Throttle Fwd But engine in reverse

[GALAWA]

I had the same experience on my catamaran.
One engine would pull rearward and the other forward when pushing both throttle levers forward.
The cause was an improperly mounted maxprop.
Maxprops are fiendishly tricky to adjust for sens of rotation and pitch.
I learned this the hard way : I had to take my catamaran out of the water for correction each (3) times I made a mistake

[Siberian Sea]

Folks are suggesting that the props are on backwards. Ok if you have twin props and they are opposing pitch it’s possible they are switched but you would know this right away because both port and stb would be wrong. It’s not possible to put one on backwards because the inside of the hubs are tapered and so it’s the shaft. Most likely it’s something with the linkage or that one prop is the wrong one if it’s a new one.

[jmschmidt]

Bullshooter is joking isn't he/she. Does anyone believe this nonsense? Props have tapered bores with keyways to fit on tapered shafts, which also have keyways. Impossible to put one on backward unless he forged the prop and shaft himself DIY style.

If you have a single control lever for both throttle and transmission, most likely the transmission control function is hooked up on the wrong side of the control unit. You have to determine if the actuator on the transmission is pushed or pulled to engage foreword or reverse. Same with the throttle control. I push the control lever forward to increase RPM but the throttle actuator on the engine injector pump is pulled aft when I do. When I push the control lever forward to go forward it pushes the lever on the side of transmission aft for forward gear. There are two ways to hook up each function. Think it through carefully and test each function before starting the engine.

[sloop537]

I had a similar issue, a set screw on the camber came loose where the throttle cables connected to the camber which switched a micro switch sending a electrical signal to a solenoid activating the Hydralics for selecting FWD or REV. You may not have the same set up but maybe this will lead you in the right direction.
What had caught me off guard was, I had docked, got up in am to move the boat and FWD was REV .

[PineyWoodsPete]

The obvious thing to do is to actuate the gearshift lever with someone in the engine compartment seeing if the tranny shift lever moves appropriately. Most likely, it's a disconnect at the cable end fitting to the lever - or of the clamp securing the cable sheath to tranny casing bracket.

I had a recent episode of the first variety entering my slip - fortunately a vinyl protector on the dock's edge. The end fitting apparently was run out very near to the end of it's treaded stud and had stripped off -a little surprising, as the hydraulic shift lever needed little effort. The only solution was to move the cable clamp forward about 1/2" for a solid bite on the threads...

[Squanderbucks]

If nothing new installed. My vote is a broken thrift cable. Or cables switched either at the transmission or in the shift lever control box.

Does it go into neutral. And shift normally into Reverse. Just no forward?

If so the the cable is broken. If so it might work in push mode but not pull.

Transmission usually has a lever that if cable is attached on one side goes forward if move to other dude if lever goes opposite.

So those things that determine how the boat moves.
Engine rotation. That is set no changing that.
Right hand or left hand pitch of prop.
Cable attachment to shift lever box. ( in push or pull mode)
Cable attachment to transmission lever.

Those are the possibilities.

[Cadence]

Originally Posted by scarlet

So.... It's a catamaran and it hasn't been out of the water. I have folding props and barnacles could be a problem.

With no servicing being done to the boat since last usage, my guess is you have nailed it with growth on the folding prop.. Did you have it in reverse prior to the problem even momentarily. Take a swim and see what the blades are doing.

[wet dreamer]

I don't see in your post what saildrive you have, but I am troubleshooting a similar issue on my yanmar sd20 and have found some help online. If yours is a SD20 pm me and I will send you a link to what I found.

[Djarraluda]

Most likely be something in the actual lever mechanism. Most are selectable so cable is either pushed or pulled to suit whatever gearbox configuration you have. Perhaps a cam has worn and flipped over? Perhaps the plate has corroded and is stuck. I would strip the lever mechanism and check. Roger

[old pirate]

Its in your transmission. A broken or worn part. Cannot remember the tech terms, but it requires the replacement of a small part, selecting the gear. Took a mechanic an hour to fix mine

[scarlet]

Originally Posted by GALAWA

I had the same experience on my catamaran.
One engine would pull rearward and the other forward when pushing both throttle levers forward.
The cause was an improperly mounted maxprop.
Maxprops are fiendishly tricky to adjust for sens of rotation and pitch.
I learned this the hard way : I had to take my catamaran out of the water for correction each (3) times I made a mistake

I haven't adjusted the props at all... Boat hasn't been out of the water this year. That wouldn't have just happened whilst the boat was just sitting at dock, right? Because last time I used the boat it was ok.... And this time it was messed up...

[scarlet]

Originally Posted by PineyWoodsPete

The obvious thing to do is to actuate the gearshift lever with someone in the engine compartment seeing if the tranny shift lever moves appropriately. Most likely, it's a disconnect at the cable end fitting to the lever - or of the clamp securing the cable sheath to tranny casing bracket.

Did that.... The cable to the engine moved fine... The cable to the sail drive didn't move at all..

[scarlet]

Originally Posted by sloop537

I had a similar issue, a set screw on the camber came loose where the throttle cables connected to the camber which switched a micro switch sending a electrical signal to a solenoid activating the Hydralics for selecting FWD or REV. You may not have the same set up but maybe this will lead you in the right direction. .

So THIS caught my attention. If I am having an electrical problem in the boat, could this have caused it? I had my 30 amp shore power cable burn out the neutral ground prong. Still investigating the issue, but could this have caused an issue with the props? I'm still learning the systems on my boat, so I apologise for my ignorance on this, but I thought the throttle controls were mechanical and not electrical.. I have yanmar engines and sail drives.

[scarlet]

I also just switched out my start batteries... Did I need to reset something?

[mvweebles]

Maybe I missed it, but when you say that when you put it in forward, it goes into reverse, is the shaft actually rotating the correct direction? What happens when you shift to reverse, shift to forward, and shift to neutral? Your left engine should have a left-hand prop (counter clockwise turn when viewed from aft of boat and engine in forward), your right engine a right-hand prop. Shafts should be rotating opposite directions in forward.

EDIT: I re-read and see you sail drives, so you won't be able to see the shaft (though depending on water clarity, you may be able to see the props). Really need to isolate the issue - linkage, cable, prop, transmission. I would disconnect the cable from the linkage and make sure the cable runs free which will isolate your issue to the transmission. Mostly likely something something in the linkage.

Good luck

Peter