The Raymarine drive unit problem

[BobJ]

Those of us with these units know the problem - they aren't very water resistant. My covers are not that effective and I'm trying to improve the situation. (A failure cost me a place or two in the SH Farallones, and it's not the first time.)

I'm going to try a long skinny plastic bag over the Sunbrella cover, maybe with a rubber band on the tiller end. What about some kind of light lube on the "piston" part to keep water from staying on it and then getting drawn into the motor?

Any other ideas that have proven to work? (No, an NKE isn't in the budget.)

 

[Harrier]

Raymarine drive unit

I use both the TP-4000 and the TP- 4000GP. Similar reliability experienced with either. I cover with a sunbrella tube, but also smear silicone grease on the piston on the theory that it adds to the "waterproofing" supposedly offered by the slippery seals mounted in the front of the black tube. This is the grease we use on rubber scuba diving equipment and is available at most any dive shop. I have NEVER had water damage failures when using this "double attack" technique!

All such failures have been mechanical, and I tend to agree with some previous posts that such failures are proportional to the degree of responsiveness dialed in. High response...more movement...more likelihood of failure.

I do tend to carry a rather high number of these autopilots (6) along with some other self-contained APs for use if needed. At my age, I do not want to NEED to sit out in the sun with my hand on the tiller! These APs are left over from the "old days", but still operate. I also use the grease on their rams.

 

[Culebra]

I haven't had any failures due to water. The motor, on the other hand, gave out en route to Kauai last June. I like Ken's idea and I may add that trick to what I currently do. For what it's worth, I have a fully enclosed sunbrella tube that tapers to a very tight sewn fit, right at the end of the ram extension. Additionally, I use whipping there, not a rubber band, to keep it in place. As the ram extends and retracts, the tube of sunbrella works like a bellows. I would think keeping the sunbrella waterproofed, or replace it each year to keep it new, would do the trick, but I'm not sure. My current one still keeps the water out (I made it just before the Transpac).

It isn't impossible to repack these things with grease, by the way. It's an idea worth considering... repack the thing every year. Raymarine will also rebuild them for you, costs around $250, I think. Well worth it before they give up the ghost... I did that once, and I think I'll do it again.

Paul

 

[Harrier]

Raymarine APs

I tape the end of the canvas tube to the end of the ram just behind the tip using plain old black vinyl electricians' tape. Easy to peel off and redo when you change ramms. You'll find that stuff all over my boat! Probably has the best per dollar value for boat use of any product on the market!

 

[Harrier]

Raymarine APs

I forgot to add: Before heading out, I spray the acrilan tubes with fabric waterproofing spray available at camping stores, etc. I also have covers made to fit the back-up APs that have self contained compasses and brains. They seem to be much more susceptible to water induced damage than the TP4000 models.

 

[Critter]

I haven't had a ram failure either with the X5 or the backup Simrad TP30. My current thinking, subject to change, is to mount a large piece of wood near the autopilot and knock on it regularly.

 

[BobJ]

Thanks all.

I discovered I can spend $29.37 per ounce for a tube of "Dielectric Silicone Compound" at West Marine, or 36 cents per ounce for an 11 oz. can of silicone spray at AutoZone. The description for use is exactly the same.

With the spray can plus some rubber bands, my drive units are ready for LongPac. As the General suggests, I'll also get some waterproofing spray for the covers when I'm at REI to buy race vittles.


Max, that piece of wood stopped working for me long ago. Maybe I need a new one?

 

[Harrier]

Raymarine AP

Bob:
The silicone spray is NOT what I'm talking about. We're talking about something with the consistency of Vaseline. Don't spend money on the dielectric (which is probably OK); get the "silicone grease" from a dive shop! Maybe 6 bucks for 4 ounces...?? It's good to preserve rubber, so can be used on lots of things. Applied to the ram, I think it builds up against the seals in the nose of the device and considerably improves their ability to foil water intrusion. Use the silicone spray on your luff tapes, etc....

I have no advice on what breed of wood to use, but I'm open to suggestions since I'm an afficionato of "knocking"....and don't knock it 'till you've tried it!

 

[Dazzler]

Silicone Grease

Not all silicone grease is equal. Be careful the the product does not contain hydrocarbons. There are lots of grease products on the market that include the word "silicone" on the label, but also contain hydrocarbons. The problem is that hydrocarbons will cause most rubber materials (e.g. o-rings and gaskets) to expand and fail. Read leak...

To be on the safe side use "food grade" silicone. This is what is sold at dive shops. A little bit goes a long way.

Tom
Dazzler

P.S. Vaseline = petroleum jelly. It will make rubber o-rings fail.

 

[BobJ]

Ah gee - since I'm a Scottish accountant (read cheapskate), you guys are harshing my mellow. I guess I'll return my cheap can of spray and look for the good stuff (I haven't used it yet so no damage to the seals).

 

[Harrier]

Raymarine AP

Do NOT use Vaseline! And I did NOT say to use it!. The silicone grease is the "Consistency" of Vaseline.....It is a grease. And it preserves rubber, unlike Vaseline, which destroys it. So I hope we're all on the same page...(I hate that term!).

Good luck on your race, Bob. Even if I lived up there, I probably wouldn't do that one. Or would i...????

 

[BobJ]

I think you would Ken - several of us will have our SSB's and are planning to chat it up out there. Otherwise it will probably be like the start of the windier Hawaii races, and about when you can start to relax it will be time to turn around and come back through the mess.

Plus it looks like I'll have to have a transponder.

 

[Dazzler]

Silicone Grease

Ken,

You came through loud and clear and now that message has been reinforced.

Tom

 

[BobJ]

I forgot to add: Before heading out, I spray the acrilan tubes with fabric waterproofing spray available at camping stores, etc. I also have covers made to fit the back-up APs that have self contained compasses and brains. They seem to be much more susceptible to water induced damage than the TP4000 models.

Ken's advice was spot on. I used diver's silicone grease on the "piston" part of the rams (also a bit around where the cord enters the other end), sprayed the cover with two coats of Scotch-Guard type stuff, and popped some rubber bands on the tip of the drive unit where it covers the tiller pin.

I made it through the whole race on one drive unit (and it was rather sporty out there). Just another reason why he's THE GENERAL.

 

[Critter]

popped some rubber bands on the tip of the drive unit where it covers the tiller pin.

Bob, I was with you until this part. What do the rubber bands do for you? BTW, congratulations - great race!

My Raymarine ram gave me no problems, but the fluxgate compass lost its mind a couple of times. With the unit in Standby, I could watch the display count slowly through a complete circle. There was plenty of water in the bilge near the compass while this was going on; maybe that had something to do with it.

Max

 

[BobJ]

The rubber bands did two things. One band kept the tip of the drive unit down on the pin - it jumped off twice due to the wave state, so I put a band around under the tiller and up over the piston near the tip.

The other band held the end of the Sunbrella cover down over the tip of the piston, so water wouldn't run up underneath the cover. I think Paul has a better cover arrangement since his is tapered down to a tight fit at the end. My cover is rectangular and sewn across the end - it's too loose.


I've had trouble with the fluxgates too, so now I have two independent pilots, each with its own compass. Either can drive the ram and I can switch between them on the fly. The new one is the X-5, the older one is a 4000.

 

[brianb]

Alternate theory

Hi Bob,


I have two ST2000's that have failed and I have subsequently rebuilt. I have a slightly different theory of the failure mechanism after studying the interior of the unit and seeing where the failures occur. Water intrusion is the issue, but i don't think it is coming in the drive shaft. My failures always occur at night or in foggy condensing conditions. I believe what is happening is the cold surfaces of the unit causes water moisture to condense inside the unit and drop onto the motor or electronics.The salts within that has deposited in the unit then acts with the water condensation creating a corrosive salt water mixture that ruins the electronics. I have looked carefully at these units and notice water not near the entrance to the drive shaft but below pointed or low surfaces where water drops form. Solutions ? I would suggest placing a plastic shield over the motor and all electronics so water cannot drop from above onto the motor. Additionally the covers are a great idea just in case other mechanisms are at work.

My other solution, which works great, is a hydraulic cylinder above deck that drives the tiller arm, the hydraulics just don't fail due to salt water issues. I have set this up for easy disconnect from tiller arm, just lift tiller. Mine is interfaced to RM control units, hence no NKE/BG, but that is a lot of work and requires some custom electronics.

Good luck.

Brian

QUOTE=BobJ;4382]Those of us with these units know the problem - they aren't very water resistant. My covers are not that effective and I'm trying to improve the situation. (A failure cost me a place or two in the SH Farallones, and it's not the first time.)

I'm going to try a long skinny plastic bag over the Sunbrella cover, maybe with a rubber band on the tiller end. What about some kind of light lube on the "piston" part to keep water from staying on it and then getting drawn into the motor?

Any other ideas that have proven to work? (No, an NKE isn't in the budget.)[/QUOTE]

 

[Culebra]

Right... I have 2 covers actually, one just like Bob's and one that is tubular across the full length of the drive unit. I much prefer the tubular one. The cover tapers and is tightened at the end with several wraps of whipping. The tube of sunbrella has to be quite loose over both the drive cylinder and the ram (until the final very brief taper at the tip of the ram). Otherwise the tube will accordion on the ram and scrunch up to a tight mess preventing the ram from entering the drive cylinder. Learned this the hard way. I like Bob's practice of spraying the sunbrella. And I like Ken's pratice of using silicone "grease" to seal moisture out, too. Neither of which I've done yet.

I've had no issues with the drive mechanism failing or with water intrusion. I dismantled a siezed drive unit en route to Hawaii only to find that it still looked really good inside. My theory (and Raymarine tentatively agreed after replacing the unit on warranty) is that one of the motors burned up from excessive use (meaning, too high of a gain for too many miles). Have you ever felt how hot they get with use? I've begun using the unit on a gain of 1. It actually works just fine in many situations (not in wind mode if you're trying to quickly track windshifts). And when a gain of 1 or 2 won't work, I have begun to treat the autopilot like any other crew and take turns at the helm on the assumption that it will overheat otherwise. (I also talk to it nicely.)

Brian's concern with condensation makes a lot of sense to me, and obviously he's seen it in action. In mine I could see no evidence of condensation. I've decided from now on to send my drive rams into Raymarine every couple years for a rebuild, or after a major passage. Not that expensive.

Paul/Culebra