My reading of the Class Rules is that the self bailers are optional in all respects, provided they are not “substantially in excess of their intended function in either weight or size.”
The usual arrangement is to have two, but I don’t see any problem with the Rules in having only one. However you are likely to wish to deploy one while sailing, and <span style=”line-height: 1.5em;”>in some circumstances</span><span style=”line-height: 1.5em;”> the one on the lee side may be inaccessible, but if you have one on each side then you can at least get at one of them.</span>
Having said that, I find that I can usually get at both of them, but then I am almost never racing, so it doesn’t matter if I spill a bit of wind and move inboard to put them both down.
A second reason for having two is the rate at which you can get rid of serious amounts of water, whether that be the result of taking seas green aboard or the result of capsize.
Unless cost is a major issue I would recommend that you fit the second one. But if cost is a major issue then go ahead and repair the hole, and make do with the one.
Oliver