Bow Thrusters, Skyhook (dynamic positioning), Joystick for docking in a hot-rod boat?
 

I have been following the IPS explosion in the yachting world, along with ZF Marine's new transmission/Twin Disc EJS for Sport fishing boats and Yachts in a V drive-shaft application, that utilize the skyhook technology, and joystick application for docking purposes. Since the shafts are in a fixed position (one direction with a rudder for steering) in the V-drive sport-fishing boat application, the ZF Marine transmissions work in conjunction with the bow-thrusters and the joystick. This joystick docking maneuver works just like the pod drives (IPS) with bow thrusters in a pod joystick application for docking purposes.

Here is my question. I thought hot rod boats went too fast and would have too much water pressure (psi) at the bow if the boat were to bow stuff a wave at 100+ mph for the bow thruster to survive without it getting blown out of the pocket? I recently saw in the Outerlimits section an example of a beautiful SL44 with 1075's and bow thrusters. It looks to me Outerlimits has figured this out the bow thruster issue with high speed boats. I would have been concerned about blowing the thruster out of the pocket it has been molded/secured to in the event of stuffing a wave at 100+mph let alone the 140mph that this boat runs (it is an awesome boat). http://www.offshoreonly.com/forums/o...ry-1075-a.html

Next question, since the outdrives on a hot-rod boat are fixed in position with a tie-bar, similar to that of V drives sport (fixed in position) in a sport-fishing boat, it would seem to me that all that is necessary is the transmissions in the hot-rod boat to be computer smart like the ZF Marine transmission in the Sport-Fishing boat application in conjunction with the requisite bow-thrusters.

Bow thruster, and joy stick docking for hot-rod boats should be here and now, but why isn't it?

Does Outerlimits or any of the other high end builders have something worked out the the secondary equipment and parts suppliers, like ZF, Weismann, Mercury, and the bow-thruster manufacturers? It would seem to me that would be a great selling feature, joy stick docking, for one of these 130mph+ hot-rods. A joystick and the SL44 pictured below, that would be a great combination for docking purposes.

That is a very good question. I have driven a Tiara with ips, the thing was amazing, press a button and it stays in place so one person can untie the boat. I have also driven a 60 cruiser. the 60 is very easy to walk sideways because the props are so large. I have not driven a 40+ go fast, but I think one problem may be the prop walk with smaller diameter props may be a problem? Obviously I am not sure, but that could make it harder for the system to work. It sure would be sweet, the joystick drive makes maneuvering a joke, but it sure was fun.

Volvo and Mercury both have joystick systems for stern drives, but the systems are dependent upon using the internal tiller arm on the drives. This is a recognized weak point, which is why high-performance boats use direct steering. Joystick systems also will not work with tie bars (another high-performance must-have) because the drives must be able to steer independently.

Eventually, a system could be developed that would use external hydraulics instead of the internal tiller. As long as some kind of super-reliable/redundant steering position sensor was used on each drive, the tie bar could be deleted, and - Viola! Done.

ACTUALLY: Now that I think about it, the DP-H and DP-R sterndrives that Volvo uses on it's diesel engines ARE equipped with direct hydraulic steering, exactly like Bravo/ITS, NXT's, Mercury #6's and Ilmor Indy drives. (See photo below) Maybe the Volvo system could be adapted to go-fasts.

The other aspect is that the system would need control of the throttles and shifters as well. Fly-by-wire systems like the current Ilmor packages could be adapted pretty quickly.

Chuck,

ZF Marine had installed two of their specialized transmissions in a large sport fishing boat with shaft drives (V drives which are fixed with rudder steering), the boat also had bow thrusters. At the helm was a joystick when used would automatically adjust prop speed for each engine, prop direction, and the necessary amount of thrust from the bow thruster to walk the large boat where ever they wanted it to go.

My thinking is the the shaft drives do not move and in a fixed position just as an out-drive hot-rod with a tie-bar would be also in a fixed position, so the computer would send the signal from the joystick to the drives and replicate the same effect that Twin Disc did for the sport fishing boat using the Twin Disc Express Joystick System, I have posted the video that shows the EJS in action. All a hot rod would need is a computer program to talk with transmissions and bow thrusters, but the engine rpm at idle and going in and out of gear, and changing direction, forward or reverse, is a limiting factor I would think. And the fly by the wire - Digital Throttle Technology would need to part of the package. It is time for the hot-rods to join the rest of technology that currently exists.

Video link:
www.youtube.com/watch?v=fP9QAemSKp8

www.youtube.com/watch?v=w8FEYDNMj1U

AND ZF Marine's JMS (joystick marine system):

http://www.youtube.com/watch?v=Uk3cR...eature=related


And product information:
www.twindisc.com/MarineProducts/EJS.html

I would think that after seeing Twin Disc EJS, I think that type of technology could work in an high performance application.

Opinion?

This artilce sold me on the system:
http://www.twindisc.com/Downloads/Ne...927_eprint.pdf

One thing to consider is the speed that a computer controlled system will shift from forward - reverse. I have the "total command" on the cruiser and when you control from the joystick the system will routinely make brisk changes in the transmission without any time delay. For example, if I am cruising at say 1000 rpm (controlling with the joystick) and I rotate the joystick clockwise, the starboard engine will drop back in rpm's. If I pull the joystick back to the upright position and maintain the same rotation, the port engine will drop to idle and the starboard engine will shift immediately into reverse. If you look up the specification for a ZF transmission, they are rated to shift immediately. In fact you can go from hard throttle to direct reverse in an emergency and according to the owner’s manual this should not hurt the transmission. How would your Bravo or NXT transmission handle this? Maybe not so good?

That is what I was thinking, that when in the joystick mode there would be a lockout to prevent the hard throttle issue you just described. In a Bravo application not sure how it would work since you shift in the drive, but in an NXT, or #6 or the new M8, or Arneson, or any fixed shaft drive, I would think the transmission is the component to make this all work for joystick docking (with the bow thruster).

I should clarify my answer for the Bravo application, in the single prop Bravo application like the standard Bravo or an XR, Mercury does not use their joystick control.

In the Bravo Three (dual prop Bravo drive), Mercury uses their system called Axius which is a joystick application and claims that you can joystick the boat engine speed up to 2200 rpms with the joystick. The Bravo Three joystick his cannot be utilized with a tie-bar, since in the joystick maneuvering mode the drives turn independently of one another like a pod drive application.

I still just do not understand why it cannot work (or the technology has not been transferred) in a single prop outdrive application with a transmission and bow thrusters. Maybe the market for this application does not exist in hot-rods. My thought would be if you were paying in excess for $300,000-$1,500,000 for your new hot-rod, anything to make it dock easier would be a minimal expense in the big picture.

Now with regarding to the emergency in reverse, according to an article I read in Powerboat a few months back, transmissions in performance boat applications (like the transmissions for the #6 drive), are not made to be throttled hard in reverse as that seemed to be a real problem that could and does cause transmission failure.

As far as going from forward to reverse quicly in an emergency, I would think as long as the engine rpm speed is dropped to whatever the acceptable point for shifting would be that would not be too much of an issue, meaning the transmisssion may be locked out from shifting from forward to reverse in the standard mode of operation for anything greater than 1200 rpms of engine speed (this is a random choice). But in the joystcik mode the engine, transmission, and drive would have preset/ceiling for engine rpm maximum in reverse, my guess.

The Twin Disc EJS(R) (Express Joystick System) requires the use of QUICKSHIFT(TM) transmissions with EXPRESS mode. This limits EJS to diesel applications only due to the RPM limits of the transmissions.

Steve

Steve,

Thank you for the response. Since the technology exists for the diesel application, with some changes and tweaking why can't technology be transferred to the high-performance (gas fuel) application? Mercury uses it is the Bravo Three application the 496 HO engine. While the 496 HO is not in the same league as Mercury's 700, 1100, and 1350 packages it is still a starting point.

I know you may not be able to speak for the Mercury product due (maybe you can speak for the Mercury product, I mat be making an invalid assumption) to the fact that your answer addresses the Twin Disc EJS product. I would think that the joystick docking market for performance and pleasure craft types boats on this website would be worth the investment (ROI) for a company to make.

Stephen

I called Mercury High Performance division today to ask if they had an Axius type product (joystick dock maneuvering) for the 525hp through 1350hp packages in the pipeline or in R&D, and the answer was "NO."

There is a hole in the marketplace that needs/could be filled. I am in the wrong line of work, should have been an engineer.