ZMA Controller described a possible loss of separation between successive departures from Key West; the reporter listing infrequent control of airspace and lack of formalized procedures as causal factors.

Narrative

While working as the RADAR Controller; Key West International Tower called for release on 3 subsequent departures. This is normally handled by NQX Approach but they were gone for the weekend and ZMA was forced to work that airspace for the weekend. I released the faster P180 and assigned a heading of 360 and climbed him to 16;000. I then released the DA40 heading 330 and climbing to 7;000; 1 minute after the P180. I then released a heading 360 climbing to 6;000. I used 30 degree divergence and 1 minute separation between departures with the faster aircraft in front. This is something I have observed at Key West Tower; and I have seen the NAVY do at NQX Approach. As a matter of fact; I have called NQX and they have told me that this is an accepted practice for them. However ZMA is telling me that we had 3 errors and that we need to use 45 degree divergence rule. The third aircraft departed only seconds from the second and advised he had the traffic in sight on initial contact and I issued visual separation between the 2nd and third. I later called Key West on the phone and they verified using visual separation. They did not coordinate this with me and they did not wait a minute for the departure. Numerous other controllers use different rules and ways to work this traffic because there is no; set; procedures in place for us when we assume the airspace. We have used this rule for some time in the past. We are not current; proficient or trained on the specifics of how to work that airspace. Recommendation; I recommend that procedures be developed and an LOA be put in place between the facilities impacted. Recommend that a training program be implemented to brief and train the entire Area on how to work that airspace. Recommend that we are given an opportunity to work the airspace periodically; so that we can maintain currency and proficiency on the established procedures.