Dealing with the water inside the fairing was the largest design risk I had moving forward with the DOL-Fin Orca’s development. My plan actually was to capture the water inside the fairing, “like a bucket”. The risk was that I really didn’t know how the mass of trapped water inside the fin would affect the feel of the monofin, and my biggest concern was that it would somehow mess up the ability to stroke the fin and produce thrust effectively.
My hypothesis was that the non-streamlined fin was already dragging a huge mass of water along with it as a shed wake, and that adding the fairing would actually be reducing the mass of water being pulled along with it. Unfortunately for me, the only way I knew of to prove if my hypothesis was true was to build and test it in the water. When this ended up taking twice as long as I originally thought it was going to take, I was getting rather nervous about that first swim and the moment of truth. It had the potential to be a very expensive failure.
Fortunately, my hypothesis turned out to be right. The DOL-Fin Orca with the water trapped inside it actually feels much lighter on the feet than did the prototype without the streamline fairings. It was a big improvement, and I knew it was going to work within about 10 seconds of strapping the fin on.
This method of using wet ballast keeps the fin lightweight when it is dry which makes for easy traveling. The DOL-Fin Orca weighs in dry at about 5 pounds (2.25 Kg). This fin design also effectively has a trunk space in it. I am thinking of making one of the fairing shells in-water removable, and using that volume inside to store a fresh-water reserve, a signal float/buoy and a strobe light. If you ever found yourself lost at sea, you would have a decent chance of survival and rescue if you have this basic survival gear available. This could be a nice safety option for sea-hiking and recreational freediving.
The feet fit inside the shroud using the same basic methods I had used on my previous DOL-Fin systems. I use textile binding straps to secure the feet to a rigid base-plate. The system is adjustable and, when secured, have no buckles or loose ends sticking out in the flow to cause drag. To add more structural stability to this fin’s interface to the swimmer, I have increased the height of the side rails of the base-plate which hold the assembly in alignment with the feet. I have also added an option to include adjustable side rails for inside edge heel support.
The binding straps are not presently padded, and although you can wear it over bare feet, I expect that it would chafe. Padding can be added to these straps, but I have always felt that it makes more sense to have the padding on your feet instead of on the fin’s straps. At a minimum a low-cut cotton gym sock can be enough padding. I usually use a low cut 3 mm dive sock in warm water and for colder water switch to a high-cut 3 mm or 5 mm depending on water temperature.
The system is different to what you are used to, but I think it has several advantages over the old methods. Once familiar with how to use it, I think most divers will come to appreciate the design.
Last edited: