Issues cutting rope

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P_A_S_1

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I tried cutting a piece of old maritime rope that has been sitting on the shoreline for years, it's a thick braided synthetic made up of four smaller strands, and it didn't go well. I tried various knives with various steels and edges from polished to coarse and all struggled, none were able to make a clean cut, all lost their edge quickly. Is that type of rope that tough? Does being weathered and exposed to saltwater make it tougher to cut? Seeing my sharp knives fail at such a task was surprising and disappointing.
 
Big ropes whether natural or synthetic fibre will benefit from using a serrated blade. As mentioned, this rope is probably impregnated with all sorts of fine grit, sand, shell etc particles that will quickly dull an edge.
I wouldn't be too disconcerted or lose any faith in your knife, there are some things that will dull even an 'unobtanium' steel.
 
KenHash said:
Rope is easy to cut with any sharp knife ashore or on a boat. The more dry and stable (position) the better.
Have you ever tried to cut old rope 80 ft down underwater?
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You make a good point. I have not cut much underwater diving, but I can see where serrations would indeed be a benefit.
 
MolokaiRider said:
You make a good point. I have not cut much underwater diving, but I can see where serrations would indeed be a benefit.
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What often happens with old rope underwater is that (1) it can be hard to keep in position, and (2) a layer of marine algae can form on the surface.
So what happens is that you are trying to cut an unstable (non-stationary) medium that is very slippery. The "teeth" of a serrated blade cuts through this and catches the rope surface quicker and easier than a straight blade. Depending on where you're diving the visibilty may also be limited while cutting the rope, amd of course on scuba your time underwater is limited so you want to get the job done quickly.

Any non-diver can test this by taking two similar knives, one straight blade and one serrarted. Go to the nearest water and test cut twigs/branches that have been in the water for some time. Enough to get soaked and flexible and with an algae coating. Straight blades have a hard time with this and take longer because they "cut" whereas serrated ones "rip".
 
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That stuff is just plain tough. And probably abrasive after being in the sand for a while. In the old days sailers used to cut marline by hammering the knife through it.
 
Just use a big axe...
Too much crap in an old rope. It'll dull ANY knife!
 
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Only in the movies do they ever cut rope like that in one backhand stroke. With a switchblade.

I came across a similar piece on a shore once and tried to have a go at it with a slicy 4" fixed blade. Yeah...no. Aborted that right quick.
 
Was cutting some moondust impregnated rope with a couple of buddies during a job detail. I had a razor sharp 1095* zip through two sections before the edge was dulled to near uselessness: Had to resort to using the point of my knife to pierce the material. After the job was done, a buddy requested I sharpen his Gerber automatic* that was made with a more modern PM steel. It was about as dull as my plain carbon steel knife. The lesson I learned was that perhaps serrations or sawbacks would have been more appropriate for the task.

*M7 mfg. by Imperial. I'm assuming the material is 1095.
**It wasn't the 06, had an American tanto profile, blade steel was either 154CM or S30V.
 
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KenHash said:
Was that piece of rope completely dry? Or moist/wet?
The main reason why most Dive Knives have serrations.
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Completely dry.
MolokaiRider said:
I use a BK-9 to clean shorelines. Works great.
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That thick rope looks like what I was cutting. Interesting you had no issues.





Thanks for all the responses, the rope was pretty grungy. I also put an acute edge on all my knives, maybe a more obtuse edge would have done better.
 
If you put a highly refined almost polished edge on your knives, that would also be a reason they didn't cut the rope as well. A rougher toothier edge would catch and dig into the rope much better than a super fine razor edge for many of the reasons people mentioned above.

Either way, old synthetic maritime rope is an absolute bear to cut.
 
Silent H said:
If you put a highly refined almost polished edge on your knives, that would also be a reason they didn't cut the rope as well. A rougher toothier edge would catch and dig into the rope much better than a super fine razor edge for many of the reasons people mentioned above.

Either way, old synthetic maritime rope is an absolute bear to cut.
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So I took one of the knives after it dulled out and sharpened it with a coarse crystolon and it tore 1/2 way through very well, then it stopped like the others. I also tried a serrated spyderco that also did well initially but couldn't make it through without slowing down and having to saw like crazy to get it done with rope fibers everywhere. Looking at the serrations afterwards they're glinted/rolled.
 
Dexter Russel makes a fully serated rope knife thats less than $10. Model 15403. It cuts like a razor and never seems to get dull. Its very thin.

I wish you had one to try out.
 
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