Yeah its more I fish a small river so always 7 weight rod ive finally got ma big rod out for a big river fishing after haveing it for 5 years and I cant be bothered buying a line for 1 day lol cheersIt won't affect your fishing!, but it will have an effect on your casting.You'll struggle badly to be honest, the line won't be any where near heavy enough to load and work the rod for you and you won't get distance or presentation. Wind will give you an interesting time too, in that your line will get blown all over the place as you won't be getting good well tensioned loops as you try to cast.Trying harder, giving it the big heave ho won't work either, you'll just be cream crackered quicker and loose you temper so much faster. You will give those watching a good giggle however!.
Try the right line for the rod, daft as it seems, it'll help you catch something!
Yeah its more I fish a small river so always 7 weight rod ive finally got ma big rod out for a big river fishing after haveing it for 5 years and I cant be bothered buying a line for 1 day lol cheers
I have a rage compact shooting head on a floating line in 7 weight I use it with my 10 ft 7 wt switch rod probs for the sake of a day maybe best just using that rather than my 13 ft 8 wt rod it's for the tayYou'd be better fishing the big river with the #7 rod and line because it will be more enjoyable and you'll probably cast further and cover more water effectively!
For the sake of one day, you could do worse than buying a cheap integrated shooting head from maxcatch. It'll lasts you a few years at that rate and so be a good investment!