Seabrace overhaul

[branwyn]

I love my Seabraces... but last year they started to misbehave.



First, they would randomly come on and off. Then, the turn bank indicator/gyro started to whine due to bad bearings. And finally, the port control box gave up the magic black smoke... the wiring and circuit burned themselves up saving the fuse from its demise... how kind!

First up, was the repair of the port control box. We'll be replacing these too, but that comes later. Note the burned wiring:



As we're headed for a long cruise to Canada this summer I wanted to get the system back online. Further, while we're at it, I figured improvements were required to increase the performance and reliability of the system.

My best friend and I started pouring over the system. He's an electrical engineer, worked for Boeing and other critical electrical system companies and all around smart guy. We dug out the old Seabrace manual (electrical circuit schematics) and then started reverse engineering the system a few weeks ago. We learned a lot... but the system is very electrically crude, even for its day.



More in my next post...

 

[branwyn]

Four new transistors, a replacement LM324 op-amp, some new internal wire and some top hats to protect the transistors and we were ready for re-installation!



Next we found out the port stabilizer feedback pot was bad. It appears the original pots were not sealed and that over time oil and other grunge gets into them. I pulled out the pots, replaced them, and sealed them and their electrical connections.



With the control box back in... we're ready for testing of the control boxes at the dock. At this point, the only components left of the original system is the mechanical (hydraulics and control motor), and the refurbished control box. The turn bank indicator, relay, and original wiring has all been stripped out. We'll be replacing all those components too... which is where some of the magic will be happening.



More in next post...

 

[branwyn]

We had a few challenges in the initial dock trials. A hydraulic line needed to be replaced and we had a few challenges getting the pot on top of the control box to play well with the feedback pot on the port side. Some more bench work on the circuit was needed.

Using our secret troubleshooting tools (Legos), we replicated the expected operating parameters on the bench. After some additional repairs on the control box circuit, we have success!

With the port control box back in the boat... we started working on the replacement technology for the gyro, power control, and helm controls.

Firing up the old turn bank indicator, you can hear the failed bearings inside the unit. We were able to extract some voltage information from the unit.

As we're still in the learning process, our setup is pretty crude to start with. Using a breadboard, we fabricate our initial control circuits that will replace the gyro. My engineering friend Glenn wrote the first version software and algorithms we're using to translate our new solid state rotation sensor. Here is a test video of the voltage output of our new rotation sensor:

After much good work and more dock testing we build a very makeshift control panel from cardboard, angle displays and some LED's. We connect our new control circuits and software to the rebuilt control boxes and fire up the engines and head out for sea trials.
View attachment 13076

The seas were calm today so we tested by doing hard turns at 10-15 knots and chasing back into our wake. Our first sea trial and beta software worked exceedingly well. Our new control circuits, rebuilt control boxes, and rough built control panel is arguably performing better than the original system already.

Stay tuned, much more good work to come including refinement to our algorithms, permanent circuit designs, and a 1st phase control panel. We're planning to replace the control boxes with modern components and working towards a glass cockpit that will allow variable and independent control of each stabilizer. We're very much enjoying this project!

Cheers,
Ryan

 

[jim rosenthal]

This is something you might publish here when you're done. Is Wilcox still in business? Sound like you might have an improved system even if they are still out there.

 

[branwyn]

Hi Jim,

When we're fully done with the rebuild and testing our plan is to do just that as it seems there are still quite a few systems in use out there. I don't believe Wilcox is around anymore.

Cheers,
Ryan

 

[SeaEric]

Excellent work! You can market this upgrade/repair protocol I'm sure. Plenty of Seabrace guys out there looking for an angel. You may have it.

 

[ian w]

Does anyone know of anybody in Fort Lauderdale who can repair or diagnose problems with Seabrace stabilisers.The parts are auto and available -it would appear expertise is missing

 

[branwyn]

Does anyone know of anybody in Fort Lauderdale who can repair or diagnose problems with Seabrace stabilisers.The parts are auto and available -it would appear expertise is missing

Hi Ian,

I don't know anyone in that area but if you describe the issue I might be able to assist.

Cheers,
Ryan

 

[branwyn]

We've started working on the electronics package that will be at the center of the new Seabrace control. Here's a little information on the control sensor for the more geeky/techy folks.

The new Seabrace NG sensor we're deploying is based on a surface-micromachined IC (integrated-circuit) 3-axis low g (gravity) accelerometer, presently these signals are used to provide highly accurate real time roll and pitch information to the MPU (microprocessor unit) for AOA (angle of attack) control of the port and starboard Seabrace fins. The accelerometer consists of a surface micromachined capacitive sensing cell (g-cell) and a signal conditioning ASIC contained in an IC package. Excuse my crude drawing:


The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as a set of beams attached to a movable central mass that move between fixed beams. The movable beams can be deflected from their rest position by subjecting the system to an acceleration.


As the beams attached to the central mass move, the distance from them to the fixed beams on one side will increase by the same amount that the distance to the fixed beams on the other side decreases. The change in distance is a measure of acceleration.

The g-cell beams form two back-to-back capacitors. As the center beam moves with acceleration, the distance between the beams changes and each capacitor's value will change, (C = Aε/D). Where A is the area of the beam, ε is the dielectric constant, and D is the distance between the beams.

The ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration for the MPU to process.

We've not yet given much consideration to how sway, heave and surge effect the system but it is on the agenda.

Much good work in progress... more to come...

Cheers,
Ryan

 

[GJH]

Very fascinating thread, though I have to admit the technology is well beyond my skill level.
Looking at your fins, they appear very similar to Naiads, and similarly located vis other motor yachts. So I am very curious as to how you go about having them affect anything but roll, given that they are at or near the pivot points for yaw and pitch, and essentially vertical to heave.

Thanks for being so thorough and taking the time to post this!

 

[rhprop]

Just go to Ebay and search " MEMS " The units to sense and produce the necessary control voltages are readily available and cheap. Every Apple IOS device and current Android devices also have the accelerometers to produce the parameters.

 

[bostonhatteras]

Congratulations on your thoughtful and technical approach to solving your problem. Everything, whether it appears mechanical or not, has a particular way and parameters in which it works. Figure that out and the mystery is solved. I'm sure you could market replacement panels for this system. Go for it!

 

[GJH]

Just go to Ebay and search " MEMS " The units to sense and produce the necessary control voltages are readily available and cheap. Every Apple IOS device and current Android devices also have the accelerometers to produce the parameters.

I understand that part, actually. You can get sensors to detect motion in any direction, and to some degree, build logic to anticipate a good part of it. My question is more around the physics of mechanically offsetting the boat movements of pitch, yaw and heave, given the placement, size and pivot point of the fins.

 

[SKYCHENEY]

Guys,
This has all been done already. One of the early forum members here did this, Mark Giovanniello. I met Mark when he installed his system on a friends 60MY. Here is his website. Great guy!

http://www.giovanniello.com/sbretrofitkit.html

 

[rhprop]

I understand that part, actually. You can get sensors to detect motion in any direction, and to some degree, build logic to anticipate a good part of it. My question is more around the physics of mechanically offsetting the boat movements of pitch, yaw and heave, given the placement, size and pivot point of the fins.

Agreed. Unless you are controlling fins, bow and stern thrusters and the rudder at the same time, the only axis controlled is roll. I was just pointing out that components are available and cheap to accomplish result. Computational components and motor drive amps are also available and realitively cheap. The fins and through hull components are the real key.

 

[tomrealest]

For any Seabrace owners who need a gyro, call
MidContinent instruments & avionics 800 821 1212 & talk to jeremy. He turned me over to Doug and Doug found the one I wanted.

item # 1394T100-20RZ [ Description ] turn coordinator 12-32 V

My gyro was making the same whinning noise and I wanted a new one. Cost was about $800. Mine has a 5 wire plug with 4 wires in the plug.

The solution talked about here is exciting but this is the easy way out.

 

[saltshaker]

Great thread! I always enjoy following these types of projects. A bit off topic but I'm curious as to which monitors you have in the shot of the lower helm. I'm looking to replace two on my bridge and have been looking at a few.

 

[GJH]

Guys,
This has all been done already. One of the early forum members here did this, Mark Giovanniello. I met Mark when he installed his system on a friends 60MY. Here is his website. Great guy!

http://www.giovanniello.com/sbretrofitkit.html

So what? We have a new poster here who is doing this on a DIY basis and providing some more detail on the technology. I'd never want to discourage that. At the end of his project, he can provide a time and materials cost vs. buying the system you linked to. Plus the thread may raise some other topics around boat movement, etc.

 

[saltshaker]

I think Sky's point is that since Mark already did this, his experience/knowledge could aid in Ryan's project. Mark did this a while ago so he would have real world knowledge of what worked and any tweaks that needed to be made.

 

[ian w]

Great thread if you have seabrace.My question is are the belt driven pumps off the 871detroits sevicable items if they are not producing hydraulic pressure.My belts are tight and fluid full but do not seem to have hydraulic pressure .Any thoughts appreciated ian w 1981 53 my