Seac Jack Freediving Watch

The Jack is a complete and reliable freediving watch computer, developed by SEAC for the most demanding spearfisherman and freediver… but that’s not all, it encompasses a SCUBA mode as well. With a special freediving algorithm, the Jack helps reducing the risk of Taravana and Hemopthysis conditions.


The Jack is your best buddy, not only when immersed, but also for your outdoor and fitness activities via its unique features.

A lightweight techno-polymer and elastomer design, user-friendly four button intuitive menu, and a graphic LCD display, makes this computer your everyday watch companion.


Hemoptysis and Taravana function

Let's review briefly what these diseases. The Hemoptysis is technically "the emission of blood from the respiratory tract" and when it comes to spearfishing/freediving, it typically indicates the presence of a pulmonary edema. In practice: presence of blood in the lungs.

What is the cause of hemoptysis and Edema? Our lungs are crossed by a multitude of blood vessels ( "pulmonary capillaries") particularly sprayed with blood. To explain such a phenomenon in very poor words, pretend capillaries are muscles. A muscle subjected to a sudden great stress in the absence of a prior warm up phase tends to tear itself. This is what happens with our capillaries when we dive to great depths without adequate warm up dives at smaller depths, this causes the presence of blood in the lungs. To reduce the risk of pulmonary edema the JACK suggests how many warm up dives you need to do and the relevant depth in relation to the target depth you can set (in the OEDEMA function).

In the example the edema value is set to 32mt. The computer will then suggest what depths is recommended to reach with the three "warm up" dives before you dive to 32mt, to reduce the risk of pulmonary edema and subsequent hemoptysis.


The Taravana ( "madness" in Polynesian) is instead a disease whose prevention is increasingly considered both by freedivers and fishermen. The symptoms of this syndrome are comparable to severe MDD (decompression sickness) during SCUBA diving and involves disorders in speech, walking, and in severe cases seizure disorders up to coma. Hyperbaric medicine is not unanimous in identifying the underlying causes of the syndrome, however the recognized factors that increase the risk of Taravana are: