Aftermarket Parts for Stern Thruster Fix

[steelydon]

I came to this forum 3 years ago to ask advice about buying a trawler and received some very thoughtful responses which ultimately led me to buy an Eagle 40. It was semi-ready to go but it spent two months in the yard while I did an extensive refit which included adding a stern thruster. Even though I placed it as low on the transom as possible once launched the thruster cavitated and provided poor thrust resulting in little use for the next 12 months since a haul out would be necessary to remedy the problem. So I headed down to Stuart knowing I had a dysfunctional thruster. While several companies offer hoods for their thrusters Lewmar does not so a friend of mine fabricated a pair while the boat was hauled out for its annual service.

While not elegant in appearance they were sturdy and functional and fixed the cavitation problem. I set out from NC to FL only to have the thruster begin to act up early in the cruise but only. Thrusting to starboard was sketchy at best and I found this to be a problem coming into Charleston City Marina, my apologies to the power cat and to the sailboat in Halifax Harbor. No damage in either event making the case for oversized fenders and a crewman that knows where to put them.

Back in NC I decided to tackle the issue. Lewmar provides an excellent troubleshooting guide for this thruster (I wonder why). I started with the inexpensive ($13 each) momentary joystick style switches that I had used at installation which checked out fine. It appeared to be a problem with the mysterious black box. I called Lewmar tech support to find out what purpose the black box served and was informed that it was limiter that provided a delay when shifting from port to starboard thrust to avoid damaging the motor and that they would be happy to send me one for $158.

It appeared to me that the box was more protection for Lewmar than the operator and that it added another level of complexity to the mix so I opted to wire direct to the solenoid, eliminate the box and the thruster worked fine, for a day. Next trip back same problem. I knew the motor worked properly so I removed the solenoid this time and scraped/sanded the contacts although there did not appear to be any arcing that I noticed.

Once again the thruster appeared to be working but then, like my friend in rehab it began its old ways shortly thereafter. So, I went online to buy the solenoid. *@^&%$!, these things ranged from $425-$550 for a Lewmar/Albright solenoid. Found an Albright DC88-3 NOS that looked the same on Ebay for $115 so I emailed Albright in England to ask if this was a suitable replacement and was advised that it would work but could not comment on extended use. Short answer, the thruster is working fine now but for how long? I figure the new solenoid will last a least as long as the OEM, 12mos +/- and that was with very little use.

Have I fixed the problem? At least for now while saving $500 on OEM parts. Should I have eliminated the black box. My Wesmar bow thruster is no so equipped and is working fine after 17 years. Will the solenoid last? They are both rated @100 amps so I guess I’ll see. One thing I’ve learned from reading TF is that OEM is not always the only answer

 

[Xsbank]

Use generic solenoids and wire it yourself. Its just a simple reversing DC motor. In fact, pull the existing solenoids apart and clean the contacts. Where is the power source and what size cables do you have? Dollars to doughnuts you have a bad ground. Check the cables at both ends, battery and motor. Does the solenoid click when you move the switch?

Actually, cut it off and throw it away, you already have a good engine and a good rudder. I can see the purpose of a bow thruster but the stern thruster is pointless. Your rudder steers the stern of the boat, its controlled by that big round thing, called the "helm" or the "wheel" in the "wheelhouse." Its the bow that gives us the grief because it isn't connected to the wheel. Sorry (running and ducking for cover).

 

[steelydon]

So. . . that big round thing is a wheel? This is some good information to have the next time I head out. The Canadian brings a little heat with the response but it is taken with the good nature it was intended.

Seriously Xsbank no need to run and cover you make a valid point and while I am reasonably proficient with a spring line I singlehand most of the time and running out to hang a forward spring while backing in can be inconvenient especially when I can stand at the, what did you call that thing, and operate a couple of switches and back straight in without having to shift f/r/f/r/f/r. If you can make it easier why not?

We powerboaters sometimes question why sailors insist on doing everything the hard way like tacking in narrow channels only to wind up aground at the edge of the channel when they zig instead of zag.

A thruster makes it easier and while a stern or bow thruster may not overcome a 25kt wind or a 3 knot current it works and when it doesn't out come the springs.

 

[Xsbank]

Hi Steely, did you get it fixed? I was having a crisis so it sounded more fraught than I meant it to. I actually have two working stern thruster motors in my garage, one propeller is toast but the motors worked when I took them off. Let me know if you need one, although with shipping it would probably be chaeper to rebuild yours...I still think the repair advice is valid. Probably a ground. If any of the cables terminate on stainless, like the grounds, that is probably the issue, notoriously difficult to get a good connection with stainless.

 

[koliver]

I was shopping for a new pair of solenoids for my windlass and came upon the Lewmar $550 offering through a marine store locally. I wondered who would ever pay that much for the solenoids that I found in an auto parts store for $27.00 each. Those replace a pair that were at least 10 yrs old and are now in my spares box as I am not sure they were the problem.
Your approach to remove suspect items from the system is likely the best approach, though I do agree with XS that you already have control of the stern with a rudder, a wheel and a big propeller, so why sweat a thruster.