Neeves
Well-Known Member
Simon,
If you are using a shackle in the anchor slot that is too big for the chain - then it is very possible the larger shackle does not need to be a Grade B (as if it is side loaded - being oversize it should be strong enough). Similarly the shackle on the chain equally does not need to be Grade B, it only needs to be stronger than the chain - because it will never be side loaded (especially if you have a mechanism to keep the chain centralised).
If you don't mind the extra expense I would buy a Grade B shackle (like Crosby's G209a) but buying one, plus spare, might be inconvenient. I like belt and braces, or over strength - but that's me. YOU need to check the strengths to see how far out I am suggesting an oversized shackle will be strong enough - but with a 90 degree side loading you will lose 50% of strength but you want WLL of the shackle (when compromised) to be greater than the WLL of the chain.
If you can I'd take the new anchor to a chandler and simply try shackles for fit - and to find out if you can get whichever shackle to 'lock up' in the slot. Most shackles are 'identical' in dimensions so one manufacturer's 3/8th" is the same as another - so if you play around you would then know what to order.
Referring to a comment I made earlier - I wish anchor makers defined which size shackles fit their anchors - ground tackle should be one integrated package fitting for size and strength - its really not difficult for a manufacturer to have all this data at their finger tips.
We played around with our alloy Excel, actually we used it, and did find the shackle locked up - and then tried the next size up, which worked well. There is a bit of trial and error.
But have a spare (I know you want the 'external' bolt for security and I suspect with both loctite and cotter pin - but one day you will take the anchor off the bow roller - and shackle pins are easy to lose!
Jonathan
If you are using a shackle in the anchor slot that is too big for the chain - then it is very possible the larger shackle does not need to be a Grade B (as if it is side loaded - being oversize it should be strong enough). Similarly the shackle on the chain equally does not need to be Grade B, it only needs to be stronger than the chain - because it will never be side loaded (especially if you have a mechanism to keep the chain centralised).
If you don't mind the extra expense I would buy a Grade B shackle (like Crosby's G209a) but buying one, plus spare, might be inconvenient. I like belt and braces, or over strength - but that's me. YOU need to check the strengths to see how far out I am suggesting an oversized shackle will be strong enough - but with a 90 degree side loading you will lose 50% of strength but you want WLL of the shackle (when compromised) to be greater than the WLL of the chain.
If you can I'd take the new anchor to a chandler and simply try shackles for fit - and to find out if you can get whichever shackle to 'lock up' in the slot. Most shackles are 'identical' in dimensions so one manufacturer's 3/8th" is the same as another - so if you play around you would then know what to order.
Referring to a comment I made earlier - I wish anchor makers defined which size shackles fit their anchors - ground tackle should be one integrated package fitting for size and strength - its really not difficult for a manufacturer to have all this data at their finger tips.
We played around with our alloy Excel, actually we used it, and did find the shackle locked up - and then tried the next size up, which worked well. There is a bit of trial and error.
But have a spare (I know you want the 'external' bolt for security and I suspect with both loctite and cotter pin - but one day you will take the anchor off the bow roller - and shackle pins are easy to lose!
Jonathan
) - just ask.
