Has any body got any experience of sailing ( Merlins) after major abdominal surgery, either practically or as a medical professional? I am not sure that my consultants really have any idea what this entails. 
I can't find anything on the web - there is normally somebody out there with something to say. Do I have to just give up or do I need to buy one of Keith Callaghan's ballasted dinghies as an alternative?
Any help would be greatly appreciated 

Had major abdominal surgery (Perforated Duodenal Ulcer) when I was 21, have 6 inch vertical scar to prove it, best advice I had was if it hurts, stop. After  12 months I was fine. But had youth on my side.

2013 had postrate removed consultant said three months off then back gently and the same as above if hurts stop.
 
good luck

And slightly further down the surgery scale, I was able to sail, quite comfortably, three weeks after a hernia repair. I was told the same as above...'your body will tell you if you shouldn't be doing it'. However, this only counts once you are off the painkillers.

Thanks guys - 5 months on the body is still protesting (its a 9inch scar - an inch for every hour on the table!) I had sort of written this coming season off - seems I was probably right.

Afternoon, You need to listen to your body and take small steps and all will hopefully be fine. Chris Lewns had major surgery several years ago and subsequently sailed 3666 and 3704 to great success. 
Since 2009 I have had 3 shoulder ops on my right shoulder due to a cycling accident. 2 of the ops did not go well, but the final one Christmas 2013 was a complete rebuild without any bits added, which was very intrusive, though keyhole surgery. 
The recovery is slow and required a lot of input with extensive daily physiotherapy. 
13 months later we have achieved a lot and have just done the B14 Worlds in Australia. Though not what it was in 2008, and ongoing daily treatment, I am competing again. 
The key is to engage a very good team around you and listen to them. If not with a physio, get a good sports physio who understands what you are putting your body through (high level rugby physio would be a great start), then set your goals and with a bit of luck you should get back sailing where you were in the fleet very soon. 
Best of luck and put a plan together with the right people involved. Every penny you spend will be well invested. 

Can't think of much to add from the medical professional (GP) angle.  A 9 hour op suggests you had something fairly fiddly done to your insides but if it is a vertical scar then the muscles themselves have not been cut and once everything has fully healed you should be able to gradually build back the strength of your core muscles to where you were before.  The key thing would be to build things up slowly and be patient - it may take many months to get fully over your op - and as has been said, to listen to what your body is telling you and back off if you are hurting something.