Which Rio M do you have?
The 2007 model (it's a Start board that's a little lighter and has no roller on the back)
Here's the specifications:
2007 Rio M
258 cm lenght
90.0 cm width
62.0 cm OFO
13.9 Kg. weight
2.0-9.5 Sail Range
It looks like this:
Do you have the 2008 model Rio M that's a completely different board?
Here's the specifications:
2008 Rio M
275 cm length
80.5 cm width
58.7 cm width OFO
14.3 Kg. weight
2.0-9.55 Sail Range
Here's a link to what the '08 Rio looks like:
How much wind are you sailing in?
Are you using a 6.4 m2 rig that's a current model sail or something older that 'you have used for years on "Bertha"?
You do not have to relearn your longboard skills.
I have the 2008 Rio M (I had the '07 Rio M and a Phantom 305 last year so I know what they were) .
Until you tell us what sort of sail your 6.4 m2 is, and a little about how you are rigging it,
it's very hard to say what your issues might be.
I've sailed the '08 Rio M alot with 4.2 m2 trainer sails (Retro Ripper 3's), with a 5.6 m2
Sailworks Hucker in alot of wind (like 20 knots), and with a 7.5 m2 Retro and 7.2 m2 NXslm Race sail.
The Rio M seems to me to be about the best compromise between a longboard and a shortboard that anyone has ever designed.
My Rio M does all the things that a number of "transition" boards were supposed to do, but never really actually performed that way as there were too many compromises.
So, I suggest that something else is wrong here.
The centerboard in the Rio M works well in sub planing mode, and the board moves nicely for me in almost no wind.
I've sailed it alot doing "A Taste of Windsurfing" and towing beginners around in < 10 knots of wind with a 5.0 m2 Retro Ripper 3 ( a very powerful little sail, for sure, but not nearly as powerful as a well rigged 6.4 m2.
It almost sounds like you are sheeting in too much or too fast (the board is moving sideways to leeward, indicating you are oversheeted beyond where your rig makes good
forward drive and well into the range where all it does is pull sideways, very hard.
If the winds are light, try sheeting in slowly and only enough to get your board moving forward. As it gains speed, you can sheet in more due to the forward movement of the
Where do you have your mast foot postioned?
Front of the slot.....middle of the slot.....back of the slot?
If you are sailing in sub planing mode, with the centerboard fully down, yes, raking the rig forward moves the CE of the rig forward and will turn you downwind.
Finding the near vertical position where the CE of the rig and the CLR of the fin and centerboard balance, will take you straight ahead.
Raking the rig back so the CE of the rig comes behind the CLR of the fin and centerboard will turn you upwind.
You can also go upwind by standing a little off center to windward and tipping the leed rail down slighty to go upwind (this engages more of the rail and makes the CB a bit more efficient) and conversely you can go downwind by tipping the board windward rail down.
If you raise the CB, then everything works backward (from longboard technique) and you will be sailing a big shortboard.
Upwind rail down to go upwind, lee rail down to turn off the wind. Board should be as flat as possible to go straight.
That's the basics and you can see that the techniques are very different (longboard vs shortboard) but the thing that makes them different is the centerboard.
Hope this helps,