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Old 11-25-2016, 10:02 PM   #15
Diving Gecko
Shooter & Shooter
 
Join Date: Nov 2014
Posts: 955
Re: Help Needed, DIY Jap Style Polespear

Quote:
Originally Posted by azspearo View Post
Most external connections are there due to the manufacture using smaller diameter tubing or solid rod. This is more common with 3/8" rod. With rod, it would be mandatory with the design. I would make the connectors internal to streamline the spear.
You'll like the 0.079" wall thickness.

I made a 12' custom spear a couple months back that went to Japan and it was 0.050" wall and it broke just when the end user went to draw it up. I really dont like this style spear and dont understand why they just go shorter and improve their hunting technique.

I'll find the connectors Ive machined and take some pics and post to give you an idea on how to design them strong.
Hi Aaron,
Thanks so much! I'd love to see a few snaps. I do like the idea of internal a lot. If I find the time and can switch parts of my brain on that haven't been used for a few decades I would like to try to the math, too as John suggests. Just for a loose guideline though I will have to make some assumptions about laminate strength and such. I do think making sure the tolerances are tight and the plug length generous, so that the force is spread out are part of the solution.

I back tracked a bit myself in my head the last two days, went over my notes and originally I was looking for something in between a long Japanese spear and a "western" one. I can see even from my first post here, that I was aiming for about 12 feet.

The time I dived in Japan with the 5.5m polespear, even though the tail end was tapered, too (mine is not), there was a lot of drag when tracking the spear. Going shorter will help reduce that.

I do think I would appreciate a long "over hang" though as in Thailand and the Philippines where I most often spear, the fish are pretty skittish.
As a side note, I am hoping to go to Okinawa at some point, too - would be great to take my own Japanese-inspired polespear to Japan:-)

Last edited by Diving Gecko; 11-25-2016 at 10:55 PM.
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