WHALES ALL AROUND!

Sidney Van Zandt, Roving Rear Commodore

(Sandy and Sidney are coming to the end of their six year circumnavigation. Sequel, a 39ft steel cutter, was designed by Sandy and built by the couple with the help of son Doug in the early 1980s.)

The highlight of our Atlantic crossing this January was the visitation of Minke whales and Risso's dolphins. When we built Sequel we welded a steel hatch in the bottom which has a 12in x 15in x 1/2in Lexan window. Most of the time we have the waterproof door dogged down, but when we think there is anything worth looking at we open it up.

About six days out of the Canaries a large (about 30ft) Minke whale came up to us. It raced alongside, then would dive under the boat and race us along the other side. With the window open we could see this whale close up, and when he came up from the deep we'd see the whole whale, his white belly and flippers bright in the clear blue water. The light coming through our window often attracts fish and squid and now this whale was really interested. Back and forth under Sequel, rolling over as it went so as to expose the entire white underbody. It would surface and show us a pectoral fin and then go back under our hull and repeat the process. For thirty to forty-five minutes we were entertained.

Several days later a school of Risso's dolphin approached us. We first knew they were there by their singing heard through the hull. When we opened the window the sun streamed through and they spent a lot of time swimming up to the window and looking up at us. At ten to fifteen feet they are the largest dolphin we have ever seen, and being blunt-nosed are very distinctive. They too played with us for about thirty minutes. We heard and saw them again about a week later. We saw Minke whales again also -- a migration of about three dozen came near to check us out and a few swam under our boat, but they didn't take time to play as the solitary Minke had done.

We have had a number of other encounters with whales during our circumnavigation. We cruised the Australian Queensland coast from July to October in 1993, and had ongoing experiences with Humpback whales. We had anticipated seeing whale activity along the coast as the Humpback whales make a yearly migration from the Antarctic to the warmer waters in northern Queensland to mate and to calve. Sandy got inspired while we were in Brisbane and put together a hydrophone using an underwater microphone used in seismic studies. We plugged it into a small amplifier he made up out of a Dick Smith Kit (the Heath kit/Radio Shack of Oz). It then plugs into an amplified speaker and a cassette recorder. During our cruise north, as soon as the anchor was down the hydrophone was dropped over the side and plugged in. Sometimes we heard nothing, but as we got north into the Whitsunday Islands we were rewarded with afternoons and evenings of the song of the Humpback whale, sometimes faint but very often fairly loud, and on several occasions quite loud. The males are the singers, the mothers and calves make clicking sounds. There is much speculation as to why they sing. We saw whales as we were sailing, but never while at anchor listening, so we have no idea how far away the singers were.

We planned our trip so as to be back in Hervey Bay (inside Fraser Island) in September. It is a well known stopping place for Humpback whales where the mother whales seem to do the final fattening and strengthening of their calves before making the big push down to Antarctica. We observed the whales nursing, sleeping, frolicking, tail and fin slapping, and breaching and falling back with horrendous spray. We were even awakened in the middle of the night by a loud tuba sound nearby (not audible on the hydrophone), and we realized it was a whale snoring on the surface. That mother and her calf began their cavorting at 0500, so we upped anchor and moved to within a hundred yards to see them close at hand.

Should we be frightened having these immense creatures so close to our boat? Except in a few situations such as in Hervey Bay in Queensland we had virtually no control over this. They arrive and depart at their whim. They do seem to show a curiosity towards us that few other yachts experience. Perhaps they are attracted by the shaft of light coming through the bottom, but we often do not open the cover until after they have arrived. We also wonder if the whales relate to our shape, which is a totally round, rather deep bottom except for a skeg and rudder. Our two bilge boards are completely housed when we are off the wind. Whatever it is, we feel lucky that they seem to feel this kinship. It is comforting, however, that Sequel is steel.

We have at times put on our safety harnesses when whales are close aboard. Shortly after leaving the Bahamas in 1991 we were overtaken by numerous pods of Minkes (up to twenty whales each). They were all very closely bunched, perhaps four or six of them under our bow cavorting just as dolphins often do. Along each side were two to four at any one time performing belly rolls, with others a bit further off. We thought that if ever we were to be bumped accidentally that would be it, but nothing occurred.

We are currently (March '96) in Trinidad enjoying this very friendly island, but shortly expect to be moving north towards Antigua, then on to the Bahamas, Chesapeake Bay by mid-May and New England in July. We are looking forward to encountering whales along the way as, except for the Chesapeake, this route roughly coincides with their migration track in the Northern Hemisphere. Our hydrophone is out and ready.

SEQUEL'S HYDROPHONE

Sandy Van Zandt

The underwater microphone, which was the most important element, we purchased through a seismic supply company in Brisbane but it is an American product. (Model MP-24 L1 -- Pressure sensitive detector -- from OYO GeoSpace, 7334 N Gessner, Houston, TX 77040. Tel: 713 439 9700, fax: 713 937 8262. They no doubt have distributors in the US.) In Australia it cost about US $120, but that included quite a bit of Australian duty and tax.

We spliced in a 50ft extension cord to the pigtail on the hydrophone, using two conductors. The joint was soldered and then insulated with tape and 3M Scotchkote Electrical Coating. So that there would be no chance of breaking the conductors we stretched a piece of 1/4in polyester double-braided line and seized it off at three foot intervals. Thus there is slack in the electrical conductor and any tension is carried by the line.

We wrapped strips of sheet lead around the conductor cable (about two pounds), so that the hydrophone would sink quickly and stay submerged even in a tidal current or during a low speed tow. The other end of the two-wire conductor of the hydrophone has a two-conductor jack which goes into the input of the audio amplifier.

An audio amplifier could not be purchased in Brisbane, so I bought a Dick Smith Kit (like Radio Shack or Heath kit) for a small 12 volt DC stereo amplifier which had a set of instructions on how to modify the construction so that you ended up with a small monoral public address amplifier. There are probably similar kits available in the US and elsewhere for small audio amplifiers.

The output from the audio amplifier goes to (1) a small amplified speaker such as one might use on a Walkman, and (2) a simple cassette recorder. With this setup we can monitor the sounds coming in, and when we wish to record we simply start up the cassette recorder.

Someone who really knew what they were doing could probably come up with a much more sophisticated system with noise filters, but we have been amazed and pleased at the quality of whale sounds we have been able to record with this simple system.

We use the hydrophone when we are anchored or drifting. We can tow this hydrophone at speeds up to about 3 knots, but after that there is too much water noise. We try to anchor in deeper water than we would normally chose in order to eliminate the clicking sounds of shellfish near the shore. A great improvement would be to be able to tow it at higher speeds without sacrificing sound quality, and we would be most interested to hear comments from anyone who could suggest how this might be accomplished.