Long run question

Yes, I think you need to switch out the gatorade for water.  It's hard to know if you're getting enough electrolytes or not. It's very different from person to person. You may consider using GU Roctane as well. It is specifically made for distance and it has buffers to help with your stomach.

GOOD LUCK!!

IMHO, your long runs should NOT be @ MP goal.  they should be run @ at an easier pace and at a pace where you can hold for the distance.  Some plans will prescribe a "Fast Finish" where one runs the last 1/2 of the run @ or near MP goal.  You want to be able to finish the run and still able to "answer" the bell for the next work-out. 

I don't know your background or current level of fitness but, on the surface, it may appear 8 flat is a little above your level at this point. 

curious, how did you come up with the 3:30 goal?   what are some of your recent races to support that?

Good idea of getting your hydration/cals worked out now.

Good luck to ya!

Couple thoughts...

I have no problem with mixing in SOME marathon-pace miles.  Generally, you'd want to do 6-10 miles easy, then run SOME (4-10) at MP, then cool-down.  The "SOME" would depend upon where you are in the program.  Early long runs (15+ miles) should probably all be "easy" pace.  Once you become accostomed to those, begin working in SOME marathon-pace miles.

As others have said, your MP pace should be indicated by past race performance using something like the McMillian Tables or Daniel's VDOT tables.  DO NOT use an unproven "goal" to establish training paces.

Finally, on the nutrition front.  It's awfully tough to choke down much while at race pace.  Be glad you figured this out in training.  Pace and exertion level plays a huge role in what you're able to digest.  When you're really pushing yourself, the blood is rushing to your muscles, leaving the GI high and dry.  I suspect pace/fitness may have played a role in your stomach crying "uncle."  I've resorted to water and Gu only, and perhaps some Enduralytes for the hot days.  NEVER use a sport drink to wash down Gu.  Use either Gu and water, or Gatorade.  You need water to dilute the sugars/electolytes you're pouring down the pie-hole!

Long runs are never easy.  You got through it and learned from the experience.  It's best to start slower and work up to that "goal pace."

I did "SOME" marathon pace miles during my long run today.  See my log for the details...

Good luck!

Yes, as others suggest, pacing was probably not great here, but pacing might not have bene the cause of nausea, thirst, etc.  I'd strongly suggest leaving out the salt tablets next time,and upgrading your sports drink from Gatoriade to something with higher-quality sugars if you feel that the Gu is not enough calories, or just go with water if you think that the Gu is supplying you with enough calories (which it probably is).

As you sweat, you lose proportionately MORE water than electrolytes, EVEN if you are a 'salty sweater', despite what certain companies would like you to believe.   By taking in all that salt, you will make yourself thirsty.  You can get further than you probably think on just water.

You took sports drink, gels, AND electrolyte tabs?

No wonder you were thirsty.  You overloaded on electrolytes.  That's a guaranteed way to make yourself sick.  That was your problem, not the pacing.  You took in entirely too much nutrition.

I disagree with not running at pace.  You did 13 at MP, I think you probably could have done the 20 at MP, if you hadn't gorged yourself.  I think there's something to be gained from running some of your long run miles at MP, so I don't see a problem with what you did.

Slight high-jack...

Scout7, how much long run at MP do you suggest?  I've got a 11/1 marathon.  I did 17 with 7 at MP Saturday and plan to get 18 w/10mi at MP this weekend.  Should I get 10+ miles at MP in during my 20-mile run on 10/11?  Then it's taper-time where I probably will do some MP running, but not as much.

How much is a highly dependent question; depends on fitness, goals, experience, personal preferences, etc.

I would say that half to 3/4 of a given run at MP is probably fine.  But that isn't every week.

Can someone confirm that gels have electrolytes?  Most of the packaging in the sports nutrition world is over hyped and no gel that I've seen has touted electrolytes.  So, I assumed there are no electrolytes in gels.  Am I wrong?

The gels I've seen have them.  So do sports drinks.

This is something I put together when I had the same question...

Assuming you trained for it, yes.

For my first Oly we showed up scary late to transition(about 10 min before the gun) due to lots of long lines.  All I had for breakfast yas a small dannon yogurt and a cup of coffee...I knew this wasn't enough.  Right after I put on the wetsuit for jog down to the beach to get ready for the swim I downed a GU...then another on the bike...then another on the run.

I couldnt believe it, I kept waiting to bonk but didn't...just 3 GU's and 100 calories of yogurt did the trick.

What I learned from that is that I may be "over-nutritioning" in training.  I still take HEED with me and no water on a long run...I figure I can hit a water fountain for that if needed.  Still playing around with it as my milage increases, but taking what is says to take on the label is just unnessacary for me.