Boatnerd Discussion Forum

Larry wrote:To be accurate, and have a large enough anchor, wouldn't the correct weight be calculated on the loaded weight? Just a thought.

The "one pound of anchor for each ton of ship" rule of thumb is a handy way for a layperson to estimate the weight of an anchor that might be on a ship. It is not the way that naval architects / engineers decide the size of an anchor to put on a vessel; actually do take loaded displacement into consideration when choosing an anchor.

The rule of thumb is just an expression of a coincidence; it just so happens that things roughly work out that way, and that is a consequence of physics and the conversion rate between arbitrary units of measure (tons and pounds).

Another thing that people seem to overlook is the part played by the anchor chain itself. There is a substantial amount of weight in all that chain and it plays a major role in the process.

Lets not forget that the weight is not the sole force in anchoring - the flukes are designed to grab the bottom and dig in.

Larry wrote:To be accurate, and have a large enough anchor, wouldn't the correct weight be calculated on the loaded weight? Just a thought.

Yes, you would think so.

To be accurate, and have a large enough anchor, wouldn't the correct weight be calculated on the loaded weight? Just a thought.

Brent wrote:The Gott's weight is 35592 tons.

That's her gross tonnage, which confusingly enough is a measure of her internal volume, not a measure of her weight.

The Gott's weight is 35592 tons. Rule of thumb the anchor should be about 35500 pounds or about 17.7 tons. This is gust a way of estimating anchor weight and I am sure that some are more and some are less.

Guest wrote:

Brent wrote:The normal rule of thumb is 1 pound per ton of ship.

Using that equation, a footer would weigh in at 45 million pounds.

I was under the impression that a footer's lightship weight / displacement was something like 20,000 - 25,000 tons. Using the 1 pound of anchor for 1 ton of ship equivalency yields a 20,000 to 25,000 lb or a 10 to 12.5 ton anchor.

Awesome, Thanks guys. That puts things in perspective. Pictures of that retrieval would be awesome! how did you guys manage to lift it, a crane barge or bags? How many anchors do you think are sitting on the bottom? (not from wrecks)

Pete in Holland wrote:In the early 80's, I worked with a salvage crew in Alpena. A 1000'er dropped its anchor and 640 feet of chain in the waters off Stoneport. We were given the task of retrieving it.

I remember being told it was a 9 ton anchor. Chain links were made from 2-3/8" round stock.

Somewhere I have photos of that whole recovery expedition. Pretty exciting for a college kid at the time.

If you find the pictures of that, please share! Would love to see them.

In the early 80's, I worked with a salvage crew in Alpena. A 1000'er dropped its anchor and 640 feet of chain in the waters off Stoneport. We were given the task of retrieving it.

I remember being told it was a 9 ton anchor. Chain links were made from 2-3/8" round stock.

Somewhere I have photos of that whole recovery expedition. Pretty exciting for a college kid at the time.

Brent wrote:The normal rule of thumb is 1 pound per ton of ship.

Using that equation, a footer would weigh in at 45 million pounds.
Sounds a tad high for an empty boat, and about 1/4 of what a loaded footer will weigh. Do they use that equation figuring loaded, or empty?

The normal rule of thumb is 1 pound per ton of ship.

A spare anchor for the Gott or Speer layed on the dock at the Soo Warehouse for many years. It was stamped 22500 lbs.

newbie wrote:I was wondering if anyone knows the weight of an anchor of a 1000 footer? (assuming they carry the largest anchors) they all look big.

I had heard 13,000 pounds.

I was wondering if anyone knows the weight of an anchor of a 1000 footer? (assuming they carry the largest anchors) they all look big.