Mike,
The type of anchor you choose is often determined by the type of bottom you drop the hook in. For example some anchors do better in soft mud then others but won’t preform as well in clay and hard mud. Size is partly determined by the size of the boat and the amount of wind you expect. If you use a chain and rope combination you might want a bigger anchor then if you use all chain.
The Danforth style anchors do well in soft mud because they have a large surface area for their weight. The Fortress has an adjustable angle and if the correct angle is chosen it does very well in soft mud however the Danforth style anchors can have trouble setting in hard bottoms or weeds because they can skip across the bottom. They seem to have more trouble resetting than many other types of anchors.The Fortress which is made from aluminium tends to suffer from this more than the steel models. Shells and small gravel can get in between the blade and the shank on the Danforth style anchor and keep them from opening properly as they tries to reset.
The Bruce anchor is one of the most popular with the Nonsuch group out here. In part I think that is because the newer style of anchors were not available when the boats were first fitted out. People tend to only replace the anchor if it drags or it becomes stuck and they have to leave it behind. The Bruce resets very well and fits nicely on the tongue depressor style bow rollers most of us have. In anchor testing the Bruce does not have as much ultimate holding as many of the newer designs of anchors such as the Spade, the Rocna and Ultra (read ultra expensive). The original forged Bruce is considered by most people to be superior to the knockoff cast Bruce pattern anchors. I used a Lewmar Bruce style anchor for a while but it was cast and not sharp enough in hard bottoms and weeds. On that type of bottom the Lewmar had difficulty in digging in and we would end up slowing motoring around the anchorage dragging the anchor across the bottom while we tried to set it. Occasionally a used original Bruce will come up for sale but they are bought up so quickly the odds of buying the right size are low.
I am currently using a Rocna with the roll bar. It has preformed better then the Lewmar, generally setting much faster. Rocna had problems with a batch of anchors when subspec steel was used. The shanks were bending under heavy loads. Rocna seems to have that problem solved and they were very good at replacing any defective anchors that were sold. All of the new ultra high holding anchors including the Fortress, Spade, Rocnoa and Ultra, if fully dug in can bend their shanks if the boat swings 180 degrees in high winds.
Rocna and other anchor with roll bars have a potential weakness. I have not encountered it yet, but in anchor tests performed in soft mud one of two things have happened. As the anchor drops to the bottom it may land on the roller rather than the tip. In soft mud the roll bar can dig in and keeps the anchor from turning over. The blade never digs in and the anchor won’t set. Alternatively during a 180 turn, which can happen when the current changes direction, many anchors will pull out and reset. In soft sticky mud the gap between the roll bar and the blade can become plugged with mud during the first set. When the anchor pulls free the mud stays in place and the anchor lays on its side so does not reset until the mud clears allowing the anchor to roll upright and dig in.
The Spade, the new Rocna Vulcan and the Ultra anchors do not rely on roll bars but rather use weighted tips to turn them upright. I have not seen any independent testing on the Vulcan anchor. The Spade seems to consistently be rated highly. They are not, however, readily available in Canada. The Ultras are made from stainless steel which is not the best material for anchors in salt water but they look nice on the bow. Another problem with them is cost. At the Seattle boat show the Ultra salesman offer me a discount that in dollar terms was more then the cost of my Rocna and the anchor was still going to cost one three times the cost of the Rocna.
In the future if I am feeling flush with money I will consider tracking down a Spade or Vulcan anchor and give one of those a try.
I own a 26 so you would need a bigger anchor then I have (22 pounds) and I can’t tell you what size. If I were using a Bruce I would want at least 22 or 33 pounds. Remember the Nonsuch is big for 30 feet, has a lot of windage and tends to sail around on the mast at anchor unless you use a riding sail. You tend to have more wind in England then we get in my area which would suggest a bigger anchor. I don’t think you would want to go with less then 15 kgs or 30 pounds.
The heading on the post was Kedge anchor. If you are asking about a anchor for kedging purposes the Danforth style of often best because resetting is not an issue and they have high holding power for their weight. I carry a 20 lb steel Danforth with 20 feet of chain and 200 feet of rope as a back up anchor and for kedging.
Mark Powers
La Reina 26C
Vancouver, B.C.