Teaching the fish to swim - stabilisers

[Simi 60]

Bought 2 pairs of aluminium paravanes "fish"

One pair has bigger surface area but lighter and easier handled but swam alarmingly towards hull - swapped sides but no difference.
These ones the tail ends slightly short of the aft edge of plate

The others are smaller surface area, a fair bit heavier and not as easily handled but swam better.
These have a bolt on afterthought alloy tail extending aft of plate and have a noticeable tweak to the tail
One swims perfectly, the other wants to swim away from the boat.

Seems some of these fish need an attitude adjustment to bring them in line. <reaches for hammer>

Short video of swimming and arms below

 

[Simi 60]

So this is on our flopper stopper arms which are 3m long 80mm alloy tube with 3mm wall and a single 10mm eye bolt running through a deck beam with oversized epoxy filled hole.
Loads on a flat day not extreme at all but bets are off if taking her up 1150rpm in some slop.

So, will likely run a chain plate 1200mm long along deck beam with several 10mm bolts epoxy set into beam
And will likely re jig these arms to 6m long 80mm tube with 6mm wall and have them more at a 45 degree angle so load path from pole end is more horizontal with roof.

And as I'll have them off for re welding, I'll probably move the arms forward to just aft of amidships position.
At least there I won't have to remove solar panels to do the chain plate work.

Or, maybe I'll just get a new set of arms made and leave the flopper stopper arms in place - undecided.

 

[Miz Trom]

Simi:


I like your flopper-stopper arms, as shown in the video. Do you use flopper-stoppers much when at anchor? Seems a bit of a shame to have to modify them, unless you simply don't use them.



I take it you bought the fish for stabilization while underway?



Cheers,
Mrs. Trombley

 

[Simi 60]

Simi:


I like your flopper-stopper arms, as shown in the video. Do you use flopper-stoppers much when at anchor?

When required, which is not that often, but when needed they make a big difference

Seems a bit of a shame to have to modify them, unless you simply don't use them

.

It's only the arms that would be modified, if I decide to go that way

I take it you bought the fish for stabilization while underway?

Correct

 

[Simi 60]

The smaller but heavy version vs the bigger but lighter and easier handled

 

[Serene]

[SNIP]

And as I'll have them off for re welding, I'll probably move the arms forward to just aft of amidships position.
At least there I won't have to remove solar panels to do the chain plate work.

Or, maybe I'll just get a new set of arms made and leave the flopper stopper arms in place - undecided.

I know physical installation considerations are important as to placement, but Beebe in Voyaging Under Power states;

"The proper position for the ends of the poles in the working position is 28 percent of LWL forward of the stern. In all locations appreciably forward of this point, performance grows progressively worse. If located too far forward, when the vessel pitches up, both fish will resist, causing double drag to no purpose."

Anyway there is a whole section in this book about design and installation, but do understand sometimes a compromise is needed to find a suitably robust installation location.

Your video looks good.

BTW I like the "punching south 30+" vid!

 

[Lepke]

On fishing boats the poles are at about 45° so when rolling the poles don't go in the water. I only put poles in the water once. I don't recommend it. The polls are rigged to transfer the load via the mast to the other side. The pole is fixed so it can't lift. Either with an attachment point low on the hull or with bracing to stout cabin structure. Usually, in addition to the line from the pole tip to the bow, there is another line from the flopper line. midway between the pole and the water and run to the bow. This takes the forward strain off the pole.

Also you may need a hole on the flopper further forward. For running at speed the flopper needs to be near horizontal but with the nose up. For trolling the nose goes down for braking to slow the boat.
The rig needs to be stout. I doubt a cabin roof, etc., would be strong enough. You're stopping many tons from rolling. A weak attachment point will be under constant repair.

 

[Simi 60]

On fishing boats the poles are at about 45° so when rolling the poles don't go in the water. I only put poles in the water once. I don't recommend it. The polls are rigged to transfer the load via the mast to the other side. The pole is fixed so it can't lift. Either with an attachment point low on the hull or with bracing to stout cabin structure. Usually, in addition to the line from the pole tip to the bow, there is another line from the flopper line. midway between the pole and the water and run to the bow. This takes the forward strain off the pole.

Also you may need a hole on the flopper further forward. For running at speed the flopper needs to be near horizontal but with the nose up. For trolling the nose goes down for braking to slow the boat.

.

Totally different requirements on fishing boats

Different loads - we aren't fishing or dragging nets
Different weather - we try to do our miles in calm weather, but occasionally there is unpleasant slop to deal with that hasn't settled down yet and that is what we are doing it for, the 12 hours of beam on slop gets a bit tiring, especial with a wheelhouse at our height.
Not really that noticeable when downstairs on the lounge, but that ain't keeping a proper lookout.

The rig needs to be stout. I doubt a cabin roof, etc., would be strong enough.

So some say but again, I think that is "perfect storm" loadings
As can be seen in the video there is not much load at all when running, not if I can pull belly into the dyneema by hand
Yes there will be more if in rougher conditions but how much?

Other factors to take into account are......
The fish are a smaller size, so less load - slowing the roll, not trying to stop it
The poles are shorter = less leverage - given the same rolling conditions a 6m pole will pull a paravane up through the water approximately twice as far in the same time period as a 3 m pole

You're stopping many tons from rolling. A weak attachment point will be under constant repair

I got told the same with the flopper stoppers he have on.
They stop many tonnes from rolling, or at least slow it down considerably, but reality is, the load is bugger all.
I know the load of paravanes is more, but I don't believe it's as much as some make out.

As an example, I have video of a 55 fter running paravanes in some sloppy conditions and the springs at the end of his poles are working but never fully compressed - but the spring compression rating is 350kg/770 lb.
To me that says the load is surely around that spring rating.

I also mentioned maybe going for longer poles - in the pic below that's a full 6 metre length.
If we go that way they will be mounted at 45 degrees
The load path to the roof will then be near horizontal
The roof then is essentially an I beam with a 15ft web with a 3 ft chain plate attached by 3/8 bolts epoxy set into a deck beam for the attachment points

 

[Simi 60]

I know physical installation considerations are important as to placement, but Beebe in Voyaging Under Power states;

"The proper position for the ends of the poles in the working position is 28 percent of LWL forward of the stern. In all locations appreciably forward of this point, performance grows progressively worse. If located too far forward, when the vessel pitches up, both fish will resist, causing double drag to no purpose."

Anyway there is a whole section in this book about design and installation, but do understand sometimes a compromise is needed to find a suitably robust installation location.

Your video looks good.

Believe me when I say I have devoured every mention of paravane stabiliser there is on the interweb and yes, compromise needs to be made if wanting them where supporting structure is.

I have seen and have pics of vessels with them anywhere between 50% and 10% and, they all work to varying degrees.

BTW I like the "punching south 30+" vid!

First time in any sort of slop in this vessel
Didn't really know what to expect

 

[rgano]

If you go with the longer/45-degree poles with near horizontal attachment at the top of the boat, would it make sense to attach port and starboard poles at a common point on the boat's centerline?

 

[Simi 60]

If you go with the longer/45-degree poles with near horizontal attachment at the top of the boat, would it make sense to attach port and starboard poles at a common point on the boat's centerline?

Why?

On ours the roof is mostly covered with solar panels
If going the 6m poles on cockpit bulkhead (where arms are now) , but attaching at centerline via mast and rigging loses solar and shades the rest of it.
If going the 6m poles on wheelhouse bulkhead, the funnel is on the centreline.

Part of being a successful installation in my eyes is cost effectiveness.
Losing solar and building mast or rebuilding funnels and adding extra structure is not cost effective.
Not if chain plate to roof attached into deck beam will yield same end results.

 

[Simi 60]

Short video of 350kg springs at work as mentioned in an earlier post.
Admittedly, not extreme weather by any stretch of the imagination but we won't be out in extreme weather.

https://youtu.be/782cLrDG1bM?si=kVTXorYZhYGSQZAA

 

[Lepke]

The longer the poles and the further out the flopper is, the more effective.


Floppers make the crew more comfortable and surer footed. They have nothing to do with fishing or dragging nets. I've seen a lot of light weight yacht rigging fail, cabins damaged, mast come down, and so on. Whatever makes you happy.

 

[hollywood8118]

Short video of 350kg springs at work as mentioned in an earlier post.
Admittedly, not extreme weather by any stretch of the imagination but we won't be out in extreme weather.

https://youtu.be/782cLrDG1bM?si=kVTXorYZhYGSQZAA

They appear to ride quite aft and outboard of the pole attachment points.


Ours hung back less than 10deg. and directly parallel to the boat while at cruise speed.


hollywood

 

[Simi 60]

The longer the poles and the further out the flopper is, the more effective.
.

And the bigger the loads

Floppers make the crew more comfortable and surer footed. They have nothing to do with fishing or dragging nets

.
Oh, ok, I was only going on what I had seen on the interwebs when looking at trollers

I've seen a lot of light weight yacht rigging fail, cabins damaged, mast come down, and so on.

Yep, but it's not like I'm trying to hold it all together with 3/16 screws and cotton.

Beebe says in his book expect loads of around 3 ton or 1500kg and I'm guessing that's on a bad day - maximum loading due to bad conditions, which we will never be in.

A single 10mm s/s bolt has a strength of 10,500lb or 4700kg
6mm dyneema has a strength of 9000lb or 4100kg
And we'll build in "fuses" to fail well before the bolts or dyneema do.

If I had a single decked boat with a mast, the rigging wire would still need to be attached to the same structure that I am attaching to now - deck beams and cabin sides taking the load.
But as we are twin decked we already have the height to get the same angles needed therefore we can do away with the mast and, the attachment points remain the same.

Whatever makes you happy

It's not about being happy
It's about working with what we have, with the constraints in place.

 

[Ric]

If you zoom in on this you can see how our paravane poles are set up. The poles are 4" aluminum pipe set in stainless base plates that are through bolted into the steel hull. There is only one spectra line/shroud to the tip of each pole. A second spectra line ends in an eye that the pole shroud passes through that eye. The second line runs to a block at the base of the mast and then aft to the control station. Pulling on that line pulls the shroud toward the base and raises the pole, which pins in position when upright. Easing that line allows the pole to lower until the shroud is tense. There is a block below the pole with a small line that you lock in place to keep the pole from bouncing in a chaotic sea. I bought the heaviest fish I could comfortably handle (30#) and then increased the surface area with 1/2" marine ply. No effect on weight but protects our paint and increases downforce. Costs us about 1/2kt @1750rpm and keeps roll under 10 degrees. We use the jib or main first, and if they don't help enough we roll them up and deploy the fish.

 

[Kit_L]

We cut our paravanes down about 30% from the original size too, figuring being able to handle them easily was more important than that last few percent of reducing roll.

Our setup on the last boat here: (need to scroll to see the setup):
https://www.trawlerforum.com/forums/s3/adventures-anika-j-49085.html

 

[Simi 60]

Next round of testing.

The two big ones that are lighter and easier to handle got the tail fin smacked with a hammer to persuade them to track straight vs under the boat.
Such a very small adjustment but now they swim out and actually break the surface and rolled on their back.

The two smaller but heavier and difficult to handle due to weight swim straight so I measured the lead and removed the two blocks, drilled new holes and centre mounted one.
Same size lead as the other pair, much easier to handle, gave them a swim and they swim straight.

I'll continue onwards with these.

 

[Simi 60]

Now for the loads
Currently off of the arm ends going to the fish I have 10mm nylon double braid strops in liew of springs
One is about 5 inches shorter, it'll load first, stretch then strop 2 will join in.
Then there is dyneema about a foot longer again just in case
Then the main dyneema line running down to fish around 12 ft under surface.

To test loads I built fuses like I did in my sailing days

Fuse of the day is 3mm VB cord supposedly with 200kg break - knotted into loop so let's say 150kg/330lb break


VB cord fuse loop added between shackle and short strop.
If/when fuse breaks it's backed up by strop 2 with dyneema strop as final backup.

Went out in 20 knots of wind but protected waterway
Little bit of slop and occasional boat wash but nothing to much.
Gradually ran up to 1150rpm
Cruise speed was down not quite 1/2 a knot.
Ran for around an hour and fuse is still intact
Zero concern about stress to roof at this point of time.

In a couple of days after next reprov we'll try and find some bigger slop.

 

[Simi 60]

Left anchorage in the dark with 20 knots and wind against tide.
Beam on was a bit messy, had to put glassware away and stow loose liquor bottles
Up top at the helm it was a wide stance and a handhold - 1.5 hours on this tack to go.
Time to launch the fishies.

Knocked her out of gear and probably still doing 5 knots speared them in at 90degrees to hull and they swam out and into position.

The wife instantly commented on the difference
Gradually took speed up to 8.4 knots (current assist) and the difference, for so little effort and coin is amazing.
Still roll, but not as much and so much slower

And the VB cord fuses have remained intact for 2 hours now.

Short arms and smaller fish
Less load, less expense
But so far, big results.

 

[Kit_L]

This ^^ was our experience, exactly. We also had shorter arms than recommended in Beebe's book (2', 600mm shorter), and fish about 30% lighter than Kolstrand recommended for our last boat's length and weight.

Reducing the roll, and slowing it down, is the goal, not eliminating it, I believe. Great work, Simi!

 

[Serene]

Good update. I have been watching closely as even though my boat is not in the same class as yours Simi, I would like to add some sort of simple stabiliser rig without going over the top.

 

[slowgoesit]

Ours are the same as originally designed by Robert Beebe. No one in the last 41 years saw any need to change them. We've used them to good effect up to Alaska and back. I'll let you know it about a month how they work going down the West Coast of the United States!

 

[Simi 60]

They appear to ride quite aft and outboard of the pole attachment points.


Ours hung back less than 10deg. and directly parallel to the boat while at cruise speed.


hollywood

Guessing that's a weight thing.

The smaller yet heavier pair we have swim at around 10 degrees, but are a PITA to get back onboard.

Removed one of two blocks of lead and they are easy to get back onboard, but do swim farther aft like in the video.
But they seem to be working so I'm good with the easy handling aspect.

 

[Simi 60]

So
The smaller set of fish more suited to a 50 fter swim perfectly after minimal coaxing with a hammer
Good fishies, dare not defy me or I will smite you again.

Bigger fish more suited to our 60ft, one swims perfectly, it just needed a couple of taps with the hammer to bring it in line and make it play the game.

The other fish is a stubborn trouble maker, must have had it in and out of the water for an attitude adjustment 20 times now.

Tap it's fin one way and it swims outboard, breaks the surface and rolls on its back and plays dead.
Tap it's fin the other way ever so slightly and it dives under the boat and hides.

Using a straightedge the differences in adjustment are minor, hard to believe such a dramatic difference in attitude.
But, the beatings will continue until it learns it's place.......just not today.