High('ish) tech steering?

[Jeremy]

I'm in a bit of a dilemma and could do with some alternative thoughts on steering arrangements for my solar powered Winsome.  Steering is accomplished by turning the drive unit, which looks a bit like a saildrive fitted through the hull in a sealed tube (Chris P(N) kindly took a photo of it, see page 63 of the last issue of Watercraft).

My original plan was to keep things simple and just hook up the small steering arm on the drive unit to a Teleflex cable and then run this up under the starboard deck to a whipstaff tiller.  Nick at Swallow Boats had already warned that they'd found getting a solid rod steering linkage to work well on the pedal version was a bit difficult and jokingly suggested that I make it drive-by-wire.  At the time I dismissed it, as it seemed to be complication just for the sake of it, but I'm now coming back around to the idea.

I know that I need to move the seats to trim the boat properly, particularly when going from solo to two up.  There's provision for this in the hull already, as the seats fit to two parallel rails bonded to the bottom planks.  Obviously, this creates a bit of a problem with the tiller position.  If I mount it in a handy position for the aft seat, then it won't be reachable when solo and sitting more or less in the middle of the boat.  If I fit a whipstaff  tiller near the middle of the boat it might be a bit of a nuisance when boarding.

Going for drive-by-wire means that I can have a steering control that's on the end of a flexible cable and could be anywhere in the boat.  The same flexible cable could equally well carry the throttle and forward/astern switching as well.  I'm already dependent on electrical power, so the added issue of electric steering doesn't seem to be too much of a problem from a reliability standpoint, anyway, I could always hook up a jury rigged system with two bits of string fed back though the aft bulkhead watertight hatch if it was to fail.  If it wasn't for the desire for a little more finesse than the two bits of string method provides I might have chosen that as an option.

Building an electric steering system isn't that hard, but I have two choices and would welcome some thoughts on each:

- The complex choice is to use electronic proportional position control, using a geared bidirectional motor and servo system.  This would replicate a traditional wheel or tiller, in that the "rudder" angle would be directly indicated by the lever, wheel or knob position.  The downside to this approach is complexity (it needs a servo amplifier, potentiometers for position measurement feedback etc), plus a slightly increased current drain, because the steering electronics would draw some power pretty much all the time.

- The simpler choice is to use the same steering motor arrangement, but just have a simple two way spring loaded steering switch.  I was looking at a system that takes about 4 seconds to go from 40 degrees one way to 40 degrees the other way, so short flicks of the switch would move the "rudder" just a degree or two.  The motor and gearbox is stiff enough to hold the steering in position without being powered.  The advantage of this system is that there are no electronics, the downside is the switch-type left-a-bit/right-a-bit control and the lack of a "rudder" angle indication (although this latter problem could be fixed fairly easily).  The left-a-bit/right-a-bit thing isn't really different from rowing anyway (at least, it isn't when I'm rowing........).

I suppose I could also look at a re-positionable steering head that uses a long Teleflex cable, but I can't help feeling that it'd be a bit inflexible and cumbersome.

I'm leaning towards the simple electrical system, perhaps with "rudder" angle indication added, but would very much welcome any thoughts.  I've been pondering on this for days and just when I think I've made up my mind doubts creep in.................

Jeremy

[BrianP]

Perhaps a simple norwegian tiller to a rudder on the stern as Tim uses on his Hobie Mirage drive setup? the long slim push/pull tiller can reach both helm seating positions without adjustment. Seems a nice simple solution that works all the time even when electrical power has failed. If paddling is the backup then the tiller can be set to help keep the boat straight in crosswinds.

It would seem a good idea to have separation space between drive and steering. How re-active, accurate and quick would a turning prop be?

Brian 

On Mon, Jan 24, 2011 at 1:37 PM, Jeremy [via UK HBBR Forum] <[hidden email]> wrote:

I'm in a bit of a dilemma and could do with some alternative thoughts on steering arrangements for my solar powered Winsome.  Steering is accomplished by turning the drive unit, which looks a bit like a saildrive fitted through the hull in a sealed tube (Chris P(N) kindly took a photo of it, see page 63 of the last issue of Watercraft).

My original plan was to keep things simple and just hook up the small steering arm on the drive unit to a Teleflex cable and then run this up under the starboard deck to a whipstaff tiller.  Nick at Swallow Boats had already warned that they'd found getting a solid rod steering linkage to work well on the pedal version was a bit difficult and jokingly suggested that I make it drive-by-wire.  At the time I dismissed it, as it seemed to be complication just for the sake of it, but I'm now coming back around to the idea.

I know that I need to move the seats to trim the boat properly, particularly when going from solo to two up.  There's provision for this in the hull already, as the seats fit to two parallel rails bonded to the bottom planks.  Obviously, this creates a bit of a problem with the tiller position.  If I mount it in a handy position for the aft seat, then it won't be reachable when solo and sitting more or less in the middle of the boat.  If I fit a whipstaff  tiller near the middle of the boat it might be a bit of a nuisance when boarding.

Going for drive-by-wire means that I can have a steering control that's on the end of a flexible cable and could be anywhere in the boat.  The same flexible cable could equally well carry the throttle and forward/astern switching as well.  I'm already dependent on electrical power, so the added issue of electric steering doesn't seem to be too much of a problem from a reliability standpoint, anyway, I could always hook up a jury rigged system with two bits of string fed back though the aft bulkhead watertight hatch if it was to fail.  If it wasn't for the desire for a little more finesse than the two bits of string method provides I might have chosen that as an option.

Building an electric steering system isn't that hard, but I have two choices and would welcome some thoughts on each:

- The complex choice is to use electronic proportional position control, using a geared bidirectional motor and servo system.  This would replicate a traditional wheel or tiller, in that the "rudder" angle would be directly indicated by the lever, wheel or knob position.  The downside to this approach is complexity (it needs a servo amplifier, potentiometers for position measurement feedback etc), plus a slightly increased current drain, because the steering electronics would draw some power pretty much all the time.

- The simpler choice is to use the same steering motor arrangement, but just have a simple two way spring loaded steering switch.  I was looking at a system that takes about 4 seconds to go from 40 degrees one way to 40 degrees the other way, so short flicks of the switch would move the "rudder" just a degree or two.  The motor and gearbox is stiff enough to hold the steering in position without being powered.  The advantage of this system is that there are no electronics, the downside is the switch-type left-a-bit/right-a-bit control and the lack of a "rudder" angle indication (although this latter problem could be fixed fairly easily).  The left-a-bit/right-a-bit thing isn't really different from rowing anyway (at least, it isn't when I'm rowing........).

I suppose I could also look at a re-positionable steering head that uses a long Teleflex cable, but I can't help feeling that it'd be a bit inflexible and cumbersome.

I'm leaning towards the simple electrical system, perhaps with "rudder" angle indication added, but would very much welcome any thoughts.  I've been pondering on this for days and just when I think I've made up my mind doubts creep in.................

Jeremy

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[alopenboat]

On 24 Jan 2011 at 5:37, Jeremy [via UK HBBR Forum] wrote:

>
>
> I'm in a bit of a dilemma and could do with some alternative thoughts
> on steering arrangements for my solar powered Winsome.  Steering is
> accomplished by turning the drive unit, which looks a bit like a
> saildrive fitted through the hull in a sealed tube (Chris P(N) kindly
> took a photo of it, see page 63 of the last issue of Watercraft).
>

The arrangement in Paradox. of having a string right round the inside
of the cabin, attached to a tiller, is fairly foolproof.

--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[Jeremy]

Thanks for the ideas.  I should have, perhaps, mentioned that the motor unit is in a sealed buoyancy compartment aft (needed to meet the RCD rules) and that fitting a separate rudder is a bit fraught, because of the slipper stern and because of the added viscous drag it would create, which is why I've made the motor rotate for steering.  The aft deck is also quite long - the distance from the waterline edge of the slipper stern to the aft edge of the cockpit coaming is about 1.5m and the beam is only about 1m at the aft end of the cockpit.

Here's a photo of the hull, minus the canopy and motor:




I can seal either an electrical cable or teleflex cable through the bulkhead easily enough, but I'm not sure about the bit of string.  I quite like the simplicity of the continuous loop idea, though, so may take a look at having something like some wires feeding through seals at the bulkhead, attached to strings running around the hull.

How easy is it so steer with the loop of string method?  I can imagine it might feel a bit odd tugging a bit of string to and fro, not to mention the way that the steering sense changes from port to starboard.  You'd need to remember which way to push/pull depending on which hand you choose to use which must take a bit of getting used to.

[alopenboat]

On 24 Jan 2011 at 6:40, Jeremy [via UK HBBR Forum] wrote:

> How easy is it so steer with the loop of string method?  I can imagine
> it might feel a bit odd tugging a bit of string to and fro, not to
> mention the way that the steering sense changes from port to
> starboard.  You'd need to remember which way to push/pull depending on
> which hand you choose to use which must take a bit of getting used to.

Did you never have a trolley/soap box as a child? Or ride a horse? As
long as the string is attached to a forward facing tiller then pull
the left to turn left, right to turn right.

It is a good idea to fit the string with some sort of handle to help
with the grip. Making these adjustable along the string allows for
varying the seating position.

If the pulleys that the string passes round are not too expensive
then there will be sufficient friction is the system to hold position
if you let go.

--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[Timmo]

I can see the attractions of the high tech solution, it's in keeping with the ethos of the boat. However, I am only qualified to comment on low tech options!

On the subject of sealing in a piece of string; this is something canoeists are used to doing. It's commonplace for rudder cables to exit the deck near the stern to reach the rudder itself.

It's often done by sealing plastic tube, up to a foot each side, through the deck in line with the cable run then passing the cable through the tubes. The cable is greased but doesn't need to be a tight fit. It takes a very long time for water to get through the small space left and, given it's only exposed to splashes and occasional waves, it's as watertight as it needs to be. Certainly such an arrangement would be quite adequate to preserve the effectiveness of a buoyancy compartment.

Whether you go the low or high tech route my feeling is that you'll find it very useful to have some indication of the direction the motor is facing. Having to turn on the power in order find out where it's pointing could lead to awkward moments in tight spaces.

Tim.

[Jeremy]

The tube idea sounds easy enough, as you say it doesn't need to be totally watertight.  I may rig the steering strings no matter which option I go for, as they wouldn't take up much room and even if I don't use them as the primary means of steering they would always be there as a back up.

I think I could manage to work out which string to pull in which direction if holding them with both hands; somehow that seems more intuitive (at least to me) as you could work on the "pull" felt in both hands, like the analogy of the horse or soap box cart.  It's the steering with one hand bit that I feel might be slightly confusing, especially as the steering isn't like a sailing boat with a bit of weather helm; it'll probably have no feel at all, like turning an outboard.  Remembering that forward turns to starboard on the starboard string and forward turns to port on the port string sounds easy enough, but I bet I'd manage to get them the wrong way around from time to time!

That's a really excellent point about the direction indicator.  I'd sort of thought it'd be a "nice to have" as it'd be self-evident as to whether you were going in a straight line or not, but I hadn't for a moment considered the starting off situation, where the thing could be pointing anywhere!  This is the downside of having the motor etc all tucked away inside a watertight compartment where you can't see it (or, I hope, hear it).  Even with the loop of string method I think I'll need a couple of tell-tales, one each side, rather like those used on a tug o' war rope, to show where the "rudder" is pointing.

I shall have to give all this more thought, thanks very much for the ideas so far, particularly the loop of string one and the timely reminder about a rudder direction indicator of some sort.

Jeremy

[Timmo]

Brief thought on the 'intuitiveness' of the pushing/pulling on a string rudder control. I've found if I think like a canoeist it works. Namely pushing back on one side (as if paddling forwards) causes the boat to steer away from that side. Pulling toward the front (as if paddling backwards) causes the boat to turn toward that hand. 

It does become natural quite quickly, honest!

Tim.

[alopenboat]

On 24 Jan 2011 at 8:57, Jeremy [via UK HBBR Forum] wrote:

> I think I could manage to work out which string to pull in which
> direction if holding them with both hands; somehow that seems more
> intuitive (at least to me) as you could work on the "pull" felt in
> both hands, like the analogy of the horse or soap box cart.  It's the
> steering with one hand bit that I feel might be slightly confusing,
> especially as the steering isn't like a sailing boat with a bit of
> weather helm; it'll probably have no feel at all, like turning an
> outboard.  Remembering that forward turns to starboard on the
> starboard string and forward turns to port on the port string sounds
> easy enough, but I bet I'd manage to get them the wrong way around
> from time to time!

You simply pull or push the boat in the direction you want to turn.
If holding the port string imagine you are holding the port side of
the boat and the boat is sitting on a turn-table. Push it away from
you to turn to stbd. pull it towards you to turn to port.
 
> That's a really excellent point about the direction indicator.  I'd
> sort of thought it'd be a "nice to have" as it'd be self-evident as to
> whether you were going in a straight line or not, but I hadn't for a
> moment considered the starting off situation, where the thing could be
> pointing anywhere! This is the downside of having the motor etc all
> tucked away inside a watertight compartment where you can't see it
> (or, I hope, hear it).  Even with the loop of string method I think
> I'll need a couple of tell-tales, one each side, rather like those
> used on a tug o' war rope, to show where the "rudder" is pointing.

I have a tell-tale on the string which lines up with a mark on the
combing when the rudder is centralized.

--
Hoping for calm nights

Alastair Law,      
Yeovil, England.
<http://www.little.jim.freeuk.com>          

[Paul H (admin)]

Jeremy,

There is plenty of "wobble" room on the Thames and things happen slowly - in 2009 we were sometimes 2 or 3 boats abreast.

MilliBee has a dead simple "Tiller Hand" that worked perfectly on the 2009 raid:



http://www.saltyjohn.co.uk/tillerhand.htm
http://stores.ebay.co.uk/Salty-John-Boat-Products

After a few hours you will be able to look at the next corner and make one tiller change that keeps you on the correct curve for 20 seconds or more, hands free.

I used a 2-stroke outboard and I could literally dive forward into the cabin for beer/food and make lunch in the cockpit as I motored along, occasionally nudging the tiller with my knee.

So forget all the low MTBF stuff (Mean Time Between Failure for non-aircraft types).

As Al said the Paradox has a similar mechanism, but the variable friction is a great feature I think.

-Paul

[Jeremy]

Thanks again for all the useful ideas and suggestions.  

That tiller hand looks very like the "wrap the tail end of the mainsheet around the tiller" jury-rig that I used to use on my old yacht when single handing.  I used to get the friction by winding three or four turns around the tiller, leading the free end of the sheet back to one of the stern cleats.  It worked very well on a broad reach, less well on any other point of sail.

I think I've settled on two systems.  I'm going to rig a couple of steering strings though tubes in the bulkhead to the steering arm on the motor, as a manual steering system.  Rather than run a loop all around the cockpit (which would end up getting in the way a bit right forward) I think I'll just have two strings, running through fair leads just under the side decks, extending to just forward of amidships and terminated with stopper knots (leaving enough slack for the steering to be unimpeded).

This will be the secondary system, I've decided to go with a proportional control servo, with a remote control on the end of a long lead (the remote will include the throttle and fwd/ast switch), for the primary system, both because I like the challenge of designing and building it and because I think it'll be handy to be able to fully drive the boat from anywhere in the cockpit.  I well recall all the gymnastics when sailing single handed and trying to judge just when it would be OK to let go of the tiller and sheet and rush forward to grab a mooring buoy; the idea of being able remain in control whilst sorting out fenders when coming alongside or whatever has a certain appeal.

Jeremy

[P.L.Oxborrow]

Jeremy,

 

In for a penny, in for a pound? Lose the long lead & go for R.C./Bluetooth/ IR & then you can run the boat into the lock while you open the gates & sluices from the bank......not necessary on the Thames, but for the rest of the system.....

 

Doesn't the steering string want to be a closed loop so that you can steer both ways from one side? I use a push/pull tiller on my sailing canoe, & while it's not quite an intuitive action, it very quickly becomes second nature.

 

Phil.

---

From: Jeremy [via UK HBBR Forum] [mailto:[hidden email]]

 

 This will be the secondary system, I've decided to go with a proportional control servo, with a remote control on the end of a long lead (the remote will include the throttle and fwd/ast switch), for the primary system, both because I like the challenge of designing and building it and because I think it'll be handy to be able to fully drive the boat from anywhere in the cockpit.  

 

[Jeremy]

I had thought about wireless control.  It was prompted by having seen this video on YouTube of a chap driving an electric canoe with a wired Wii nunchuck:



It occurred to me that a wireless Nunchuck would make a very neat boat controller................

The idea with the two strings is simply to have an emergency back up.  It'll mean steering with both hands, but that's probably OK as a get-you-home measure.

Jeremy

[Michael Rogers]

Jeremy, I suspect my twopenn'orth isn't worth that much, but in case it helps, re your back-up steering -
Timmo describes a norwegian tiller: I haven't heard it called that, but my double-ender has such a push-pull tiller arrangement, and I can absolutely assure you that anything which seems counter-intuitive about it disappears extremely quickly, and it becomes as natural as waggling a tiller, or spinning a wheel. Once used to it, you wouldn't get it wrong, even under stress, eg an emergency reaction. Not that it's relevant to your potential use, but it has advantages over a conventional tiller in a small boat in terms of how you can move the end of the 'rod' from side to side (and therefore sit in various positions) without moving the rudder.

I'm sure the same rapid familiarity would apply to any steering-string system.

The one disadvantage of push-pull or string (or indeed a wheel) vis a vis conventional tiller steering is that they don't automatically tell you the position of the rudder, as a conventional tiller does simply by its position in relation to the boat. Some glancing aft is called for, a lot in some situations. In your Winsome, as you can't even see the equivalent of the rudder, some sort of helm-direction-indicator would seem to be to be essential.

[BrianP]

Article on Duckworks about electrical remote steering for trolling motors.

 http://www.duckworksbbs.com/plans/simpson/steering/ElectricSteering.pdf

[Jeremy]

Thanks for that link, Brian.  I think it is the same system that I spotted on a YouTube video some time ago, it certainly looks similar.  

I've made the mechanical parts for a steering servo motor, having found that I couldn't get anything off the shelf at a reasonable price.  I used a geared motor coupled to a toothed belt, with the output shaft coupled to a feedback potentiometer.  I just need to finish off the servo amplifier that will drive this and then I should have a fairly powerful system that can be simply controlled by a small steering wheel that just sends a voltage to the servo.  This will give me rudder angle indication as well, which will be handy as the whole motor and steering assembly is tucked away in a sealed compartment.

Here are some pictures of work so far:





The plan is to couple the shaft from this servo to a short arm that will move a slightly longer short "tiller" attached to the motor to turn it.

Jeremy