Anchor Size

[eje]

Anchoring.com has tables with recommended anchor sizes for various sized boats I do understand there is more to selecting an anchor than simply the length of the boat, but my question is this:

They recommend a 45.5# hinged CQR/Plow for a 33-49 ft boat, but a 30-40 ft boat only needs a 22# Wing/Delta. Other than the hinge these anchors are the same basic shape. Why would the same boat need a hinged plow twice the size of the delta?

[rslifkin]

Different size charts may have had different criteria for wind speed, etc. So some are more conservative, others will give you an anchor barely adequate to handle a light breeze on an otherwise calm day.

[kmacdonald]

Just dont oversize it and you'll be OK.

[psk125]

Different anchors may also only come in certain sizes. If a company only makes a 200 pound mushroom, they are going to say it works for boats from 8' to 60'. If they add a 10-pound version, they'll differentiate, maybe suggesting that it should be used for boats from 8' to 12', as a lunch hook. Lots of variables. Displacement, as well as length, makes a difference in the size anchor you might want. Chapman's has a good, conservative chapter about anchors and anchoring that could be useful to read.

[Mike OReilly]

So... right off the bat I would ignore any sizing chart that lumps such a huge ranges (33-49 feet or 30-40 feet) into one recommendation. Clearly they are not to be trusted.

Secondly, do yourself a favour and get a better anchor. Both these are poor performers compared to most modern anchors. Look at Rocna, Manson, Mantis, Excel, Spade, or other similar "new-gen" anchors. They are just better.

[eje]

I wasn't trying to generate a metaphysical discussion on anchor sizing. I was just commenting/wondering out loud on the apparent difference in holding power of two anchors with similar shape -(other than the hinge)

[fish53]

The vessels total tons (in long tons) times 6.8 for a decent estimate of weight for a working anchor. If you want a simple discussion of the qualities of various types of anchors you're asking for opinions, and you know what that means.

[Annie in WA]

another criteria is where are you cruising. We spent 20 years in the Pacific Northwest vacationing on or boat with protected harbors and sticky mud. Now we are cruising full time on the Pacific Coast of Mexico with more weight on board, open roadstead anchorage s and tropical storms. We did great with a 33lb Bruce and 50ft of chain in the PNW but now have a 55lb Rockna and 250ft of chain with a 1200 watt windlass. We are a 34ft double ended double headsail sloop.

[thinwater]

Oh dear, here we go....


a. Google "anchor testing" to see some third party stuff.



b. Google "Panope anchor" for some very good video and discussion of anchor behavior.


c. Anchoring.com is all knock-off stuff. There is just no way of saying what you are looking at. Honestly, there isn't anything on that site I would buy.



And finally, read up on anchors. Books. Forums. There are a lot more variables than weight. For example, a given anchor will hold 10 times as much in good sand as in soft mud, so arguing over 5-10 pounds is sometimes overblown. Perhaps we should start with "what do you have now and what has your experience been?"

[thinwater]

Originally Posted by eje

I wasn't trying to generate a metaphysical discussion on anchor sizing. I was just commenting/wondering out loud on the apparent difference in holding power of two anchors with similar shape -(other than the hinge)

Delta



Excel



I've had both. Very similar looking. The Excel holds about 150-180% of the Delta and is much better at setting in difficult bottoms.

The point is that apparently small differences in shape can make huge differences in function. Try putting the wings on a plane upside down. Looks pretty much the same.

[kmacdonald]

The dinosaurs have returned to proclaim bigger is always better and anyone that says different is stupid or not credible. They also claim to know more than the new gen anchor manufacturers but stop short of producing any scientific data. A n=1 anecdotal account is all the proof they deem necessary.

[jamhass]

Basic approach to anchor sizing:
1. Buy an anchor
2. Install it on the boat.
3. If passers-by don't laugh, go buy a bigger anchor and return to item 2.
4. Continue until #3 is satisfied.

[MicHughV]

the trick is to have more than one anchor at your disposal....if one doesn't do the job....try another...
have two different one's ready on the bow.....two more below as alternatives...

and then....very important...regardless of anchor selection...know how to deploy and set it correctly !!!

[kmacdonald]

My Fortress FX-7 (4 pounds) blows the doors off my Rocna 15kg (33 pounds) in soft silty mud.

[rslifkin]

Originally Posted by kmacdonald

My Fortress FX-7 (4 pounds) blows the doors off my Rocna 15kg (33 pounds) in soft silty mud.

Bigger is better within the same design generally. But the fortress is a very different design than the Rocna. Much more surface area at a given weight. It's basically a trade-off anchor. It's not as versatile in all bottoms and situations, but in the situations where it works well (such as soft mud), it works *really* well.