Hi from Nico, Italy. I don't own a Phantom 380 but an old Mistral Echo 298 and a new Mistral Ventura 343 from 2009, both with adjustable mast track. As Mistral has stopped any raceboard production I'm interested in knowing about the starboard joint, if you mean the one thant can be seen here on the left http://www.star-board.com/2012/products/accessories.php
Seeing from ebay.de windsurf section, actual joint is always called "powerjoint" and seems to be a standard, even the head of the pin is different, I suppose not the shape. Anyway for my Ventura Keppler Surf Shop in Pforzheim has sold me a (pricy) Bic joint who works perfectly with both Ventura and Echo, it has ha way thinner head than older Mistral.
The older Mistral, similar to the one made by Starboard, has thicker head so curiosly doesnt work on Ventura, but I'm reducing it with a grinder to make it fully compatible with my Ventura.
So if even the starboard is a "powerjoint", if you don't find the original Starboard one, a Bic sould be compatible, here I can fine it cheap at Decathlon. Pay attention that the Bic has a weird and imho useless side wing to fix the uphauling rope that has caused big scratches on the eva surface of my Ventura, so I've now cut it away and I suggest to tho the same before having the surface of the board signed or scratched.
Anyway I'm interested in knowing from Starboard staff if the Phantom Joint is compatible with the powerjoint standard and so with Bic and (new) Mistral, or if it's different. And I also would like to know about the choice by Starboard of a nice and thick kardan joint instead of a rubber one, if this can give advantages in raceboarding compered to a classic rubber one, even a thick boge one.