[member=1908]asajj[/member] Yeah it does. Overlaying works in the opposite way to underlaying, in that it involves putting a higher stake at the exchange - so if your selection wins at the exchange then you will make more money because you've put 'too much' money on to lay and, alternatively, if it wins at the bookies then you will have made a bit of a loss or less profit. However, if you've overlayed for some sort of offer which includes getting a refund or free bet if your bet wins at the bookies then you will have the free bet to come.....I think that is the situation that you're describing. Your numbers look correct to me, however I don't know the terms of the specific offer you're talking about - if it's where a free bet/refund is triggered when the back bet wins at the bookies then your thinking is absolutely correct!
I've seen people overlaying for a couple of reasons:
1.
To extract more profit from a free bet/make a £0.00 QF loss on a QF bet. Not linked to any offer, but people do use overlaying when they are 'sure' that their bet is going to lose at the bookies. This is risky because you never know with sports and results can go either way....if your selection does lose at the bookies then you might have extracted more profit but if it wins at the bookies then you've given yourself less profit/a heftier qualifying loss.
2.
To make a 'free bet/refund if selection wins at the bookies'-type offer, free of a qf loss. These offers, without overlaying, don't guarantee a free bet and often incur bigger qf losses as they tend to be on less-popular markets such as first goalscorer etc, so overlaying can mean guaranteed £0.00 qf loss if you don't hit the refund/free bet. It also means that if you do hit the refund/free bet then you'll be making less profit from it, but you've saved yourself a potential £2-3 qf loss if you don't.
The second one is what you're talking about, where you can overlay to give yourself a £0.00 qf loss if the bet wins at the exchange or a heftier qf loss if it wins at the bookies (but with the fb to come). I use this method if I do something like "Refund on winning First Goalscorer bets" because they often aren't many close matches and the qf loss can be about £3 on a £20 stake...and it's not even that likely that my bet will win and hit the refund so I don't want to risk losing £3 qf loss at a time on each of these offers. Overlaying will certainly give you less profit in the first instance than if you layed as normal and did end up hitting the refund, however it's not guaranteed that you will ever hit the refund on these offers so taking £2-£3 qf losses on them isn't worth it in the long run, for me at least. So, I overlay for £0.00 qf loss if there's no refund, and a lower profit if I do hit the refund.
Example of doing the offer with and without overlaying, using the figures you gave:
A. Calculating as normal, no overlaying
Back bet at Unibet, £20 on 3.5
Lay bet at Betfair Exchange, £18.67 on 3.8 (liability is £52.28)
Qualifying loss: -£2.28
POSSIBLE OUTCOME 1: Bet wins at the bookies. Win £50.00 at Unibet. Lose £52.28 at Betfair Exchange. Free bet is triggered due to winning at the bookies. Assuming that you can retain 75% from the £20fb, that's £15.00 minus the qualifying loss = overall profit of £12.72
POSSIBLE OUTCOME 2: Bet loses at the bookies. Lose £20.00 from Unibet. Win £17.72 at the exchange. No free bet is triggered. Overall profit of -£2.28.
B. Overlaying the qualifying bet
Back bet at Unibet, £20 on 3.5
Lay bet at Betfair Exchange, overlaid by putting £21.05 on 3.8 (liability is £58.94)
Qualifying loss: dependent on the outcome
POSSIBLE OUTCOME 1: Bet wins at the bookies. Win £50.00 at Unibet. Lose £58.94 at Betfair Exchange. Currently sitting at a loss of -£8.94, however the £20 free bet has been triggered. Assuming that you can retain 75% from the £20fb, that's £15.00 minus the qualifying loss = overall profit of £6.06
POSSIBLE OUTCOME 2: Bet loses at the bookies. Lose £20.00 from Unibet. Win £20.00 at the exchange. No free bet is triggered. Overall profit of £0.00.
So, you can see that by laying normally you have the potential to make a £2.28 qualifying loss if the refund isn't triggered, but the profit from the free bet (SHOULD you hit it) is higher, however overlaying means that you're basically covering your arse should the free bet not be triggered. I much prefer to overlay when it's the kind of offer that is unlikely to actually happen.
You can use trickybet
http://www.trickybet.net/lay-calculator, which is pretty good because there's a 'custom match' scale, which you can maneuver to choose how much to overlay.
