Elbows
Member
I've just taken my 2 year old Raymarine ST1000 Tiller Pilot apart to give it a clean and service as I noticed a spot of condensation inside the window. What a crappy piece of design it is! It had already let me down once last year off Start Point in fairly heavy weather singlehanded at night. The two screws that hold on the electric motor had worked loose as there was no thread lock on them. When I got to Plymouth I quickly got it working again without inspecting anything else as I needed to get sailing.
This time I had a good look over the rest of it and was unimpressed with the design and the quality control. It was clearly on the point of failing again and it's just a case of which bit would break first.
The roll pin which fixes the toothed-belt pulley to the main threaded rod had worked part way out and was in the process of destroying the toothed belt.
There's far too much end float of the threaded rod so the belt alignment is all over the place.
The outer end plate of the ram guide was bent and the plastic guide bush was broken. This happens because the unit has no way sensing when the ram has reached the end of it's travel so it keeps on applying full force, presumably until some time limit has been reached when it shuts off the motor and displays a message. The construction isn't strong enough to resist this force. The rapid clicking noise it makes at the end of it's travel must be one of the toothed belts slipping which can't be good for the belt or the pulleys.
The circuit board isn't given any sort of sealing after the components have been soldered on so there are bare metal terminals all over it which can corrode and short out if any salt water does get in, which is pretty much envitable over time.
There's no thread lock on any of the screws holding the mechanism together so it's just a matter of luck whether they work loose or not.
If you buy cheap things then it's likely that they're not going to be very well made and won't last long, but the recommended retail for this is £525. That's not cheap for a fairly simple and shoddily made mechanical device, and the electronics involved don't cost a lot these days.
It would be relatively straightforward to eliminate most of these problems at the design stage, in fact the existing design would need only minor modifications, a few extra components and a few lines of code in the firmware to add the ram position sensing. The unit must have paid for it's original development and tooling costs long ago so the company could easily afford to sort it out and still make a decent profit.
The impression I get is that it's designed to fail soon after the warranty runs out. It's not just the rip-off aspect that annoys me, it's the waste and environmental impact this sort of attitude results in. The management arseholes who make these decisions know perfectly well that a lot of these units are going to end up in landfill soon after the warranty runs out, but they don't give a toss because they're making a little more money than if they did it properly.
End of rant.
-----
Fortunately I caught it early enough that it's worth saving. I'll build in a couple of microswitches and diodes to shut off the motor when the ram reaches the ends of it's travel, remake the broken/bent bits, lacquer the circuit board and assemble everything properly with loctite. Liberal use of silicon grease should keep the worst of the salt water at bay. I use a plastic cover when it's likely to get wet but inevitably some moisture does get in.
Keeping the water out is tricky as hermetically sealing something like this would be very expensive to design in and I do have some sympathy for the designers on this point. As the ram moves out the volume of the internal space increases so the air pressure drops and damp air will be drawn into the unit. The motor generates heat and if the unit's been sitting in the sun the air inside can get quite hot. If it then gets a glob of cold spray over it the air inside will cool rapidly and that will also cause low pressure inside.
I've got a couple of ideas for solving this but I'm not sure how practical they are. A flexible tube could be connected between the tiller pilot and the inside of the boat so that relatively dry air is sucked in. It'd be a bit of extra faff when plugging the unit in but with a suitable connection arrangement for the tube it could work.
The other idea is to have a flexible bladder inside the unit which is connected to the outside air. As the inside air pressure drops the bladder will expand to equalise it. A small polythene bag would probably work but I'm not sure whether there's enough room inside for it to expand sufficiently.
This time I had a good look over the rest of it and was unimpressed with the design and the quality control. It was clearly on the point of failing again and it's just a case of which bit would break first.
The roll pin which fixes the toothed-belt pulley to the main threaded rod had worked part way out and was in the process of destroying the toothed belt.
There's far too much end float of the threaded rod so the belt alignment is all over the place.
The outer end plate of the ram guide was bent and the plastic guide bush was broken. This happens because the unit has no way sensing when the ram has reached the end of it's travel so it keeps on applying full force, presumably until some time limit has been reached when it shuts off the motor and displays a message. The construction isn't strong enough to resist this force. The rapid clicking noise it makes at the end of it's travel must be one of the toothed belts slipping which can't be good for the belt or the pulleys.
The circuit board isn't given any sort of sealing after the components have been soldered on so there are bare metal terminals all over it which can corrode and short out if any salt water does get in, which is pretty much envitable over time.
There's no thread lock on any of the screws holding the mechanism together so it's just a matter of luck whether they work loose or not.
If you buy cheap things then it's likely that they're not going to be very well made and won't last long, but the recommended retail for this is £525. That's not cheap for a fairly simple and shoddily made mechanical device, and the electronics involved don't cost a lot these days.
It would be relatively straightforward to eliminate most of these problems at the design stage, in fact the existing design would need only minor modifications, a few extra components and a few lines of code in the firmware to add the ram position sensing. The unit must have paid for it's original development and tooling costs long ago so the company could easily afford to sort it out and still make a decent profit.
The impression I get is that it's designed to fail soon after the warranty runs out. It's not just the rip-off aspect that annoys me, it's the waste and environmental impact this sort of attitude results in. The management arseholes who make these decisions know perfectly well that a lot of these units are going to end up in landfill soon after the warranty runs out, but they don't give a toss because they're making a little more money than if they did it properly.
End of rant.
-----
Fortunately I caught it early enough that it's worth saving. I'll build in a couple of microswitches and diodes to shut off the motor when the ram reaches the ends of it's travel, remake the broken/bent bits, lacquer the circuit board and assemble everything properly with loctite. Liberal use of silicon grease should keep the worst of the salt water at bay. I use a plastic cover when it's likely to get wet but inevitably some moisture does get in.
Keeping the water out is tricky as hermetically sealing something like this would be very expensive to design in and I do have some sympathy for the designers on this point. As the ram moves out the volume of the internal space increases so the air pressure drops and damp air will be drawn into the unit. The motor generates heat and if the unit's been sitting in the sun the air inside can get quite hot. If it then gets a glob of cold spray over it the air inside will cool rapidly and that will also cause low pressure inside.
I've got a couple of ideas for solving this but I'm not sure how practical they are. A flexible tube could be connected between the tiller pilot and the inside of the boat so that relatively dry air is sucked in. It'd be a bit of extra faff when plugging the unit in but with a suitable connection arrangement for the tube it could work.
The other idea is to have a flexible bladder inside the unit which is connected to the outside air. As the inside air pressure drops the bladder will expand to equalise it. A small polythene bag would probably work but I'm not sure whether there's enough room inside for it to expand sufficiently.