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Old 10-17-2022, 12:16 PM   #1
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Paravanes

About two months ago I started manufacturing the Paravans with the corresponding equipment.
I have found a lot of information here on the forum, so I want to share my progress with you.
Because the mast should be easy to go down through the many bridges, I did not want booms next to the mast, so the booms are horizontal.
The existing boom, which is attached to the mast, is replaced, at least that is the intention, for two booms that are extendable.
Here a few pictures, as first making the pulleys, six pieces.













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Old 10-17-2022, 01:13 PM   #2
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Wow, you are a craftsman. I wish I would be able to do this. When I see this craftsmanship I understand why you built your boat all by yourself............you can do it better than most yards.

If you have some spare time................I do have some things on my wish list for my boat.
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Old 10-17-2022, 08:36 PM   #3
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Wow, you are a craftsman. I wish I would be able to do this. When I see this craftsmanship I understand why you built your boat all by yourself............you can do it better than most yards.

If you have some spare time................I do have some things on my wish list for my boat.
Thanks for the compliment, time, time is my biggest enemy but sometimes I make parts for other people.
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Old 10-17-2022, 09:25 PM   #4
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first, I make one boom, if it is mounted then we will test. When the test is good, we continue and 'I make the second boom.
The intention is to operate the paravanes electrically.
the two electric winches are also purchased after the test.
one part of the boom is made of plywood.
In the wooden boom comes a stainless steel tube that can extend.
The stainless steel tube locks automatically when the tube is extended.
Here are a few pictures of how to make the boom.





















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Old 10-17-2022, 10:16 PM   #5
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do you have a sketch showing what the entire rig will look like?
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Old 10-18-2022, 11:34 AM   #6
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do you have a sketch showing what the entire rig will look like?
Hollywood
Hello, I have edited a photo on which you get an impression of how the booms are placed.
The booms can be turned outwards, then the paravanes can go down



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Old 10-18-2022, 09:52 PM   #7
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When you swing the booms out do you have a fore guy to the end of the boom to take the paravane load as well a a cable to the top of the mast. The loads can be fairly large and all of the component need to take up the load as the boat roll and pitches.

In your sketch there would be a thrust load on the boom end on top of the house. Is it properly supported, Do you have a sketch of the deployed paravane with all of the lines? It would help.
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Old 10-18-2022, 10:48 PM   #8
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When you swing the booms out do you have a fore guy to the end of the boom to take the paravane load as well a a cable to the top of the mast. The loads can be fairly large and all of the component need to take up the load as the boat roll and pitches.

In your sketch there would be a thrust load on the boom end on top of the house. Is it properly supported, Do you have a sketch of the deployed paravane with all of the lines? It would help.
First of all, great Dennis that you think along, that is also the reason that I started the toppic here.
For me this is an unknown road as well as for 99% of the Dutch people.
I will make a few sketches of the rigging.

Thank you!

Greet,

Pascal.
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Old 10-19-2022, 11:13 AM   #9
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Again a few steps from making the boom with the corresponding stainless steel parts.
A lot of work goes into polishing the stainless steel parts.
The boom is provided with 9 layers of epoy / paint, no maintenance in the coming years.



















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Old 10-19-2022, 12:08 PM   #10
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Elegant for sure. I’ll assume that with so much forethought, the vessel will be equally enforced to spread the considerable loads. Very interesting design.
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Old 10-19-2022, 06:38 PM   #11
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How heavy are the booms? Commercial fishermen make the booms and mast from aluminum because it's lighter. Weight up high causes more rolling and less stability. Stabilizers need strong rigging and solid attachment points.
A doubt your cabin top is strong enough. In mild weather, maybe.
The booms should align with the mast and except for small boats the booms are mounted on the sides. When deployed, the booms are about 45°. Too close to the water's surface and they my be torn off when the pole end dips into the water.
The booms are self supporting via the mast. And you need lines running to the bow and stern from the boom end to keep the boom in position. And another line usually attached to the hull below the boom mounting to keep the boom from jumping as the boat rolls.
You do nice work.

Enclosed is a diagram for a commercial boat of 43'.
It's from https://www.kolstrand.com a major supplier of commercial gear.
There is more info there.
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Old 10-19-2022, 10:53 PM   #12
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How heavy are the booms? Commercial fishermen make the booms and mast from aluminum because it's lighter. Weight up high causes more rolling and less stability. Stabilizers need strong rigging and solid attachment points.
A doubt your cabin top is strong enough. In mild weather, maybe.
The booms should align with the mast and except for small boats the booms are mounted on the sides. When deployed, the booms are about 45°. Too close to the water's surface and they my be torn off when the pole end dips into the water.
The booms are self supporting via the mast. And you need lines running to the bow and stern from the boom end to keep the boom in position. And another line usually attached to the hull below the boom mounting to keep the boom from jumping as the boat rolls.
You do nice work.

Enclosed is a diagram for a commercial boat of 43'.
It's from https://www.kolstrand.com a major supplier of commercial gear.
There is more info there.
Thanks for the support Lebke and the information.
The boom weighs 21 kilos (46 ib) times two, which is quite heavy.
Compared to the boat I think it is not too bad, boat is 36.74 feet long and 12.46 feet wide and weighs 14 tons (30864,716 ib )
The fixing points of the booms come on a stainless steel plate that is fixed on the deck, on this plate the two winches are also mounted on.
The stainless steel plate is fixed on the mast base and that is a strong point.
The mast base rests on the wheelhouse roof and also runs through the wheelhouse by means of a very heavy stainless steel tube.
This tube goes through the wheelhouse floor and eventually rests on the diesel tank, the tank is also very heavy built, I see no problem in that.
I understand the forces that come on the rigging, I will make a drawing how I think I will perform the rigging.
Sorry for my flawed writing style, I use a translator.

Pascal
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Old 10-19-2022, 11:40 PM   #13
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So far the last pictures so far I have come with the manufacture of the boom.
I hope to mount the boom at the location of the existing boom in the coming days.
Then the testing can start, if the test is successful then I can start with the final actions, placing the boom on the wheelhouse roof
















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Old 10-20-2022, 01:04 AM   #14
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The mast base rests on the wheelhouse roof and also runs through the wheelhouse by means of a very heavy stainless steel tube.
This tube goes through the wheelhouse floor and eventually rests on the diesel tank, the tank is also very heavy built, I see no problem in that.

Pascal
Hi Pascal. Be very, very aware that the compression load on your mast base will be several times that of any other load on your system. Geometry is not your friend! Construct an accurate rigid body diagram of your paravane system. Make sure you have the dimensions accurate. Then solve for the various forces in each part of your paravane system. I expect you will be very surprised by the compression load in your mast.

You state this load will be landed on the diesel tank. That's a poor design choice. The mast compression should follow through to the keelson of the boat, NOT on the tank. I simply can't imagine a sound mechanical design of such a system ultimately resolving it's loads via a diesel tank. Ever been aboard a sailboat where the mast base lands on a tank? No, they land directly on the keelson. Even deck-stepped masts land directly on a bulkhead, which ultimately transfers this load to the keelson.

Regards,

Pete
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Old 10-20-2022, 01:29 AM   #15
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Hi Pascal. Be very, very aware that the compression load on your mast base will be several times that of any other load on your system. Geometry is not your friend! Construct an accurate rigid body diagram of your paravane system. Make sure you have the dimensions accurate. Then solve for the various forces in each part of your paravane system. I expect you will be very surprised by the compression load in your mast.

You state this load will be landed on the diesel tank. That's a poor design choice. The mast compression should follow through to the keelson of the boat, NOT on the tank. I simply can't imagine a sound mechanical design of such a system ultimately resolving it's loads via a diesel tank. Ever been aboard a sailboat where the mast base lands on a tank? No, they land directly on the keelson. Even deck-stepped masts land directly on a bulkhead, which ultimately transfers this load to the keelson.

Regards,

Pete
I understand your reasoning, but if you saw the construction of the tank you would look at it differently.
The tank is made of a waterproof bulkhead.
In the tank there are various pendulum bulkheads plus the tank is part of the engine foundation.
The steel varies in thickness from 5 to 10mm is stronger than the hull.

But great that you think along!

I'm going to buy a digital force meter, then I can measure how much force is ultimately applied to the different components.

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Old 10-20-2022, 01:51 AM   #16
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paravanes

I do not think that a paravane system necessarily leads to large downward forces on the mast. On my Willard 40 (~18tones) I have used paravanes in very rough conditions extensively for 15 years. The line supporting the pole ends goes HORIZONTALLY to the mast head. Loads are transferred from one pole to the other but there is minimal compression on the mast. I have never understood why most boats have the pole-supporting lines making an upward angle to the mast head.

Also, there is no need for an aft guy on the pole end. The aft drag of the vane is plenty to keep the pole from moving forward.

I agree that the mast should not be supported by a tank top. On my Willard the mast thrust goes down to a heavy horizontal beam in the engine room. that beam is supported by vertical members at the ends that go down to the engine beds which are part of the hull..
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Old 10-20-2022, 03:07 AM   #17
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I do not think that a paravane system necessarily leads to large downward forces on the mast. On my Willard 40 (~18tones) I have used paravanes in very rough conditions extensively for 15 years. The line supporting the pole ends goes HORIZONTALLY to the mast head. Loads are transferred from one pole to the other but there is minimal compression on the mast. I have never understood why most boats have the pole-supporting lines making an upward angle to the mast head.



Also, there is no need for an aft guy on the pole end. The aft drag of the vane is plenty to keep the pole from moving forward.



I agree that the mast should not be supported by a tank top. On my Willard the mast thrust goes down to a heavy horizontal beam in the engine room. that beam is supported by vertical members at the ends that go down to the engine beds which are part of the hull..
A worthy post and opinion - as I recall, in addition to years of sail and trawler cruising, you are a retired Professor of Physics from UC Berkeley.....

Peter
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Old 10-20-2022, 10:41 AM   #18
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I would suggest that you hire an engineer/naval architect to take a careful look at what you have built and the structural load paths thru your boat. Also look at the shift in cg with the equipment you are adding and stability of the boat. In my opinion you need an engineered solution which is not possible with just A number of suggestions from this forum. Goal is a safe design that accomplishes your requirements.
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Old 10-20-2022, 11:40 AM   #19
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I would suggest that you hire an engineer/naval architect to take a careful look at what you have built and the structural load paths thru your boat. Also look at the shift in cg with the equipment you are adding and stability of the boat. In my opinion you need an engineered solution which is not possible with just A number of suggestions from this forum. Goal is a safe design that accomplishes your requirements.
Hi DennisB1.

Yes, right on. Attempting this sort of work, while relying on anecdotal information from this forum is not a good idea. The forces exerted on a vessel in a seaway are little understood by the laymen. And how those forces are resolved into the structure of the vessel, in a configuration including paravanes, are neither intuitive nor trivial. These forces can, and do, cause damage to a poorly designed vessel, and can lead to unsafe conditions at sea.

Regards,

Pete
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Old 10-20-2022, 12:13 PM   #20
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Ya know....everytime subject of paravanes comes up, there are a handful of posts admonishing the OP to get a naval architect, about how the forces are extreme, how he will sink in a storm, blah-blah-blah.

Y'all realize this guy built this boat 25+ years ago, has sailed it in the north Atlantic? I mean even a brief glance at the pictures in this thread show some topnotch talent, a well-equipped shop, and some serious knowledge.

Pascal (OP): Thanks for sharing - looks great. I can't quite figure out how your booms will swing out without the standing rigging interfering, but I have no doubt you've already figured that out.

Peter
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