PDA versus Laptop

bilbobaggins

bilbobaggins

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Alright! Alright! I give in! I *will* get an electronic gizmo from Santa wot will do my nav'ing for me....

I travel a lot on others' boats ( Yeah! Yeah! 'Only once on each.....' ) and tend to carry the nav gear I might need in my bag. "Four 2B pencils, 3 head torches, 2 charts of Channel, 1 HB compass, and a partridge in a pear tree...." )

Actually, HH GPS, several charts, some almanac extracts, tidal atlas, Goodey Plotter, HH VHF, HB compass, ginger sweeties, MyOwnChocyBiscuits, box of used wx. forecasts.... This stuff usually resides in a small navbag stuffed into my kitbag.

I'm impressed - no, awed - by what yottie journos manage to get out of their electronic gizmos (YW now - Sheahan/Pugh ) and would like to enhance my street cred a little in the 'wired navigator' stakes. PDA or laptop or palmtop - or W.H.Y?

I'm unlikely to want to project a Powerpoint presentation of our passage plan onto the mainsail, but do need specs to read our racing numbers. And I've yet to work out how to plot a 7-shot star sandwich fix onto a TFT screen. But for 'cooking' coastal passages, and if I can get the stuff I need to carry all ( or most ) in one nifty little jewelbox, count me in.

Question is, what type? What are the pros and contras? What does the team think?
 
If you intend to use it for navigation work I would guess a laptop is the way to go. I don't know what software there is for PDA's in that application other than the likes of Tomtom, etc which are not much use on the wet stuff. Add that to a small screen, fidly input, etc. and you soon begin to see the advantages of a laptop.
My experience of Tomtom on a PDA is that it is a bit memory hungry and crashes it fairly regularly.
I use a PDA for convenience of size so I can knock out emails and quotes whilst on the road and not have to lug a laptop around. Otherwise I would much rather use a bigger machine.
 
The best is a laptop without a doubt!! BUT:

Its power hungry,not always water proof sometimes not even damp proof! Depends on the model Of course a waterproof drop proof?? one costs more that say a standard solid IBM. The choise of software for a laptop and e charts is large and very useful even user freindly and priced from free (seaclear) up to costly and or very user freindly

Even on a largeish boat 10m+ you should have a storage place which is dry aired to reduce humidity and a safe place to use it (dosent slide off the nav table)Then either a 12vto laptop adapter, or signwave inverter both will need about 7 to 10amps!!! from your battery

With a PC you can even whatch a dvd write a letter or play games while becalmed!

A PDA is small powerful has a limited range of nav software but within that range you will find charts gps plotter weather charts plus your emails and skype

Most good one have wi-fi and bluetooth a full size key board can be added, they are easy to keep safe and dry (i had one aboard my folkboat which leaked badly every day while in Swedish summer rain) use almost no power can be charged 12v to universal adapter useing less than 1 amp. They cost far less than a laptop and can be taken into town when in port either as a guide or just to use to phone /fax/email home while relaxing in a cafe

Down side small screen, becouse its a touch screen will crash when cleaned(even when the cleaning done while off) and though the emails can be writen quickly you have to take great care not to miss tap or you have to reset the text possition which can become irritating

Best take a PDA really great useful inspite of very limited software(irritates me that phone have more free softwear!!!) and 90% is paid ware.

If you can aford to try a laptop and have enough power the thats the very best way to go--perhaps both??
 
you can also but a laptop for the same price as a decent PDA, if you want to go halfway and have plenty of cash you could buy a "Flybook" wonderful piece of kit.
 
I use Maptech charts on my NavMan PIN 300 via the Memory-Map Pocket Navigator Software.

The latest Yachting World magzine has a great article on how user friendly it is.

Thanks

M0rt
 
Laptops have a larger screen but use more power.
I personally use a laptop with a Fortuna USB GPS, works superbly.
I do not own a PDA but the article by Matthew Sheahan in Yachting World makes me think about getting one.
 
Well of course it depends why you want to carry so much around ?

As a crew / helper - surely the boat has enough normally to satisfy even the most curious crew ? But I often carry my Notebook PC - a humble IBM Thinkpad with enough charting and software to cater for all south coats and France etc. I also carry a 12v dc - dc connector to power it. Rarely does it come out of the bag ... as pals boats have plotters and their own pc's etc.

I also have a HP Jornada PDA with Ozi-Ex CE mapping on it ... very good -but useless in daylight .... can't see enough detail in the light. Go into cabin and dim area - excellent.

If I was a delivery guy or going on an unknown boat - then I would plump for BOTH ... why ? You don't know what power is available on the boat - maybe the batterys are shot, engine charging suspect etc. If power ok - then PC is way to go, if not then its hope that PDA can get enough power from it / last out with sparing use of PC when absolutely necessary ....

Depends on reqt's ......
 
[ QUOTE ]
And I've yet to work out how to plot a 7-shot star sandwich fix onto a TFT screen.

[/ QUOTE ]
The best I have come across is AsNav - here is an example -

celestial-screen-002.jpg


Persoanlly consider that Astro is the fall back system for when all electrics fail, so have the manual plotting sheets and proper books.
 
AsNav certainly looks interesting, thanks, and I'll give it a whirl. However, I cut my teeth on The Air Almanac and AP3270 - Red, Yellow and Green Bands - and have used Harry Baker's versine-based 'Reed's Heavenly Bodies' with some success.

I suppose if I find myself doing anything other than cross-Channel outings next year, I'll have to find my Rude Star Finder and polish up my gnomon....!
 
Re: PDA versus Laptop.... Asnav ....

Very nice and I know written by MN for MN ...

Only thing missing is the determination of position closer to danger for safety.

It is practice in nav to choose a position inside the probablitity area that affords safety margin ... we would choose a position closer to danger to make sure we stay away and clear. Mathematical averaging as this does puts the position as an averaged dot without accounting for this matter.

Small point but valid in a seagoing environment.
 
Re: PDA versus Laptop.... Asnav ....

Choosing point that is closest to the danger is definely valid for coastal Nav where your 3 point fix should really be no larger than a mile even at extreme range from the coast.

I grant there may sometimes be the odd case where in the middle of the ocean you might worry about something within 5 miles, but personally think you are making a point that is inappropriate for astro. I certainly have never worried to that extent about how close the land is when in astro territory! After all the nearest point of land is normally the ocean floor
 
Re: PDA versus Laptop.... Asnav ....

The AsNav example has some points of interest. Where actually is the fix position?

It would appear that the two Sun shots are symetrically arranged around local noon; that being so, one wonders why a straightforward Noon Sight/Meridian Observation is not employed. Then there is the question of visibility of 4 navigational stars and 1 planet, in the noon sky. I may well be wrong, but I seem to recall that the only reliable means of identifying and observing stars in daylight involved the USAF Star Tracker equipment - and that was only installed in the B-52 strategic bomber! Not an appropriate lump of yottie equipment, even if found at the Beaulieu Boat Jumble....

I'm wondering if the AsNav programme treats each shot as equal in reliability, for that Venus shot looks a bit suspect to me. I'd be looking hard at my corrections for that one. And did we get 3 shots of Vega? If so, I'd be averaging them....

The whole complex business of resolving a 'Most Probable Position' from a complex jumble of position lines had 'Dagger Navs' and 'Spec N' types arguing the toss for most of the latter half of last century. One good thing about GPS is that the arguments in the darker corners of the Royal Institute of Navigation have moved on. For my money, the practice of planning and working a Star Sandwich Fix ( a;b;a;b;|a|;b;a;b;a ) averaged and resolved around the mid-time is a lot faster and more reliable that a search all around the horizon for stars that aren't yet visible, or are just gone, or are obscured by cloud, or are too high or low..... One can usually arrange a Sun Shot for Longitude close to evening twilight, then a convenient bright star - north or south - for latitude, with just a little transfer of the earlier position line for MOO, to yield a sound sandwich fix. ( vice-versa for am, obviously. )

Or is this all getting too 'geeky' for this forum.....?
 
Sights ....

Standard MN practice - especially if using AP3270 ....

3 bright stars .... with good angular spread around horizon and also good elevation. 2 sets of sights using the 3 - with a couple of the others listeds as back-up ready if cloud or other happens.

Most would not mix planets and sun etc. as then this means getting out two books and working it all out. Simplicity and speed is the requirement along with accuracy.

Running up a sun line to cross with stars is a suspect item ... as a ship is looking to stars to provide a more accurate position than the run-up morning PL's to Noon cross that is the ships Noon job.

The Asnav plot as posted on this thread is IMHO a good example for posting and showing capability ... but the choice of bodies is suspect.
I realise that Asnav does not need AP3270 and other books .... but - this is where I will pass a REAL personal comment - having used all sorts of Nav Calculators, PC's etc. on this very topic - I still go back to AP3270 - as its the quickest and easiest way to pre-set sextant and find your star etc.

As my Father said ... (He was THE senior Nav Superintendent and Air Ops Inspector for DoT and the CAA before he retired etc. ) - The sea taught the world to navigate ... then air took over ...... So thank you for Air Nav Tables AP 3270.

Until the day I stopped on ships ... I used AP3270 and also my Ti59 Texas Instr. Nav Calculator .... Knocking out 6 stars in minutes ... I doubt I could do it so fast now - as it's been some years since last serious sextant work ... but I really enjoyed it .....
 
Re: Sights ....

Yes. It's a little bit of nav geekery fun to argue the toss about astro techniques - but makes a change from the run-of-the-mill 'what is the best anchor' thread.

My air-astro training started with sun LOPs, then 3-star fixes, then 2-star sandwiches - 5 and 7 shots. The Bomber world preferred 2-star sandwiches, with the azimuths chosen parallel then normal to the track. This became a 'Fix Monitored Azimuth' technique, where alternating shots 'along' and 'across' were used continuously to feed error corrections into a flight director box. In the hands of a well-practiced crew, this gave consistent accuracies of better than 0.5nm - with NATO Competition crews reliably doing better than 0.25nm, with calibrated equipment - at 600kts. I still have a Mear's Slide somewhere, for the 'Acceleration Corrections' i.r.o. small heading and groundspeed changes. Haven't used that in a while.....

Different Commands stipulated their 'preferred' technique, for possibly fairly good reasons.

Activity rates differed radically from MN norms, where yooz guys had a wander around in your carpet slippers before breakfast, another 10 minutes at lunchtime while the ice in the gin melted, then a few minutes of gentle activity before Horlicks at bed time. My colleagues and I were required to produce and use 3 astro fixes per hour minimum, and sometimes 4, while the FMA technique mentioned above was continuous, with a LOP and input every 10 minutes. Busy bees!

I still hold that KISS is best on a small sailboat. A few well-chosen heavenly bodies from AP3270, with a group of high-grade sights of each - inspected, corrected and averaged - is the route to success. Anyway, there's usually lots of time on a sailboat to consider one's accuracy, reductions, and strategy.

'Man is not lost - he merely forgets which way is home....'
 
HP Jornado 520 PDA & Acer Notebook ...

8f17e946.jpg


Jornado PDA running Ozi-ex CE with Bembridge apps. chart shown.

Here with a closer look .....

9878199d.jpg


Now here is the Acer Notebook just inside cabin with Seaclear running ....

April21_24_2005_008.jpg


Now originally I had GPS feed to the Acer via its USB cable and then a USB cable out to the PDA ... having signals on "Passthrough" in Seaclear. This meant that if I stopped Seaclear (any chart program providing Passthrough will have same effect ..) then the PDA lost its GPS input.

So I then cobbled together a RS232 junction box ... so that now the GPS fed signal via serial 9 pin to the box, this then divided the signal to two serial sockets .... PC connected to one, PDA to the other .... this then meant that both PC and PDA were independent and didn't care if other was on or not ... It meant that I was limited because of changing from USB ... but to be honest unless you are running super-sophisticated stuff - an older RS232 equipped Notebook is fine .... most older sets had USB as well - so you have best of both worlds.

DSCF0263.jpg


The home-DIY RS232 splitter ......

FYI - The HP Jornado 520 with 2 expansion cards cost me about £60 .... with cables as well.

The splitter box is a standard Domestic small electric junction box that you put screw terminal block in ... the RS232 sockets etc. from Maplins, cable is standard telephone cable. Cost about £5 total. (ignore the extra pin plug that has been pushed onto end od cable plug ... it's so I don't lose it !! The plug is a standard plug same as you would find on end of mouse cable etc.).

Hope this helps .....
 
OK my humble opinion. The PDA is a wonderful piece of gear (I have a HP2210) but unless you have good, young eyesight then they are terrible. Keep having to put my glasses on (after finding and cleaning them). Notebook PC is easist and cheapest for secondhand but to be truthful I would use a handheld GPS and paper chart. I know that is not one of your options but just what I prefer and I am no dinosaur as Electronics Engineers, PC Whizz, My boat is like a christmas tree with all the goodies I stick on but always end up using a real chart (with a Yeoman Plotter usually) and a GPS.
 
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