Paravane ? - debris

[rsn48]

So here I sit on an Easter Monday watching Sea Venture's latest offering. And in their transit the paravanes have been deployed. But they have been deployed in an area with potential debris.

So my question is simple: what happens when a paravane line snags a log or what have you?

 

[MV La Costa]

So here I sit on an Easter Monday watching Sea Venture's latest offering. And in their transit the paravanes have been deployed. But they have been deployed in an area with potential debris.

So my question is simple: what happens when a paravane line snags a log or what have you?

Not much, logs and sticks roll away and release themselves. My worst problem has always been Bull kelp building up on long trips...

 

[mvweebles]

In Don & Reanne Douglass's book "Cruising the Pacific Coast," the had a picture of one of their fish snagging a crab trap. They reeled it in, untangled, and continued on their way.

Guess it depends on your cruising grounds how frequent something like that might happen. Personally, wouldn't deter me from paravanes.

Peter

 

[slowgoesit]

Sea Venture also uses a lesser strength length of chain closer to the fish that will break if it hits something REALLY substantial like a large log, or the bottom if you forget to retrieve when entering skinny water. Worst case, you lose a fish which are relatively inexpensive, and not a fin attached to a shaft that goes through your hull like a fin stabilizer uses. Fin stabilizers have been know to not breakaway as designed and actually breach the hull . . . ie; how much water can your bilge pump(s) handle? Probably not enough to keep up with the water inflow two feet below waterline with a 2" hole . . . . JMHO

 

[Sealife]

Our biggest pain was saragasso weed in the Eastern Carib. After a few days it took 1/2 to clear it all. Once we caught a pot of Key West at night when wife was on watch, probably dragged it 30 miles before I came on watch and realized the autopilot was on full right rudder. But otherwise no problems, although we run the plywood birds as our sacrificial offering.

 

[rsn48]

So I posted the question on Sea Ventures vlog and here was Jim's reply:


Highlighted reply
Cruising Sea Venture
1 hour ago
Rick, Great question. The chain cuts right through bull kelp and other type items on the surface. Logs have just spun off of it. It the fish really snagged something bigger, like a big log or the bottom or something, it is designed to fail at the chain. It would take approximately 7,500 lbs of force to break the chain, which is the designed weak link in the system. This protects the boat from being pulled over or any damage to the paravane system. We do have an extra set of paravanes and chains on board. But, I think this is extremely rare. So far, when we have hit logs with the chain it has just spun off. They are not that far from the boat - 20 feet away, so it's not like we would normally ever come that close to a log, but you could at night. Thanks, Jim

 

[Lepke]

I ran paravanes, flopper stoppers, for years, commercial fishing the North Pacific. I never had a problem. Things like kelp can be cleared with a boat hook, but it usually frees itself. The up and down motion of the chain saws thru kelp. In the days when there were thousands of salmon boats, some with families on board, diapers were the biggest problem.

 

[DCDC]

2017 discussion after KK42 sank in Canada canal after pushing a fin shaft through hull.

https://www.trawlerforum.com/forums/s59/perils-stabilizers-32779.html

 

[Fish53]

One thing to consider is where the pole hinges, if it's too low when you snag something substantial enough it can actually make the boom rise and put slack in the forestay which will possibly bend the pole at the hinge. A lot depends on the geometry of your particular rigging and boat but I have seen this happen on my boat simply from catching lobster gear.

 

[HopCar]

I ran paravanes, flopper stoppers, for years, commercial fishing the North Pacific. I never had a problem. Things like kelp can be cleared with a boat hook, but it usually frees itself. The up and down motion of the chain saws thru kelp. In the days when there were thousands of salmon boats, some with families on board, diapers were the biggest problem.

Lepke you used the term Flopper Stopper to mean paravane. When I’ve done that in the past I was told that flopper stoppers were the things you used at anchor to prevent rolling. I learned the term flopper stopper back in the early sixties and it meant paravane.

 

[MurrayM]

Lepke you used the term Flopper Stopper to mean paravane. When I’ve done that in the past I was told that flopper stoppers were the things you used at anchor to prevent rolling. I learned the term flopper stopper back in the early sixties and it meant paravane.

Yup, getting those names right can be important. You want to careful who you waltz up to and proclaim, "Hi, my names Bob and I've got a woodie" at a dockside bar.

 

[Fish53]

Actually the term paravane stems from their development for use on minesweepers and anti submarine work in the first world war. This was an offshoot from early commercial trawlers use of trawl doors, vessel stabilization came later. Flopper stopper's origins are irrelevant.

 

[Larry M]

We had three system failures in maybe 14-15000 miles. A swivel between the wire and nylon broke, we blew a fish apart hitting a dead head square on and we had one fish break do to age. The plywood was weak from water immersion.

We also snagged long lines and gill nets and even hit an unlit 25’ something fishing boat at night. Other than the noise of impact it is not a sudden stop. The half inch nylon acts as a shock absorber plus the distance of the fish from the hull, you seem to pivot around the fish/object if that makes any sense? I think going 7 knots helps. Also, if there was a so called fuse, I’d be afraid that when it was loaded up and failed, when it unloaded, I think it would be like a sling shot and I wouldn’t want to be anywhere near the rigging.

 

[Hippocampus]

Think I understand the basic physics underlying the Canadian warning about paravanes.

One side fails or wave height +/or roll is sufficient to get one fish out of the water. Then the other one is working unopposed so augments roll to the point of capsize. That report mentioned examples to the best for my recollection so it’s not just a theoretical concern.

In my ignorance would think a weak link in the chain or other sacrificial device would make that occurrence more likely. Why are they used? Has the Canadian report had any impact on insurability or premiums?

It’s the same kind of thing with gyros. In extreme weather the motion of the boat can exceed the range of precession. Stresses in the boat may exceed structural integrity with repetitive occurrence. Out of sync precession may decrease ultimate stability.

Having a stabilization system you need to turn off or retrieve in a dangerous setting just when you want it most make no sense to me. Where’s my thinking wrong?

 

[rslifkin]

Rolling the fish out of the water can be solved by running them deeper. For the failure case, I wonder how hard it would be to implement some kind of release with a strain gauge so if one fish breaks off (showing no downforce) it can just dump the other one?

 

[IRENE]

Not much, logs and sticks roll away and release themselves. My worst problem has always been Bull kelp building up on long trips...

This has been our finding also, but with less than 100 hours of use. Not an issue here in the PNW, even on night passage.

 

[IRENE]

Hippocampus,

Is this the referenced report? This report I provided a link to provides “common sense” guidelines, and much of its discussion would apply to similar activities and systems aboard. Line handling, raising and lowering the tender, and anchoring come to mind. You need to know what you doing, but there is no high degree of difficulty or danger.

I don’t have any concern that one of my paravanes at 300 square inches could create enough downforce to negatively impact our stability. Of course, we will never be overloaded with ice aloft or excessive catch.

Additionally, why would you retrieve or turn off a properly operating system? Have you used any of these systems?

https://tc.canada.ca/en/marine-tran...ety/ship-safety-bulletins/bulletin-no-15-2000

 

[Hippocampus]

No, I come to this forum devoid of meaningful experience. Finally, in process of arranging road trips to settle on which boat.
Current candidates are
Steel with no stabilization except sail plan.
Several GRP with fins and one with fins and fish.
So trying to absorb knowledge. Given absence of meaningful experience I throw out what I’ve read or others tell me to judge its validity. You’re comments are most helpful in that regard.

 

[mvweebles]

No, I come to this forum devoid of meaningful experience. Finally, in process of arranging road trips to settle on which boat.
Current candidates are
Steel with no stabilization except sail plan.
Several GRP with fins and one with fins and fish.
So trying to absorb knowledge. Given absence of meaningful experience I throw out what I’ve read or others tell me to judge its validity. You’re comments are most helpful in that regard.

For your intended usage, an unstabulized boat is not an option. Pick any of the options - fins, fish, gyro, Magnus (whatever they are), but for long distance runs, you will want some sort of in-water stabilization. Sail probably won't do it.

Peter

 

[hollywood8118]

I totally agree with Peter's statement above. Un stabilized displacement boats get really uncomfortable quickly. I have owned a paravane boat personally
And skippers others , have also skippered active boats and would take either. Dialing up the setting on active fins is a nice ablity when it gets stinky. Never have been on a passage and thought either wasn't worth the time to deal with. On Volunteer we made the crossing North to the San Juan's less than 10% without deployment of the fish.. they were one of the Admirals favorite attributes of that boat, we miss the ability even on the semi displacement Ocean Alexander as she often gets a bit too rolly.
How many former sailors here used to hoist the main when motoring a sail boat to reduce roll..
Hollywood

 

[Slider70]

I have ran stabilizers on three previous commercial fishing vessels for over 20 thousand hours over 28 years. Running at trolling speed or 7 knots. I have experienced a few challenges during that time. One was picking up a low floating tree trunk, roots & all. Another a cargo net off a freighter. Fun getting both of them off. But mostly bull kelp annoyance. The kelp comes off relatively easily.

The most challenging though is running through Dixon Entrance or Hecate Straits in the shallows dodging commercial crab traps. The most worry some are ghost traps that have been in the water for some time and missed being picked up by their owners. Often, over time, these traps get buried in the sand. Haven't hit one as I paid major attention when in waters that might have ghost traps and generally tried to stay out of the shallows where they are mostly found. But even then, I have counted 20 or more of these ghost traps on almost ever crossing between Rose Spit and the top end of Banks Island.

But I would not even consider travelling it these waters without stabies during my commercial days. I don't have stabies on my pleasure craft as I am now retired and avoid the seas that might require them.