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Old 21-09-2010, 00:43   #1
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Challenge: Self-Steering

At the moment I have a Narvik pendulum and an elderly Autohelm, both of which attach to the tiller.

The Narvik is a clever device but looks oh so fragile. The Autohelm is an amp guzzler.

Just been reading Alex Rose's My Lively Lady. He mentions Hassler. I checked out the Hassler site and see various configurations.

I have a transome-hung rudder. 24 degrees off vertical. I kind've like the idea of attaching a servo to the rudder, thence to a vane, with a 4:1 helical reduction gear between vane and servo, as either the primary or back-up.

Alex, in his book, mentions issues with over-steering until Hassler introduced a gearing system. For the life of me I cannot find the gearing ratio.

Anyon out there know what this ratio is?

The Hassler site is http://www.jesterinfo.org/haslerselfsteering.html
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Old 21-09-2010, 01:07   #2
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Hasler's are ancient history from the '60s. Didn't know they were still made or parts still available. The Aires, Monitor, Navik, etc. are all newer models with horizontal pivoting windvane which made them way more senstive. The vertical pivoting vane on the Hassler had to be reefed to cut down sensitivity when the wind got up and weren't very sensitive in light air unless the vane was way large.
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Old 21-09-2010, 01:12   #3
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Hasler's are ancient history from the '60s. Didn't know they were still made or parts still available. The Aires, Monitor, Navik, etc. are all newer models with horizontal pivoting windvane which made them way more senstive. The vertical pivoting vane on the Hassler had to be reefed to cut down sensitivity when the wind got up and weren't very sensitive in light air unless the vane was way large.
They seemed to have served Alex Rose well.

Its the gearing ratio which has me perplexed at the minute.
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Old 22-09-2010, 23:57   #4
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They seemed to have served Alex Rose well.

Its the gearing ratio which has me perplexed at the minute.
I have studied the Sarana site details and conclude the issues are all down to relatives. By that I mean the relative force applied to the trailing edge of the rudder required to to move it sufficiently to reset the desired vessel course.

That force is determined by the force applied by the vane to the tab and, the relative rate at which that force is applied. That seems to be what Rose means when he mentions the differential Hassler built into his system.

In turn, both the force and the relative rate of application (the differential bit) is inextricably linked to the force capable of application by the tab.

This second part is clearly determined by one of two factors.

The first being the distance of the tab's force from the gudgeons of the main rudder, and the size of the tab. Ergo, the further aft the tab, the less needs to be it's size.

In the Sarana model the tabe hangs out way back from the rudder and, in my opinion invites two problems. The first being fouling by underwater objects. The second being...Something hanging way out there is subject to multiplied forces when the vessel is in the sea from hell.

Also, I note the Sarana model requires the tab to be locked. One presumes this is for when the vessel is going in reverse.

My intention is to build first the tab and using racing dinghy gudgeons, secure that to the main rudder.

That then results in the control shaft sticking up behind my rudder head. Then I can build a simple brace for a bearing...a high impact nylon bearing.

Under the landing plate for that bearing will be a collet which will hold the tab in its gudgeons. If ever I wish or need to remove the tab I will simply undo the collet, lift the tab from the gudgeons, then feed the shaft down and clear.

Next is the connection between tab-shaft and vane. I'me going to follow Hassler's approach for this but use one helical and one straight-cut gear, made of high impact nylon...at a ratio of 3-to-1. Ergo, three degrees of turn of the vane will exert one degree on the tab.

I'm guessing at this ratio but I have to start somewhere.

However, that ratio is inextricably linked to the surface area of the tab.

My intention is to begin with my best guess, plus 50%, then try it all out.

As needed I will shave off the tab, vertically, till the best fit arrives.

I'm presuming my best guess plus 50% will create huge oversteering issues, so I'll have plenty of test-room as I shave the tab down. Sooner or later the ratios will arrive at the best fit. Never perfect, but good enough.

Furthermore, I will be able to modify the vane area by simply making it out of sail cloth then reefing it a bit, if required. Miniature roller reefing is easy enough to make.

You see, when ocean sailing, and not in a hurry, a few degrees of course, here and there is hardly likely to cause stress to the Captain. :--))

But I say agin, the thing I like about the Hassler concept is it's robustness which, in counterpoise to the thing I don't like about the Narvik is its delicateness. Lovely design, but what state will it be in after say, five days of being bashed around in a force ten gale?

In such a gale, either laying ahull, or on a drogue, the tab I can lock. The vane I can simply make disappear with the roller reefing, and then slam the companionway door shut, dog it and simply ride out the drama.

Materials.

Heavy galv pipe is way stronger than solid anything. So heavy galv pipe will be used for the tab axle and the vane axle. The vane will be made of two bits of much lighter galv pipe, plus couter balance. The 'sail' will be made of 12 ounce cloth on a little roller reefer.

All bearings will be made of high impact nylon.

The tab will be of high impact nylon, bolted to the tab axle. The stuff is easy to work once you know how. It doesn't collect any foul, and breaking it is more or less impossible.

Most off all, given this system is about as complex as a mouse-trap, I can carry spares for Africa.

Now all I have to do is make it work. :--((

I figure it worked for Alex. I have the design. It's just a matter of slowly modifying the modifiable bits till it works for my boat.
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Old 23-09-2010, 03:45   #5
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I built a rudder trim tab version for a 32 foot boat twenty odd years agoe.that one took me from new zealand around the pacific and then to australia.I also built the one I have now and that has taken me from australia to new caledonia and back.
each one costs about $600.00 in materials
my design has support tube and frame bolted to transom ,next a tube goes down centre of support tube which has a wooden rudder attached.I have found that for every 10 ft of boat length this rudder should be 1 square foot.next another tube goes inside of previose two tubes , half inch protrudes past rudder tube.on the bottom of this tube is welded a bell cranck,this tube controls trim tab.
trim tab is hinged on trailing edge of rudder and has a bell crankc 8 mm solid rod conects the two bell crancks and I have found a 2 to 1 ratio works well.trim tab is 25% of rudder area.wind vane is connected to last tube needs to be 5 times greater area than trim tab.
so $600.00 all up made of stainless no bearings required ,next to no moving parts and when in use you lock the main rudder amidships and if main rudder system does stop working I have a secound one on transom as back up.
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Old 24-09-2010, 01:12   #6
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Originally Posted by 4900bruce View Post
I built a rudder trim tab version for a 32 foot boat twenty odd years agoe.that one took me from new zealand around the pacific and then to australia.I also built the one I have now and that has taken me from australia to new caledonia and back.
each one costs about $600.00 in materials
my design has support tube and frame bolted to transom ,next a tube goes down centre of support tube which has a wooden rudder attached.I have found that for every 10 ft of boat length this rudder should be 1 square foot.next another tube goes inside of previose two tubes , half inch protrudes past rudder tube.on the bottom of this tube is welded a bell cranck,this tube controls trim tab.
trim tab is hinged on trailing edge of rudder and has a bell crankc 8 mm solid rod conects the two bell crancks and I have found a 2 to 1 ratio works well.trim tab is 25% of rudder area.wind vane is connected to last tube needs to be 5 times greater area than trim tab.
so $600.00 all up made of stainless no bearings required ,next to no moving parts and when in use you lock the main rudder amidships and if main rudder system does stop working I have a secound one on transom as back up.
I think I understand the concpet, but it seems you set this rig up so that the self-steering does the work, not the main ruddder. Is that the case?
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Old 24-09-2010, 03:34   #7
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yes when wind vane is engaged main rudder is locked amidships.that is one of the reasons why I like this system over others .you can sail millions of miles and main rudder is as good as new.
In your instance I realize you would need to atach trim tab to your transom hung rudder,areas and ratio still apply.for a few dollars more I would use stainless instead of gal-lasts longer and looks a lot better .put a zinc anode on pintal.
you will need to have some way of locking trim tab in line with rudder for when reversing.
I will try to post a photo or two.
another advantage with this system is I still have dinghy on davits and solar panel on top of davits
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Old 24-09-2010, 17:55   #8
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Originally Posted by dpex View Post
At the moment I have a Narvik pendulum and an elderly Autohelm, both of which attach to the tiller.

The Narvik is a clever device but looks oh so fragile. The Autohelm is an amp guzzler.

Just been reading Alex Rose's My Lively Lady. He mentions Hassler. I checked out the Hassler site and see various configurations.

I have a transome-hung rudder. 24 degrees off vertical. I kind've like the idea of attaching a servo to the rudder, thence to a vane, with a 4:1 helical reduction gear between vane and servo, as either the primary or back-up.

Alex, in his book, mentions issues with over-steering until Hassler introduced a gearing system. For the life of me I cannot find the gearing ratio.

Anyon out there know what this ratio is?

The Hassler site is Hasler Self Steering
I have been using a trim tab on the rudder for all my boats for decades. I have two methods of varying the negative feedback ratio, She will self steer down wind in 2 knots of wind. Bullet proof below the waterline. My book has the drawings for it.
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Old 24-09-2010, 23:18   #9
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Originally Posted by Brent Swain View Post
I have been using a trim tab on the rudder for all my boats for decades. I have two methods of varying the negative feedback ratio, She will self steer down wind in 2 knots of wind. Bullet proof below the waterline. My book has the drawings for it.
I think we would all be keen to learn your method of dealing with negative feedback, if for no other reason than keeping our relationships in tact.:--))

As regards the benefit of stainless over galv...At least Galv I can cut and weld at sea if I have to. Moreover, in some sad-arsed ports, I suspect getting galv pipe will be a lot easier than getting stainless.

I'd also be keen to know if anyone has a calculation to work out the relative forces between a vane and a trim-tab.
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Old 24-09-2010, 23:55   #10
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I think we would all be keen to learn your method of dealing with negative feedback, if for no other reason than keeping our relationships in tact.:--))

As regards the benefit of stainless over galv...At least Galv I can cut and weld at sea if I have to. Moreover, in some sad-arsed ports, I suspect getting galv pipe will be a lot easier than getting stainless.

I'd also be keen to know if anyone has a calculation to work out the relative forces between a vane and a trim-tab.
One of the things which has been irking me about this whole self-steering bizo is the fact that most configurations are well aft of the main rudder which, in my case mean some 2feet beyond the pushpit.

That doesn't seem like much till one has to do some remedial work in a force 10.

And so I've been playing with rather ugly, yet practical designs for an extended platform, made of galv pipe.

Today I had what I hope beyond hope is a brainstorm. Would love your opinions.

My rudder head is in the massive range. I ran some lines today and discovered the shaft for the tab would come up to within 5 inches of the rear of the rudder head. Hmmm. That gives me room to play with variable differentials for the connection between the vane action and the tab action.

But the entire edifice will be mounted on the rudder head with only one horizontal brace for the vane shaft. And this will be attached to the existing pushpit

I spoke with a sail-maker today. He confirmed that a heavy cloth sail could still be wound up. I've got past rope-controlled roller reefing for the vane sail. I have designed a simple collapsing handle to wind in the sail when all goes to hell in a handbasket.:--))

So now I will have two variables to play with. The connection between the vane and the tab....I figure I will have about 3 inches either side of a central point to vary the driving arm to the tab. Plus I will start with a way oversized tab and cut it down till some balance is achieved.

Attaching the windvane to the rudderhead in a way which mechanically seperates the two is easy.

By heavens! I believe I have the formula about right. If this works it means I will never have to go aft of the pushpit....well, apart from a bit of a lean over.... to remove all parts, including the tab. And I reckon the whole lot will cost me about $400.
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Old 04-10-2010, 14:20   #11
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I think we would all be keen to learn your method of dealing with negative feedback, if for no other reason than keeping our relationships in tact.:--))

As regards the benefit of stainless over galv...At least Galv I can cut and weld at sea if I have to. Moreover, in some sad-arsed ports, I suspect getting galv pipe will be a lot easier than getting stainless.

I'd also be keen to know if anyone has a calculation to work out the relative forces between a vane and a trim-tab.
With my engine driven welder( 100 amp dodge alternator $25 from the autowreckers) I can weld stainless just as easily as galv, at sea or anywhere else.
With the wind vane shaft about 1/1/2 inches ahead of the trim tab shaft and the attachment point between the two about an inch behind the rudder shaft, I get negative feedback. I can adjust the difference, but have never had any reason to.
When one of my 36 footers began a circumnavigation , they had a bilge full of scrap stainless form the pulp mills. Eventually they used it all up, on small projects
One of the complaints cruisers have is missing the little projects. As my alternator not only welds , but runs my angle grinder, I can fabricate anything out of scrap stainless, anywhere, and love doing it.

A man without a project is a man without a life.
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Old 05-10-2010, 00:24   #12
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With my engine driven welder( 100 amp dodge alternator $25 from the autowreckers) I can weld stainless just as easily as galv, at sea or anywhere else.
With the wind vane shaft about 1/1/2 inches ahead of the trim tab shaft and the attachment point between the two about an inch behind the rudder shaft, I get negative feedback. I can adjust the difference, but have never had any reason to.
When one of my 36 footers began a circumnavigation , they had a bilge full of scrap stainless form the pulp mills. Eventually they used it all up, on small projects
One of the complaints cruisers have is missing the little projects. As my alternator not only welds , but runs my angle grinder, I can fabricate anything out of scrap stainless, anywhere, and love doing it.

A man without a project is a man without a life.
Re the adjustment required to remove/lessen negative feedback; I also have devised a way of altering ratios till I get the balance right.

First, I will be able to move the connect point between vane and servo by up to five inches, so that gives me a heap of latitude. Second, because I'm going to make the vane from heavy sail cloth, which I can reef from zero to full-size, I figure I will be able to attain some good balances. We shall see. :--))

But I'm interested in your welder. You say it runs off a DC alternator. Where does one get such a welder, and what are they called?
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Old 07-10-2010, 14:50   #13
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It's called a Dodge 100 amp alternator . One gets one from an autowrecker. Usually sell for around $35. My book shows you how to hook it up.
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Old 11-10-2010, 18:42   #14
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Brent, I believe dpex was asking what make and model welder you are talking about, or did you fabricate the entire unit yourself.
You were very clear about the unit being powered by a 100 amp alternator....and "In your book" you tell how to hook "It" up, whatever "It" is...(and that is The Real Question here)
So do we have to buy your book for a single question, or would you be so kind as to say what (besides the power source coming from the alternator) comprises this neat sounding welder?
Did you perhaps source out some items from a Miller, a Lincoln, or a Hobart unit to develop yours or is it just a Dodge alternator with a wire going to the stick ? (Just kidding)
I am very interested in this project of yours as well, thank you for bringing it up.
Tony
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Old 12-10-2010, 14:43   #15
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Didn't have to source out anything. It's simply a big square dodge alternator, from the auto wreckers, with the positive connected to the stick. Had to go for a 9 inch pulley on the engine to get the speed up enough. A commercialy built one I once owned, had a 9 inch pulley on a 3800 RPM gas engine, so i guess the more speed the better.
A 60 watt 120 volt light bulb on the output , prevents frying the diodes when you break the arc.
Yesterday, I built an anchor winch with it, in my cockpit.
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