Howzit Miles.
When Hunting from a boat we also use the bungee style lines trawled behind the boat, also 4 by the way. But if there is more than one boat in the area and the fish dont rise to the bungees we also use a rod and reel with a swimming spinner like a rapala to try and bring the fish closer. When diving from a boat and leaving spearos in the water to ambush a school I think you could use your reel gun with a shortened float line making it able to easily find your divers. We also add a flasher to this eqaution which the divers just watch closely ,similar to the shore dive one.

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Dive safe and shoot straight
- Hénré -
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"Thinking is the hardest work there is, which is probably why so few engage in it"
- Henry Ford -