Making the leap from OLY to Half Ironman

As said by everyone, you do have enough time to build up the bases you need for sure.  It'll really depend upon the time you have available to train, as it is more than an Oly for sure, especially depending upon your goals for it.  So, evaluate your time, check out the plans like JeepFleeb mentioned and pick one that works for your schedule.  A HIM will truly test your mettle, but it's a great way to get deep into training.  This winter is a great time to work on your base training, possibly work on your weaker discipline of the three, and then next season work in a solid training plan with some good build-up races or events. 

Have fun with it! It's a tough distance, but a satisfying one too!

I am planning the same leap - this year was my first season, I did 4 sprints and an OLY, one more sprint to go and then a half marathon.  Next season I am looking at olympic and one or possibly two half irons and maybe some sprints sprinkled in.....

I figure I have all year essentially to train....I have done SOME longer bike rides but will clearly have to make it a regular diet.....

my winter plans include adding Master's swim to my time with my swim coach to help increase my volume, the bike class I did last year and as long as the weather holds outdoor rides too in addition to the runs....

The swim is only 400 yards longer than Olympic - it is the bike and run that essentially double (or so)

totally doable - just put the time in....

The swim and bike won't require too much more than you're already doing. Just add some long rides and you should be set in those areas. You will likely need to do lots more running than you've been doing. The other factor that comes into play much more than an oly is nutrition. You will need to train so that you get in enough fuel on the bike so you can run 13 miles. Of course you will still take in nutrition on the run, but the bulk will come on the bike. It could take some trial and error in training to find what works for you.

Have fun.

 I'm in the process of making that transition myself.  I like to set an ambitious goal first, and then figure out how to make it a reality. I have a few more weeks unil the race, but my observation so far is a lot more hours training. I did a marathon earlier this year, and I've logged waaaay more weekly hours training for the HIM. 

  If you have the time, go for it, you only live once! (I may come back and amend this comment after the race)

Start slowly increasing your run volume early.  It's the toughest on the body, and your body needs the most time to adjust to the running buildup.  Build up too fast on the running and bad things will happen.  What constitutes too fast really varies from one person to another, but you have your 10% per week rule of thumb as a guide.  For me, my body didn't want more than maybe 5%, and my knee let me know that I did too much. 

Good job on the oly!

I don't think that's stupid.  Its pretty much the same as what I did.  2 sprints last year, started the year with a marathon in April (almost one year to the day, since I had started running), a couple sprints this season, one long sprint/short oly, one oly, and a HIM this past weekend.  Just like anything else, if you prepare yourself for the race, you'll do fine and have a great time doing it.