Originally Posted by Tim M
You could try righting it. A 4m shouldn't be too hard. Plus (according to your profile) you have an ex RNLI engine which will have been adapted at some point to run having been inverted.
I disagree - righting a 4m RIB is going to prove difficult. For one thing - the weight of the motor, in addition to everything else that's in the boat (fuel tanks, anchor) will add considerable ballast to the upturned hull. Bare in mind - anything that's on the floor of the RIB (which isn't strapped down) will now be on the seabed, including the fuel-tank (assuming it's portable) if it was full.
Even flares are likely to be in forward hatches or consoles and going under the upturned boat is dangerous. In order to do this - you would need to take off your lifejacket, which isn't advisable.
Assuming this happened just now in coastal waters in the UK - the sea temperature is going to be a chilly 15 degrees dipping to around 7 degrees in the winter. A boat flipping over will happen quickly - so it's not going to be as simple as it sounds - to simply grab an emergency pack.
My main concern would be to get everyone up on top of the hull and to stay there. Even experienced swimmers are going to find it difficult in anything but a calm sea to make any headway - given currents, sea temperature and sea state. There was an accident on the Forth estuary a matter off weeks ago - see link http://news.bbc.co.uk/1/hi/scotland/...st/7551350.stm
If you have a waterproof handheld VHF - put out an emergency call on CH16 giving details and approximate position. Friends/family that are aware you are away for the day will know the general area you are in and your plans (A to B) etc.
I make a point of phoning my wife when I'm out fishing to give an approximate position, 2-3 times a day and expected time back at the slipway.
Basics should be good communication - handheld VHF, lifejackets (auto-inflate), knife, waterproof light and whistles.
Hopefully it will never happen - but if it does, at least you're prepared.