Prop Rope Cutter

[Nicholson58]

Originally Posted by stillbuilding

Has anyone tried using a tree-lopping saw cutter on a long handle to clear a line or more rubbish? Some of those are 15' or so aluminium handle and look like they might do the job.


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Not probably sharp enough. I have a rope hook-knife which has so far not been used. It looks wicked enough and cuts on the pull. It mounts on a pole for use on deck. Both sides cut and the inner V is wicked sharp. 14 inches long.

Hook Knife Emergency Prop Tangle Cutter 14"" Handle



Here are photos of the knife & our prop & shaft. After a bit of research, I don't see a good way to use the commercial devices. The shaft is 50 mm and the hub is big and close to the strut. Circular cutters are huge diameter for these hubs and would seriously impact flow to the 24 inch 3-blade. The hub & shaft are hollow with mechanism for pitch adjustment from the cockpit. (Hundested prop).

[zboss]

Originally Posted by Nicholson58

Not probably sharp enough. I have a rope hook-knife which has so far not been used. It looks wicked enough and cuts on the pull. It mounts on a pole for use on deck. Both sides cut and the inner V is wicked sharp. 14 inches long.

Hook Knife Emergency Prop Tangle Cutter 14"" Handle

Yep - thats the one we have.

[SailRedemption]

Speaking of the burn off method, we pulled a crab fishing boat out that had been running with some line around the shaft for who knows how long. The shaft got so hot that it caused the ss to crystallize under the line. One day when backing the shaft gave way and snapped like a peppermint stick and the wheel went by by.

Moral of the story, don't try to burn the line because the heat generated could cause serious issues with the shaft.

[Steadman Uhlich]

Murphy's Law says that the bad things happen at the worst possible time.

Wrapping a prop with a rope may seem like an easy fix (jump overboard and cut the line with a knife), especially if the only time it happens is when one is near a dock and the conditions are benign.

But, the sea/wind/wave/water/crew conditions and lack of time available may make that "easy" solution impossible to implement safely or at all.

I found a few more photos of the recent example of a sailboat lost due to a wrapped prop AND rudder.

Sources say the prop and rudder were wrapped by a jib sheet, causing loss of power and steerage and control while the boat was approaching close to the rocky shore of a narrow inlet.

The strong winds (20+knots) pushed the boat onto the rocks, resulting in a total loss. The crew was rescued by the USCG.

To me, this illustrates the prime reason to have a prop rope cutter installed on my boat.

[Pete the Cat]

Originally Posted by ssullivan

They work, but are used in my area to mainly cut through lobster pots when one is too lazy to keep a good watch. Not a very good idea, and very inconsiderate to the people fishing for a living.

As others said above - I have never fouled a prop on a line.

I live in Maine. I served as a harbor master here. You can call us "too lazy to keep a lookout" but my guess is that you have not sailed here much. There is no effective lookout for a lobster pot buoy that is a few feet below the surface--as happens when the guy puts too short a lead on it, a shallow toggle, misestimate of depth or tide
, or the pot drags off the underwater shelf---a common occurence. Of if you have to travel in dense fog or chop or both--it can be impossible to avoid them. I picked up a 1" black poly line in Miami harbor that was floating just below the surface that ripped out my cutlass and sheared the coupling bolts. I have a shark toothed cutter now. Yes, I try to avoid the lobster pots and try to respect the fishermen who are making a living out there, but they often pepper the narrow navigation passages up here with pots (because the lobsters like shallowing faster water) and they know very well that they will lose gear, but as a lobsterman told me "don't think we do not keep track of the losses in our decision on where to place pots". In other words, some loss is a cost of doing business. I think we need to keep a lookout, but it is only prudent for the situation you will encounter if you come up here. I think most folks up here use the shark's tooth type of cutter. I average cutting a pot or two each summer up here for 600 or 800 miles I sail in a season, and I do not feel too bad about it considering the number we have to avoid in some areas. The lobstermen have cages around their propellers, but they still cut their own pot buoys occasionally.


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[jongleur]

Why do they use floating line?

[SailRedemption]

Originally Posted by jongleur

Why do they use floating line?

At least down here in Louisiana, the crabbers use the black poly line not because it floats, but because it's cheap and also, it lasts a long time with uv, saltwater, and can take a beating when the traps are cleaned regularly with a pressure washer. Oh and it's light, especially after being soaked in water.

[jongleur]

Even in a thoroughfare? Those reasons don't outweigh
the downside for everybody concerned.

[mikereed100]

Originally Posted by jongleur

Why do they use floating line?

Because it's cheap. All the fisherman I know use line weights to keep the line from lying on the surface.

[zboss]

My god... what would happen if hunters could plop down steel trap cuffs in the middle of the highway! Why are fisherman allowed to do this? I passed under several bridges on the ICW that had traps right in the middle of the bridge underpass.

[Neeltje]

... And if you liked the ICW crab pots, you're just going to LOVE the ones sprinkled throughout the southern Saint Johns River! I just moved Neeltje from Saint Augustine to her new digs in Palatka, and must have run over a hundred of them between Green Cove Springs and there without ever leaving the channel. And it gets even worse south of Palatka. Who would have thought there were that many crabs to trap in the first place?

Since Neeltje has the turning radius of the Queen Mary, there's no way I can avoid all of them, and so far I've been lucky enough to see all the ones that slipped under her bow come bobbing back up at the stern, but how long do you think that will last?

Hence, my latest Brain Fart: a Kort tube! From what I've read, these were initially designed to increase low speed thrust (which wouldn't hurt), but from the looks of them, they could also make a pretty efficient prop cowl. Granted, such a device will probably increase her turning radius to that of the Q.E.2 and make me use the thrusters more often, but off the cuff, what do you think of the precept?

Jacques

[chris95040]

Has anyone ever just filed the leading edge of their prop blades to a knife-edge, maybe just at the first inch or so from the hub?

It certainly wouldn't be very nice to handle after that. And its probably expecting too much for it to be able to just cut right through a rope, rather than sawing its way through like the typical rope-cutters.

[Neeltje]

Originally Posted by chris95040

Has anyone ever just filed the leading edge of their prop blades to a knife-edge, maybe just at the first inch or so from the hub?

It certainly wouldn't be very nice to handle after that. And its probably expecting too much for it to be able to just cut right through a rope, rather than sawing its way through like the typical rope-cutters.

From what I've seen in the videos, lines and nets seem to get tangled around the shaft before they actually reach the prop itself. Props are also airfoils of a sort, and I'd hesitate before sharpening their leading edges too much.

Jacques

[Steadman Uhlich]

Originally Posted by Neeltje

... And if you liked the ICW crab pots, you're just going to LOVE the ones sprinkled throughout the southern Saint Johns River! I just moved Neeltje from Saint Augustine to her new digs in Palatka, and must have run over a hundred of them between Green Cove Springs and there without ever leaving the channel. And it gets even worse south of Palatka. Who would have thought there were that many crabs to trap in the first place?

Since Neeltje has the turning radius of the Queen Mary, there's no way I can avoid all of them, and so far I've been lucky enough to see all the ones that slipped under her bow come bobbing back up at the stern, but how long do you think that will last?

Hence, my latest Brain Fart: a Kort tube! From what I've read, these were initially designed to increase low speed thrust (which wouldn't hurt), but from the looks of them, they could also make a pretty efficient prop cowl. Granted, such a device will probably increase her turning radius to that of the Q.E.2 and make me use the thrusters more often, but off the cuff, what do you think of the precept?

Jacques

We think alike!

I had thought of a prop cowl, shroud, duct, or nozzle for the same reasons.

But, after watching the way the net, lines, ropes, and wires were sucked into that prop (see the video I linked earlier in this discussion), I think the prop VORTEX is what pulls that line into the shaft and wraps it prior to entanglement of the blades. In other words, it appears to me that the shroud/duct/cowl/nozzle may NOT prevent the vortex from capturing the line and wrapping the line or material around the prop shaft as it turns. It may help, but I think a line cutter (like Spurs) installed would be more likely to prevent the snag and prop stoppage.

Also, the RICE tube or nozzle (like a Kort Tube) was tested to be the most efficient for reducing fuel consumed and for increasing the thrust. Pretty cool stuff. Rice is Nice.

Here is a Kort Tube (or Kort Nozzle) for those like me who like to see what we are discussing:

NOTE: This may be the right size for Neeltje since it handles like QE2. (Jesting of course!)

By the way, I would love to go for a sail on your boat some day! I think it is a cool type of boat and great to see one (or two) are on the USA coast. The Dutch build such good boats of all types.

[deblen]

If you have never cruised the coast of Maine,you can't appreciate how near impossible it is to avoid pots-as explained by Pete the Cat.Even on a clear calm day,which is rare,they are everywhere that a boat will float.Narrow channels (<100ft wide) tend to be relatively clear at port entrances,sometimes,simply because of line cutters.Add thick fog(common) &/or darkness.......
Thankfully,lobster fishermen are supposed to use a 30+ ft length of sinking rope at bouy end,& the rest is floating rope to avoid bottom chafing.This helps,until the guy sets a 40fathom line in 10fathom water,cause he is to lazy to coil the excess & tie it to the pot.Now you have a bouy floating straight up "over there",but,unknown to you,the pot is on your other side,with a length of floating rope ,on surface,between them.Believe me,nobody cuts across rope intentionally,regardless of how great a cutter you have-the outcome is a crap shoot. Best you can do is keep close,continuous watch,slip into neutral as you pass over,never maneuver in a pot field,& never use reverse-unless you are snagged-& then very gently.I.ve been anchored by pots & warp,12mi. off coast,for several hrs.I'm not going to crawl into 45deg water in 4ft seas & try to cut three or four ,or even one,warp out of my rudder(because I was sailing) or my prop (motoring).This ain't the carribean. A fisherman will soon come along to haul his gear & will tow you in,or whatever.Been there,done that.Just the way it is.