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Making my own monofin (progress)
- Thread starterMerlin
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
It can take a long time to get an up-to-date response or contact with relevant users.
laminar said:
Hi Pete,
sorry I thought this thread was dead and burried by now
About your questions:
1. I did not use fiberglass because I wanted to make the cheapest monofin possible (I am a broke college student) that worked reasonably well for trainning only (not to break any records) if you catch my drift
2. The finish on mine is VERY smooth, actually the lexan sheets are smoother than WW fins Ive seen. The only problem is that lexan scratches very easily when pushing off the wall. But it is not a really big deal, they are still very smooth (they are not deep scratches).
5. The lexan sheet that I used is 2mm thick. They are not very stiff at all, Greg (commonerg) has WW mod 2, medium stiffness and they feel quite a bit stiffer than mine.
Lexan is very strong when it comes to flexing. I have actually bent the blade nearly 180 deg without any problems and they do not deform either. The weakest link of my fins is not the blade but the footpockets because I just used a pair of bifins footpockets (free).
Like I said, my custom fins are good for trainning especially for a beginner like me because they are easy to use but not for more advanced users. That said I have been able to do 75m relatively easily with them and should reach 100m hopefully soon, so they can't be that bad. I am getting a new WW mod2, med stiffness in a few days, so I will finally be able to compare them to a "professional" monofin.
Good Luck
Last edited:
Peter,
That is beautiful carbon! Looks way nicer than anything I've seen from SpecialFins or Mat Mas. I would love to see one up close!
Yes, I'll be making my own footpocket.
Merlin,
My experience with Lexan was funny one. efattah ordered some fins from Breier Brut a long time ago and they were too stiff and the footpockets were way too soft (absolute crap, in fact). So Eric got the idea to put in lexan inserts into the footpockets. After a couple of deep dives, one cracked under my right footpocket, making for an unnerving spiral ascent. Merlin, your fin might work very well in the pool under light loads, but ascending from depth with a 5kg weight belt might lead to disaster! :duh If you do take it diving in the ocean, I would test it with sprints up from depth and lots of ballast with a descent line...
-------
Diving over the last few years has led me to a couple of ideas about the monofin that I would like to pursue further. Having bigger companies make these custom design is hit and miss, as Eric discovered, 22 monofins later!
1. Width: Most freedivers aren't going to spend the hours in the pool learning correct finswimming technique. Furthermore, correct finswimming technique is not necessarily optimal for freediving. I disagree with the Solomons on that point. Most normal sized fins are unstable at slow speeds (freediving) and without proper training. Making the fins wider is the easiest way to stabilize the fin, although the stiffness has to be just right. A good measurement that I've liked (my old cracked WW custom fin) is 90cm wide X 60 cm long. The fin naturally "gulls" just enough to grip the water and you never have any side to slide instability.
2. Stiffness: I'd say the majority of freedivers use fins that are too stiff for constant weight and dynamic. Watch any AIDA competition video and you'll see what I mean. A stiff fin needs speed and excellent technique. When the fin is too stiff it stalls. People with stiff fins also use too much leg technique, because that's the only way they can get their fins to flex is by "kicking."
3. Lift profile: The reason why I will never use a monofin with an attached Omer or Sporasub footpocket is that the flex characteristics under the footpocket are pretty bad, not to mention the extra drag those footpockets create. This affects the shape of the foil that creates lift on each monofin stroke. With a significant portion of the fin "flat" and not "curve", lift is lost and drag is created.
For me, the ideal monofin would have the following features:
1. Asymetrical foil shape: different flex profiles for up and downstrokes.
2. The perfect ratio of width, length, and thickness
3. A super light footpocket that doesn't add stiffness to the top of the fin (or else is built with the desired stiffness in mind)
4. A material more durable than carbon. A mix, perhaps?
5. Easy to make and to make fine adjustments in stiffness and foil profile.
I have a design that would fulfilll all these requirements, but I have no prototype, which is why I'm asking about construction techniques. I would really like to get an overview of working with fiberglass: the layering technique and the cut-away technique. Is there a guide anywhere to making your own sheet of fiberglass?
I want to get started!
Pete
That is beautiful carbon! Looks way nicer than anything I've seen from SpecialFins or Mat Mas. I would love to see one up close!
Yes, I'll be making my own footpocket.
Merlin,
My experience with Lexan was funny one. efattah ordered some fins from Breier Brut a long time ago and they were too stiff and the footpockets were way too soft (absolute crap, in fact). So Eric got the idea to put in lexan inserts into the footpockets. After a couple of deep dives, one cracked under my right footpocket, making for an unnerving spiral ascent. Merlin, your fin might work very well in the pool under light loads, but ascending from depth with a 5kg weight belt might lead to disaster! :duh If you do take it diving in the ocean, I would test it with sprints up from depth and lots of ballast with a descent line...
-------
Diving over the last few years has led me to a couple of ideas about the monofin that I would like to pursue further. Having bigger companies make these custom design is hit and miss, as Eric discovered, 22 monofins later!
1. Width: Most freedivers aren't going to spend the hours in the pool learning correct finswimming technique. Furthermore, correct finswimming technique is not necessarily optimal for freediving. I disagree with the Solomons on that point. Most normal sized fins are unstable at slow speeds (freediving) and without proper training. Making the fins wider is the easiest way to stabilize the fin, although the stiffness has to be just right. A good measurement that I've liked (my old cracked WW custom fin) is 90cm wide X 60 cm long. The fin naturally "gulls" just enough to grip the water and you never have any side to slide instability.
2. Stiffness: I'd say the majority of freedivers use fins that are too stiff for constant weight and dynamic. Watch any AIDA competition video and you'll see what I mean. A stiff fin needs speed and excellent technique. When the fin is too stiff it stalls. People with stiff fins also use too much leg technique, because that's the only way they can get their fins to flex is by "kicking."
3. Lift profile: The reason why I will never use a monofin with an attached Omer or Sporasub footpocket is that the flex characteristics under the footpocket are pretty bad, not to mention the extra drag those footpockets create. This affects the shape of the foil that creates lift on each monofin stroke. With a significant portion of the fin "flat" and not "curve", lift is lost and drag is created.
For me, the ideal monofin would have the following features:
1. Asymetrical foil shape: different flex profiles for up and downstrokes.
2. The perfect ratio of width, length, and thickness
3. A super light footpocket that doesn't add stiffness to the top of the fin (or else is built with the desired stiffness in mind)
4. A material more durable than carbon. A mix, perhaps?
5. Easy to make and to make fine adjustments in stiffness and foil profile.
I have a design that would fulfilll all these requirements, but I have no prototype, which is why I'm asking about construction techniques. I would really like to get an overview of working with fiberglass: the layering technique and the cut-away technique. Is there a guide anywhere to making your own sheet of fiberglass?
I want to get started!
Pete
Yeah that's mainly why I ordered a WW, since I am going to do some constant this next weekend with Greg. I just would not trust this fin for any serious constant dive. But I am sure my footpockets would be the first to go though, which would make for an interesting ascent indeed.laminar said: