I was playing with my brother-in-law today.

On a par 3 there is water all the way across the front of the green. There is a completely vertical wooden wall that goes about 3' down to the water from the grass. There is a 2x6 that lines the top of the wooden wall.

He drove his ball and hit the side of the wall into the drink. He dropped on the green-side of the water and said the wall is part of the land and he may drop there. I told him he must actually carry land for you to drop on it.

He dropped on the green side and played his ball. He claimed to have received a bogey.

Was I wrong? I asked the pro shop and was told that you must drop on the tee box side of the water in that situation. I told my brother-in-law and he revised his statement. He said his ball somehow hit the top of the wall and then went right into the water. Well, not the "top" rather the exact edge of the top board. lol

Anyways, what's going on here. No hazard markers were to be seen anywhere on the front or rear of the water. Only the sides of the water.

Btw, the third guy in our group said his ball hit the vertical wall. Not the top.

I'll take a guess but I am not a rules expert.

If asked to rule, I would say that the wall and all structural material that makes up the wall are defacto, if not actual, boundaries of the hazard. A hazard marker stake is in the hazard, by definition. So would be the hazard boundary line. And thus, so would be the wall. Therefore, the ball must clear the wall and hit actual non-hazard ground in order to be judged as having cleared the hazard.

But then, I always rule against the brother-in-law.

No hazard markers, you play it as a water hazard (yellow stakes).
In that case it doesn't matter where he hit the wall or green....he could even hit the green and spin it off into the water and the result would be the same.

Drop on the "tee" side of the water hazard.
Tell him he lost the hole (matchplay) or was DQed (stroke play).

I was of the understanding that if you carry water and land on the other side you may drop on the side your ball contacted. I've seen pros do it.

Only if it is staked as a lateral hazard (red stakes).

I think the bottom line is that your brother in law is full of it. But you are probably not alone in this situation!

If his ball had carried the margin of the hazard and gone backwards into the hazard, assuming it was red stakes, he could drop, no nearer the hole, at the point where his ball crossed the margin of the hazard. From what you described, he never carried the margin of the hazard.

The rule is applied from where "the ball last crossed the margin of the hazard."

IF and only if, the hazard is red staked (lateral water hazard), the ball may be dropped within two club lengths of the point where the ball last crossed the margin, no closer to the hole.

From the OP's description of the hole (and confirmed by the pro), the hazard seems to be a normal water hazard in which case the two club length drop is not available.

Read the rule here: http://www.usga.org/bookrule.aspx?id=14304

Excerpt:
Drop a ball behind the water hazard, keeping the point at which the original ball last crossed the margin of the water hazard directly between the hole and the spot on which the ball is dropped, with no limit to how far behind the water hazard the ball may be dropped...

Assuming it's not a lateral water hazard, based on what you have written, the key points with a regular water hazard are in bold.

Even if this were a lateral water hazard, all of the similar holes I have ever seen, with wooden walls like that, and marked, have stakes or a painted line at the top of the wall, not at the water line. Anyone I know who plays golf with any degree of regularity recognizes that if you don't make the top of the wall, you didn't make dry land out of the hazard. Of course, if this is a regular water hazard, it doesn't matter anyway, as discussed above.

Which reminds me of one of my pet golf course peeves ------- places that do not adequately mark things like hazards and OB. Why is that so hard? It's a service to the people who have paid to play, AND it speeds up play. But that is probably another thread.

I told him this and it did not go well. lol

He kind of went crazy. Said I was obsessing over it by looking it up.

Sounds like a classic case of 'the best defense is a good offense'.

Whatever, WE all know -- if he doesn't get it, well ..., his problem, not yours. Sorry for the animated icon. I couldn't find an appropriate one, but maybe this is close. Happy Birthday to him.