hylass
Well-Known Member
[ QUOTE ]
the holding power of the anchor is much greater if the pull is parallel to the seabed and that is where a heavier chain can assist. Also a heavier chain has a larger catenary effect than a lighter one which serves to dampen shock loadings on the anchor
If it were the case that a heavier chain will not have a significant effect on holding power then why are heavier chains fitted to larger boats? This is less to do with the breaking strain of the chain which is far in excess of what is required but more to do with the catenary effect of the heavier chain
IMHO, it is well worth increasing chain size in order to maximise the performance of the existing anchor
[/ QUOTE ]
NO! NO and again <font color="brown"> NOOOOOO </font>
As you said, the holding of the anchor is related to the angle of pull.. but the line can be either chain or <font color="red"> ROPE..</font>
Except if you are using Ship size chain to hold a dinghy, the holding of the chain itself ( <font color="blue"> from our own tests</font> ) is approximately two time its weight.. 30 metres of 10 mm chain weight = 68 kg : holding 120 kg.. but the 30 metres have to be lying on the bottom.. ( <font color="blue"> 120 kg is approximately the force exerted on a 4,5 meter boat by 30 knots of wind.) </font>
<font color="red"> YES YES YES </font> the pulling angle of the chain will be parallele to the sea bottom ( <font color="blue"> Horizontal </font> ) but this is only true with <font color="red"> winds lower than 25/30 knots </font> ( <font color="blue"> see the excel programs from the Alain Fraysse's Web page</font>) and with winds lower than 25/30 knots, nobody care about his anchor..
<font color="green"> Please note that I'm ONLY talking about rough weather conditions where anchoring could really be a problem and with "normal size" chains. </font>
With winds greather than 25/30 knots, your chain is nearly bar tight , then its pulling angle will be <font color="red"> NEARLY </font> the same of an all rope line, your "bar tight" chain will no loger give any "catenary" effect and will not dampen shock loads on the anchor, that's why, with an all chain rode, you should <font color="red"> ALWAYS </font> use a snubber.
Why are heavier chains fitted to larger boats? to increase the breaking strain!. Again if you look at Al's web page you will see that there is not only static loads but also dynamic loads and that the (short) pic of load can reach and even overcome the breaking strain of these "big" chains..
On this side of the "Big Blue" most boats are using only a small lenght of chain and then rope.. and their anchors are as efficient that the one you are using on your side of the Ocean..
At similar <font color="red"> SCOPE </font> , the increase of efficiency between an all chain rode and an all rope rode is not significant..
the holding power of the anchor is much greater if the pull is parallel to the seabed and that is where a heavier chain can assist. Also a heavier chain has a larger catenary effect than a lighter one which serves to dampen shock loadings on the anchor
If it were the case that a heavier chain will not have a significant effect on holding power then why are heavier chains fitted to larger boats? This is less to do with the breaking strain of the chain which is far in excess of what is required but more to do with the catenary effect of the heavier chain
IMHO, it is well worth increasing chain size in order to maximise the performance of the existing anchor
[/ QUOTE ]
NO! NO and again <font color="brown"> NOOOOOO </font>
As you said, the holding of the anchor is related to the angle of pull.. but the line can be either chain or <font color="red"> ROPE..</font>
Except if you are using Ship size chain to hold a dinghy, the holding of the chain itself ( <font color="blue"> from our own tests</font> ) is approximately two time its weight.. 30 metres of 10 mm chain weight = 68 kg : holding 120 kg.. but the 30 metres have to be lying on the bottom.. ( <font color="blue"> 120 kg is approximately the force exerted on a 4,5 meter boat by 30 knots of wind.) </font>
<font color="red"> YES YES YES </font> the pulling angle of the chain will be parallele to the sea bottom ( <font color="blue"> Horizontal </font> ) but this is only true with <font color="red"> winds lower than 25/30 knots </font> ( <font color="blue"> see the excel programs from the Alain Fraysse's Web page</font>) and with winds lower than 25/30 knots, nobody care about his anchor..
<font color="green"> Please note that I'm ONLY talking about rough weather conditions where anchoring could really be a problem and with "normal size" chains. </font>
With winds greather than 25/30 knots, your chain is nearly bar tight , then its pulling angle will be <font color="red"> NEARLY </font> the same of an all rope line, your "bar tight" chain will no loger give any "catenary" effect and will not dampen shock loads on the anchor, that's why, with an all chain rode, you should <font color="red"> ALWAYS </font> use a snubber.
Why are heavier chains fitted to larger boats? to increase the breaking strain!. Again if you look at Al's web page you will see that there is not only static loads but also dynamic loads and that the (short) pic of load can reach and even overcome the breaking strain of these "big" chains..
On this side of the "Big Blue" most boats are using only a small lenght of chain and then rope.. and their anchors are as efficient that the one you are using on your side of the Ocean..
At similar <font color="red"> SCOPE </font> , the increase of efficiency between an all chain rode and an all rope rode is not significant..