I just come by chance to this thread.. and I’m horrified to read some comments and suggestions!..
Please allow me to have different opinions!.
First I should introduce myself: I’m Alain POIRAUD, some of you know who I am: the designer
of the SPADE anchor
and also a living aboard
since more than 13 years now.. and I pretend to have some knowledge and experience on this subject.. :0)
I’m not coming there to say the Spade anchor is the World best… we have never say that.. they are already enough World best..
Let’s look at these different points:
"The original Bruce is a good anchor. I wouldn't say the best, but still a good anchor."
Up to my opinion, the Bruce is not “the best” but, like others, it has some advantages:
- it is THE or one of the best setting anchors, and this is due to a very good study done by Peter BRUCE. It is interesting to read the original Patent of this anchor.. pages and pages talking about penetration, angles and so on.. As Alan Wheeler pointed out “This is mainly in angles and shapes of flukes and angle and shapes of the shoe/board.”..
But also as TALBOT states rightly
"Main reason for the popularity of the Bruce is not its holding power, but the easy stowage on the bow."
And John D was also right “The Bruce does not seem to do really well overall.” .
In ALL tests I have seen, all over the world and without any exception, the Bruce was one of the worse for holding.. and on the opposite to what Alan Wheeler says, “a Bruce will hold and hold well, because of it's shape.”.
No, sorry, the Bruce will set well because of it’s shape but doesn’t hold well as it doesn’t have enough surface area..
.“The Genuine Bruce was designed for the North sea oilfields.”
This is only a “Pontoon Gossip” Peter Bruce has ALSO designed anchors for oilfields, but they are completely different from the “Bruce” which is used on our sailing boats.
“The Bruce is unrivalled in a soft mud bottom.”.
WAOOOOOO.. I have to agree: - the poor holding of the Bruce is unrivalled in a soft mud bottom
“I am really trying to find an all-purpose anchor. “
Sorry but it doesn’t exist. When designing an anchor you should compromise between several factors to have an anchor which give satisfactory results in most situations. But this specific product can be exceeded in sand by a product specifically designed for sand or in soft mud by product…
Over several years, “Practical Sailor” have tested anchors in most seabeds and conditions (setting – veering etc..)
No the Spade, has not been the first in all tests.. best in holding in sand; second for setting in sand but only at the sixth position in mud… but as PS said: “The multiple-test approach and the SPADE's consistent showing, make it the first product to make two appearances on Gear-of-the-Year lists."
.“So basically... what I'm getting is that I really need to have a good variety of anchors to work in many types of bottoms that I will encounter.”
Not really, just because you will not know for sure what will be the type of the sea bottom you will anchor in.. IMHO nearly all anchors work quite well in “standard” type of bottoms.. and nearly all have problems setting in weed, and hard bottoms (hard sand, coral
.. ) So, take an anchor designed for these “difficult” grounds and it will have all chances to work also in “standard” bottoms. (see "How's" of what makes a good anchor.)
"A heavy anchor is not the only answer,".
Right, as lightweight aluminium anchors will have, size for size, the same holding than heavy steel
anchors but at half the weight..
“The holding power of an Anchor, is not in it's size”.
Again, sorry but up to my opinion, the holding power of an Anchor, is related to it's size (surface area) and to the shape of this surface (concave the best)
Now my turn to explain the "How's" of what makes a good anchor.
A good anchor must first and foremost hold, and ideally increase its holding power as forces incur heavier loads on the vessel. If the load on an anchor exceeds the holding powers of the seafloor in which it is planted, the anchor must slowly drift, conserving its maximal and constant resistance and should ideally never disengage from the seafloor.
In order to hold, an anchor must first deeply penetrate and set in the various types of seafloors
To ensure a speedy setting in virtually all types of seafloors, there are a certain number of physical characteristics to respect:
Regardless of the tool, depending on the substance, two parameters ensure good setting:
- The proper setting angle and
- The highest amount of pressure possible.
The optimal setting angle adapted for anchoring
is the “wood chisel.”
Plow anchors, once resting on a hard surface, assume a “spatula” angle with respect to the seafloor. Once the tip encounters a softer spot, it embeds by measure of its own weight to its upper apex, thereby assuming the “chisel” angle, which allows the anchor to completely embed. As previously mentioned, on a compact or weedy seafloor, the plow remains in its “spatula” angle, without setting.
Anchors such as the old FOBs, with a bulky hind portion, tend to do a “handstand,” alighting on their flukes. At this point the flukes meet the seafloor almost perpendicularly, raking the surface without setting.
Three principle examples of this are the Bruce anchor, the German “Bügel” anchor and the SPADE. All three approach the seafloor at an angle superior to 90 °, up to 120 °. These anchors have the reputation for rapidly setting in a majority of seafloors.
Razor Blade Angle:
This angle, superior to 150°, is typical of plate or articulating anchors (Danforth – Fortress). They necessitate contact with a sand ripple or soft area for their fluketips to pierce the seafloor surface; they then assume the chisel angle and set. On compact or weedy seafloors, these anchors shave the bottom without taking hold.
Pressure is defined as force divided by surface area. Here, we have two variables: force (daN) and surface area (mm²). The force must be as high as possible and the surface as small as possible to maximize the pressure. A number of anchors have sharpened setting edges, as do the Fortress
, the Bügel or the Spade.
The distribution of weight in the fluke tip makes sense in anchor design as it facilitates setting. We can see a great disparity amongst fluke ballasting in various anchors: The fluketips of flat anchors and the CQR
comprise between 12 and 16 % of the total weight of the anchor, while the ballasted tip of the Delta
contains 28% of its total weight. The best distribution of weight is the SPADE anchor, with 47% of its total weight in its point.
We can see that an anchor will tend to set more easily in the seafloor when it launches with the appropriate penetration angle coupled with the maximum pressure on its fluke tip.
Anchor holding depends on three parameters: its surface area, the form of this surface and the anchor’s auto-stabilizing capacity, meaning its ability to stay completely embedded.
In general, plate anchors without a stabilizing stock (Britany – FOB) offer only a weak holding capacity. As soon as force upon the anchor increases, these anchors quickly rotate and disengage one fluke at a time.
Anchors with a stabilizing stock (Danforth – Fortress) are more stable since their stock prevents rotation, therefore hindering (but not preventing) the anchor from dislodging. However, once their holding capacity is exceeded, they rotate and disengage without any chance to set again.
Once set, auto-stablizing anchors (Bügel, Delta
, Kobra, SPADE, and Oceane) remain fully embedded in the seafloor, their holding power limited only by the seafloor in which they are implanted. Under high load, these anchors will slowly begin to drag when they reach their maximum holding capacity without disengaging.
The larger the surface area embedded in the seafloor, the better the hold. Should the weight of an aluminium Fortress
and a steel
Danforth be equal, the surface area of the Fortress would be three times as large, offering the higher holding capacity.
The form of the anchor surface is also important in determining holding power. The concave shape has by far the strongest holding coefficient, followed by the flat and the convex shapes.
They are many other factors, but setting ability and holding are the most important ones.
Now, lets talk about other mooring
related subjects.. where I don’t have ANY commercial
Before giving my own opinion on these subjects, I will be pleased to invite those of you who want to know these points more deeply, to have a look at the very well documented Web page “Tuning an anchor rode” http://alain.fraysse.free.fr/sail/rode/rode_b.htm
"The chain plays just as important a role.".
For me the chain is the part that connects the boat to the anchor, and that’s all… OOPS sorry!.. this is also the best means to avoid shaffing of the anchor rode on the seabed..
. “The heavier chain will help to make the anchor dig in,”
NO, take any anchor with a wrong penetration angle and a bad weight distribution in hard sand. You can take any chain size you want. Your anchor will NEVER penetrate.
“The chain will also play a bigger part in damping any oscillation on the anchor rode. to act as a shock absorber” .
YES True.. with only light winds when nobody cares about the anchor holding.. but as soon as the wind
build up (25 to 30 knots) and when you really need damping, your chain is nearly bar tight and doesn’t procure anymore damping effect.. that’s why you should always use some nylon rode or at least a snubber.
."The chain also acts as a means of keep the attitude correct, "
No, if the anchor alone is not able to keep the correct attitude, then the chain will not make it a good anchor
."Chain is more important to the holding power than the anchor is,"
If you believe this point.. it is time for you to think about changing your anchor.. :0)
The increase of holding given by the chain itself, compared to the holding of the anchor is just negligible.. It is the anchor which give the holding and not the chain..