Installed a helix mooring anchor last weekend... - Page 7 - SailNet Community
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post #61 of Old 11-04-2012
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Re: Installed a helix mooring anchor last weekend...

Harry Tams,

I googled the anchor/mooring system that you mentioned and here is my take on it. These helix anchors are pretty small meaning that the holding power per helix is going to be pretty low. In a relatively hard bottom, this would be okay for a smaller boat but not a larger one. The trick with helix anchors is that you need to match them to the bottom. The professional installers will often take a sample from the bottom to analyze so that they can estimate the holding power from the different size helix's. Also, the stated weight is pretty light which makes me think that these are lightly constructed. It is quite possible that they are plenty strong to resist bending, my concern would be the reduction in strength related to corrosion because thin pieces lose a greater percentage of their strength for the same amount of corrosion.

Regarding the Octopus mooring system, I really dislike mooring systems where multiple anchors are put together to increase the holding power of the system. The problem is that until you have 5 or greater anchors in a star pattern, there are directions of loading where a single anchor will take all of the loading. If the force on this single anchor is too great, then it will pull out and the next anchor in line will be shock loaded with all of the load and likely pull out. Therefore, every anchor needs to be sized to carry the entire load so there is no need for multiple. There are ways to load equalize in all directions but I am unaware of any that I would trust for a permanent mooring because they are prone to chafe, fouling and sticking. The major advantage of setting multiple anchors in a star pattern is that the direction of loading does not change so that you can use anchors like danforths. Since the helix is symetrical about its vertical axis, the direction of pull does not matter.

In the right circumstances, I feel that a well engineered helix install is one of the best mooring systems possible. However, I feel that a single helix should be used which means that it must be pretty large for a reasonably sized boat.
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post #62 of Old 11-06-2012
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Re: Installed a helix mooring anchor last weekend...

Klem
That's what I suspected. They are light. Discovered they are hollow; not solid. Great for 500kg load minus a safety factor in a temporary setting. Thanks
Goodone1
Did you follow up Helix Anchor and get a cost delivered to Australia? They seem like the best option I've been able to find.
Harry
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post #63 of Old 11-06-2012
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Re: Installed a helix mooring anchor last weekend...

G'day Harry
I enquired about the Wombat system last year but eventually gave up because I couldn't get any specific info about the holding power from the manufaturers/developers. My impression was that they were for smaller than 30 ft-ers. Finally I had a 10ft helix anchor made locally. I'm goimg to attempt to install it Nov. 17th by the method described in the forum. Wish me luck.
Cheers
Goodone1
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post #64 of Old 11-06-2012
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Re: Installed a helix mooring anchor last weekend...

Quote:
Originally Posted by goodone1 View Post
G'day Harry
I enquired about the Wombat system last year but eventually gave up because I couldn't get any specific info about the holding power from the manufaturers/developers. My impression was that they were for smaller than 30 ft-ers. Finally I had a 10ft helix anchor made locally. I'm goimg to attempt to install it Nov. 17th by the method described in the forum. Wish me luck.
Cheers
Goodone1
I do wish you luck!

And I also wish you will report to this group how it went.

Thank you in advance.
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post #65 of Old 11-21-2012
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Re: Installed a helix mooring anchor last weekend...

Harry
With the help of three friends, I installed my jerry- built helix anchor using YARDPRO's 'PVC pipe' method over the weekend. We moored sternfast two metres off the wharf and secured port and starboard bowlines to the river bank and a houseboat moored nearby.
On our first attempt we snagged something about 2 metres down and for a while, were unable to screw up or down. We eventually retrieved it with the assistance of a 4WD and managed to drill the full 3 metres on our second attempt. It was tough going... even into swamp marsh !!

If you look closely at YARDPRO's photos, you'll notice the wooden disc fixed to the anchor shaft to keep the shaft in the centre of the PVC pipe. It's a touch off genius that works like a charm!

I apologise for the lack of photos...all hands on deck were busy.

Sean G
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post #66 of Old 11-21-2012
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Re: Installed a helix mooring anchor last weekend...

Hello Sean G
Re: "If you look closely at YARDPRO's photos, you'll notice the wooden disc "

I don't know where to find the photo's you refer to.

I would expect the job to be difficult. 10' (3m) is a long way into the earth!

How did you rig it? Rubber Bungee?

Harry
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post #67 of Old 11-21-2012
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Re: Installed a helix mooring anchor last weekend...

My apologies
The answer to my own question is in the first post by Joel73 on 5/15/08
Harry
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post #68 of Old 11-27-2012
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Re: Installed a helix mooring anchor last weekend...

Greetings Harry
Re: The helix anchor rig
The marina pool depth varies by 1 ft (plus or minus) depending on the prevailing wind and the river flow; which is regulated by a system of weirs and dams upstream. I felt fairly confident therefore just using a nylon rode from the eye of the anchor to the buoy and a slightly longer chain as back-up.

I would have prefered a bungee rode but was quoted about $1000 so I'll see how this set-up works for a while.

I don't really have any hard data to back me up; but I'm sure that if we had hurricanes here, the anchor would hold fast.
Cheers
Sean
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Re: Installed a helix mooring anchor last weekend...

Sean

Re: "...using a nylon rode from the eye of the anchor to the buoy and a slightly longer chain as back-up.

I would have preferred a bungee rode but was quoted about $1000 so I'll see how this set-up works for a while".

A thousand dollars ($1,000) seems like too much 'profit' for some good quality tested rubber extrusion with attached fittings.

Can anyone assist with a more reasonable source of rubber (bungee type) mooring rode that can replace the use of chain for a permanent mooring?
Harry Tams
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post #70 of Old 11-27-2012
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Re: Installed a helix mooring anchor last weekend...

There has been quite a bit about helix type mooring, around Sydney in relation to protecting the sea grass. I haven't had time to look it up but I think I read it in the Afloat magazine.

Simon
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