you beat me to it... I have seen hand clocked times off by as much as a half a second.... If it wasn't clocked with electronics, most organizations won't even recognize it...
here is a widely used guideline, which would give him a 10.84
To convert from hand to FAT for sprints up to 200 meters (55 hurdles, 70, 100, 200 & 200 hurdles):
This procedure is used by both the Big Gold book and NFHS. First round the time up to the nearest tenth. Then add 0.24. For example, if an athlete runs 8.51 in the 55 hurdles, it should be rounded up to 8.6. If on your meet sheet you already correctly rounded up to 8.6 you do not need to do it again. Now add the conversion of 0.24 which gives a final time of 8.84.