prv
Well-Known Member
We had a first run out in the like-a-zapcat-but-not-a-zapcat at the weekend. Fun, but not sure we're getting all the speed out of it that we could. To see what's going on as we experiment with engine trim, weight position, etc, we decided we needed a GPS-driven speed display.
Given that the necessary components cost peanuts to manufacturers, I assumed there'd be a Chinese factory knocking these things out for a few quid on eBay, but it seems not. The nearest available was a GPS bike computer at £75+, and of course that would be in miles or kilometers per hour rather than knots (which we'd put up with if it was cheap, but not at that price). Or a car unit, which is a mirror-image designed to reflect off the windscreen, isn't waterproof, and needs a 12v supply.
In one of those "sod it, I'll have to build my own" moments that seem to come all too frequently with boats, I've now ordered a £7 GPS module (intended for model planes), a 7-segment display, and a sheet of veroboard. I have a couple of spare PICs and a programmer knocking about from previous (uncompleted
) projects. So in a couple of weeks when it all arrives, I'm going to dust off my very rusty embedded programming skills and see if I can get it all working together. If so, it'll go into a waterproof box with a transparent top, and get strapped to the front of the boat somewhere.
That's as far as it goes for me, but my partner in the boat reckons that other people might want the same thing. I've told him he's welcome to build and market my design if he wants to, and we'll work out some split of any profits (which I don't expect to be large). I'm posting this as I'm curious whether other small motorboat users might be interested, or whether he's wasting his time.
The finished item will be a watertight plastic box about the size of a *** packet, or perhaps a little thicker. A waterproofed toggle switch on one side would turn it on and off, and the only display would be a set of digits on the front reading out a speed in knots (00.0 to 99.9). The one I'm building will have half-inch numbers as that's what was handy, but a productised version might well have larger ones. These are the red glowing kind, not an LCD. When you first turn it on the display will show a "progress bar" animation until the GPS gets a fix, then it just reads out speed until you turn it off again. Batteries would probably be three AAs, needing a screwdriver to take the front off the case to change them (hence the external on/off switch).
I think our use case is unique enough that there's no market for this - most people who want to know their speed probably have a GPS anyway with a speed readout. The reason we don't is that my existing nav kit is all built into the sailyboat, the zapcat-esque environment is too rough-and-tumble for a phone with Navionics on it, even with a case, and there's no point spending the money on a handheld plotter to navigate within the Solent where we've both sailed for most of our lives.
But am I wrong, and someone else would want this?
Pete
Given that the necessary components cost peanuts to manufacturers, I assumed there'd be a Chinese factory knocking these things out for a few quid on eBay, but it seems not. The nearest available was a GPS bike computer at £75+, and of course that would be in miles or kilometers per hour rather than knots (which we'd put up with if it was cheap, but not at that price). Or a car unit, which is a mirror-image designed to reflect off the windscreen, isn't waterproof, and needs a 12v supply.
In one of those "sod it, I'll have to build my own" moments that seem to come all too frequently with boats, I've now ordered a £7 GPS module (intended for model planes), a 7-segment display, and a sheet of veroboard. I have a couple of spare PICs and a programmer knocking about from previous (uncompleted
) projects. So in a couple of weeks when it all arrives, I'm going to dust off my very rusty embedded programming skills and see if I can get it all working together. If so, it'll go into a waterproof box with a transparent top, and get strapped to the front of the boat somewhere.That's as far as it goes for me, but my partner in the boat reckons that other people might want the same thing. I've told him he's welcome to build and market my design if he wants to, and we'll work out some split of any profits (which I don't expect to be large). I'm posting this as I'm curious whether other small motorboat users might be interested, or whether he's wasting his time.
The finished item will be a watertight plastic box about the size of a *** packet, or perhaps a little thicker. A waterproofed toggle switch on one side would turn it on and off, and the only display would be a set of digits on the front reading out a speed in knots (00.0 to 99.9). The one I'm building will have half-inch numbers as that's what was handy, but a productised version might well have larger ones. These are the red glowing kind, not an LCD. When you first turn it on the display will show a "progress bar" animation until the GPS gets a fix, then it just reads out speed until you turn it off again. Batteries would probably be three AAs, needing a screwdriver to take the front off the case to change them (hence the external on/off switch).
I think our use case is unique enough that there's no market for this - most people who want to know their speed probably have a GPS anyway with a speed readout. The reason we don't is that my existing nav kit is all built into the sailyboat, the zapcat-esque environment is too rough-and-tumble for a phone with Navionics on it, even with a case, and there's no point spending the money on a handheld plotter to navigate within the Solent where we've both sailed for most of our lives.
But am I wrong, and someone else would want this?
Pete
