Making my Own Monofin

[Mermaid Photine]

After quite a bit of research, some overzealous planning, and coming back to reality, I have decided to make my own monofin. I want something less flexible than my Finis Wave, and I wanted a "fishy" shape.

I decided on 3/16 in UHMW (stands for Ultra High Molecular Weight) in a dark green color because it was the cheapest. I went to a local plastic company, Piedmont plastics, for the UHMW. I was in the warehouse and the man I was talking to had the plastics I was looking at wheeled right up to me! They were very friendly people, and because I came in person instead of over the internet, I learned of the plastics they had cut sheets of and the stuff they just wanted out of the warehouse for a superduper discount! I haven't read of any other monofins made out of this material, so we shall see how it goes!

I have ordered some 3mm neoprene to sew into a footpocket and bolt down to the UHMW shape (from seattlefabrics.com They have the best price I have found for small, specific ammounts of neoprene, but in large quantities, they aren't the best price. I called them to ask a few questions, and the lady was very helpful and friendly. I eagerly await the delivery!)

I cut the UHMW into two pieces: the shape of the monofin and support for it so it (hopefully) won't snap. A band saw cut throught the plastic fairly well. I am in the process of sanding the shapes by hand now. I will be getting some serious muscles from it, I think. :crazy:

I will be testing some of the plastic scraps to see what sticks to them (the warehouse man said that nothing glue-related would) perhaps caulking or some type of rubber or neoprene cement. Looking into the future, it would be nice to know this ahead of time should I want to make myself a tail out of something other than spandex so I could glue the fluke down to the monofin.

Once the neoprene arrives, I will brush up on my research of how to sew neoprene. After that, I'll figure out how to bolt everything together and try it out! I want to get this done before the end of August, while the water is still warm and comfortable so I can see how the UHMW holds up to repetitive bending.

If I can figure out how to load the photos onto my computer, I'll post them. :)

[Odette]

plastics are best heated to stick together but the fumes are dangerous. the only adhesive that would possibly work is a two-part epoxy.get the marine kind at ace hardware. most plastics are bad with sun exposure rather because of leeching chemicals or they degrate easily. leave a test piece outside for an hour and see if any changes occur.i did this same thing about a month ago.

[Spindrift]

I learned to weld plastic for my engineering classes. Other than that maybe silicone will make them stick together. The epoxy idea seems good as well.

[Little_Orca]

I don't have anything helpful to add, I just can't wait for some pictures. I am totally a visual girl. :)

[Mermaid Photine]

I've finished the sanding- I feel rather like a noodle, and I'll fish a small scrap out of our bin to set out in the sun. It's 5:00 here, so the sun's not at its strongest, but I can just levae it out for a little while longer, I think.

[Kanti]

I really hope you end up doing it~
I thought alot about making my own monofins, but all the molds and plastics, etc.. I'd think it would be so
much stuff and I would have to learn wayyy too much before every purchasing anything.

Good luck! I would love to see some custom monofins~

[taom]

Tell us how it goes! I've been considering constructing a monofin out of UHMW and I'm super interested in hear how you experience goes.

[Mermaid Photine]

The scrap I set out in the sun at 5:30 pm and forgot about until 11:30 am the next day survived ( I thought it might. The warehouse man said this is the stuff they use to make billboards.) I am now waiting on my neoprene to get here. 5-14 days!

The most annoying thing I have been dealing with so far is the "creep" of the plastic. Creep means that if UHMW is left in a way that it may droop and ben for long enough, it will continue to droop and bend for days. I'll have to store the monofin completely flat whenever it's not in use to fix this.

taom, how's your fin going?

[Syrenia]

I used epoxy when making my first monofin. My flippers still have not come off, and I've ripped and pulled as hard as I could. I'd definitely go with the epoxy.

[Mermaid Photine]

I'll probably end up bolting the fin shape and crescent shaped support together, though epoxy sounds like it might work, too. I'll soon try testing out what DOES stick to UHMW for opossibly hopefully glueing it into neoprene for a tail in the future.

[taom]

@MermaidPandorah
I've already made a monofin but by a completely different method. I want to experiment with different methods to discover which is the best economically as well as performance wise (I have an etsy business with my beau and I pat for materials as I make money. That way I limit my mermaid budget while paying for the things I need.) I think I'm going to get a piece of this plastic next, though, and try it out.

Simply of out a desire to learn, what causes the creep?

Also, sometimes glues don't stick because the surface is too smooth. Now, I have negative experience with this material, but would roughening it with sand paper or some other abrasive aid glue in adhering?

[Mermaid Photine]

http://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene <--- The wikipedia on UHMW

Some highlights:
" It is odorless, tasteless, and nontoxic."
"it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms." Good news for us pool mers.
"It is used in skis and snowboards, often in combination with carbon fiber (http://mernetwork.com/wiki/Carbon_fiber), reinforcing the fiberglass (http://mernetwork.com/wiki/Fiberglass) composite material, adding stiffness and improving its flex characteristics." Hopefully this means it can bend and flex like a monofin needs to, as well
"Under tensile load, UHMWPE will deform continually as long as the stress is present - an effect called creep (http://mernetwork.com/wiki/Creep_(deformation))." If I put half of a piece hanging off a ledge, the plastic slowly, over time, droops more and more over the ledge.

Today I took a scrap of the uhmw and a few rag fabric scraps and tested out three possible adhesives: silicone caulk, contact cement, and E600 glue (a glue I usually use for "gluing the ungluable" when making jewelry.) I did not roughen the surface of the uhmw, but I'll tell you what happens one they all have dried/cured!

[Capt Nemo]

Good chance that nothing will stick to it. Paint will easily scrape off. You would have to either bolt it together or thermal weld it.

[Winged Mermaid]

Very interested to see how this works out! DIY monofins can be very trial and error so be prepared, and good luck!

[Mermaid Photine]

All three adhesives I tested (contact cement, silicone caulk, and E6000) by gluing a rag to a scrap of UHMW plastic were easily peeled off, with the easiest to peel off being the caulk- it took no effort whatsoever; it practically fell off, and the E600 being to most difficult- I had to tug a little, representing normal wear and tear. None of these materials could be used to glue UHMW to more UHMW ore to the inside of a tail fluke. For the monofin construction, I will have to go with bolts.

[Capt Nemo]

You can weld UHMW. It's a stick welding method using a heat gun and PE sticks. Don't know how well it works, as I've never tried it. Maybe I'll go to Harbor Frieght and pick up a kit. I have a bunch of 3/4" scrap from a tesla coil I built with it. If I can get it to weld solid, I'll let you know.

[Mermaid Photine]

I'm back. :)

I got flusterated because I couln't solve my problem: I wanted neoprene foot pockets I could bolt to the UHMW, alas, bolts just aren't made wide enough to be absolutely sure the stretchy neoprene won't rip. A lip around the foot pockets would make the fin too wide for what I wanted it to look like. I am going to look for some swim fins or training fins on the cheap to bolt onto the UHMW instead. The remaining neoprene I have will be used for whatever tests or evil expiraments I feel are necessary.

*rides on to ebay with heroic music in the background*

edit: placed a bid on ebay. I'll know if I got the fins in two days. wish me luck!

[Mermaid Photine]

Won the flippers. They're supposed to come before October 7th.

Aren't shubunkin such cool looking fish?
http://www.google.com/search?tbm=isch&hl=en&source=hp&biw=1772&bih=929&q=shubunkin&gbv=2&oq=shubunkin&aq=f&aqi=g10&aql=1&gs_sm=e&gs_upl=1094l3090l0l3207l11l10l1l1l1l1l284l1781l0.3 .5l8l0

[Mermaid Photine]

The flippers came. Wonderful, bright yellow things. I cut them into pieces. :K I took the footpocket halves and bolted them onto my UHMW shape, 6 bolts on each footpocket- two just above the toes, four at the insep on top of a metal plate that will help distribute the weight. I'll cover the ones at the instep with some neoprene inserts.

I'll sew a giant lycra scrap sock for the monofin this week (don't want it to scratch!) and I hope to go and test it at a local indoor pool next weekend. Yep. I'm skipping homecoming to go mermaiding. I feel really cool. :D

I'll see if I can load some pictures.

[Mermaid Photine]

Reposting this:
Huzzah!
Tested the monofin yesterday. I've been waiting for this all week. It functioned!
Also, the pool was awesome! It was indoor, and really nice and warm. I didn't want to leave. The lap lanes that I was swimming in were half shallow (3-5 feet) and half deep (about 11 feet). I usually try to swim in the diving well as much as I can in the summer, but it's often in use as a diving well and I'm not allowed in. Yesterday, I could swim around without worrying about divers. The water was so deep and clean! I loved it!
It was much stiffer than my FINIS Wave, and it let me swim faster. I switched between the two for some comparison, and when I used the wave, it was the same too slow/am I kicking wrong? feeling that I get after taking the monofin off and expecting to swim just as fast. It's a little hard to kick downwards, but I figure that is just a problem with my ankle strength.

The screws that held the footpockets down were covered with some caulking to prevent scratches on people, pool, and monofin cover, however, the caulk cracked and wore down, and the cut ends of the screws began to tear through the l
lycra. I'm really glad I caught this now, when all there is to dammage is the monofin cover. I'll replace the caulk with a scraps of neoprene.

The foot inserts that cover the screws in the foot pocket will need to be glued down. They wiggled out a little with each kick.

The toe area got a little squished due to the way the fins were made and the way I decided to bolt them down. There are matching blisters on either 2nd toe of mine. I cut down the foot insert wile at the pool in hopes that it would fix the problem. It got better, but my toes will still rub. I can either loosen (completely redo) the toe area screws, or I can cut out the toe area of the foot pocket, like my Wave. Both would be an awful lot of work (it took forever to get those screws just right!), but I think I'll try redoing the screws first because it is at least reversible.

All minor issues considered, I am absolutely excited about my monofin. I'll be ordering myself some neoprene soon to make a tail out of. I'll work on my ankle strength, and hopefully I'll be a mermaid by this coming May!

[Mermaid Lorelei]

It sounds like you've been working wonderfully hard on this and I'm glad to see you're having success with it!

[neonmermaid]

Do you have pictures?? I'm trying to do the same thing!

[Mermaid Dottie]

is this the stuff you're using?
http://www.grainger.com/Grainger/Sheet-Stock-1UVZ3

[Mermaid Photine]

Yep, but we got it in green- they had it at a discount price.

[Mermaid Photine]

FINALLY
I have a picture. I seem to be allergic to documenting my final work. xD
9899
Fweeee!
It's shorter than I originally planned because it was difficult to control and kick with. The material I used is really quite strong. The biggest challenge, though, was when I realised that I could not use glue.

[Ashe]

Cool! I like the fluke shape. Do you plan on keeping it that way?

[MerAnthony]

http://mernetwork.com/index/album.php?albumid=417&attachmentid=6756
I made mine out of polycarbonate an it worked well. But for what you used I will keep this in mind when I decide to make another.