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Old 24-03-2013, 11:27   #16
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Re: A tablet to replace it ALL: how, which one, which apps?

Thank you all for your replies. In order to make it clear for some and save some of you valuable time searching for the answers:
- YES, tablets with a real GPS (almost all of them except for Kindle's and iPads that aren't 3G) work anywhere in the world, offshore cruising. What will not work will be any app requiring a network (wifi or cell) to function. But many apps do not require this, and many marine map apps can be downloaded in advance and stored in the GPS, like a marine GPS.
- YES, it is possible to view some tablets in full sunlight, and many users reported no problem at all with their tablets. Some tablets are better than others, and iPad isn't the best for that (samsung and huawei got pretty good reviews for that purpose). Users using a bimini / dodger reported no problem at all with any tablet, including iPads.
- YES it is possible to make a tough tablet. (or buy one: toughbook is on the market, other military tablets are, and excellent cases are available like the Andres case I mentioned. And I am not talking about crappy waterproof bags, but real tough cases or real tough tablets, probably tougher than your average marine GPS. However, buying it makes it an expensive option, ranging between $400 and a few $thousands. Making one is nothing impossible, with cheap and strong available marine grade plastics such as polycarbonate, that by the way are better than many marine made branded instrument housings. It also allows you to make it thicker if needed, and custom made, which doesn't hurt. I made the housing for my new autopilot for $60 fittings and mounting included, and believe me it is proof everything, will last longer than me (and I am 29), and it looks good. Making one for a tablet includes the additional challenge of the touchscreen functionality, but I am confident it can be overcome (again: in the industry, you have these kind of things. What do you think they use to protect their computers and tablets on off-shore oil platform in the antarctica?

Can I use a tablet as a reliable GPS? the answer is YES, 100%. GPS in tablets are as reliable as most marine GPS. Electronics in tablets is way better than in your marine instruments. And applications for GPS are many, better, cheaper and more updated (iNavX, navionics, to mention only the most famous). The only thing that limits the use of a tablet as a GPS is the HOUSING, that hasn't been offered yet to general public already manufactured. But as mentioned, you can make your own or be creative.
For the record and if anybody is interested, the motorcycle market already came with waterproof shockproof cases for smartphones and excellent mounting options that can be charged while protected. Smartphones have GPS, can use the apps, and this makes a perfect marine GPS for almost nothing (under $100, including case, phone, and worldwide maps). But personally, I want a bigger screen.

So if you want a GPS, nothing holds you back, but I want MORE. ON TOP OF THE GPS functionality, I want to use my tablet to replace INSTRUMENTS, basically knotmeter, compass, and electronic windvane?

KNOTMETER: Recording the speed accurately is fine with a GPS, and is BTW more accurate than the crap they ask you to put in a thru-hull, that needs to be calibrated, is either inaccurate or affected by the conditions of sail, not to mention barnicles. A raymarine top end bronze thru-hull sensor records your speed with a precision of 0.1knot every 1/2 second. That's only twice faster than any crappy GPS, it is 5 times slower than good sport GPS based speedometer (every 1/10th second) that market between $100 and $300 (mentioned in my first post), and it is not more precise in the reading, it is to say: these things are a thing of the past anyway, and are meant to disappear.
With a GPS, recording the acceleration and deceleration is the issue, because this depends entirely on the refresh rate of the GPS in the tablet. I do not know this refresh rate. Anybody has it, or knows of a tablet with a refresh rate of at least 5hz, or knows of a way to add a GPS antenna to increase the refresh rate of any tablet? These system exist but I found them only in bluetooth versions, meaning working with batteries. I want something I can plug on the tablet, the tablet being plugged to the boat power.
Another possibility (???) would be to use the accelerometer of the tablets. I know nothing about those. Anyone knows if they can record acceleration and deceleration, and if there is an app that records the speed using both the data of the GPS linked to an algorithm based on the data provided by the accelerometer?
I assume this would be possible, but I simply don't know if the app exists.

COMPASS: all tablets have a compass, but is it precise enough? Anybody? How to measure/ know this?

WINDVANE: this is a gadget on the tablets. It is a guesstimate, that will definitely not have the precision of a real windvane. However, it will be enough to give indications, and anyway it is totally secondary to me, as I am not blind and I know where the wind is coming from anyway.

Bottom line:
1- If all you want is a GPS, wait no longer, take a tablet, or a smartphone if you want to spend less and have a case already made with marine compatible mounting options. But again, I know that for a fact, that's not my question. I want more.
2- I need to know how a tablet can perform as a knotmeter and as a compass
3- I need to know of an app that would allow me to show SIMULTANEOUSLY the GPS functionalities (map, position, course, etc) and the SPEED IN KNOT, the BEARING, and the WIND in instruments like display. Does it exist?

Thanks again for your help. Thanks to kaeri2 for the maxSea option. Does it display also speed and wind? Also, I would like to avoid iPads (for screen quality and for financial consideration, the 3G is expensive). AND, maxSea doesn't look as good as a GPS app as iNavX. Basically, I need iNavX, but for android, and with the display of instruments.
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Old 24-03-2013, 11:33   #17
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Re: A tablet to replace it ALL: how, which one, which apps?

Oh, and I just to add one thing. Most people think that they pay more for a marine dedicated application because it has been specifically engineered for that purpose, hence it is better. Not true. You pay more because the market is smaller. If tablets were aimed exclusively at sailors and nobody else had a use for it, it would sell for tens of thousands. In fact, we would probably not even have invented tablets, as it would have been too expensive in R&D. In ten years, cellphones, computers, tablets have become so great and so cheap in the same time for only one reason: mass market. And this mass market doesn't include marine instruments. YET.
So if you want to pay more for less because it makes you feel better, go for it.
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Old 24-03-2013, 12:20   #18
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Re: A tablet to replace it ALL: how, which one, which apps?

decca, you're missing out on some basic information. First of all, a GPS does not give you "speed". It gives you "speed over ground" which is a totally different number from "speed through the water" which is what you get from marine knotmeters using thru-hulls. If you have to ask what the difference is or why it may be important, you don't have any grasp of the issue. One does not replace the other.

Then there's the naive concept that you can armor an existing touchscreen. No, you can't, and no, that's not how ruggedized industrial displays are armored, either. You can't just slap some lexan in front of a capacitive touchscreen (or a resistive one, and you should be aware of why there are two types as well) and somehow make it work. Industrial touchscreens are either built using a totally different technology (like IR sensors in the screen frame) or with a totally different build-up in the screen materials. The "armor" is an integral part of the screen, not just something bolted up to it.

Can you put a screen protector, a thin mylar or vinyl cover on top of a screen to give it some extra protection? Sure, but that's not going to be the same as armoring it up, industrial style.

Nice concepts, but you might want to read up on Robert Heinlein: "Any sufficiently advanced technology will be indistinguishable from magic." If you don't understand the fine details of the technology, you might as well be conjuring up magic.

Just because stuff LOOKS similar, don't make the mistake of assuming it is all the same.
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Old 24-03-2013, 12:45   #19
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Re: A tablet to replace it ALL: how, which one, which apps?

... no, I still remain convinced that to be as good as dedicated marine instruments, a tablet-based system needs a marine-grade tablet, with all that entails. I also note that most computers, including tablets, are designed for 2 to 4 years of use in room-temp, indoors conditions. Even in some sort of case... the extremes of temperature, humidity, vibration will not be kind.

A real speed thru water knotmeter requires a sensor - paddle-wheel, venturi, ultrasonic... something. Compass requires more than just calculating heading from successive GPS readings, there should be a real electronic compass, mounted in the best possible spot, which might not be the helm. Depth requires... a transponder obviously. Ditto for wind speed/direction. All these sensors can reach a tablet or central PC wirelessly.

Quote:
3- I need to know of an app that would allow me to show SIMULTANEOUSLY the GPS functionalities (map, position, course, etc) and the SPEED IN KNOT, the BEARING, and the WIND in instruments like display. Does it exist?
Linux. There are several. Check out Navigatrix to try a few.

Going off on a tangent... I dunno that a touchscreen is the best possible way to control the system. A line of assignable buttons across the bottom of the screen, some sort of mouse replacement (arrow keys, trackball, joystick) would be more useable through all conditions and with gloves.

Durability plus a better interface... of course I've just described a marine chartplotter. Oops.
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Old 24-03-2013, 14:09   #20
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Re: A tablet to replace it ALL: how, which one, which apps?

Thank you lake-effect for the Navigatrix recommendation, I'll give it a try.
Still waiting for anybody with the Hz information? (no offense, but I'm not looking for advices or "you can't do it" stuff. I'm looking for information about frequencies and apps. Then I'll do it, and I'll show you ! Thank you in advance)

Regarding other comments:

SOG vs Water speed: This is an obsolete debate, except maybe for extreme racers. The main reason for going for water speed was to obtain instant speed and be able to know the effect of sails trim. Now GPS do that fairly well (even used by racers on smaller boats). There is no other added value. It is impacted by the currents and the tides and the waves, true, but so is the SOG, so it really doesn't tell you anything more.
except maybe if your doing the America's Cup, you don't need it.

Practical use of a tablet: True, if you are crossing Cape Horn single handed, you might want something else than a touch screen. True, if you are racing around the world in extreme conditions, you probably want something else than a touch screen. And then, there are the others, the 99.9% who take their boats out in good to mild conditions and cruise around. They are fine with a touchscreen. And here I am talking about the people who actually sail: the average number of days sailed for people who own a boat in the US is 14 per YEAR. Out of these 14 days sailed, more than 70% is a simple evening sail / day sail, and the vast majority of times, not single handed. Whoever would recommend for these normal boat owners to drill thru-hulls in their boats and to get expensive marine electronics would just be a plain bad advisor. I am living aboard, cruising extensively, and I am confident that a tablet will do it. If conditions are crazy, I stay at the dock. If I were to do a singlehanded circumnavigation now, I'll probably add a handheld GPS as backup

It is not the best: TRUE! It is not! But it is good enough. Some people are like those alpinist who would not climb a mountain without their GPS and their $20,000 worth of gear, while the locals do it barefoot, with no equipment and faster.
There will always be people to think that the only safe way to do something is with the latest technology that wasn't even available a few years ago, and in an overprotective society, always tons of others to follow their advice. There will always be people saying it's impossible. And then there are others busy doing it.
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Old 24-03-2013, 15:07   #21
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Re: A tablet to replace it ALL: how, which one, which apps?

Been contemplating something similar for different reasons.

I found these - slightly on the pricey side though.

Several options I've been considering are:
- Some tough standalone tablet PC
- Laptop (or marinized computer) downstairs, waterproof screen upstairs
- Screen / data relay to Android device - perhaps remote desktop like this

Still exploring....
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Old 24-03-2013, 15:47   #22
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Re: A tablet to replace it ALL: how, which one, which apps?

Quote:
Originally Posted by decca View Post
Still waiting for anybody with the Hz information?
... A raymarine top end bronze thru-hull sensor records your speed with a precision of 0.1knot every 1/2 second.
Well there's two things here: how fast data is being sent from a sensor, and how fast the tablet screen is being refreshed. PC Screen refresh is around 30 to 60 redraws a second. Fast enough?

Re hull sensors - the Raymarine one you're referring to is probably networked (NMEA 0183) and if you've ever looked at a NMEA data stream... a few complete updates per seconds is typical. But a 30 ft boat isn't changing STW that quickly, so even one reading per second is more than fast enough.

The 'sports' type GPS you refer to - I believe you'll find that they employ some form of averaging/extrapolating function to produce what looks like a smooth speed response.

I have a good handheld GPS. Of course it has a speed display. But that number often jumps around a fair amount... more than I think the boat's speed is actually jumping around. It seems silly to depend on the signal from several satellites for determining boat speed when it's so easy to ... just measure it.

Quote:
Originally Posted by decca View Post
SOG vs Water speed: This is an obsolete debate, except maybe for extreme racers. The main reason for going for water speed was to obtain instant speed and be able to know the effect of sails trim. Now GPS do that fairly well (even used by racers on smaller boats). There is no other added value.
Um not quite correct. The reason that speed through water has been recorded for the last 600 years or so is to provide data for dead reckoning navigation.

You will of course say that with GPS this is no longer necessary. With WORKING GPS, I might agree with you. If you're betting the farm on the GPS in your magic tablet, and for whatever reason the GPS module dies...

Quote:
It is not the best: TRUE! It is not! But it is good enough.
Well, here's the thing: for safe boating, you need to have everything as reliable as reasonably possible. The time you most need your radio and your navigating instruments is when conditions are the worst. Some things you cannot control, but some things you can.

It doesn't make sense have all your marine instrumentation entrusted to a tablet that wasn't intended to survive marine conditions. Choosing our equipment is one of the few things about boating that we can control.

This is why I still insist that if you don't have a tablet intended to serve in marine conditions, it is not good enough to be your primary system.
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Old 24-03-2013, 16:04   #23
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Re: A tablet to replace it ALL: how, which one, which apps?

At the outset, I was always pro-iPad as a back-up navigation device and as a reference tool for all the manuals. Then I discovered an unforeseen issue.

The charger! My charger died during a short multi-day trip. Suddenly my anchor alarm (Drag Queen) was not available, nor were my reference books if the engine had issues, or any of the other manuals. If you decide to go full iPad be sure to carry two chargers on board. I was almost going to go the same route as you, but on the T-33 the main sheet can "sweep" the SS rail forward of the wheel when you come about. If I have a crew I can walk the sheet around, but without a crew, every so often the sheet gets fouled. If I had the iPad mounted there, it would be launched over the side. You may want to check the mounting area

While I have always loved Garmin and used the GPSMAP 7* series for over 10 years, I can update all my iPad charts in a few minutes when on WiFi. This makes the iPad charts more current than the Garmin 440 in the cockpit.
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Old 24-03-2013, 16:10   #24
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Re: A tablet to replace it ALL: how, which one, which apps?

decca, what on earth is the practical purpose of "requiring" the GPS in your tablet to refresh a minimum of five times per second? A sailboat is a fairly slow moving vehicle, essentially a jogger not a motor vehicle at all. What do you expect to do with a position update every 1/5th or 1/10th of a second, when the boat is only moving at 10 knots on an optimistic day?

And how can a human being, reading the display, even SEE updates that are happening at the frequency? All you're going to see in screen jitter. Digital instruments are always averaged down because more information presented more often, simply can't be processed by the person looking at them.

What's the purpose? AFAIK every design and every device on the market considers what you "require" to be "too much information". You're looking for a GPS position fix every time the boat literally moves 1-1/2 feet. They rock, they roll, they pitch and yaw. All you're going to read is background noise.

And while you've got the GPS going chatterbox, isn't that also going to create problems with all the other instruments trying to sneak a data block into the nav device at the same time? Or were you planning to give the GPS a communications line all its own, with no device contention to worry about?

And why would tablets, which are constantly trying to gain battery life, do something horribly battery intensive like make constant use of the GPS refreshing positions ten times faster than anyone can use the data? Good way to suck the batteries dry, which means a good thing to omit from the programming in that application.
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Old 24-03-2013, 18:57   #25
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Re: A tablet to replace it ALL: how, which one, which apps?

I am at the same page with you.. marine electronics are outdated and 10x the price.. tablets or smart phones are way to go.. along with a handheld gps for redundancy.. or 2 x tablet...
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Old 24-03-2013, 19:26   #26
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Re: A tablet to replace it ALL: how, which one, which apps?

Just to comment on desired data rates . . . If the data stream is driving an autopilot it is generally desired to have 10hz in the heading data (which can be either compass course or apparent wind direction in many autopilots) to make the autopilot as responsive as possible to changes. The best pilot systems will have 10hz, while the cheaper ones will use 1hz.

For all other data 1hz is generally viewed as plenty . . . Unless you are Grand Prix racing, when you will want 10hz position to help you on the start line approach and 10hz true wind calculation for trimming.

1hz position and speed data is just fine for chart plotting, and non-racing calculation of true wind, which I think is what this thread is about.
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Old 24-03-2013, 19:53   #27
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Re: A tablet to replace it ALL: how, which one, which apps?

Sooooo much intelligence wrapped up into one page.
I love cf.
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Old 24-03-2013, 20:41   #28
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Pantech element 8" android tab and water proof with built in gps etc love ours its 2 years old and still strong amd waterproof without a case. And u can find them for 150.
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Old 24-03-2013, 21:18   #29
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Re: A tablet to replace it ALL: how, which one, which apps?

It's not quite true to say that only racers need a proper knotmeter:

Crossing strong, variable currents in a boat whose speed is well within the same order of magnitude as the current is not advisable using only GPS, even when you have accurate current data: (and if you don't, or don't know how to use it to make a viable passage plan, you shouldn't put yourself in that situation)

it's not possible to stick to your passage plan without knowing your speed through the water.
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Old 24-03-2013, 21:29   #30
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Re: A tablet to replace it ALL: how, which one, which apps?

I have nothing of value to contribute to this thread but wanted to just say...

I CANNOT wait for the marine chartplotter people to be forced into real competition, lower prices, and real innovation. I'm so sick of seeing the absolutely incredible prices they charge for proprietary systems that aren't all that special.
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