chris mills, post: 441977, member: 6244 wrote: I'm surprised they didn't empty the pool to carry out the tiling. Must have been interesting (and quite expensive - surely they didn't use the pool while the tiling was going on?)
There is a problem with older pools generally, in that many of them were surveyed before too much thought had been put into the overall interaction of wall tolerance, pad tolerance (and boom tolerance, if you are unfortunate to have one). Now when these are looked at more closely they are often found to be not quite what they were certified as.
Retiling is a common problem, as the original grout doesn't always get cut fully off, so the tiles then protrude. The most common cause of a pool failing on the length is the top nosing tiles, which always seem to ride forward as they are laid. This is more of a problem when there is an end gutter at water level with an upstand for the timing pad extending above. The lower nosings ride forward and then the whole of the upstand tiling is plumbed from that line
From memory the tiles were cut back and the face not re-tiled, just finished with a Sika product, so I think it must have been the case that the offending tiles were only down to the level of just below the water line. They put scaffolding in the pool with the workers standing on that in the water, using air driven tools. I do remember that as you say the top nosing tiles were forward of the ones below.
chris mills, post: 441975, member: 6244 wrote: Richard,
There was a New Zealand Surveyor, Mike Elliot, who I worked with on the London 2012 Olympic Pool. He would be able to give you all sorts of info on what can go wrong with pools.
Hi Chris, this just came in in time. I have a tender to measure some swimming pools to ensure that they comply with FINA standards. The Client was not really sure of some things. Thought I could ask you.
1. In the measurement of the pool, how do you properly define the centre of the lane of the start and finish. As I would expect a slight difference due to slant which will add mm's to the distance.
2. How do you measure the verticality of the wall, when the pool is filled.
Thanks and cheers
Sireath,
I'll assume that these are pools without a bulkhead to change the length - that makes things more complicated.
1) The requirement for length applies to the whole width of the lane and for depth between +300 to -800mm from water level. It's generally accepted that you take a grid of 9 points - left, centre, right at +300, water level and -800, hence 9 length readings in each lane. If timing pads are not in place then I would treat each lane rope set as reading for both lanes, but if pads are in place then you need to read 9 on each pad. I use a flat back target (the GDM RMT one) as this spreads the touching area over the tiles joints, hence you pick up any tile which is sticking out slightly. It would be easy enough to make a suitable backplate for any other type of prism.
I always use a station at each end of the pool. These are set using the tile lines as a guide to be square to the pool and close to central. Take this as a baseline zero and set the instrument to coordinates. Check read the Y value at the centre and outer lanes. If there is an obvious twist I adjust the Zero angle so that the far face appears to be more or less square from the three coordinates (assuming the face is straight!!).Then the instrument is pretty much square to the face when reading Zero (check again after adjusting in case you went the wrong way). Read the far station and put a coordinate and bearing on it.
Now when you read the faces you are reading coordinates, not distances, so all you need to do is take the difference between the two figures for the length, so you are not measuring skew distances. As well as booking the figures in the recorder I also write them down so I have an immediate visual check on the lengths - any problem and you can investigate immediately. Even if the figures are short ALWAYS complete the full set, so they can be used for remedial works.
Before I survey I normally do a "feel" inspection, running the palm of my hand across the full area of tiles to be surveyed, which quickly identifies any protruding tiles you might need to additionally check. Make sure the nosing tiles do not protrude. A visual look along the face will also tell you a lot.
2) Verticality. Measure when empty! If you can't then the device I illustrated earlier enables you to measure it over the depth required. Use the spirit level unit to measure the -800 depth and then a standard target will do for water level and +300mm.
When pricing up, if any of the pools are indoors then allow half an hour for the instrument and prism to acclimatise to the temperature and humidity in the pool area. You'll need that time in any case to assess the job and pick suitable spots for the stations. Also, allow for a three station calibration set up on site prior to observing. Remember that "-0mm" means exactly that.
Use my contact details if you need any more information - it'll probably get a bit too technical for general browsing here.
Once upon a time the boss tacked a Target card to a chunk of 4x8 long enough to straddle a street Mon case. The idea was to put a plumb bob on the dimple and align the card center with the string.
half bubble, post: 442223, member: 175 wrote: Once upon a time the boss tacked a Target card to a chunk of 4x8 long enough to straddle a street Mon case. The idea was to put a plumb bob on the dimple and align the card center with the string.
That brings back a flood of memories.
Back in 1970, one of the first things I was taught was how to set a backsight.
We had company business cards with a red and white target on the back. We stuck a nail thru the top and bottom to use for backsights on 36" lath, plumbed above the traverse point. For well monuments we stuck them in a 1x2 guard stake, and used the lid to keep them from blowing away... usually with a cone, but not always.
One evening the boss announced that he had to pay for a flat repair, the nail with business card/target was still in the tire. From then on we used cup tacks to fasten the target to the 1x2.
I would not like to put something big like a chunk of 4x8 in the road without a bunch of cones, somebody could get hurt.
PS: lath, 1x2s, nails, , cup tacks (on a tack ball), targets, plumb bobs, etc. were always at hand.
"Don't get out of the car without them!"
I guess not so much any more.
Peter Ehlert, post: 442237, member: 60 wrote: One evening the boss announced that he had to pay for a flat repair, the nail with business card/target was still in the tire.
Although I didn't witness the event, I was told of the time a representative from the local electric utility arrived at my former employer's office and placed on the boss' desk a section of power pole that had been notched with a chainsaw. In the notch was a nail and paper target with the company name on it. Along with the section of pole was an invoice for pole replacement.
