Question Truefins

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I got my first dive in with the fins yesterday at Blue Heron Bridge. @landonnin1 was kind enough to capture video as soon as we got in the water. We had quite a large group of divers (7), 6 of which are scubaboard users. The plan was to get in the water around 12pm, and we had to arrive early for parking. This gave us hours to talk about whatever. I brought out the fins for show and tell. Everyone was curious and wanted to get an opportunity to hold a fin. I pulled the spines out a couple of times and let everyone see the spines.

Show and Tell:
Initial comments from the group:
What do they do?
They are heavy.
Why are they shaped that way?

I showed how the green spines don't flex one direction and explained how you can mix spines to customize flex. This concept seemed to intrigue everyone. A couple of people pulled their fins out and told stories, good and bad. I talked about how you could pull the spines out and roll the fin up for travel.

My thoughts:
Yes, they are heavy. I don't know if they are any heavier than the Hollis F1. I couldn't dive the F1's because they made me ankle heavy, so I was concerned about this going in. They were not that heavy underwater, and I'll speak more to this later. They definitely have good propulsion. The fins felt awkward at first. The medium springs fit well, maybe too well for my size 11, and my foot was hurting after about 45 minutes. I think this could be solved with a large spring. The foot pocket, otherwise, fit like a glove. The ability to adjust the spring would be nice, which is an option on the fins I normally use (Dive Rite XT). Occasionally, I had the feeling that I kicked something or someone, but I think it was the spines all engaging a limit at the same time. I had no trim problems. One annoyance with the shape of the fins, occasionally I'll get my fin caught up in my dive flag rope between my legs and it was extremely difficult to get the rope back to the other side because it would catch the shape of the fin where the spines insert. Maybe an angle adjustment would solve this. To get my foot out, I would have to roll to my back. I will try the fins again with anther colored spine, but I need to do something about the spring tension first. One of the biggest surprises was the ability to do a back kick to backup, they were very responsive.

The Video:
Landonnin1 was recording me when I was swimming out from shore and adjusting my camera, when I had no idea he was doing it. His thought was it was the best opportunity to capture my natural use of the fins. Some of the kicks were me feeling out the fins. They felt different and didn't appear to affect my buoyancy or trim. I'm uploading the videos to YouTube, when they are done, I will post the links here.

Weight and Bouyancy:
Because I'm carrying my large camera, a dive flag, and fins, I clip off the fins to my waist D-ring. Upon reaching standing depth, I removed my fins, clipped them together, and clipped them to my waist, or so I thought. I'm halfway to my truck and I realize I don't have the fins attached to me. 2 of the divers had already exited before me, but one was still geared up. We went back to the beach looking and looking. Do they float? The lifeguard said he saw some fins floating in the current, so Michael ran up the bridge to see if could see them. I snorkeled around and Matt went back underwater. There were so many people at the beach, did someone find them? I found Jenny taking pictures of something, so I swam to depth to get her looking around too. We looked for like 30 minutes and could not find them. Usually lost fins/masks are turned into a local LDS, so we gave up. We get back to the parking lot and one of our group members had found them and recognized them as the ones I was showing everyone. They said they were on the bottom, fins tips in the sand, foot pocket up in the water column.
Thanks for doing that. If you had lost that fin we would have sent you another.

Truefin is a little lighter than the Hollis F1. As I recall the weight of the large F1 was 3.8 pounds/fin, and Truefin is around 3.5/fin including spring straps. Regarding buoyancy, Truefin is around -3 ounces with spring straps, and I think the Hollis F1 was around -16 ounces, but I don't recall what the heel strap was with the Hollis F1 we weighed.

Regarding the flutter kick with Green spines, I guess it would depend on the individual, but the angle of attack during the 'toe down' power flutter kick between Green and Blue spines is the same, so you may find the Green spines flutter kick well. The difference would be how you want the fin to feel during the return flutter kick, and whether you want to be able to exert thrust during the return flutter kick. Green spines more readily produce thrust during the flutter return kick because the blade remains flat during the flutter return kick. However, typically during the flutter return kick most users may just want to relax the ankle a little to promote circulation and let the blade follow the streamline without attempting to exert thrust.
 
If any of you testing these fins need a bigger strap, direct message me... We have on order the large R558 and R559. I think we are finding that if you are using dry suit boots, then you may need a larger strap. These large straps will be in stock in about a week to ship out. We are still debating whether we should just ship these fins with ratchet straps, but I think most prefer spring straps,,, not sure.

Trident R558 v R559.jpg
 
Personally, I might not purchase the fins if they don't have spring straps. Or if there's a way to give different strap options, say on Amazon? I guess it depends on your target market too. I know one person who uses the ratchet style and they also dive with a snorkel, he has over 1000 dives, so these divers exist. I would pay more for springs, but I wouldn't want to have to make an additional purchase to figure out which straps are compatible.
 
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Interesting. Looks like there’s a mix of yellow and blue splines in the same rail.
You have a sharp eye,, I should have noticed that in this clip. Until we can machine endurance test 'mix and match' configurations of the spines, we are currently not suggesting setting up the fin with hybrid spines. Hybrid spine configurations can result in discontinuous curvature (slight kinks) in the spine during full articulation, so perhaps there could be higher stresses at the curve transitions while under load, but I'm not sure that is really significant.

Nevertheless, spines have a lifetime guarantee against breakage regardless as to how they are configured. By the way, we have intentionally broken spines and assembled the broken spines in fins, and they generally just perform like average spineless fins. Once we have the machine endurance test results of hybrid spines (1 million kicks at 1 kick/sec), and we also get a lot of real world diving history with these fins, we'll be able review our spine materials and injection molding processes, and optimize the spine properties if needed,,, and mixing and matching will be an interesting option for a user to experiment with. The number of possible configurations when you are mixing and matching vertebrae is quite large. ..Note that 'mixing and matching' is a different issue from using a Blue spine at one rail (big toe), and a Green spine at the other rail (little toe) for what we think provides for optimum frog kicking, because there is no 'mixing and matching' when you just swap different spines, and each solid color spine articulates along it's own smooth curve angle of attack.
 
I think I am focussed on that because you've mentioned it a few times and having read the manual and technical site it seems like a choice that would need to be carefully thought through to ensure the new curve created was desirable and not kinked. So many options - these fins are great for gear heads who like to fiddle.
 
I think I am focussed on that because you've mentioned it a few times and having read the manual and technical site it seems like a choice that would need to be carefully thought through to ensure the new curve created was desirable and not kinked. So many options - these fins are great for gear heads who like to fiddle.
We had some discussion regarding hybrid spines at the technical site for awhile, and you may have seen that, but I think we removed that discussion until we can complete more testing with those configurations. When you consider mixing and matching colors (geometry), in addition to being able to turn any of the individual vertebrae upside down on a given spine, I haven't even tried to calculate the number of possible geometrical configurations possible, but as I say,,, for now we are just keeping things simple and only showing solid color spines.
 
These are the three spines shown at the full 'toe up' articulation (such as during the flutter return kick or power frog kick),,,,,,,, and the full 'toe down' (such as during the power flutter kick or return frog kick).

Blue and Yellow 'toe up' the same, and Green and Blue 'toe down' the same.
fin with spines 100d.jpg
spines.
 
https://www.shearwater.com/products/perdix-ai/

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