Yup - use a hose, garden variety, with a high pressure nozzle on the end - and very liberally wet just the area where you think the leak is.
Get someone you don't like very much to go inside the boat - with a torch .......with a bit of luck you might kill two birds with one jet, as it were .....
And another thing....... I am constantly chasing leaks on my teak decked boat.
One method has been to make a temporary seal on the suspected joint, seam fitting with duck tape. If the duck tape does the job then that is the site of the leak. You then do the job properly!! (thats the bit I keep meaning to get on with) You will recognise my boat should you see it!!