Boat turns rt. now, ? skeg adjustment

[Expidia]

Last year I moved the skeg on my Daughter's Mercury 1999 25 hp two stroke and that corrected the steering to the right.

We took it out yesterday and once again steered to the right when letting go of the wheel doing about 18 mph.

When we got home the skeg position was far to the right and bolt was tight. When we first got the rig last year the skeg was loose and I took the boat out with wrench in hand and tried the skeg on the left and on then on the right from the dock. I forgot which side I got it to correct the over steer to the right.

The water is still 40 degrees, so I didn't want to stand in it to adjust the skeg as the docks at the ramps are not in yet.

I had a shop change the impeller 2 weeks ago, but I don't see a reason he would have had to move it from the side where it was. It is all the way over to the right side now.

I'd prefer to adjust it in my driveway, so I don't have to go with her for another test run because the river is 20 miles each way.
Anyone know which side left or right the skeg (when viewed from behind the boat) should the skeg be to correct for oversteer to the right side.

 

[Expidia]

Re: Boat turns rt. now, ? skeg adjustment

Wow, no responses, I know I'm asking about a Mercury here, but the question is really not brand specific.

Make believe I'm asking the same question for a Johnny Rude

 

[emckelvy]

Re: Boat turns rt. now, ? skeg adjustment

You move the back of the "skeg" aka Trim Tab in the same direction the boat wants to pull. So if the boat's pulling to the right, move the back of the trim tab to the right, and vice-versa.

If the boat's still pulling to the right with the skeg all the way over, you've got other issues. Check your impeller and the bottom fin (this is the real "skeg") for damage as problems here can also make the boat pull.

Here's an excellent old thread discussing your exact problem, maybe some of the additional tips (such as the worn/distorted motor mounts) will help guide you to a solution:

http://forums.iboats.com/showthread.php?t=132394&highlight=pulls+trim+tab

HTH........ed

 

[buzzm19]

Re: Boat turns rt. now, ? skeg adjustment

I am not a rocket scientist, but why would you want to adjust the skeg in the same direction the boat is already going, unless you want to turn right faster. The adjustment is opposite, if it goes right adjust to the left and vise a versa same thing as back asserd. Buz

 

[turbinedoctor]

Re: Boat turns rt. now, ? skeg adjustment

Buzz, if you are looking at the motor from the back looking forward try to imagine the water flowing over the trim tab. With the tab straight there is no deflection of the water so there is no compensation. If you move the trim tab so the rear of the tab is favoring your right then there is a left hand compensation much like a rudder. The more you move it to the right the more the compensation.

The reason you have to do this on outboards is due to the torque of the engine. I don't have a I/O so I don't know if it matters as much to them.

Hope this helps.

Durwood

 

[trendsetter240]

Re: Boat turns rt. now, ? skeg adjustment

I love these trim tab questions, it always boggles people's mind to try and justify why you turn the skeg in the direction it pulls. But yes, this is what you do. Great visual example by turbinedoctor

Expedia, I bet the mechanic forgot to mark the position of the trim tab when he changed the impeller. There is a nut underneath the trim tab that has to be removed to drop the leg. If you don't mark the position before you take it off then you are back to square one.

 

[turbinedoctor]

Re: Boat turns rt. now, ? skeg adjustment

I love these trim tab questions, it always boggles people's mind to try and justify why you turn the skeg in the direction it pulls. But yes, this is what you do. Great visual example by turbinedoctor

Expedia, I bet the mechanic forgot to mark the position of the trim tab when he changed the impeller. There is a nut underneath the trim tab that has to be removed to drop the leg. If you don't mark the position before you take it off then you are back to square one.

Thanks Trendsetter.

I thought about that nut earlier but forgot to mention it. Thanks for pointing that out to Expidia. Should help answer a question or two for him.

Durwood

 

[Dunaruna]

Re: Boat turns rt. now, ? skeg adjustment

The reason it is often misunderstood is because the adjustable rudder/tab affects the motor, not the boat.

If you turn the trailing edge of a boat rudder to the right, the boat turns right.

If you turn the trailing edge of the outboard tab to the right, the motor turns left which causes the boat to turn left.

Now look at this backwards -
The boat is wandering to the right so to compensate you want the motor to turn left. To get the motor to turn left, turn the tab to the right.

Clear as mud.

 

[turbinedoctor]

Re: Boat turns rt. now, ? skeg adjustment

That's a great follow up to the above mentioned. Thanks.

Durwood

 

[Expidia]

Re: Boat turns rt. now, ? skeg adjustment

Thx for all those quick replies.

I had mentioned in my first post that maybe the mechanic tightened it down to the right cause that's where it was.

It does not have that much travel in either direction anyway. It's not stuck. I can feel it hit it's stop in either direction. The bolt is on the top of the cav plate.

I know it makes sense if the boat is steering to the right, then the skeg should be moved towards the right to compensate for steering right. I think of it as a little rudder.

But what threw me was when we got home it already was tightened down to the right.
When we first got the boat that skeg's bolt was loose and the skeg was just flappin around.

So I took it out myself with a wrench and adjusted it last season and had it steering perfect. But I couldn't remember which way I adjusted it because I seem to think it was opposite to correct it because I had to do it twice where I would have started off with it on the right.

I thought I'd ask here because maybe it had more to do with correcting the boat's steering as to the rotation of the prop.

I asked because I did not want to drive 40 miles round trip to test it in the water. It's not my boat! You can't test it in a tank for this.

As another poster has said . . . if that skeg was to the right than I have other issues.
Last season it ran perfectly straight after I adjusted it (I should have marked it). I did not make any changes since last season but the Mechanic may have changed the position of the tilt pin?

When we were doing about 20 mph I looked backv and there was a slow trip coming down from the top of the transom under the splash catcher. That catcher does not leak it was dripping down from the wood under the aluminum that caps off the wood in the transom.

So I looked back at the spray off the O/B and it was very heavy spraying forward against the transom probably getting through some accessory holes or the bolts holding the o/b on the boat. I moved the tilt pin towards the transom one hole. It was around the middle of the 5 holes before I did this. The dripping stopped. Boat handled OK after I moved the tilt pin but I was not driving on the way out. I took over on the way back and noticed it was pulling to the right. In the center hole it may not have been pulling but it was dripping. There was 3 inches of water in the bilge before we turned the pump on. But that might have been from cleaning and hosing down all the rugs a few days ago and water probably was puddling in between the ribs and was being blown back at 20 mph.

I know what the issue is going to be just because of all that spray. I know it's going to be that the O/B was installed too low by the dealer.

I'm going into the garage and take some pics.

Update: Sad, it's exactly what I thought it was going to be:

This is is where I brought it home after pulling pin in closer to transom, leaked stop but still heavy back spray against transom.

Th

Pin moved back to center hole position where we used it last year:

Straight edge held under cav plate:

There is about a 4 inch space there from the bottom of the boat . No holes to change though. It's a clamp on top resting on the transom. Two small bolts outside at bottom of bracket.

I don't want to raise it and find we have less control but I'll have to take the two bolts out and bring different sizes of wood pieces down to the river and place them under the clamp to move it up so the cav plate closer to even with the bottom of the boat. While Im test running it without those bolts in place though if I go in reverse to hard it could be bye bye O/B

I had to move my own O/B up a hole to cut out the back spray when I bought it. It's amazing how little these dealers know or put inept mechanics when mounting O/B's to a new rig. This one is 11 years old. My 2007 was mounted off too so it looks like as the years pass things don't get any better.

Looks to me that they just hung the clamp over the transom and bolted it down. Or the dealer thought the cav plate was those two upper fins because one of those fins is even with the bottom of the boat.

It's a 20 inch transom, but that O/B hanging that low might mean the O/B is a long length model.

Oipinions welcome before I start drill'in holes in my Daughter's boat?

Update: Damn, I checked checked the O/B's model plate. Says 1999 25 EL

That's the problem, I'm sure that EL stands for extra long! The transom measures 20 inches.

Other choice now is to find a reducing the shaft type kit or a used lower medium length unit.

I might just say screw it and get her an adjustable jack plate? I already invested $700 into it for new carb and impeller and it runs excellent.

I might try and talk her into trading it on Craigslist and getting a 25 4 stroke new or used. I don't like the idea of cranking this EL up too high and maybe throwing off the center of gravity on this small 14.5 foot aluminum.

I can't believe I missed this EL mounted on this boat. She bought it off Craigslist and sent me down to CT to pick it up last season for her. I was so excited at the conditon this 11 year old boat when I saw it that I missed the fact that it had an EL shaft O/B on it.

I figured if the O/B was not great, the boat was still perfect and we could sell the o/b on CL and get her a 4 stroke. I wish I knew it was an EL before I invested the $700 into it.

 

[Expidia]

Re: Boat turns rt. now, ? skeg adjustment

Uppdate: Geez, another fly in the ointment!
I called my dealer and he looked up the ser # of the o/b.
EL does not stand for extra length. The E part means electric start.

It is a 20 inch shaft (without measuring I thought it was a 25 inch). I'll have to take another look at the back of the boat when I get home. I think the transom might have a cutout section where the clamp goes on. I might be losing 2 inches there.

I certainly don't like how low that shaft is because not only is it dragging in the water and causing spray, she will only wind up damaging the lower unit in shallow waters at some point. It doesn't have a shallow drive position like my 9.9 stroke has.

I asked him to quote me on a new Merc 4 stroke with poer trim and off the cuff he said in the $4400 range (Yikes). I'd love to replace it because it also does not have power trim which is bad for her too. She's small and it's a pain for her to pull this motor up. Adding oil is a pain too. I know there are leverage arms to lift an o/b I might buy her one of those. When I see the bottom coming up fast on my rig I love just pushing the button and raising the o/b.

Either way, for now, a cheap jack plate might be the best way to go rather than start moving it up and drilling holes. I worry about the efects of the jack plates set back and if that will have a negative effect on this small aluminum. I figure, if we dont like the way it handles as it needs to be 4 inches higher. I can always return or resell the jack plate if it does not work out.

Still would like some feedback or opinions on why that 20 inch leg sits so low if it is the correct model for this boat.

Thx

 

[Expidia]

Re: Boat turns rt. now, ? skeg adjustment

Follow up: Here is what a "Poor Man's" jack plate looks like:

I started by going to a local metal shop with a piece of wood the I formed to fit the space after removing the two bolts, loosened the clamps up and raised the o/b to the top of the transom. Cost me $26 for them to cut a piece of aluminum stock.

Next I sanded it clean and drilled a hole at each end, to keep it from sliding and counter sinked the holes. Squirted some 4200 sealer into the hole and screwed in two oval head stainless sheet metal screws.

You can see in this shot where the clamps are now 1 1/2 inches higher.

The cavitation plate is pretty close to being even now:

But too windy to test drive it today.