Neumatic Matters: Force Fin?

Hey fellow matters,

I have been having a great time on my K-mat using churchhills this past month. It’s been truly awesome. Ordered a pair of viper V7’s size L, I’m a 9.5 US, and they were way too narrow. So I am looking for a longer fin to give me some boost. I have a pair of old school scubapro fins I am going to try and possibly modify but I was wondering if anyone out there has tried these:

Also tried to email Greg Deets but no luck so far.

thanks for any input.


I’m waiting for Prof Deets as well. I used Vipers awhile and when I tried them on first time they were too narrow. Few months later went back to shop on impulse and tried again and they fit fine so I think they may have slight variation between batches. Currently using DuckFeet and they are pretty comfortable for me, I have wide foot, 7D. Force fins look interesting but I’ve never tried them. Woman on KSUSA site from HI thinks they are the ultimate best. Would love to get feedback from someone who has actually used both Force and Ducks or UDTs.

prof deets seems to be a pretty busy guy, as you will find out (or are in the process of finding out) – if you go to you can buy them for about $62.00 + shipping, and the service is very good. trust me on dis one – it just ain’t worth the $10-15 discount to wait for prof deets to hook you up. (as a matter of fact, he’d probably prefer you going to a real outlet. seriously - he seems to have a lot of different works/research/projects going)

last week i just called Voit using their 800 number (which i got from the archives) and ordered them when dr D din\dn’t reply to me emails

i broke the strap on my UDT’s while in hatteras two weeks ago----bought a pair of churchill makapuu’s to finish the week out with—Just not the same at all----i need my modified UDT’s!!! power is good!

thanks i’ll give’em a call. tried marine-rescue, they only had an XL left and they figured since they were on back order that it might be best to try them in the fall. need my boost sooner than later…just thinking the force fin might be a good option, adjustable for bare foot and bootie, winter and summer fin in one.

I bought a pair of the original Force Fin about 15 years ago from Sharper Image and it’s my favorite pair of fins. I was having problem with foot cramps especially with the duck feet fins. Churchill’s were okay but not as good as the Force Fin. I use mine for body surfing, body boarding, swimming and diving. I love these fins but they are pricey but they are built to last.

hey - don’t know about those “I Robot” force fins, they’re pretty trippy lookin.

but b4 i had udts i was using blue duckfeet – not as much flex in the fins, but they’re pretty close to udts I think. Got mine on ebay for $20 or so.

I Robot fins, that’s pretty funny. called voit earlier got the run around, they took my #, said they’d provide me with the name of a retailer in my area that could order the udts for me. i am almost to the point of giving in…and going asimov style. :wink: thanks for the input Uncle D, they must make them pretty well if they’re going that long, something to think about. i’ve had my tank like scubapro jetfins for about 17 years and i’ve only replaced the straps once.

FYI for those interested in the UDT’s. 360/voit called me back and unfortunately for me they didn’t have any in size L, they might in medium and small and if you fit that they’ll take your order.

they don’t know when they’ll have more in stock since they are transitioning to having the fins made in the US. in case your curious…

I have been using force fins for over 10 years now and love them for diving. I have also tried them with my mat but they have been less than satisfying. I can’t pin it down on any thing in particular. They have a lot of power but they seem to take a little longer to spool up to speed. They are very comfortable and durable and you never have to worry about foot cramps.

I have also used DaFin which is also very comfortable with plenty of power (for me). But the fin I am currently using is the Flips strap fin. It is by far the most comfortable fin I have used and has plenty of power for my needs.

disclaimer: I am just talking about the comfort aspect here. I don’t want to fuel the power debate with the UDT fans.

What happened to my post? Hey those Strap fins look pretty good and they are cheaper than the force fin. I think they are worth a closer look. Comfortable fins mean more water time. Power fins are a bonus too!


The new version of UDTs (USA mfg) is supposed to be slightly different flex pattern and amount. I’d love to see controlled test of Force vs UDTs. Though maybe i did via mat forum link on flips…tested in pool against current, several different fllippers by Navy Seals. One was Force, one was unnamed giant stiff bladed paddle fin. The Force fins won out slightly for long distance under water cruise and the UDTs(?) won slightly as I remember for the short sprint. All based on time/distance vs oxygen consumption. Mat forum down at the mo so cant’ check the link

Hey surfersensei,

I’m getting quite interested in this mat lark and am planning to give it a try with a donated Surfster, but I need to get some fins. Having never particularly considered bodtboarding etc. I’m completely clueless in this area except to say that I understand I need something a bit ‘more’ the std. BB fins. I was looking at Force Fins but they’re really pricey over here and those strap fins look interesting, so, a couple of questions based on your experience, if you would.

  • Their website makes one-size-fits-all claims - have you tried them barefoot and with booties? (I could do with some fins I can wear summer and winter, which is not the same deal, temp-wise, at all here in the UK.)

  • Does that strappy bit secure them enough to generate speed quickly?

  • How long have yours lasted? (I’m guessing I’ll have to get a friend in the US to ferry some over for me, which I can’t ask that often.)

Thanks in advance for your help.


Just phoned Marine and they do not have UDTs in ANY size and said they doubt they will have any until Fall. Rats!

hey surfsensei,

those flips look good. comfort is a high priority, since i got the mat i’ve been getting cut and cramped by my churchhills…of course that could be the due to the fact that i can never bring myself to leave the water anymore when i am on the mat.

without fueling the power debate with the udts, could you give an opinion on the power generated by the Flip strap fins based on its own merits?

This is kinda long but I thought interesting. Took it from a very long article where some guy organized friends and did various tests on many different fins for top speed, max thrust and oxygen consumption. Most not too relavent here but this part was. (Force Fins he found generally tested relatively poorly BUT with strong exception and figured out was because they take special style kick to make work well and have a fair learning curve for most users.:Experienced Force Fin users tested near top but not the very top in all catagories) So here’s the part I though interesting:

Feel versus real ...

On a somewhat subjective note, one of the interesting aspects of fin performance that I’ve stumbled across is that perceptions can be misleading. I’ve not only heard about it from others but experienced it first-hand myself many times. Two of the main aspects with differences between feel and real involve speed and “weight” in the water. A third aspect, involving the feeling of strain, appears to be more real. I’ll discuss all three. Except for a couple of examples where differences between the good and not-as-good performances involve the same brand, I’ll just speak in general terms to avoid focusing on particular names.

Speed. For some weird reason, many fins that feel really fast are not in fact fast when actually measured. And, to the contrary, some that feel slow (until you compare them and pay closer attention) are actually very fast. Also, using wide kicks with some fins gives a feeling that one is going faster than with narrow kicks, but it may not actually be the case. Stop watches and UW speedometers don’t care what fins you are wearing or how you are using them, and the instruments don’t lie; they report simply how long it takes to get from one point to another or how fast you are actually moving through the water. These measurements often contrast with one’s sensation of movement! As an example involving the same fin but different materials and different speed performances (at least for me), with the Apollo Biofin XT I feel like I’m really moving – but the speed simply isn’t there on the speedometer, whereas the Apollo Biofin blue and black versions have a feeling that is neither fast nor slow (the best word I can come up with for how they feel to me is “smooth”), but they both produce excellent speed. The bottom line is that you can’t always trust how it feels. This problem of perception occurs both in relatively calm water and in strong current. If in doubt, check it out and go with the instruments or other side-by-side comparisons.

“Weight” in the water. Another misleading feeling underwater is the “weight” of the fins. This feeling has little to do with actual mass of the fins or their weight in the air (also see section below about physical measurements). Rather, the sensation of UW weight seems to be related more to resistance to movement, that is, drag in the water, or perhaps the difference between thrust and drag. Some of the lightest fins feel the heaviest in the water and vice versa: some that are actually heavy, feel the lightest in use. However, some fins that are actually light also feel light and the same can be said for heavy. A good example for the contrast between feel and real weight involves the ScubaPro Twin Speeds. The Twin Speeds come in both full foot and open heel versions. Both are light in actual weight (for their respective full foot or open heel categories) but only the full foot version feels light. The open heel one feels heavy in the water, “heavier” than some of the other open heel fins that are actually heavier. The bottom line is that there seems to be little relationship between actual mass and perceived “weight.” Actual weight is probably only a factor when one is carrying them above water, on the way to a dive site or in luggage when traveling.

Strain. As described in its own section above, the perception of strain in the water is something that I haven’t yet been able to measure or categorize well (or correlate with other measures such as speed or efficiency), although all divers know what it is and I think the differences are there and very real. Strain basically involves resistance to the movement of the fins in the water, probably involves or is closely related to drag, and there seems to be a high correlation between strain and muscle cramping. “Strain” is perhaps the single biggest, and most easily perceived difference between paddle fins and split fins.

hey walrus

I have long thought that a sewn on adjustable strap on udts would be a great modification…you didnt throw away that fin did you?

if you havnt perhaps a discussion of the potentals is in order…


sorry ambrose, i was sooooo pissed off when it broke i threw it into the fish cleaning bin on the way off the beach. THEN, to make matter worse, i had to go to three widely spaced surf shops to find a pair of churchills to finish the week with. i need to work on the anger thing sometimes, sorry

on a good note my new UDT’s came today—:wink: however , and this could be goood for someone-----the black UDT’s for me are fine BUT the small Customs for my wife arrived as blue and black XL UDT’s According to the early notes here–these may be the last XL UDT’s around for a while…any one want to talk :wink:

whddp, walrus?

do i understand correctly you have black udts and yr wife has blue-marbelled udts? if so, do you notice any difference in flex. I got black udts – i was told they had more a little more flex in the blades than the blue marbelled.

for that matter, can anyone here comment on the red-marbelled type? I heard the green-brown are supposed to be even flexier? when someone gets the green/brown rubber type – puh-leez post a pic.