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The entire suspension system and fin assembly can be moved aft to the second set of holes 
in the Orca Bracket if more length is desired to give the fin a little more leverage to the fin. 
 

Pre-Dive Checkout: 

 
Before each use, visually inspect your DOL-Fin for damage and/or loose hardware.  Never 
use a DOL-Fin that has loose hardware or shows signs of structural damage or cracking.  
A small fatigue crack can propogate quickly and result in a potentially catistrophic part 
failure during a dive.  One of the great benefits of your DOL-Fin is its modular design that 
makes part repairs and replacement very easy to perform.  So, if a visual inspection shows 
that something on your fin is loose, broken or compromised, don’t just dive it as is; 

fix it!

 

 

Inspection Checklist: 

(1)

 

Check the hardware.  Make sure that all the nuts are appropriately tightened and 
that the nut locking mechanisms are properly engaging the screw threads such that 
none of the hardware can come apart during use.  Visually inspect the hardware for 
corrosion.  Replace any screws, nuts or washers that show signs of weakening. 

(2)

 

Visually inspect the aluminum structural parts for damage from fatigue, cracking or 
corrosion.  Cracked structural components must be replaced. 

(3)

 

Visually inspect the suspension straps and suspension guides for cuts, cracks or 
signs of weakening.  The suspension action should be pliable and responsive.  
Replace any suspension componants that show damage or that seem degraded, as 
that can diminish the DOL-Fin’s performance. 

(4)

 

Check that the Foot Binding Straps are in good shape and that the shoe’s Velcro 
straps have adequate holding strength.   

(5)

 

Extend the fin tip bungees to visually inspect the fasteners and materials of the 
bungee assembly for wear or broken parts.  Insert the fin tips into the foil ends in 
swimming configuration, and inspect them for desired shape, curvature and twist.  
If necessary, massage the fin tips with the hands until they hold the desired shape. 

 

Use and Operation: 

 
Your DOL-Fin is a revolutionary swimmer propulsion device and works differently from 
traditional swimming fins.  It is important that you read this section before using your new 
DOL-Fin.   
 

 
 
 
 
 
 

 

 

 

 

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The Orca2 monofin is designed to be used with dive socks.  To provide the maximum 
level of energy transfer to the monofin, the straps do not have any padding attached to 
them and instead rely on padding worn on the foot to eliminate chaffing of the straps on 
the foot.  If a dive sock is not available, a cotton gym sock will do almost as well.  The 
more padding between the foot and the strap, the more movement is possible and the less 
connected the foot will be to the fin.  So, adding strap padding on top of the dive sock 
would be counterproductive and it was therefore not included.   
 
YouTube video (

http://youtu.be/Mpwvsch6hQk

) shows some useful information on how to 

adjust the binding straps to get a good fit for your feet.  If diving with thick dive socks, 
you can often get a better connection with the Orca2 by diving down about 6 to 7 meters 
and pulling the heel straps again to snug your feet into the binding straps while the dive 
socks are compressed.   
 

Selecting a Trim Setting for the DOL-Fin: 

 
The DOL-Fin can be configured with different settings for the lateral fin’s suspension 
system through the use of different suspension guides and the mounting holes selected.  
These suspension guides modify the rotation range of the fin relative to the frame and the 
different mounting options modify the length of the lever arm to the fin.  Changing these 
settings affect the dynamics of the hydrofoil and the overall thrust and feel of the fin.  
Your DOL-Fin can essentially become many different monofins through selection and use 
of different trim options.   
 
Start with the short arm configuration and the shorter stock length top suspension guides.  
If you feel like you want more thrust from the downstroke relative to the upstroke, you can 
replace the top suspension guide with a longer suspension guide that will produce a higher 
angle-of-attack of the fin blade during the down stroke, resulting in more thrust.  Then try 
moving the entire fin and suspension system assembly to the aft set of mounting holes to 
configure the fin on the longer arm and see if you like that setting better or worse.  Select 
the combination that feels best to you.  In general, a longer top suspension guide will 
provide both more thrust and more resistance on the fin’s down stroke, whereas the 
extended suspension/fin mounting will provide more thrust and more resistance on both of 
the fin’s strokes.  As the top and bottom suspension guide parts are the same parts trimmed 
to different lengths, it is easy to make a custom length top guide by trimming the part for a 

Summary of Contents for DOL-Fin Orca Mk-2

Page 1: ... of the DOL Fin equipment to verify the structural and mechanical integrity of the unit to the swimmer s own safety and risk standards Even easy dives can become dangerous when equipment unexpectedly fails Never attempt to stand with both feet engaged into the DOL Fin as you will be unstable which can cause you to fall over and can lead to injury Be careful when using your DOL Fin around others as...

Page 2: ...ructural support between the high aspect ratio fin and the swimmer s feet Figure 1 shows the Orca Body as seen from its underside with the fin suspension systems installed and labels some important features As it is shown in Figure 1 only the fin needs to be attached to complete the monofin 4 of 16 Installing the Foot Binding Straps The Foot Binding Straps are user replaceable and can easily be re...

Page 3: ...nations are offset from the centerline of the Suspension Strap This offset is visible by looking at the side edge of a Suspension Strap To properly mount the Suspension Straps to the Orca Bracket the nylon laminations should be offset away from the Mounting Tabs on the bracket and close to the fin as depicted in Figure 3 Mounting the Suspension Straps upside down will affect the fin s angle of att...

Page 4: ...evel of energy transfer to the monofin the straps do not have any padding attached to them and instead rely on padding worn on the foot to eliminate chaffing of the straps on the foot If a dive sock is not available a cotton gym sock will do almost as well The more padding between the foot and the strap the more movement is possible and the less connected the foot will be to the fin So adding stra...

Page 5: ...s body more streamline for drag reduction and speed The fin motion produces alternating patterns of starting vortices of the oscillating fin which forms a reverse Kármán vortex street to focus a powerful jet of water flowing through the volume affected by the fin as illustrated in Figure 4 The fin motion is shown in black The reverse Kármán vortex street and resulting flow of water are shown in gr...

Page 6: ...ing to remember is that the DOL Fin is a Dynamic Oscillating Lateral Fin not a Dynamic Oscillating Skewed Fin The fin should always be stroked in a direction that is orthogonal 90 degrees to the span i e long axis of the hydrofoil fin If the fin is twisted in roll relative to the diver s upper body and the diver inappropriately strokes the fin orthogonal to his upper body rather than orthogonal to...

Page 7: ...the safest way to dive Be sure that you have appropriate clearances around you before starting your rolling back entry You don t want to injure others as you roll back or get your fin caught on anything in the boat 14 of 16 If the rolling back entry is not used an entry similar to a shore diving entry can be used whereby the diver first enters the water and then dawns the monofin Never attempt to ...

Page 8: ...his is a subtle method by which divers can optimize their fin s performance to their individual swimming style 16 of 16 Youtube video DOL Fin X 20 Fin Tip and or Bungee Replacement provides a complete tutorial on how to replace fin tips and or bungee assemblys This video can be accessed here http youtu be pJzDBW7KE2c The following explains the process in words To install a new bungee system begin ...

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