear together. The dive team went out first to take best advantage of the weather in case a change came through. Another group was sent to Porpoise Cay to complete the survey work there. I took a team of snorkelers out to look for evidence of the wreck of the Mahaica, a ship wreck in 1854. We decided to use a ‘manta board’, an aqua plane that allows a snorkeler to be towed through the water as they look for evidence of shipwreck remains. We could cover up to 2.3 kilometres in a half hour tow. With visibility underwater about 20 to 30 meters, we could search a swath up to 60 meters wide. We were able to complete 4 lanes in just over two hours. We figure that we were able to cover about a quarter of one square kilometre in our morning effort.
The various teams started arriving back at Nimrod about 11:15. Staff checked in with the deck supervisor to ensure everyone who left in the morning was returning for lunch. GPS data was downloaded, dive reports were filed and the plan for the afternoon formulated. Everyone assembled for lunch at 12:00. After lunch the mid-day briefing was held and afternoon assignments made. The magnetometer team was the first one scheduled to depart at 1:30, followed by the dive team, the manta board team and finally the survey team who was going to work on the Porpoise anchor and ballast scatter.
Now after a full day of work in the field, we are once again downloading GPS data, drawing finds, reviewing photographs and trying to fix malfunctioning magnetometers… all with only 15 minutes to dinner time. It promises to be a long Saturday night and we are not talking about a night on the town.
Nigel Emmy and Matt surveying Porpoise Cay
6 December, Sunday
Sunday morning and we get a cooked breakfast! Bacon, eggs, toast & muffins, yoghurt etc… There are dive teams going back to the gullies to search for more evidence of the Cato wreck.
The ‘magnificent manta boarders’ are going to search of the wreck of the Mahaica today. This ship was a commercial sailing vessel that wrecked in 1856. Supposedly it drove itself straight onto the southern side of Wreck Reefs and then slid back into deeper water. A previous report indicates that it lies 320 metres to the west of the Porpoise wrecksite. We have calculated the latitude and longitude of a position off the southern reef opposite the Porpoise anchor. From this point we drew a line due west 320 metres and calculated the Lat. & Long. of that position. We will drop a buoy at that location and use our estimate as a starting position for the search.
The manta board team took off in the ‘Red Rocket’ inflatable at 8:30. We went around the west end of the reef and along the southern reef edge to find the starting point of the search off the Porpoise anchors. No one was all that anxious to jump in the water, so I volunteered for the first tow search. About 10 minutes into the tow we had covered the 320 metres distance and almost magically two large anchors appeared beneath me. We had found the Mahaica! Only very rarely does a shipwreck search go so well, so quickly!!!
The whole team jumped in the water and did a reconnaissance swim over the site. The two anchors were the most prominent feature of the site, but there was evidence of additional anchors, anchor chain, iron frames and standing rigging. We were back at Nimrod by 11:00 and started processing the survey data before lunch. After lunch the team returned on SCUBA to start recording a measured site plan of the wreck. Two other dive teams went back to search the gullies for any further evidence of Cato on the outside of the reef. With more diving being done, our bottom times are getting shorter to ensure that we stay within the limitations of the dive tables.
See you tomorrow!
Paul
Contributed by Paul Hundley, Curator – Australian National Maritime Museum