"Slow Vessel" switch

R

Rich Pietraszko

New Member
Sep 24, 2014
7
United States
Boat Info
2002 480MY
Engines
Cummings QSM11
[FONT=wf_segoe-ui_normal]My 2002 SeaRay 480MY has a "slow vessel" switch that never seemed to do anything. While installing a new MFD I traced the wires and it turns out the switch interrupts the nmea wires between the original chart plotter and the Raymarine S2G-AST Autopilot? What would that switch do and how would cutting the nmea connection accomplish it? Thanks![/FONT]
 
I think that reduces engine RPMs, for slower speed, when docking etc. I'm sure there will be more responses.
 
I have those on my boat. Slow vessel reduces the RPM from 650 to 550. It is needed in the marina due to the wake at idle speed. If I don't use it I need to go in and out of gear to slow the boat and not create a wake.


Sent from my iPhone using Tapatalk
 
Also called a trolling switch for slow trolling for slow fish.
 
I should clarify there is a separate "slow idle" switch that I obviously use all the time so this "slow vessel" switch is something different. It is only connected to Nmea wires between chartplotter and autopilot.
 
Rich Pietraszko said:
I should clarify there is a separate "slow idle" switch that I obviously use all the time so this "slow vessel" switch is something different. It is only connected to Nmea wires between chartplotter and autopilot.
Click to expand...

Maybe turns on a beacon that appears on other vessel's radar indicating that you are slow moving? :huh: Just a guess...
 
I've never seen such a switch but am guessing why someone might have put it there. GPS fixes when stationary or moving very slowly tend to jump about quite a bit, especially on older units. Even though the difference is only a matter of feet as each successive fix is just a little different, the receiving unit will interpret the difference as a change in heading and speed. When I observe my plotter along side the pier, the heading vector is constantly shifting around dramatically. So, the installer may have wanted to shut off that input when moving slowly trying to use the autopilot, although most probably don't engage the autopilot at very low speeds. Just a theory.
 
alnav said:
I've never seen such a switch but am guessing why someone might have put it there. GPS fixes when stationary or moving very slowly tend to jump about quite a bit, especially on older units. Even though the difference is only a matter of feet as each successive fix is just a little different, the receiving unit will interpret the difference as a change in heading and speed. When I observe my plotter along side the pier, the heading vector is constantly shifting around dramatically. So, the installer may have wanted to shut off that input when moving slowly trying to use the autopilot, although most probably don't engage the autopilot at very low speeds. Just a theory.
Click to expand...


That's the best answer yet but this is an original factory switch installed by SeaRay. The manual conveniently doesn't mention it.
 
If it's not a Slow Idle, if it's not a Sky Hook, have we discussed an idea of trolling valves?

P.S.
I just noticed that your boat is 2002, Sky Hook wasn't available at the time. We can scratch that thought.

An obvious question comes to mind, have you tried engaging the switch? Anything different happens?
 
Last edited:
Good question Alex. Yes I've tried it while cruising and found no effect. It wasn't until I was installing a new MFD that I traced the wires and found it just interrupted the Nmea wires. Another clue, its right next to a second "engine sync" switch that has no function. That's "engine sync" and "slow vessel" side by side on the main panel and also "engine sync" and "slow idle" on a separate right side panel. I've had good luck emailing Searay these kinds of questions in the past but I've asked this one three times to no avail.
 
Without a pic of the switch panel it's a bit hard to make an educated guess. However, based on what you describe, it sounds like it could possibly be a switch used as an additional "accessory switch" for future installations.


I've never seen any switch terminating any kind of data transmission, be it NMEA0183/2000 or SeaTalk. If your conclusion is based on the labels attached to the wires, oh well, how many times we see that they're just not matching. If it was pre-wired for something that SR was planning to install, then SR should be able to tell you. Lack of their response doesn't help. See if Rusty can help you get an answer from SR.


In any event, since you've confirmed that the wires are terminated, then I would rule it off as a "dummy switch", which you can use later for something.

That's all I can think of at the moment, based on the info we've got so far.
 
I got curious and pulled the 480MY manual. There is a picture of the control station switch panel on page 2.15 that shows the switch. By its placement next to the engine synch switch you would think it has to do with the engine. I did not see any reference to how the switch was to be used.

On page 6.31, Fig. 6.31.1, DC Wiring Schematic, the Slow Vessel switch is shown buried in the spaghetti. It is annotated "WIRING W/CAT OPT". So the switch appears to have been put in for the Cat engine and not Cummins and unused when the boat was built. As Alex says it was not unusual for Sea Ray to install switches and not use them although is can be confusing for follow-on owners. The switch must have been wired to NMEA (for whatever reason) after delivery.
 
So I think my final conclusion is this. The redundant "slow vessel" and "engine sync" switches in the main panel probably came with factory blank covers in the switch holes and the previous owner must have added two new switches there for his own purposes. Thanks for all the input guys.
 
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