Nice summary - the recommendation is that it should be a minimum of one size larger and I tend to think (when thinking of other things) that minimum is not enough.
An alternative view might be, rather than carry that whopping great monster about on the bow.
For mud and sand, where surface area might be the issue - why not carry a Fortress
, they have low weight for monstrous surface area, easy to deploy, stores well. For weed, I have an open mind on whether bigger is better, why not carry the stockless anchor
, see the current
Supreme thread and carry that recommended (USL code) sized anchor
as per normal.
If you choose a style and then go two sizes bigger, what do you do about back up? (one surely would not go to Newfoundland
with only one anchor?). And if you feel the need for the '2 sizes big' you presumably have the same philosophy for the spare (or when you lose the primary you'll need abandon the cruise) If your USL size is 25kg - then 2 sizes up is 40kg? As a spare its difficult to store unless you have 2 bow rollers), its difficult to get to the bow roller (from wherever you store it) and connecting it up and deploying it would be a nightmare.
My example at the end of my post suggests a 15kg anchor if loaded (I accept its probably the ideal seabed) will develop a holding capacity of 5,000kg - this seems to leave an awful lot in reserve for less ideal substrates (for which you also have the Fortress). It also suggests that in a Storm with wind
in a constant direction - it will simply bury itself, further (and a nightmare to retrieve!).
One of my fears would be that under normal conditions you simply cannot set a '2 sizes bigger' with the engine
of a yacht that should be using the recommended USL size. By set I mean bury the fluke and most of the shank. Consequently under normal conditions your anchor is ready to fall over, rather than shuffle round in a wind
or tide change. It might stay set, it might re-set by itself - but there again - it might fall over, catch a bit of seaweed and never re-set. I'm not denying the value of as much anchor as you can get, whether that's one big or 2 smaller ones, in a breeze - the weakness is in normal conditions, anchored in a tidal estuary.
I agree with you that 5kg is neither here nor there, so to upsize from 15kg to 20kg is not an issue, but upsizing from 20kg to 33kg is slightly different and then 33kg to 55kg?
Its an Excel thread, so it will be interesting to read views from people who actually use them - but it will be equally interesting to read views from people with other 'modern' or efficient anchors. (I'm not wanting to get into a debate over 'modern' - make you own interpretation, I'll respect it without question!)