Advise on anchoring set up.

[kas_1611]

Many areas with coral reefs don't like you anchoring at all as the anchor kills the reef and as such have started to put in mooring buoys to prevent this damage.

If you are going anywhere near coral, or think you maybe, or for that matter limestones, hard sandstones (gritstones) or any igneous/volcanic rocks then ditch the rope and go all chain.

60m of 8mm G70 weighs around 85kg or 185lbs in American, which is your average human, so all this talk of saving weight doesn't add up to much on a cruising vessel when you consider 210litres of water weigh 210kg/462lbs, 210litres of diesel weighs around 180kg/370lbs then there is all the food, bikes, toys, dinghy, outboard, safety equipment etc etc. Given you will only save 60kg by having 15m of 8mm but risk losing a $$multi-thousand yacht ask yourself is it worth it.

Keiron

[noelex 77]

All chain is the gold standard that long distance cruising boats should be aiming for. With reliable boat anchor winches and high tensile G7 chains the weight disadvantage is less important than ever.

If you are ever caught out having to use to use a line rode in a coral, rocky or foul bottom where there is a significant abrasion risk, there are a couple of solutions. Even if you have all chain rode these options are worth noting in case you lose your chain.

1. Adjusting the scope so the rode is above the bottom.
While we think of anchor holding power as related to scope it is really related to the angle of pull of the anchor shank off the bottom. If there is one link of chain left on the bottom the anchors holding ability is not practically improved by letting out more scope.

If you are diligent enough to adjust the scope based on the wind strength and current so that the rope is above the hazards, but there is always some chain on the bottom your holding ability will not be compromised. There comes a point with stronger wind where this is not possible and the chain will lift off the bottom, but this happens with an all chain rode at only a slightly higher windspeed. In some anchorages dead lumps of coral, rocks or debris can be a long way off the bottom and the system does not work (as well as live bommies, but you should avoid contact with these anyway for the health of the coral). With these cautions in mind it can work surprisingly well.

In light wind you need to be prepared to adjust the scope to very low numbers (less than 2:1 if you have little chain).

2. Buoy the rope rode.
The idea is much as above, but to create an automatic system. In strong wind the force will still sink the rope and it will work normally. The floating rode is a hazard to other boats and this risk needs to be considered.

Originally Posted by Franziska

Dynema is very chafe resistant.Would it be strong enough in coral areas? Coral specialists,looking forward to your comments.

I am surprised there are no reports of sailors using dynema for an anchor rode. In abrasion resistance it would lie somewhere between chain and conventional nylon or polyester rode. One drawback is that it floats, but this could be overcome with a kellet or a small amount of weight added to the core (like leaded line).

[Franziska]

@noelex

I am surprised too that there are no reports on using dynema.
Suspect it has to do with the fact that it does not stretch and introduces high loads in the vessel structure.
Still there are means to overcome this, be it riding weights, snubbers, dampening devices or a long nylon line before.
Maybe someone has tried it we'll see.

[Southern Star]

Unlike chain, Dynema will still be susceptible to being sliced by coral. or sharp rocks on the bottom. In addition, the catenary effect of the heavier chain causes the angle of the chain/rode (and the corresponding pull up on the anchor) to be reduced in light to moderate winds. This improves holding power.

Brad