In Jervis Bay it can occassionally get quite ugly if the southerly swell gets in so you have to have a good mooring and look after it if you don't want your boat ending up on the beach or worse still, the rocks!
This 30 second video was taken a couple of days after a recent event.
When this swell came through I was delivering a yacht from Airlie Beach Qld to Jervis Bay NSW and we were stuck 800NM away at Southport Qld so even if we'd wanted, we wouldn't have been able to do anything else to make things safe. It's all about pre-incident planning.
Unfortunately, while we were at Southport, my great mate Neil (Centre) got the bad news that his yacht "Element" was one of twelve on the shore. So we did the only thing that we could, went to the pub and invented a new drink for him called "Element on the rocks!"
Many boat owners and even more insurance companies don't like it here because of the risk of damage but this is Tondy's home and when it's good it's very very good so I take a calculated risk.
I manage that risk by inspecting my mooring at least every three months and swapping out components regularly. I purchase all of the components (and keep the receipts), splice all of the lines and install all of the gear myself.
I usually take my GoPro video camera when diving on the mooring so that I have video evidence to keep my insurer happy. (I use Pantanius and they have been great.)
I also get an annual inspection by the local mooring contractor.
Tondy's displacement if fully laden would still be under 10 tonnes.The sea bed here is about 1 metre of sand sitting on volcanic rock (basalt?) so I have found the following set up works best for me.
1. One 350kg railway wheel chained to a second 350kg railway wheel (side by side) with heavy chain.
These wheels bed themselves into the sand over time and therefore it would take an immense amount of sand movement to expose them and they are hard to pull out of the sand due to their flat profile and weight. I'm not a fan of concrete blocks because they lose nearly half their weight when you immerse them in water plus they don't bed into the sand and so they just bounce along the bottom when put under extreme loads.
I like to use at least two cable ties on any shackles that are easy to inspect, like the ones on the swivel at the surface because it allows me to quickly see if there has been any loading or undue friction placed in that area and I inspect these every time I'm on the boat and swap them out regularly.
For the large shackles on the sea bed I use galvanised wire mousing on galvanised shackles. I found out early on that stainless wire on Gal shackles can cause galvanic corrosion due to the dissimilar metals which can result in the thread of the shackle pin corroding in a very short time and then you are relying totally on the mousing to hold the pin in. I normally throw a couple of cable ties on as well just for good measure.
Risk is risk and no matter how calculated you are, bad things can still happen.
This mooring system is over engineered because I have allowed for the possibility of another vessel (or vessels) dragging it's mooring and getting hooked up on mine whereby my mooring would need to hold the extra load. This nearly happened a little while ago when a heap of junk "Mooring minder" broke free and hit Tondy causing $8000+ damage to her bowsprit before then going on to hit two other boats.
There is talk (in this video below) of a breakwall being built but I'll believe that when I see it and even then I'll keep my mooring 'bombproof".
One last thing about moorings here is that I am situated in a marine park and new moorings now have to be the "environmentally friendly" type to preserve and promote seagrass in the area. Existing "old school' moorings such as mine are allowed and I actually believe that my set up is no worse than the "Environmental' setups that I've seen in this area. I'm happy to do anything that helps the seagrass but I am yet to be convinced with any of the systems around so far.