Running about 50 the boat lost forward thrust. Reverse works. No bad noises no grinding or other noise. Cone clutch?

Thanks

Probably 700hp 100 plus hours on the drive. Mercury hp oil every 20 hours. No metal the last change.

Pull the top and see if the bearings in the cap let go and rained down in your drive.

What year is the drive? Or what does the serial number begin with, if it is older that OM then it has thin floored gears and you more than likely broke the floor out. If that is the case, there is an upgrade kit to put the better gears in, then you will find the next weak link, the tower in the case.
Hope that helps.
Dick

Drained the oil. It looked fine no metal. The magnet was clean. Pulled the top and back cap every thing looks good. No broken parts.
Dick this is supposed to be an XR drive. The upper looks newer than the lower.I can't find any thing obvious. This is my third year with the boat and drive. Also can' tfind a serial #i. Just stickers with a bar code.

Any thoughts on this problem would be great.

I'm not an expert -- engine coupler going out?

3pointstar

if he has rev its not the coupler

straight cut gears or helical

Straight cut.

xr then

My bet is either the floor broke out as Mr. Gadgets suggested or you could have lost the clearance in the clutch cone if a thrust brg (Torrington Brg) or washer broke, this has happened to me more than once, you may still have reverse but not for long. and no metal will show in the oil.

Keep us posted!