Sealevel

[petem]

The term ‘sea level’ strikes me as being a bit of a landlubbers term. Used by the the sort of people who ask you if you're sailing your boat down to the med and back (from uk) for your week off in the summer.

Anyway I digress. I know that depths on charts are quoted as the height above Chart Datum or Lowest Astronomical Tide. Clearing heights for bridges and the like are quoted above Mean High Water Springs. Different reference levels are given to provide the ‘benefit of the tide’.

Now then, I am in the process of buying a brand new investment property that is on the Severn flood plain. The environment agency have recommended that all housing is at a certain level above the highest ever flood level (recorded in 1947). The EA state that the highest flood level reached 12.8m AOD(N). Can anyone tell me what AOD(N) stands for?

My handheld GPS has an Altitude display, so is it possible to verify the height/altitude that my house is being built at? What exactly does Altitude on a GPS equate to? And what kind of accuracy can one expect of the altitude reading?

Answers on a postcard please.

 

[Guest]

AOD, After other disasters springs to mind.

Paul js.

 

[byron]

'Above Ordnance Datum' that's what 'AOD' stands for. What the '(N)' signifies maybe someone else can say.
As regards the altimeter part of a GPS. Personally I have never quite understood it as it varies so much. I mean when at sea it can show huge plus or minus variations. Any Pilots out there can explain please.

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[jfm]

Re: using GPS

Dont worry about datum of your GPS. Go to the house and measure altitude. Then drive to river, do same. Look at difference. If it's not massive, panic

 

[boatone]

AOD(N) - think this is 'above ordnance datum (Newlyn)
see following for detailed differences against chart datum:
http://www.pol.ac.uk/home/tides/datum.html

As far as altitude display on GPS is concerned forget it. Had long discussion with GArmin about this vis-a-vis my Garmin 12 handheld. Basically, satellite configuration measurements used for low cost sea/land GPS units is not suited to accurate altitude measurment as angles of view are very narrow in altitude sense and difficult to calculate slight changes in altitude.

TonyR
boatone@boatsontheweb.com

 

[Guest]

Re: blimminek peteM

One minute you're selling nice targa cos of the stuipd government. Now, your buying a spare house in a possible bog. A boat would surely be much better? Specially on the flood plain. And specially if er well praps the house doesn't go up in value, as well as down, or whatever they say in the ads? So all things considered ESPECIALLY if you consider that you might die sooner rather than later and in perhaps only two years, whuich might SOUND aa bit morbid dearest but just think we''l have worked all our lives and etc. So you ought to have a nice boat while you can enjoy it. Or a fast motor. Or both.

 

[bob_tyler]

Re: blimminek peteM

Surely Noah designed a house suitable for this site - believe he was his own Naval Architect.

As it is a bit late to use him, try a Naval Architect for your new house.

 

[byron]

Re: using GPS

No No No ... that's far to easy, look for something complicated. DUH! Why didn't I think of that

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[Bergman]

Suggest you speak to locals, or if no locals try council emergency planning officer.

Find out if flooded last year if not should be ok

Worst floods for million years or something

My neck of the woods had army out in force and Chinooks ferrying sandbags around.

I missed it all - I was in Saudi - and it even flooded there!

Best of luck

 

[petem]

Re: blimminek peteM

Sorry, MattS particularly shoddy of me. I know that really another boat would be the best investment - NOT! Hopefully one day I will have rebuilt my finances sufficiently to get back on the water.

In the mean time, does this mean I will have to do the only decent thing, log off this forum and go out into the world of the Lurker?

Regards, Pete (aka Swampy).

 

[Guest]

Re: certainly not

You can jolly well stay on this board and give us all a good laugh er I mean we'll come round and park our boats on your front pond.

 

[petem]

Re: certainly not

I have always wanted a berth at the bottom of my garden now I might be getting one!