well l have had the boat for 1 month now.I've not been on the water yet and l bought the boat from a person who knows nothing about boats either.They had to move so a good deal was for sale..NOW l have an inboard Mercruiser87 Stingray. l tried to put it in water last week and as l reved the motor the boat does not move. I've heard (spun hub),(lower unit), broken hub shaft..Finally l took it to a mechanic and he told me that it was because l was pushing the throttle button in and then shifting to reverse or forward..He said the throttle disingadges the shift gear and that was why the boat reved but does not move..HAS anyone ever heard of this? CAn this be the problem?

The throttle button is probably an interloc to prevent accidental movement of the throttle. Pushing it means you are going to change the throttle setting -----for this to lock out the gear shifting would be very reasonable. Always shift with the throttle in idle, and the button released.

Yes this can happen. If you press your throttle only button your boat wont go anywhere.

There is a big button on the throttle where it pivots. It allows you to put the boat in neutral. To put it in gear, just pull the trigger on the bottom of the handle and push the throttle forward, do not push the round button at the pivot point.

When u start a cold engine you're probably going to need to rev the engine so it does not stall- u certainly do not want to fly into the boat in front of u so by pushing in the disengage button u can safely warm up the engine by giving it a little gas.Once the engine is warm u probably wo not have to repeat this procedure but if u do that does not mean anything is wrong. While l am out fishing long drifts when l start the engine there r times l have to push in the button to rev my engine so it does not stall. That is the purpose of the disengage button..

Congrat is on taking her to a mechanic and the mechanic is right on the $$$. You are disengaging the throttle by pushing in the button. You may only want to use it if the vessel has sat for awhile and you need to prime the engine before starting her up. Otherwise there is no need to use it.only if necessary.

Yep, that is one cause of the problem you describe.

That button is there to raise RPM is without engaging the transmission.

Try just throwing her in gear and see what happens.

Good luck

l hope the old owner showed you how to start the boat. The mechanic is correct, you do intentionally disengage shift until the engine is running smooth. then you go to the neutral position and the gears will in-gage, so if you push forward, it will go in gear. push further and the boat will move faster. l think you should get a experienced person to show you how to pilot your boat. Good luck!