after reading the thread about ply-fins i got to thinking
would billit alum. work? and what would some of the drawbacks be other than cutting your foot off in a mishap.
they would never break, crack delam ding etc… fairly lt.weight
although in certain areas they might act as a VERY BIG FISH lure. shiny!
I think if you tried to sell them they would never sell because of being too dangerous… and besies beigng shark bait, you could probally paint them… future fins came out with something like that, the vector foils… they use woven aluminum glassed over foam… I think that would be less dangerous… but still fishy… they wouldn’t corode either is another plus I guess but unless they were really dull, they would probally to be way to dangerous for practical use.
try it! greenough has used stainless steel to make fins, so why not aluminum??!!
on the note of aluminum fins, i have a large piece of lexan that i have been laying fins out on that is extremely flexible. Its about a 3/16ths of an inch thick, and i was wondering that if i glued two pieces together then cut out my outline and slapped a few layers of glass on, could i foil a fairly decent flex fin?
how much does aluminum cost in sizes big enough to make what you need? it sounds like it could be nice and strong too… and you wouldn’t need to glass it, but you probally could. But I doubt if you ran over the guy who dropped in on you they wouldn’t be very happy… but they might not again in the future…
Aluminum corrodes REALLY badly, in salt water! Gets pitted, blackend, and really abrasive after a short time. You get electoalisis, spelled with a Y in there somewhere.
Bad…
Think it is spelled electrolysis. With aluminum, it basically turns into a heavy, brittle piece of sponge.
Thanks, it’s always nice to have educated people on this forum, who can spell too!
what metal is it that Laird and the mauai [sp?] crew use for their ‘foils’ then ? THAT stuff sure has to be STRONG ! [yes, and DANGEROUS, too ! you don’t want to see my photo of what a normal fibreglass fin did to my groin, trust me! If it had been metal, I would have died, for sure.]
ben
I’m pretty sure the foil boards use stainless steel. The company that makes them also sells powder coated aluminum parts for the foil. With a proper coating and electrical insulation from the other parts, aluminum could work ok, people do make boats out of it. As soon as the coating fails or wears off, you will start to see problems. Fins tend to get worn or scratched from contact with the bottom, don’t they?
Aside from regular corrosion, which is not as much of a problem with stainless steel as it is with aluminum (although there is a reason they call it “stainless” and not “stainfree”) the problem with electrolysis is this: if you combine two dissimilar metals in saltwater, you basically end up with a battery and the more chemically active of the metals will waste away. For example, fin screws on an aluminum fin would be problemaic. On boats, even plastic and wooden boats, they use sacrificial zincs which are very chemically active compared to the rest of the metal parts. These sacrificial zincs are electrically connected to the metal parts, such as the engine, and in saltwater must be replaced regularly to keep the other metal parts from corroding. Maybe you could attach a US penny with the copper plating sanded off to your aluminum fin?
As a boat guy -
Aluminum, by itself, isn’t really a problem. It’s when other metals or electrical fields get involved you get electrolysis. Some aluminum alloys work just fine in salt water, all by themselves, no paint no nuthin’, zillions of small aluminum boats around that last quite well with no paint. Add copper or something, and the more electrolytically active aluminum tends to go bad on ya. Bigger aluminum boats, and they build ‘em well over 100’, they use epoxy barrier coats and often a tributyl tin based bottom paint which doesn’t affect the aluminum the way copper based bottom paints do. Bronze ( a copper alloy ) gets downright awful, a bronze through hull in an aluminum hull will damage the hull within hours.
Stainless steel and aluminum get along pretty well, though again there are incompatible forms/alloys. The plastic fin box/stainless screws/aluminum fin setup you’re describing shouldn’t have any problems at all. If you wanted colors, there’s always anodising plus lots of powder coat systems, the powder coat paints should be fine in salt water until chipped. Then, life could get interesting, depending on the pigment chemistry.
If you really wanted to use zincs… well, i’d imagine a little zinc wire or something like zinc sheet stock, such as is used for weather stripping and such, could glue that on somehow or other. Though I can’t really think of why it’d be all that necessary in such a system.
hope that’s of use
doc…
on the note of aluminum fins, i have a large piece of lexan that i have been laying fins out on that is extremely flexible. Its about a 3/16ths of an inch thick, and i was wondering that if i glued two pieces together then cut out my outline and slapped a few layers of glass on, could i foil a fairly decent flex fin?
You can use colored glue, when you glue the two pieces together, that way you will have a center line to foil your fin from. Mike Eaton uses 1/16 lexan as side fins on his Bonzers. They work will and last a long time. Lexan is used as bullet proof glass.
awesome, thanks for the reply
Quite a few duck hunters I know are having the hulls of their aluminum boats sprayed with Line-X, the truck bedliner stuff. Apparently, the surface is the perfect combination of soft, rough, and uniform all at once (that doesn’t sound like it makes any sense, does it?). It decreases drag (from vortices) so much that 12’ skiffs are going down from 9hp motors to 3-5hp, but going faster. It also inhibits barnacle & algae growth - not an issue on surfboards but interesting for salt-water based boats. I wonder what a treatment like that would do to fins…