Right, Saturday's Hennessey (I can't be arsed pricing it up) and the explanation of the weights. Here we go.
Firstly, the concept of handicapping is that every horse should cross the line at the same time, and the job of the handicapper is to allocate each horse racing what is called a 'mark' and that will determine what weight they carry in relation to the other horses in the race, unless they are the highest rated horse in the race in which case they are assigned 11-12 over jumps. The lower your mark, the less weight you carry in relation to the top weight. Just think of it as the handicapper trying to slow down the best horses.
Top weight in this carries 11-12, and Denman off a mark of 182 will saddle that. So for every 1lb below that number of 182, you carry 1lb less. So if you're running off 165, you'll get 17lbs from Denman and race off a weight of 10-9, and 5lbs would be 11-7 and so on and so forth. With horse racing, the minimum weight in a National Hunt handicap is 10-0 (unless your jockey is a youngster and is permitted a claim which I'll explain later. So, as a result, there's horses in this race running out of the handicap as they're handicap rating is in excess of 26lbs below Denman. Take Niche Market as an example, this will help us understand the concept of a jockey claiming weight as well. Niche Market is racing off a mark of 148, which as you can work out is 34lbs below Denman, so in effect he should be carrying 34lbs less and running off 9-6. But, as a consequence of the minimum weight being 10-0, he is forced to run off that, and effectively he has an 8lb penalty. If Denman was out of the race and Neptune Collonges was top weight off 11-12 off his mark of 164, he'd be 16lbs below that and racing off 10-10. But Denman is in it, so Niche Market is forced to carry 8lbs more than he otherwise would. Every horse rated below 156 will be running with more weight than they otherwise should be, this is known as being out of the handicap. Over jumps, most work to a theory of 1lb per length, so if you're 8lbs wrong, you're basically (and this is very basic to help you understand and not in any way to be taken quite so literally as it sounds) 8 lengths worse off before you even start the race.
Now, as I said before there's the concept of a claiming jockey. When you're first starting as a jockey, you are permitted what is called an allowance. As you ride more winners, you gradually lose it. Generally speaking, you start off with 10lbs, then 7lbs, then 5lbs, then 3lbs and then after you ride a certain number of winners, you're forced to ride without it. So, we'll go back to Niche Market, his real racing weight is 10-0, and the jockey, Ian Popham, is allowed to claim 5lbs. So as a result, Niche Market will be running off 9-9, it's not listed on the racecard in this way however and you have to manually subtract the weight yourself.
Any queries, I'll answer 'em.