Fishtail at WOT - Play in Rudder? Or file down trailing edge?

[Mark rsa2au]

Hi Guys

Looking for thoughts on what may be the cause from anyone with experience in this. I think it is play in the steering cable but can't remember if this is adjustable or if it needs to be replaced? Does anyone know? ( '99 PS 205 DD) There is the option to file the trailing edge of the rudder to induce some drag but as it has not done this before I would prefer not to.

Boat has started to fishtail noticeably at WOT when we are barefooting. Not done this before, but this season had developed to the point where we really feel it now. At all other speeds the steering is great, does not pull to one side, and at most speeds below say 28mph you can let go the steering wheel and it will track straight. At WOT ( 45mph approx) it still does not pull to either side but there seems to be a very small amount of play in the steering wheel, and if you hold the wheel to one side to take up the play the boat will turn/drift in that direction and the fishtail stops. This seems to indicate play in the steering system?

Visually it all seems solid, and when I grab the rudder at the trailing edge there is a very small amount of side to side movement - say 1mm (1/32 inch?) at the rear of the rudder as if the steering is being turned. There is no other movement if wriggled from the bottom of the rudder, or up/down.

The boat is at the lake 3 hours away, so will be taking spares / tools with me this coming weekend to do maintenance and any ideas would be appreciated.

[chrislandy]

My old 205 had a lot of steering load at WOT, it sounds like you might have a bind somewhere allowing play. I would start by cleaning & greasing everything that has a nipple, it made a huge difference to steering feel when I did mine. Then check the rudder play, forward/backward & port/starboard + up/down

[dpb185]

Tracking fins tight ? Never had this problem (I've never ran my PS WOT !), just throwing things out there.

[waterlogged882]

Hi Guys

Looking for thoughts on what may be the cause from anyone with experience in this. I think it is play in the steering cable but can't remember if this is adjustable or if it needs to be replaced? Does anyone know? ( '99 PS 205 DD) There is the option to file the trailing edge of the rudder to induce some drag but as it has not done this before I would prefer not to.

Boat has started to fishtail noticeably at WOT when we are barefooting. Not done this before, but this season had developed to the point where we really feel it now. At all other speeds the steering is great, does not pull to one side, and at most speeds below say 28mph you can let go the steering wheel and it will track straight. At WOT ( 45mph approx) it still does not pull to either side but there seems to be a very small amount of play in the steering wheel, and if you hold the wheel to one side to take up the play the boat will turn/drift in that direction and the fishtail stops. This seems to indicate play in the steering system?

Visually it all seems solid, and when I grab the rudder at the trailing edge there is a very small amount of side to side movement - say 1mm (1/32 inch?) at the rear of the rudder as if the steering is being turned. There is no other movement if wriggled from the bottom of the rudder, or up/down.

The boat is at the lake 3 hours away, so will be taking spares / tools with me this coming weekend to do maintenance and any ideas would be appreciated.

My first thought aligns with another point in the thread. I suspect there is wear on a bushing that inner-lines the rudder's shaft port. I do not know this for certain on your year model but betting a U.S. dollar to a donut, a rebuild (as applicable) is probably the solution.

Drop the rudder and see about removing the rudder port. Before you do, look up inside the port and see if there are O-rings (usually old boats), or open-faced seal(s), or a bushing the lines the inside of the port. That port often sticks to the hull so consider that. I use a beveled 1" wide wood chisel to wedge under the rudder base plate and break it loose. Many other options. A fellow here made a post about his rudimentary rudder puller. Worked like a lucky charm.

I think any way you look at it (no pun intended) a rebuild would do more good than anything. I personally would not shave any part of the rudder to (try) counteract the consequence of a problem. Get rid of the problem...no more consequences. Rudder not altered. Don't fill any gaps with grease, get rid of the gap (if that is the issue).

I will also say this; if I were this deep into the issue, I'd also replace the steering cable while I had access to the rudder tiller arm. That said, while I had the controller apart and the floor up, I'd also replace the throttle cable.

US $0.02

.

[Mark rsa2au]

Thanks Guys

Over winter here downunder I greased all the cables and nipples as I do every year including the rudder port. This fishtailing did not happen last season but then we had a shortened season with COVID lockdowns and it has only become noticeable this season. Right now it is mildly disconcerting but not sure if it is going to get worse. At Slalom speeds it is great, tracks straight and does not pull either way, but at barefoot speeds (43+mph) it has a real wriggle.

Looking at online photos I am not seeing any adjustments in the steering cable system to take up any slack, so the option is to take up some tools and tighten every bolt and join incase something has rattled loose. If that does not help I will look at replacing the whole system- steering cable, rudder port and the steering rack, that way I know it is all safe and good to go.

chrislandy will check for any binds or loose connections, thanks. There is no movement in the rudder up/down, or left/right from the bottom, but about 1-2mm if held at the rear of the rudder.
dpb185 good to check the fins.. and yes we run WOT a lot. Each of us will have about 2-3 runs, so about 25 mins of full throttle max speed every morning.
waterlogged882 agreed, if I can't find anything obvious it may just be worn and in need of replacement, however it has started with out warning and never done it before so incremental wear seems less likely than a loose bolt/fitting..

[curver900]

If you do not have load on the wheel and if you give very light input the boat should pull. Test get someone to grab hold of the rudder and someone in the boat while it is on the trailer and you hold the steering wheel and they move the rudder if there is play too much play between the two it is most likely your cable. Make sure you go full left right on the rudder you would feel any binding or other concerns as well...

Another test would be to remove the cable from the rudder and do a similar test.

Start with just the steering cable and then go one at a time. Using the above you should be able to tell what is wrong.

good luck!

[Mark rsa2au]

Looks like it is a worn steering cable clamp block. When the rudder is wriggled you can see the excess play in the ball joint on the clamp block. If you hold the ball joint tight the play in the rudder is no longer.

Any options to tighten this up? I will order a new cable clamp block but freight is 3-6 weeks away so hoping we can find a temp solution..?

Appreciate any ideas? My wife (and brilliant driver) is not keen to be at WOT with the “wriggle” in the tail.

[Mark rsa2au]

Updating for future reference:

There was about 5mm play in the steering clamp block ball joint, which allowed enough forward/rear movement for the rudder to have free movement of about 2-3mm when holding the tail of the rudder.

I was expecting to have to replace this clamp block, but after pulling it apart I saw that there was some notable wear in one position. Clearly this is 20 years of normal wear and tear with out adjustment. I pulled it all apart, cleaned re-greased and put it back with the ball opposite to its original position ( upside down?) and this took out all the play. Bolted it back up and there is no more play in the rudder. Yet to water test but I suspect this will solve the issue.

Now to the next challenge... how to level the steering wheel. It was not level before I did the repairs, and is still about 1/4 turn to the right when the rudder is dead ahead. There seems to be no adjustment in the steering cable at the rudder end. I have also moved the threaded steering cable tube 2-3 turns each way to see if this adjusts it but there seems to be no change. ( I loosen the steering cable clamp block, loosen the steering cable lock nut, and rotate the tube in the thread of the steering cable block which seems to move it forward/backward) All this seems to do is position the rudder so that the angle of the rudder is equal from left to right when rotating the steering wheel, but does not seem to adjust the steering wheel angle to be level when the rudder is straight.

I am aware that prop torque etc will mean that the rudder will not be dead center when traveling straight, but the steering is actually a 1/4 turn to the right when on the water traveling straight.

Any suggestions?

[FrankSchwab]

Pull the steering wheel, rotate it 1/4 turn to the left, and reinstall it. You may not be able to get it perfect because there are a finite number of splines, but you'll be able to get it pretty danged close.

[Mark rsa2au]

Pull the steering wheel, rotate it 1/4 turn to the left, and reinstall it. You may not be able to get it perfect because there are a finite number of splines, but you'll be able to get it pretty danged close.

Thanks for the suggestion. I think mine has 5 Allen head screws instead of splines, so when I looked at rotating the steering wheel this way, it would be either 45 degrees left or right due to the screw configuration. I did notice that the angle of the steering wheel does change for straight ahead depending on the speed, but it was always angled either side of that 45 degree. I have not been able to find any adjustment in the actual cable yet to bring the steering back to level- seems strange that this is not adjustable...

Had the boat out on the weekend and it seems the fishtail is now resolved. The removal, cleaning and reinstalling the steering cable block with the ball at 90 degrees to its original position has removed all the play from this end. There seems to be some play in the linkage from the cable to the rudder, no doubt from 20 years of wear, so this allows some play in the steering system but the very noticeable fishtail has gone. Over winter ( Downunder in Australia) I will remove the fuel tank and see if this linkage can be tightened or replaced.

[chrislandy]

Mark, thats the wheel connection to the hub, if you pop off the centre cap there should be a single nut