No it doesnt.
If the boat doesn't have salt water on it, and presumably hasn't been in the water, that would blow away the theory that any body was dumped at sea.
Whose theory? Your theory.
If a body was dumped at sea, and he cleaned it up, why would they want to make a big deal out of no salt water being found?
It's not about whether the boat was or was not in the water at the Marina that day. It's about whether sp's alibi holds true or not. If the boat shows no evidence of salt water, this means that SP lied about his boat being in the water at the Marina.
(RC:)Whose theory? Your theory.
Will you please explain to me why, in the middle of February when you posted this, you didn't think the police were going on the theory that the body was dumped at sea? I didn't follow this thing very closely (I'm still not), but as far as I know, there was never any other theory? If that's the case, why exactly did you post this? Simply to be argumentative? Or were you trying to make a point that you didn't make clear?
As soon as the body was found, this post came to my mind, and I never understood why you had the impression that the police didn't recognize a 'dumped at sea' theory.