What’s your boat’s displacement?
If you think an Excel 5 is the right anchor, I’d have thought 10mm chain is the go. As to length, I’d have thought 40m is the minimum and 50 or more would be better.

woko said..
Time has come to replace anchor & chain. I'm reasonably sure I'll go with the excell #5 anchor. The quiz is chain size, originally issue was 30mm of 10mm, which weighs 69kg, 45m of 8mm weighs 68kg, I have both 10mm &8mm Gypsy's, the 8mm is $130 cheaper, either way a 14mm top rode will be onboard. Thoughts about 10mm v 8mm ?

Hi, I would go 8mm high test galvanised, readily available from Sydney lifting located at Mount Kuring-Gai NSW 2080. I have used them and it was an easy experience. 👍

Woko, I was thinking of going up to 10mm on my 4000kg 38ft catamaran. She does have a fair bit of windage but much less momentum than most. I was hoping to get 10mm to increase momentum at anchor - reducing accelerations. But the cost of a new gypsy has me going back to 8mm with a bigger nylon bridle snubber. I would have thought that 10mm woulde be the case for a big heavy Spray - she can take the weight. If youer anchor winch can do it, why not get the heavier chain? It is a couple of sleeps at anchor compared to going into a marina. If you trust your setup the money will be paid back soonish with good sleeps in windy anchorages - and less chance of losing yor boat (And you don't want to be the next in our series of "Stupid sailors getting themselves - and others - into danger and polluting the beaches with their yachts")

No idea about chain size (or anchor size), but I love our Excel 5 on a 5 ton low windage 36 foot mono.
We replaced a CQR with an Excel, a Danforth with a Fortress and sundry crappy dinghy anchors with a Mantus and every time I have been shocked with the improvement both in holding and in ease of use. The Excel comes up much cleaner which is a real boon when dealing with Port Stephens mud. I think you’ll be happy with the brand of the new hook.

Accelerating quickly would be a novel experience on a spray ! But I take your and kankama's points of the heavier chain being a more comfortable ride in certain circumstances. Cheers