It's actually a good question. My initial thought was humm maybe.
Time, Temperature, UV and other "factors" influence the Breakdown of the rubber compound.
What is happening to the rubber exactly, not sure, so I would quess not contagious and that seems to be true from my own experience.
Could be a small factor. What say you Dan?
Welcome to SPEARDIVER.
Dan, I get another Gold-Star for bringing a new member in. :stars2:
From our dialog, he's a great fit all of you guys, even Georgy... 
It looks like 1/4 thread. So maybe a 5/16 shaft?
Did you keep the tip for your collection to go with story?
A+ in my book, you got to dive with George...
Welcome
Tosses hook to reel in Wishihadgills and me in with interest. Where did he go?
Wishihadgills: I told Joe about you getting through school, He was interested in seeing where you are as a resource and current capability.
Need some young blood in Engineering ranks. Hook you up with a seasoned P.E. Mech Engineer who made his own jet engine in his garage.
Welcome to SPEARDIVER.
I'm north of the SF Gate by an hour+ or so.
If you find some deals on used gear, I can do some repairs and replacement parts. The NORCAL forum is a good source for used gear and hookups. MATT MATTISON runs it and is speardiver member too. This is small forum and great group of locals. Not world-wide like this one.
I got to get Dude George's signature slip tip done first thou. I know he's watching. 
the Stainless wing sure did hold up well compared to the carbon steel tip. (a guess)
The C steel plated maybe, but long gone with time.
Very interesting.
Be happy to help. First of all, don't get broad looking at too many aspects of the entire speargun design unless you just want to touch off a little on each part.
A better paper might be just a couple aspect of the design. Which one's you say... Well what is your interest, mech engineering is pretty big.
Define how deep you want to go with a few metrics. Schedule time ( a year), how many man-hours you willing to put into it. What is your cost budget? What is the audience's expectation? Guessing you want to do physical data collection to verify the calculations.
Optimizing each aspect of the gun seems like a lot, is my point.
If I was grading you, seeing you dig deeper on a feature would be better than just touching everything a little.
Optimizing: What does this really mean? Max energy applied to target. or maybe accuracy and better groupings on target.
Welcome to SPEARDIVER.
Get a hold of Dan.
Give him details, actual gun model and dimension info, how strong you are to cock the bands, what you going after and shot range. He will get you setup right the 1st time.
See Freedivestore link on top.
It was bad luck for the diver i hear, it went around a (mooring?)line with the shooting line attached to spear in it, that turned it back at him
That makes more sense to why it was coming at him vs trying to get away. A good thing to think about. If line length was different or the mooring line father away, it would have missed him.
Spotted this event on CNN, was going to post and see Ramon beat me to it.
The picture of the swordfish looked strange. Looked like it had damage to the back of the top fin.
Wonder if this was actual fish or a file picture.
Nice write up, I enjoyed reading it.
I bought a Koah a few years back, totally happy with mine. Dude George got one too, he's puts it to the test more than I do. Lets see what he says.
I tend to use my polespear the most in evaluating design changes and new tip concepts.
My long Koah not the right gun for the murky waters of Northern CA. I got it for traveling to nice water.
Building your own, all based on your time and craftsman ability and available tools.
Metal DIY-er add on parts are available, Dan sells most of them in Freedivestore ( Link on top).
You will get lots of comments with that question.
WELCOME TO THE FORUM.
Nice, You didn't draw any blood when using the pointed tool either...
Your fast with the knots too, I got fumble factor over here.
Welcome to the Forum. Lots of knowledgeable divers here.
You got questions, they have answers... Especially George... 
Welcome to SPEARDIVER
I have been down there a few years ago. I can hook you up with locals there.
One of them runs charter boats for fishing and diving, the other one was a diver guide. We were there for a few days and had a safe rewarding experience. My dive buddy here in CA has been down there with these guys many times.
PM me and I will provide their contact information.
We were eating our meals at one of divers parents house in Chimo. Only time I spend in PV was getting on and off the plane and then directly to the boat to leave.
Very Nice Read, Thanks for sharing.
Welcome to the forum, Lots of good information and comments here.
I've dove the Gulf Islands up there in a wet suit. Yep it was cold, but about the same as Northern CA.
You are located in a great area.
Which pole spear did you decide upon out of Curiosity? :thinking:
What was thought process?
