Hey Everyone,
If the poll about favorite type of freediving included DPV's I would have selected it :>)
While at Divetech in Grand Cayman I was very fortunate to be able to play on two different types of scooters and on a wall that was only a 5 minute scooter ride away to depths as deep as 3000 feet.
We had the Dacor scooters which are in my opinion the better of the small, plastic, non-riding scooters. With a new battery they are fast, mobile and with enough practice I perfected a 3 minute acrobatic routine that has a person, twirling, spinning and barrel-rolling along the reefs and sand flats.
It was also a really fun scooter to just go plunging to depth with if you could get the right technique to hold on to the thing, equalize and steer yourself. I used to love buzzing the scubadivers on our wall during their 100 foot dives, wave to them, then go plunging into the blue to around 160 feet and then up. I've had the Dacors as deep as 200 feet, but stopped there becuase the plastic body was making popping sounds. This was while wearing a spareair in case of flood :>)
We also had the Farallon Mark 7 (I think) which is an aluminum body torpedo shaped scooter that you ride like a sport bike. It was 50% faster than the Dacors, had foot holds so you were pushed and could hold the handles with one hand while equalizing or attempting to rip your partners mask off on the scooter beside you. Dan Hodgins will appreciate that memory :>)
The Farallons had a depth rating of 400 feet and I've used them several times to that depth while on trimix scuba. I also used the Farallons to depths as deep as 260 feet while freediving and Brett LeMaster and I used to take them to go and freedive a wreck called the Carrie Leigh in Cayman that started at 150 feet and went to 220 feet before a hurricane moved it deeper down the wall.
It was always a blast to freedive the wreck with the scooters. You started down the mooring line to meet the wreck at 150 feet near the stern where the wheel house was located. At around 90 feet the wreck would come into site and we would break from the line and head to the bow to touch and go and then follow along the wreck, which sat at around a 30 degree angle bow down, back to the stern to the wheel house and then up the mooring line. We would do this several times while alternating as buddies.
Now the words of CAUTION! These were great experiences and were a ton of fun. Unfortunately, lack of education and information at the period for us also led me to experience an DCS hit while scooter freediving. Because you can get down very deep, very effortlessly and repetitively without much surface interval, you can saturate nitrogen (N2) into your system just like on scuba. The real problem comes with ascents that near 300 feet/min and short surface intervals becuase there is really no apparent need to rest because theirs no effort.
While practicing to set the first ever depth record in freediving on a DPV (demonstration record for Farallon) I suffered type II DSC hit. It was also contributed to from my many trimix and technical dives that I would perform routinely, but at the time I believed that a week surface interval would offset the risk of accumulated DCS problems from scuba.
Luckily now a Dr. Batle from Spain has worked on and developed a set of freediving tables. These tables were developed after many spanish spearfishermen using DPV's developed DCS while working in the 50-60m range. Keep in mind that it's just not scooters, but any form of deep REPETITIVE freediving without adequate surface intervals. It was this form of table that he developed, a table that specifies surface intervals between freedives.
Example with Dr. Batles tables;
If you attempted a freedive to 21 meters for 1:30 (spearfishing) you should wait on the surface 2:20 before your next dive.
If your next dive was to 36m for 1:30 (intermediate level competitor) your surface interval (SI) should be 3:27.
A dive to 69m for 2:20 which is typical of an expert competitive freediver the surface interval before any other freedive is 9:13.
He developed a simple rule of thumb; If the depth of your freedive was < 25 meters then your SI should be twice your total dive time.
If your depth was > 25 meters then your SI should be a minimum 8 minutes.
His article/paper is called "The Attitude a Breath Hold Diver Should Take to Avoid Arterial Gas Embolism". He's Associate prefessor of University of Balearic Islands (Spain) and Chairman of Medisub, Hyperbaric Research Institute.
Hope this helps and if you get the chance to freedive on a scooter, it's well worth the rental price.
