Open Source Anchor Project

[Cotemar]

This OS anchor is starting to look like the Engineers swing set.

[Delancey]

I think some of my best thoughts while I ride my bike to work. Today I wondered if we should incorporate a bottle opener in the shank? I mean when we're not using it, our anchor just sits there in its underwear drinking coffee and smoking cigarettes in the kitchen, making as more prone to hobby horsing.

Might be nice to give our little anchor some additional utility, another purpose in life. Would be a great marketing tool. We could give anchors away at the boat show!

All in favor say aye!

[Cormorant]

Don't forget the fold-out nail file and scissors. Plus a plastic toothpick.

[Cotemar]

Originally Posted by Delancey

Today I wondered if we should incorporate a bottle opener in the shank? I mean when we're not using it, our anchor just sits there in its underwear drinking coffee and smoking cigarettes in the kitchen, making as more prone to hobby horsing.

Might be nice to give our little anchor some additional utility, another purpose in life. Would be a great marketing tool. We could give anchors away at the boat show!

All in favor say aye!

AYE!!!

[nimblemotors]

Originally Posted by martinworswick

how about having 2 shanks instead of 1?instead of 1 on the centreline you could have 2 with the same slot in style attachment located maybe half way between the centreline and the outside of the fluke,attached at the eye,this would,i'd imagine be stronger when a sideways force is applied,it would also give it 2 'feet' to sit on giving a better angle for the pointy bit to dig in.maybe having 2 shanks would affect its ability to dig in though?thoughts?

A related idea is with my idea of fiberglass shank, would be made in two halves,
two L shapes that would be joined together to form a single shank.
This way they are made with a single fiber that forms the L.
Could just be bolted together, with some separation with a core and have two different slots that fit into. In the pic, the yellow is the core, which could just be another peice of fiberglass (cheap csm fibers).
The red part is the fluke which the L's bolt onto to.

Anyone can make fiberglass parts, requires no special tools or equipment.

[Delancey]

Originally Posted by nimblemotors

A related idea is with my idea of fiberglass shank, would be made in two halves,
two L shapes that would be joined together to form a single shank.
This way they are made with a single fiber that forms the L.
Could just be bolted together, with some separation with a core and have two different slots that fit into. In the pic, the yellow is the core, which could just be another peice of fiberglass (cheap csm fibers).
The red part is the fluke which the L's bolt onto to.

Anyone can make fiberglass parts, requires no special tools or equipment.

If I was designing a composite anchor I would use an epoxy fillet to join my shank to my fluke. The great thing about it is that because its a radius, it is a tapered joint that transitions loads without stress concentrations. By sizing the radius properly it is possible to achieve a material-strength connection, which means the material will break before the joint fails. Usually has layer of reinforcing fiber of the top. Look up "stitch and glue plywood" there's all kinda stuff.

Better yet, Gougeon Borthers on Boat Construction-
http://www.westsystem.com/ss/assets/...k%20061205.pdf


Also, I'm telling you. Forget glass, think carbon/Kevlar.

[Delancey]

Originally Posted by nimblemotors

A related idea is with my idea of fiberglass shank, would be made in two halves,
two L shapes that would be joined together to form a single shank.
This way they are made with a single fiber that forms the L.
Could just be bolted together, with some separation with a core and have two different slots that fit into. In the pic, the yellow is the core, which could just be another peice of fiberglass (cheap csm fibers).
The red part is the fluke which the L's bolt onto to.

Anyone can make fiberglass parts, requires no special tools or equipment.

Composites open up a lot of possibilities, few of which do us much good for the OSA. Here's a lightweight design that is kind of interesting.

[nimblemotors]

Originally Posted by Delancey

If I was designing a composite anchor I would use an epoxy fillet to join my shank to my fluke. The great thing about it is that because its a radius, it is a tapered joint that transitions loads without stress concentrations. By sizing the radius properly it is possible to achieve a material-strength connection, which means the material will break before the joint fails. Usually has layer of reinforcing fiber of the top. Look up "stitch and glue plywood" there's all kinda stuff.

Better yet, Gougeon Borthers on Boat Construction-
http://www.westsystem.com/ss/assets/...k%20061205.pdf


Also, I'm telling you. Forget glass, think carbon/Kevlar.

Great, thanks for being condescending. I'm outta here.

[Delancey]

Originally Posted by nimblemotors

Great, thanks for being condescending. I'm outta here.

Don't be like that. I'm trying to help you.

Fiberglass has poor cyclic fatigue resistance. It's just not a good choice for an anchor that is going to spend all its working life receiving cyclic loads.

Because of this fact, to be structurally sound your anchor would have to be overbuilt, this is in and of itself is directly at odds with your stated objective of making a really lightweight anchor. I think its a fine idea and I wish you the best of luck.

[Delancey]

For those of you interested in knowing how to design a material-strength joint using epoxy fillets but don't have a degree in engineering. You don't need an engineering degree, here's how you do it-

Make a T shape joint out of whatever material (plywood, glass panel, whatever) you're using with a fillet of whatever size looks right on both sides, the length doesn't matter. Probably a radius at least the same size as your material thickness for starters. Clamp your piece with the top of the T down on the table and torque the vertical part sideways until it breaks.

If the vertical part breaks outside the joint, you're done! If it breaks inside the joint your radius is too small or you don't have enough fiber reinforcement over the top. Do it over, but make it bigger or add more fiber reinforcement until it breaks outside the joint.

Also, the filler you are using to make the joint can matter be it high density, colloidal silica, whatever.

[Delancey]

Here's an economic thought for ya. Life ain't fair, cheat.

We are shooting for production by the masses as opposed to mass production, but it's the information age and information is our stock in trade.

One of the problems with we face in achieving maximum efficiency lies in the fact that as a one-off we are a bit hamstrung by having to cut these funny shapes out of a rectangle, this means we're going to end up with a lot of waste material left over.

When you mass produce parts like this you do what is referred to as "nesting" which means you figure out how to organize your shapes to get the highest yield per sheet. This can include optimizing the shape as a part of the design process which we will get to later.

Now here's the thing. There are businesses scattered here and there who do nothing but cut parts all day long. We game the mass production system and solicit quotes from these parts-cutting businesses to give us volume pricing on our cut parts.

When you want an anchor here's how it works - you go to the OSAP website, there's a map, you click on a link to your regional parts-cutter guy's website or contact info, you place your order, two weeks later your anchor parts show up on your doorstep.

You're going to do your part by dressing the edges and finishing the slot in the fluke, adding angles and the roll-bar once they arrive.

Meanwhile the parts-cutter guy already has the his cut-file programmed (usually a set up charge but that's been taken care of), he takes what's left of the previously cut sheet and pushes a button. Packs it for shipping. On-demand anchor parts.

He's happy because he sells cut parts, we're happy because we made the system work for us and spent less money.

CNC plasma cutting will be the cheapest for steel. http://en.wikipedia.org/wiki/Plasma_cutting

CNC router could be an option for aluminum.
http://en.wikipedia.org/wiki/CNC_router

[kitehawaii]

Cut the curved spade part out of 55 gal barrel.

[avb3]

Originally Posted by kitehawaii

Cut the curved spade part out of 55 gal barrel.

And if that is not strong enough, layer several sheets together clamped with bolts. It may work... Barrels are ubiquitous.

[Delancey]

Originally Posted by avb3

And if that is not strong enough, layer several sheets together clamped with bolts. It may work... Barrels are ubiquitous.

Barrels could be viable. We're still waiting for data on shank and fluke materials thicknesses for 20kg/44lb class anchors before we can start designing the fluke. Ideally from as many different brands possible. Anyone?

[Cotemar]

Barrel anchors may work out well. You can get them anywhere on earth for free.
Its green and who doesn’t like being green.
You can cut a steel barrel with regular everyday tools.

They will last a long time even without galvanizing. Just slap on some metal paint and your good for a long time.