I fell in off the back of the swim platform bit of our cruiser in the middle of December 6 years ago ,Slippery surface due to moisture turning to ice as the sub set around 4pm ,I only went into my chest as my legs hit the outdrive leg under the water giving me a chance to grab the bar at the back of the swim platform .....cold jesus you lose all strength straight away and i couldnt pull myself back onboard as the platform was a foot or so above water level.....now you stop thinking straight the cold confuses you and i was about to let go and swim around the floating pontoons of the marina to find a one of the ladders that are there in the water for such a reason......doubt i would have made it in the darkening light...there was a bloody extending ladder 6" from my arm on the boats swim platform that i had forgoten about ...the bloody cold made my mind go blank ...office of marina had shut and it could of been tragic lonely place in the water on your own as it gets dark .
My point is the cold you can`t believe how cold the river is unless you have had the missfortune to fall in .
Matt a fellow portaboaters site has a good bit added on boat and cold water safety ,Watch the video in the link http://www.hechtjaeger.co.uk/styled-12/index.html
in short wear a lifejacket and a floatation suit as well so much the better...just looking for one now face .
Just realised same vid as Andrzej