I had a slightly different experience. When I was induced I was aparently contracting every 2 mins, but couldn't feel it. After 2 lots of the gel the contractions gradually got a lot more painful, so they moved me to the labour room with the pool (which I had wanted to use). They checked me and I had not dialated at all or 'softened' but they allowed me into the pool to help with the pain.
4 hours later, with no pain relief, I gave birth to my whopper son (9lb 3) in the water.
Upon getting into the warm pool, I immediately relaxed and I believe this is what kick started things to start dialating..
I too had SPD in pregnancy and a knee injury so birth positions like kneeling would have been tricky. The pool enabled me to be comfortable enough through labour. So much so the midwife had thought I would take a lot longer than I did and was most surprised when the urges to push began. This was the only time she checked me for dialation (in the pool) to find me ready to go! The rest of the time, checking was simply using the machine to check the heartbeat (a waterproof one).
As for positions in the pool, it's up to you how you labour, I found lying/floating on my left hand side, head resting on the side most comfortable. I dabbled with other positions but it very quickly became obvious there was only one position for me.
For the pushing stage, I was standard 'on my back' position holding my knees, but this was ok with the spd as there was no pressure on my pelvis as this part was floating.
I can't quite remember how I wasn't sinking (OH can't remember either) but think my back was resting on the built in seat thing, with the back of my neck resting on the side of the pool (if that makes sense...)
I remember the midwife trying to get me to keep myself near the surface (god knows how she expected me to).. Either cos she wanted to see what was happening or was worried the baby would drown or something... I knew this would be ok tho as I had seen waterbirths on the telly and knew that was not an issue during the birth.
I had thought it was best to keep baby on your chest in the water a bit to keep warm too but remember the midwife getting me to keep him out of the water... whether she was not very experienced or thought the water a bit too cool by the point I'll never know.
Son was then checked, wrapped up and handed to other half whilst I was helped out of the pool to deliver placenta on the bed and await stitching...
As for what to wear, I'd had my nightie on before getting in but when I was allowed to get in, that was whipped off quick smart and I hopped in nekkid! I didn't care one bit as it was only OH, midwife around and the comfort was more important at that stage... I do remember a woman coming in offering sandwiches and jelly at one point! LOL. But like I said, I didn't care at that stage..
Definitely planning a water birth next time.. Just umming and ahhing about whether to go for HB or local birthing centre.. Might take a shirt to wear in the pool to maintain a BIT more dignity next time but it'd probably annoy me and end up coming off anyway! DEFINITELY want a waterbirth either way.
Ooo scary long essay I have written here... Sorry, when the birth story starts coming out I can't stop!