Is that seahorse blood I see on the roll bar?!
Typical seabed in Greece. Mostly sand, a small amount of mud and thin weed.
Catenary & Scope In Anchor Rode: Anchor Systems For Small Boats
That's fine if you're a mathematician. For sailors relying on the catenary to reduce snatch, Viv's photo is plenty straight enough to give 3/5 of sfa shock absorption.
Well a simple catenary is mathematical and as an Engineer the loads on a catenary is very important when you are dealing with a catenary like in suspension bridges
I use a nylon bridle about 20m in total length (i.e. ~10m each side). This provides enough elasticity in the conditions where the rode is almost straight. And in light conditions it is then purely the chain order which provides for the "elasticity" in the system.
1. 25 kg is already large for a Rocna with your boat. I use a 16 kg Rocna on a 35 ft boat.
So can you advise, from all your experience what combination of chain to rode you think best. I have 60m of 10mm chain on a 50 foot cat (9 tonnes loaded) with a 32kg Rocna which so far has never moved an inch in any conditions. However, I have just spent a bit of time and money removing a 60 kg anchor platform from the front of the boat to replace with a 12kg aluminium ladder frame I built to save weight, so having over 100kg of chain up front of the boat does seem to leave room for further weight savings but I have always believed it to be safer than rode due to the extra weight. Reading some of the detailed posts on here seem to disprove that. So given there must be some chain at the deep end, what do you suggest for chain to rode out of my 60M? And given I always use a bridle on a cat should I go strong dyneema rode or stretchy polypropylene etc ?
Hours of observation using mask and snorkel. I have many photos too, so rewarding in clear Greek waters. Some here Oversize anchors – necessary? although not actually in F6 winds
There is data on the load applied by a boat in reverse - good source is the YM test on propellers a few years ago. A boat and engine combination like Vyvs (and mine) with a 30hp engine achieves a pull in the region of 250-300kgs. Varies according the the prop, but his Bruntons, my Flexofold on my last boat and Featherstream on the current, all with 30hp achieve near the top end of that. A 3 blade fixed would be similar. Data on the loads in relation to wind speed for different kinds/sizes of boats you can get from a number of sources, principally the ABYC and directly from empirical data such as the Practical Sailor tests which show similar loads in the speed range 25-30 knots (F6/7).
On my boat I use all chain, but use a stretchy nylon bridle if the conditions look like they might warrant it. I attach this to the chain and then let out the chain until the bridle is taking the load, and then a couple of more metres, so the bridle can stretch before jerking on the chain.
