How rapidly does one lose fitness?

Having recently started paddling again, with the last time I paddled regularly (3+ times a week) being in February, I have started to wonder how much fitness one loses after such a long break.

My last paddles have been in the region of 6km each, about half an hour, and I was pretty tired at the end of it. Given that my goal is the Cape Point Challenge, a whopping 56km, I have a long way to go. I have to be fitter than 56km come December, since I believe one must always have a little extra in case things go wrong (e.g. a head wind, very choppy seas, swimming to shore). I'm looking forward to all the training, the time I spend on the ocean is always worth it, and it always makes whatever I may be worrying about look insignificant afterwards.

To get back to the topic, I think fitness dissipates pretty quickly, is dissipate the right word? My guess, if I had to put a figure to it, is 50% per month. So if you could paddle 20km, then do nothing for a month, you'll be able to do 10km, then after another month of no paddling, you'll be down to 5km which is pretty much rock bottom. Will consult scientific authorities when I have the time.

Operation B-grade and Some Surf Then Cape Point

After a month or more of no paddling I've lost just about all my fitness, could probably do 10km but would be nackered after that. Having just read all the articles about the recent ARB World Cup, and knowing that I can't go on like this, I have made up my mind, its time to launch Operation B-grade and Some Surf Then Cape Point. B-grade comes first since I am convinced that without that level of fitness the Cape Point Challenge, which I did not do last time despite just barely qualifying, will only be painfull. Some Surf, and by that I mean riding proper waves like at Muizenberg or Big Bay, comes next since I need to be able to handle getting out in big surf. The last time I saw big surf was at the Knysna Sedgefield 2006. That was horrific, I wasn't fit enough, didn't have enough juice, and just made it to the massive backline. Once I let the first wave slide ahead I made my move and I will never forget seeing the monster that took me out, I was later told that my ski shot up into the air on impact while I got taken in by wave after wave.

Anyways, from next week I'm paddling at least twice a week during the week and once on weekend. That will be untill the end of July. Then things will build up every month with intensified effort in August. Life is too short to not paddle!