autopilot - wheel drive versus tiller drive

[BOAT]

I guess i was thinking that the wheel pilot has less resistance and also has more ratio - so it would have finer tuning on small adjustments. I'm all backwards, how did I get to this conclusion?
Ugh, First off,
My neighbor that owns the Catalina 38 in the harbor also owns a company that specializes in sound proofing and he is going to work out the specifications for making the AP silent but I needed to get some cavity data for him so I went under cockpit with a tape and i sort of started studying the whole steering system. The arms that extend from the rudder shaft seem long enough to simulate a "tiller", but when I move the rudders with my hands from under there it just seems like the whole thing is harder to control from that long 'bar' than it is from the wheelhouse, (I guess the correct term is "tie rod" and "pedestal").

Anyways, I was just imagining me as an auto pilot trying to steer the boat from under there by moving that tie rod around and i found it to be rather hard to be really accurate. It's hard to stop at an exact spot without over-steering just a teeny bit, It's like when I get the rudders moving they don't want to stop - it takes force to stop the rudders from moving after I get them going?
Am I making any sense??
I dunno

So that hydraulic piston thing is pretty strong, right? I imagine the force needed to throw those rudders around at 6 knots and i guess i got a little worried. I'm tempted to connect the hydraulic piston thing directly to one of the tiller arms instead of that "tie rod" thing because the tie rod just does not have a good feel in my hand to me when I try to quickly move it from side to side - and I think it could bend too if I do it from the middle, like it will put "spring" into the system? Am I just being too anal again?? This always happens when I engineer something, I get really anal. You think I'm just being stoopid?

[RobertB]

Boat,

There are no hydraulics involved in the EV-1 system. The Wheel pilot has a rotary actuator, the tiller a mechanical linear actuator. Both are electric motor driven.
The biggest difference is that the wheel pilot is easy to disengage on our boats, the tiller requires a monkey in the rear berth to do so. Therefore, people who have the tiller version generally leave it engaged.
As far as where to connect, the tiller arms are actually a bit shorter than the system was designed for but really should not matter much. I do not know how you could hook to both rudders without using the linkage. Also, to hook directly to one tiller arm, you need to engineer a mount near the center of the boat. I considered that but there is no structure available to make this easy.

[BOAT]

Boat,

There are no hydraulics involved in the EV-1 system. The Wheel pilot has a rotary actuator, the tiller a mechanical linear actuator. Both are electric motor driven.
The biggest difference is that the wheel pilot is easy to disengage on our boats, the tiller requires a monkey in the rear berth to do so. Therefore, people who have the tiller version generally leave it engaged.
As far as where to connect, the tiller arms are actually a bit shorter than the system was designed for but really should not matter much. I do not know how you could hook to both rudders without using the linkage. Also, to hook directly to one tiller arm, you need to engineer a mount near the center of the boat. I considered that but there is no structure available to make this easy.

Huh, "mechanical linear actuator" . . . . . . . . . Okay, now your starting to sound like mastreb

Look, I am sort of the bowling ball of sharp knives when it comes to the design of an 'M.L.A.' but one thing you mentioned I CAN be good at is the "monkey in the rear berth" now, THAT I can do!

So if the tiller arm is a bit short (and I was thinking that myself) - (I figured that one out all on my own! ) then any thoughts on extending one of the tiller arms to use as a connection point for that "M.L.A" thing???

Should I consider putting an extension on one of the tiller arms?

[RobertB]

I considered the tiller arm extension but after thinking about the very short cord rudders (these need much less force to move than larger rudders) and talking with RayMarine tech support, we agreed that using the existing lever arm was OK. I chose to use a clamp on attachment to the linkage versus the screw on type used by others to eliminate drilling holes in my linkage (introducing a possible point of failure due to a hole and the need to remove the linkage). I also like the challenge of designing something custom and the fact I was too cheap to buy the additional part.

[BOAT]

I considered the tiller arm extension but after thinking about the very short cord rudders (these need much less force to move than larger rudders) and talking with RayMarine tech support, we agreed that using the existing lever arm was OK. I chose to use a clamp on attachment to the linkage versus the screw on type used by others to eliminate drilling holes in my linkage (introducing a possible point of failure due to a hole and the need to remove the linkage). I also like the challenge of designing something custom and the fact I was too cheap to buy the additional part.

And are you are getting the performance you desired with the short tiller arm? Everything okay and is it real accurate like mastreb's wheel pilot? It hold the course really really good and adjusts for lean, heel, and so forth like mastreb??

No issues?

[Tomfoolery]

You need to match the stroke on the linear actuator to the lateral distance the attachment point on the arm or link travels from lock-to-lock. If you make the arm extension too long, the actuator won't have the stroke to control the rudders through their whole range. If it's too short, the rudders will travel lock-to-lock, but you're wasting actuator stroke, and the forces in the actuator will be unnecessarily high.

For meatball engineering, you can temporarily attach the blind end (opposite the rod) of the actuator to whatever it will be mounted to, with the rudders angled to the max such that the actuator is short, and mark an attachment point on the rudder arm or link. Run the rudders all the way the other way, and measure from the actuator rod end attachment to see if you get more or less than the max stroke. This can take a number of iterations, as there is an infinite number of combos of attachments to do what you want, but you need to find at least one.

Without engineering design tools and/or mathematics, this is the only way I know to do it. But it's the easiest way, too, with such a simple linkage, as it's very visual and intuitive.

[BOAT]

Actually it's even easier than that - all you need to know is the full stroke distance of the 'piston', (M.L.A. - actuator?) whatever the hull it's called - anyway, once I know the full distance the 'thing' can travel I will take a teeny bit off that length and use it to create an arm that has the same travel distance as the length I calculated. After that the only trick will be to make sure I get the "MLA thing" mounted so that it's exactly in the middle of it's stroke length when the rudders are exactly straight in the forward direction.

Getting it exactly in the middle might take a little adjustment at one end or the other so I probably should take that into account in my attachment plan.

The guy creating the sound deadening bulkhead wants to know what kind of decibels he is dealing with - any of you guys know that?

[Tomfoolery]

Actually it's even easier than that - all you need to know is the full stroke distance of the 'piston', (M.L.A. - actuator?) whatever the hull it's called - anyway, once I know the full distance the 'thing' can travel I will take a teeny bit off that length and use it to create an arm that has the same travel distance as the length I calculated. After that the only trick will be to make sure I get the "MLA thing" mounted so that it's exactly in the middle of it's stroke length when the rudders are exactly straight in the forward direction.

Getting it exactly in the middle might take a little adjustment at one end or the other so I probably should take that into account in my attachment plan.

The guy creating the sound deadening bulkhead wants to know what kind of decibels he is dealing with - any of you guys know that?

But the stroke (length) isn't the whole story. The geometry will change based on where it's anchored at the blind end. You don't have to use the actual actuator; a wooden dowel would work, or even a ruler. But you need to check both ends of the stroke referenced to the actual mounting point.

[RobertB]

I considered the tiller arm extension but after thinking about the very short cord rudders (these need much less force to move than larger rudders) and talking with RayMarine tech support, we agreed that using the existing lever arm was OK. I chose to use a clamp on attachment to the linkage versus the screw on type used by others to eliminate drilling holes in my linkage (introducing a possible point of failure due to a hole and the need to remove the linkage). I also like the challenge of designing something custom and the fact I was too cheap to buy the additional part.

And are you are getting the performance you desired with the short tiller arm? Everything okay and is it real accurate like mastreb's wheel pilot? It hold the course really really good and adjusts for lean, heel, and so forth like mastreb??
No issues?

No issues yet - the boat has not been in the water since the install

I did discuss the stroke and geometry with RayMarine and expect it to work.

[mastreb]

Hey boat,

My 38 has exactly the same steering system as you described, and the linear ram used for steering is connected just as you would expect, with a longer full stroke piston distance than the lock-to-lock steering. Look at the part numbers I posted, as that linear ram is likely the least expensive that will do the job for you friend's 38.

It's silent. I hear absolutely no noise from the autopilot. There is a 1/4 fiberglass bulkhead surrounding all sides of the steering compartment however. I doubt any noise dampening will be needed.

[BOAT]

But the stroke (length) isn't the whole story. The geometry will change based on where it's anchored at the blind end. You don't have to use the actual actuator; a wooden dowel would work, or even a ruler. But you need to check both ends of the stroke referenced to the actual mounting point.

Hmmm, well I don't want to miss something so you know what tom? I think I just might mock up the entire installation in wood first before I commit to a design. I might need to get a few dimensions on some of the parts from you guys to create an accurate mock up. It might also give me the design of the cable operated "door catch" that I want to put on it so it can be disconnected from the helm, (not that I have anything against monkeys, I think I might even be related), but I must admit I like the easy steering action of my boat when I am trying to work the motor around to parallel park at some of the tight docks I frequent in Oceanside Harbor - you need to swing the motor quickly and change gears from forward to reverse fast to get into some of the tight spots. I would rather not compromise what to me has been good steering performance.

For the rudder tiller extension my plan is to leave the existing one in place and bolt something on top of it. Did any of those Raymairine guys mention what the best pivot length would be considered "optimal" for their unit? At least that gives me a starting point before I start grinding out the metal arm. (Something like that is not going to be mocked up very well in wood)

[BOAT]

Hey boat,

My 38 has exactly the same steering system as you described, and the linear ram used for steering is connected just as you would expect, with a longer full stroke piston distance than the lock-to-lock steering. Look at the part numbers I posted, as that linear ram is likely the least expensive that will do the job for you friend's 38.

It's silent. I hear absolutely no noise from the autopilot. There is a 1/4 fiberglass bulkhead surrounding all sides of the steering compartment however. I doubt any noise dampening will be needed.

Yeah, Johns boat is big like yours - I'm not sure what his AP is made of. The specs John (my neighbor) wanted were for MY boat. He said he can create a super lightweight bulkhead that will make the AP I install on boat completely silent - be he needs to know the cavity dimensions on 'boat', and the decibels of the AP and other stuff. He engineers sound barriers that stop sound better than mass barriers - like he has a 1/8 inch thing he uses that stops sound as well as a concrete block wall. He is going to make a bulkhead for me to stop all the sound from getting out of the transom after i get the stuff installed. I have been talking about it for a while with him because I wanted the motor sound to be lessened when underway while down below, and now it's going to be a 'twofer' he's gonna significantly lessen the sound of the outboard inside the boat and eliminate the sound of the AP all in one shot - I get a 'twofer'.

I'm still struggling with how I want to install the "liner ram" ? as you call it. That seems to be the big sticking point here. And I'm not sure about what the "push rating" is on the "ram" Kadet and the other are using so I'm concerned I might be over taxing it with such a short swing arm that exists now on the rudder tiller arms. I think is less than 12 inches? That's a pretty short tiller!

You have the wheel pilot so you AP is getting all the advantage of a nice smooth steering ratio from the wheel gear in the pedestal. I'm just wanting to make sure the performance of the tiller unit will be comparable.

[beene]

Here's mine



Single best investment in my boat yet

G

[BOAT]

Yeah, we know about yours and John's and Matt's - you guys all have that "bagel" one. So far that one has the best reviews on this site for accuracy. I'm still waiting for reports on some of the more recent "tiller" type installs. I'm curious if there is a difference in the performance.

[innervations]

When underway I cannot hear the tiller drive at all. Moored I can hear a whirring sound but this was for testing the AP initially and of course the AP is off normally when not underway. I would not bother with sound proofing for the tiller pilot but each to his/her own.