Most setting issues with Fortress anchors are because:
• The shank / fluke angle is set to 45° and the bottom is a hard soil. While the 45° angle will dramatically increase the holding
power in a soft, silty, soupy type of mud, the anchor is likely to bounce along the bottom and not set in a harder soil at this angle. The 32° angle should always be used in these cases.
• The Mud Palms, which are included with all Fortress & Guardian anchors, are not installed. The Mud Palms
lift the back end of the anchor up so that the flukes take a more aggressive angle into the sea bottom.
• Of course, falling back too quickly, using too short of a
scope, and difficult bottoms like
grass, weeds, and rocks can be problematic as well.
As I posted elsewhere, it is our firm contention that a properly set and well-buried Fortress anchor, with its two massive precision-machined and sharpened flukes, is not more likely to break free from a sea bottom during a
wind or tidal shift than other anchor types, particularly those with far less surface / resistance area.
This contention is based upon the opinion of a 40+ year US
Navy soil mechanics and anchor design expert, the 25 years of testimonials we have heard from Fortress owners all over the world, particularly from those in our
hurricane region and "backyard" here in south
Florida, as well as from independent test results.
One such independent test was done by the Sailing Foundation, in which they conducted straight, then 90°, and finally 180° pulls on the anchors tested. A 24 lb Fortress model FX-37 held to the maximum of 4,000+ lbs in the three pull directions, and no other much heavier
steel anchor (i.e. Bruce,
CQR, Davis,
Delta, Luke, Max) was close.
All of that noted, we will readily acknowledge that sailboats oftentimes do not have the
engine power to back down hard enough on the more massive Fortress anchor to bury it deeply, and therein lies a key issue in how it performs (or not) during off-center loads.
Here's an interesting comment from the Sailing Foundation test which illustrates this point:
The Fortress set so deep that the rode had to be hauled in to 1:1 and significant power applied to rode by the 83,000-pound tug to break it free. It is doubtful that a sailboat would have windlass power to break it out. Perhaps large primary winches or a rising tide might be adequate. However, it is also doubtful that a sailboat could have set the anchor that deep in less than a full hurricane.
Our company founder/owner, who was a lifelong and very adventurous boater with a 1,000 mile trip up the Amazon River, several Atlantic crossings, and a
circumnavigation on his resume, said that "once an anchor breaks free from a sea bottom, it is oftentimes no longer an anchor....it is a massive ball with no remaining sharp edges in which to re-penetrate into the sea bottom".....and in this circumstance, re-setting is not possible.
This is one of the reasons why we note in our "Safe Anchoring Guide" literature that if you are expecting a wind or tidal shift, its a good idea to set two anchors for maximum
safety.
Otherwise, a large heavy plow type might serve your sailboat better.
Safe anchoring,
Brian
Re: Leaving Your Boat at Anchor on a Windy Day
"
from the chain ferry...
. 
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