Single strobe wide angle position? And diffuser or not?

[gnirtS]

Im currently using a canon 10-22mm wide lens and a single Ikelite DS-160 strobe.
Im really struggling to find a decent position for this strobe for wide angle so looking for tips. If ive got it spaced a long way out from the housing i seem to drastically lose power to the extent i struggle to light the subject for example.

Also, as its wide angle and a single strobe is it best if i keep the diffuser on or off? (assuming i dont need the extra power without)?

Im really struggling to light up entire objects (specifically a diver!) currently.

(and yes, ive seen the tutorials here).

What sort of position would people suggest i use for a close up, head on shot of a diver swimming towards me for example and would that be with/without diffuser? How close to the housing assuming subject distance is 0.5m or less? Stupid as it sounds, would i be better off going a bit further away, zooming in to compensate so allowing the expanded cone of light to better cover the diver?

[bvanant]

For the given scenario I think I would put the strobe as close to the port as I could and only far enough back from the front of the port to not see the light in the port. As for zooming, I think most folks wold agree that having less water between you and the subject will be best, less backscatter, less adsorption of the light etc. I would definitely use a diffuser to get the widest beam.
Bill