DIYEFI.org Forum

Last night I couldn't sleep and got reading about anchors and thinking about their operation etc. As a result I have about 50 tabs (from ~600 total) open with anchor info/pics. I want to close them. So I'll summarise here...

• Old style anchors suck.
• New style anchors rock.

New style = pointed fluke with fixed shank and roll over bar.

Old style brands:

• CQR < bulk of my experience.
• Bruce < more recent experience
• Danforth < very old school, not used on real boats in my lifetime :-p

New style brands:

• Rocna, original?, kiwi designed, china built (these days).
• Manson, kiwi clone?, kiwi built?
• SARCA, ozzy anchor
• Spade, no roll bar, weight based
• Mantus, yanky? Unprofessional marketing, but design looks best.

I plan to copy the Mantus if they're not really cheap to buy and it's not too expensive to have galvanised once built.

Rocna "4" = 200nzd including chain http://www.trademe.co.nz/motors/boats-m ... 861795.htm
"4" = 4kg and fluke of 460cm2 http://www.rocna.com/product-range/sizing-guides/
4.5kg Manson is also 200nzd without chain.
The Mantus is not available on trademe

Another reason to make my own would be to do better than what I can buy. For that, I'd need to understand the problem thoroughly.

Better might mean:

• Balance (ends up the right way up by itself/more often/more easily/more quickly)
• Weight (less of it to carry around in the boat, design is more important)

To address these you need to move this way:

• More weight in tip and to a lesser extent in the fluke
• Less weight in the shank
• Less weight in the roll over bar

So perhaps an aluminium shank bolted to a steel or bronze head could work very well. I could likely get a bronze fluke made up without too much hassle. A big piece of high grade aluminium will be pricey, though. Or perhaps a small piece of thick alloy around where the shank is, and a box section out to a thick eye at the other end. Alloy would suck on a permanently at sea boat, as it'd corrode and become unreliable, but on a trailer boat, this would be nice to have.

Pictures that I have cached, click to enlarge:


Rocna:






Manson:







SARCA:










Spade:






Mantus:












Fred.

A few more interesting designs:

Box Anchor:




Bulwagga:




HydroBubble:




Images added to previous post. Discussion of details next.

Fred.

The notch in this picture is to keep the anchor clear of the hull when tight up against the roller:





The bevel on the edge of this picture is the opposite of what you want:





The bevel on the edge of this picture is exactly what you want:





The extended point on the front of these two pictures is beneficial in a rocky environment:







The float in this picture is a nice touch and might help the anchor land at a good angle:





The bars from fluke to roll bar, and from roll bar to shank in these pictures would:

• keep it strong while pulling through sand, or hitting other things
• help it not hook up on things while upside down

I'd like to combine those features with my own thoughts and come up with something even better:

Weight and strength could be added to the centre if the fluke was W shaped rather than U shaped like most of the new stye anchors.

Alloy + bronze = light up top, heavy down bottom, strong and balanced.

I could try out my theories using ungalvanised mild steel at low cost.

Fred.

There is my new project. Anchor with name STORM.
Project is still in progress. I will upload photos by steps.
The .dxf file for autocad laser cut is in attachment.


FREE DOWNLOAD ULTIMATE VERSION OF CUTTING FILE AND MORE: Dropbox - MARINE BOAT ANCHOR STORM DIY AUTOCAD (.dxf .pdf .jpg .cdr) https://goo.gl/kyj9bH



p.s. I am sorry for my bad english. English is not my mother tounge.



There are more pictures
https://mojalbum.com/mantus-marine/mant ... ocad-dxf/2

the new design for shank is curved like on Rocna Vulcan or other anchors. To turn achor always right when is lifting up. So you do not need to buy accessories.

Some good videos,
https://youtu.be/BCEBOOnDcOU
https://www.youtube.com/watch?v=A6NmCqdUfRo
https://www.youtube.com/watch?v=4YKV_yvIdaA
https://www.youtube.com/watch?v=gBB6TFSZepI
https://www.youtube.com/watch?v=JNBypaLMXlw
https://www.youtube.com/watch?v=Sj_dPrjteGg
https://www.youtube.com/watch?v=uxCUDRXPJkk
https://www.youtube.com/watch?v=bpNNUkdhw0s
https://www.youtube.com/watch?v=HvrzP65h5SE
https://www.youtube.com/watch?v=l59f-OjWoq0

Thanks for posting those pictures from your thread! And the videos, too. The last two, in particular, are the most credible, scientific, and interesting :-) I'd already stumbled upon them, but thanks for cementing the links in this thread!

About your drop box link, I can't download without logging in, or so it seems. Any way to change the permissions on that link? If not, maybe I'll try to create an account.

I am keen to laser cut a small variant as a test unit so I can start playing with this at minimum cost.

We have a 4.3m flat bottom skiff that has a shitty danforth style anchor on it, that I'd love to upgrade:

https://twitter.com/FredCookeNZ/status/ ... 3427246081
https://twitter.com/FredCookeNZ/status/ ... 2138186752
https://twitter.com/FredCookeNZ/status/ ... 3449985024












A mini STORM much like the dinghy mantus would be a great place for me to start in helping you testing :-)

Given I'm unable to get the files, I feel OK asking how big/heavy the design currently is? And can you scale it up or down easily for different applications?

From the Mantus tables, for the big boat (12.5m/40ft/12tonne), I'd want a 20, 25, or 30kg unit depending on what sort of weather conditions I was aiming for. Big boat (currently with a bruce clone cast in manganese bronze):








Any thoughts on pushing the tip weight up over 50%? Instead of making the main flute from thin material and reinforcing the tip, would it make sense to create the flute from multiple pieces welded or fastened to each other in some pattern that pushes rear weight down and front weight up? Main arm weight contributes to that too, however you don't want that too high or it'll affect the way it falls/sinks/lands.

Don't worry about your English, feel free to post bilingually so we have a record of your native intent along with a best effort in English :-)

Happy to have someone to discuss this with! Very happy that you're working on it and sharing the design.

Perhaps I can help you with the sharing depending on your intent commercially.

On the end of this page is cutting file: https://files.fm/u/p77sss7v

The final shank will be bigger. The final stock will be big minumum like this one or bigger.