At 95 Kg, in any sort or rough or choppy water the best board to learn on would be a Start Large.
It is by far the most stable.
But, it usually only takes a few sessions on the Start Large (100 cm 39.3" wide) for new sailors to
develop the techniques to be able to sail a much narrower board.
So, some of your issue is the narrow HiFly board, and some of is you haven't learned to correct uphauling and where to stand techniques yet.
You can make it much easier and pick up a used Start Large (this will become a great board for early planing once your skills improve (with large sails of course).
Or you can carry on with the HiFly and give your self some time to learn the board.
Wish you were here in the USA as I love to work with new sailors with exactly this sort of issue.
It almost always ends up being a "how to you uphaul and get under way sequencing issue with
a good bit of incorrect foot placement.
Have you been taught to sheet the sail in and add power AFTER you have both feet behind the mast foot.... or before you have your front foot behind the mast foot? This is usually the biggest issue.
You have very poor balance if your front foot stays in front of the mast foot when you are getting underway. If you do not add any power until after you have both feet behind the mast foot and are balanced over the fore/aft centerline of the board you don't fall in as much.
Also the manner in which you add the power of the sail can be very upsetting to your carefully acheved
balance. Try sheeting in with one finger on you back hand on the boom. This will get the board moving, and a board that's moving is much more stable than a board that's stationary.
Add the power of the sail very slowly and gently. This is not a full hand strength thing.
Last edited by Roger; 10th October 2011 at 08:02 PM.