Spade aluminium anchor

[Lars_L]

What is there for the disadvantage of a Spade anchor that is made of aluminium? It has the same surface area as its counterpart steel anchor, and aren’t it the surface area which is essential if the anchor hold?
When I anchor, I let the anchor down and then let out a good bit more of chain. Then I pull backward with the engine, but the chain makes the force on the anchor along the bottom. Is the anchor properly balanced, it will bury itself. Then will the weight of the anchor not have any meaning, or?

Fortress anchor is made of aluminium and are well recognized for its holding power. There are disadvantages in certain situations, but it's not because it's made of aluminium, it's the construction itself that has weaknesses.

[chris mac]

I have the A80 on a 26 foot boat. The reduced weight is good for boat balance, and retrieving(no windlass)
The steel versions are rated a little higher for boat weight, but I'm well within spec.
Only drawback is the aluminum shank isn't covered by warranty for bending or breaking, like its steel brothers.
In terms of digging in, it still has the weighted tip so orients itself properly as you pull. Mine sets much quicker than the danforth it replaced, and holds well.
When I get my liveaboard, I will be upgrading whatever is on it to a steel Spade. With a windlass you might as well get steel, if just for their incredible warranty.

[UNCIVILIZED]

Disadvantages would be it's reduced weight causing it to be more difficult to properly set. And also to self-reset if it gets pulled out/loses it's grip on the bottom. A lot easier to bend the shank. Plus it would require more coaxing in order to set well when using it in a tandem anchor setup. Meaning one anchor behind an anchor, on the same rode.

Edit: I'm thinking that it also would have more trouble than a steel anchor when you're moving/being moved down current. Since it's lighter weigh could cause it to sail above the bottom under such circumstances. Something which I've seen written about it, & other light weight anchors, in evaluations/reviews from 20 - 25yrs ago.

[Suijin]

All other things being equal, the heavier anchor is going to dig in better/faster. Certainly a lot of chain dragging an aluminum anchor along helps it to set, but there are circumstances where weight makes a different, such as in grass beds. Also, a heavier anchor is going to stay set and reset better than a lighter anchor (again, all other things, like specific design, being equal).

The danforth design lends itself to lighter construction as it is flat with articulating flukes. But being lighter than most other designs (even the steel version), there are circumstances where it will have difficulty getting enough "bite" to start a set.

I've never used a Spade anchor so can't comment on it specifically, but the general design seems like it would benefit from increased weight, which explains why the lighter aluminum versions are rated lower than their steel counterparts.

[Training Wheels]

I've been using an A100 as my primary anchor for about 5 years. I chose the aluminum as I try to keep the boat light, and I don't have a windlass. It has worked flawlessly for me.

[groundtackle]

Have a look at Panope's vids on our site regarding an aluminum Excel. Link is here:
Ground Tackle Marine
He has shown the Al doesnt perform as well as the heavier steel version but still very good. I played with it and didn't find any negs. No camera on it and feel there was little if any overly long set duration. Couldn't bend it. Leaving it in the water for long periods is not recomended, it is aluminum. It's expensive as it takes additional labour to fabricate properly. We have them on many vessels, stowed as a backup to its identical heavy galv brother. We also have the reverse where the heavy is stowed below deep and the lighter sister is up for vessel performance. Have them on RIBs, cats and race weight concerned vessels. Comes apart for stowage.
ce

[sparrowhawk1]

I think to be fair you would have to compare anchors of the same weight. It seems to me the aluminum would be bigger so you would have more holding power but it might not be able to penetrate grass or hard bottoms as easily. But the main reason I'm posting is to say that I've been using fortress anchors for long-term anchoring and I've had to replace 3/8 inch galvanized chain several times but the fortresses which are made of aluminum show very little corrosion.

[stevewrye]

We have a steel Spade as our primary anchor. Best anchor ever as far as we are concerned. But a little advice when setting it. It sets much better with at least 4 to 1 scope than it does with 3 to 1. If we are going to use a 3 to 1 scope in a tight anchorage I set it with 4 to 1 or more then bring it in to 3 to 1. It took a few times of pulling the anchor out of its set when backing down on it at 3 to 1. At 4 to 1 anchor sets very fast and sticks no matter how hard we back down on it. Amazing what a few feet of chain and angle will do for the spade when setting it. We have never dragged while at anchor with a 3 to 1 scope even in a blow or a 180 change in wind.

As far as the aluminum Spade I think you made the right choice with no windlass.