Loop spliced into 3-strand - strength

Sticky Fingers

Sticky Fingers

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Hi

I've now finished making my docklines. Quite pleased with the results of my splicing after a bit of practice.

Anyone with knowledge on this able to tell me what effect on breaking strength would be of splicing the soft loop into the end of the line, compared with the raw strength of the line, or a bowline.
 
A "short splice" is generally said to have minimal impact on the breaking strength of a line whereas a bowline might reduce the breaking strain by about 50%
 
Scala said:
'Short' being a max pf 4 or 5 tucks I guess?
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In this case "Short Splice" as opposed to "Long Splice"

When doing a Long Splice you taper the strands before doing the splice - the result is a splice that is no fatter than the original rope (used for joining two ropes). When making an eye you would almost certainly use a short splice - i.e don't taper the strands.

A long splice does reduce the strength of the joined rope, the short splice not.
 
Scala said:
Hi

I've now finished making my docklines. Quite pleased with the results of my splicing after a bit of practice.

Anyone with knowledge on this able to tell me what effect on breaking strength would be of splicing the soft loop into the end of the line, compared with the raw strength of the line, or a bowline.
Click to expand...
A properly done eye splice will be stronger than a bowline
A bowline retain 60% of the breaking strenght
A splice retain 95% of the breaking strength
source http://www.boatus.com/boattech/casey/rope.asp
 
That's good thanks :)

I'm going to monitor my docklines over the next few months to make sure the splices remain good, and it's inconceivable that 14mm 3 strand would get anywhere remotely near breaking point, so in some ways the strength reduction is academic.
 
bedouin said:
In this case "Short Splice" as opposed to "Long Splice"

When doing a Long Splice you taper the strands before doing the splice - the result is a splice that is no fatter than the original rope (used for joining two ropes). When making an eye you would almost certainly use a short splice - i.e don't taper the strands.

A long splice does reduce the strength of the joined rope, the short splice not.
Click to expand...
Doing the long splice I learnt you do not taper the rope before you do the splice.
If maintaining the diameter of the rope is important you can thin the strands before doing the tuck's in step 5
http://www.samsonrope.com/Documents/Splice Instructions/3Strand_C1_Long Splice_AUG2012_WEB.pdf
 
One other factor is the diameter of the bollard or eye round which a line is passed.

A rope needs 8 times its diameter to retain 100% strength; at a turning point of the same diameter as the rope, the BS is reduced by 50%. (Figures for HDMPE rope)
 
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knuterikt said:
A properly done eye splice will be stronger than a bowline
A bowline retain 60% of the breaking strenght
A splice retain 95% of the breaking strength
source http://www.boatus.com/boattech/casey/rope.asp
Click to expand...

This depends on the rope.
A higher modulus rope will lose more strength due to a knot, as the most highly loaded strands do not stretch enough to share the load with the other strands.
A bowline in dyneema can be quite weak in terms of the rope's BS, but mostly dyneema is used for low stretch rather than high BS anyway.
A bowline in nylon might retain a very high % of the breaking load.
 
lw395 said:
This depends on the rope.
A higher modulus rope will lose more strength due to a knot, as the most highly loaded strands do not stretch enough to share the load with the other strands.
A bowline in dyneema can be quite weak in terms of the rope's BS, but mostly dyneema is used for low stretch rather than high BS anyway.
A bowline in nylon might retain a very high % of the breaking load.
Click to expand...
The OP asked about three strand rope.

But since you bring it up.. with bowline in a high modulus rope with cover in polyester you can see that the cover break before the core because of stretch and then the bowline will slip...
 
Ideally a short splice is three tucks with the full thickness of the strands, then one tuck at two thirds thickness, and one tuck at one third thickness. This tapers the end of the splice, reducing stress concentrations. Of course, ideally a splice should be served over, but I admit I rarely bother! If the rope is partcularly slippery, then more tucks are advisable.

I vary my splice according to the use; lines unlikely to have much load (e.g. fender lines) are simply three tucks, mooring lines are the full works and at least a partial serving over the splice.

I agree with those who say you don't thin the strands in a long splice; the whole point is that at any point in the splice you have one strand from one end of the rope and two from the other. However, long splices are rarely appropriate these days; we rarely need to have splices passing through blocks, which is the whole point of the long splice; there is no change in the diameter of the rope throughout the splice. It is weaker than a short splice, as well.
 
The Q was initially about a 12" soft loop splice (for a fixed dockline), I made these with 4 tucks for all 3 strands, then tapered by removing strand 1 at tuck 4, then strand 2 at tuck 5 then strand 3. Would you serve over in this use case? I didn't but could do.
 
I've only ever had one mooring line snap. I'd spliced the loop in myself. The loop itself snapped about half way round where it was looped around the cleat. Neither the splice nor the standing part it was spliced into were affected.

It was only a 10mm line I used as a shock-absorber in addition to the doubled up mooring lines. The GFS was forecasting 66 Kts at the marina and it probably was topping that went it went, so all in all I was happy with the performance of the splice.
 
Scala said:
The Q was initially about a 12" soft loop splice (for a fixed dockline), I made these with 4 tucks for all 3 strands, then tapered by removing strand 1 at tuck 4, then strand 2 at tuck 5 then strand 3. Would you serve over in this use case? I didn't but could do.
Click to expand...

Sounds good to me. If you cover it you can't inspect it, but tightly served it's less likely to loosen. I'd leave it.
 
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