RobbieW
Well-Known Member
Interesting article on 'Anchor Testing and Rode Loads' in Practical Sailor at the moment. A critical look at the 'straight pull' approach currently taken by many.
Anchor Testing
- Thread starter RobbieW
- Start date
Blueboatman
Well-Known Member
Refreshing intelligent read, eh?
Practical Sailor has survived rather well since its creation, sans adverts.
Straight line anchoring, don't bend it like Beckham!
Practical Sailor has survived rather well since its creation, sans adverts.
Straight line anchoring, don't bend it like Beckham!
Mark-1
Well-Known Member
I think most sailors instinctively agree with this, but good to see my own predjudices confirmed in print.
So what did we find? First a quick explanation of the accompanying graphs, which are based on hundreds of pairs of readings. In generating the graphs, we focused on the maximum or peak loads, since we regard the extreme high loads to be of most interest. (No one wants to base their anchor choices on the lowest loads.) The curves for lower windspeeds are based on actual data; the extrapolations for the higher windspeeds are generated using the formula for the plot. The charts tell the story. The maximum loads decreased with increased scope—hardly an earth-shattering discovery. More important was the amount of load, which generally stayed below 700 pounds at the scope ratio normally recommended for anchoring (at least 7:1). Of particular interest was the fact that virtually all of the peak loads were shock loads, caused as the boat veered about in the wind. However, as the scope ratio increased, the peak snatch loads reduced until at 10:1 scope they had almost disappeared.
We never experienced a long sustained load. The load would develop, to whatever maximum over 15 to 20 seconds, peak and then decrease. This is in complete contrast to how anchors are normally tested, and the basis of those “holding capacity” figures.
Ex-SolentBoy
Well-Known Member
Good read, but they did it in flat water and admit that waves can significantly increase the peak loads.
They did hint a bit about bendy shank modern anchors as well.
They did hint a bit about bendy shank modern anchors as well.
Mark-1
Well-Known Member
Good read, but they did it in flat water and admit that waves can significantly increase the peak loads.
But they also said peak loads can be eliminated with enough scope. Which I think most sailors know, but I've seen that denied on these forums.
Ex-SolentBoy
Well-Known Member
Not by me!
Elimination though was at 10:1 which is quite hard to achieve for many given a deep keel and over a metre freeboard.