As a beginner I'm trying to get a better understanding of hook lengths. How long should they be? why would you lengthen or shorten them? and is there any guidelines as to the differential, if thats the right word, between main line and hook-length?

I've been looking at some ready made carp rigs in the tackle shop which use a 12lb + braid, this seemed excessive to me. Would you have to use a very strong main line or can you have a weaker main line?

David what sort of fishing are you talking about and what are your target fish, also what size fish are you targeting.

I'll be course fishing at commercial fisheries so I guess a bit of everything. Does the type of fish make a difference to the hooklength?

Yes it depends on whether you are float fishing or ledgering and if the latter whether its a paternoster rig, bolt rig, free running or method. But whatever rig it is your hooklength should be a lower breaking strain than your mainline, the reason being if you get broken off you don't have a fish trailing yards of line or lead around that could tether the fish and kill it. Tell me how you intend to ledger and the type of venue and stock and line bs and I'll offer what advice I can. Also there on the sight several sites about rigs.

I'll be using the simplest rigs as I'm only starting. I will be using a float and a feeder rig, probably at Woodlands, Thirsk. i was intrested due to seeing some rigs in magazines that use a braid with a much higher BS for the hook length.

I'll be using 5lb line, possibly 8lb. I've been told that the venue has a good stock of carp.

For ledger try 8lb mainline first put on a run ring with a swivel then a bead tie to a another swivel. Start with a 5lb hooklength of around 18ins hook size will depend on bait. Use the run ring with a swivel to attach bomb of around 1-11/2 ozs. For float suggest 5lb main to 3lb bottom. Use a waggler and lock bulk of weight around float with say a no 8 1/2 way down and a no 10 shot approx 12" from the hook. Plumb the depth and start with bait just touching the bottom if fish start taking on the drop then shallow up. Don't be afraid to keep varying the depth until you find the level the fish are feeding at although tgis is likely to alter through the session. Don't be afraid to ask experienced anglers on the bank for help, I think you'll find most will be helpful. Hope the above helps.

David don't get bogged down with the rigs for big carp, there is sense and reason in using hook lengths that are stronger than your main line, but it involves fish friendly rigs that allow the lead to pull free if broken or snagged.
As a bit of an all rounder I don't particularly like to categorise fishing into types, but to make things easy if you are going to fish commercial fisheries, then stick to match style tactics initially and use a lighter hook length than main line as described by Richard.
With regard to length of hook link, it is not too important with float fishing.
When it comes to ledger or feeder fishing it can all depend on how the fish are having it on any given day. Start with a length of around 15 - 18 inches (sorry don't do metric) if you find you are missing bites experiment with longer or shorter lengths till you start to hit the bites. Sorry no quick fix.
One last point if you intend to fish the method then use a very short hook length, 3 - 4 inches should be OK, but again if you are not certain stick to the simple things and build up your knowledge gradually.

Just one other point, you mention using 5lb and 8lb BS line. In open water, ie. no snags you should comfortably be able to land fish at least twice the size of the breaking strain of your line by using a sensibly set clutch and by backwinding when playing the fish.

Thanks for all the responses. So much to think about it start to bog you down if you think to hard. One last question though, Dave you say 'experiment....till you start to hit bites'. why does the hook length effect seeing the bites? is it that the fish might eject the bait on a shorter length as it feels resistance, meaning you have to be super fast to hook the fish.

Funny creatures fish, just when you think you've got them sussed they do somthing different.
Don't quite know how it works but on some days a longer hook length is needed and on other days a shorter one works better. If you are not getting any bites at all it is probably nothing to do with the length, the time to start making adjustments is if you are getting bites but missing them.
It's a bit like tinkering with the shotting pattern or using a different float, the change often makes the difference, possibly the fish wise up to a certain set up.

Ok thanks for all your time. I guess its a lot of trail and error for use beginner's, I wont give up though!!!

Thats the spirit David.

Keep at David, it's not an exact science and sometimes luck plays a big part, but just remember, the more you practice the luckier you get.

Lengths of hook lengths. That is a most interesting subject.

On the river Trent I use hook lengths up to 5 feet (1.4 metres)!!!

The reason is that the bait is a far as possible from the lead. Barbel have a tendency to catch the main line with their fins thereby being spooked.

Since I started using very long hook lengths, I have caught a great deal more barbel. And that will do for me I guess.

my self i would use anything from 6-8lb main line its hard to tell you never know what you will it could be BIG or small so its always useful to have a stronger line than neceserry myself i use 6 lb mainline and thats held carp to 12lb for me so give it a try e-mail me if you catch anything at Danpear20@aol.com