Hard Pull to the Right

[79MERC1150]

Don't know if this is the correct place for this topic, but here goes. We have a 1980 Astroglass 176 bass boat with a 1979 115 Mercury outboard. My father bought the boat new as a birthday present for my Mom. That's what she asked for. When my mom passed away in 1994, I bought the boat from Dad, so I know its history back to day one. The boat is mostly a garage decoration, and has low hours on it. From the beginning the boat has suffered a hard pull to the right. The dealer was unable to correct it, and sereral repair shops have attempted to fix the problem over the past 30 years, without success.

The pull is severe when the boat is under power and first planing off. At 25 to 32 MPH, the pull is significant, and gives weaker drivers a workout. At full throttle, between 54 and 56 MPH, depending on the wind direction, the pull diminishes some. The boat has a deep V stepped hull design, and does not pop up on the last step until 45 MPH and above. At speeds of 45 MPH, and above the boat is riding on the last step, and the bow tilts forward, down towards the water.

The trim tab has been set in every possible position, and makes little to no difference. The engine has a long tail shaft, and sits 2 inches off of the floor when parked, however the cavitation plate is two inches above the bottom of the hull. I have played with the tilt/trim in every possible position, and can make the boat stand on its bow, or on its stern, however the pull remains. Nothing is bent or broken, and the problem has been there since brand new.

We have kept the old girl in the family, mostly because all of the kids, and my siblings, and my Dad are emotionally attached to it, kind of like a favorite family pet. Lately the grandchildren, there are 11, are starting to get interested in sking, kneeboarding, and tubing, and some of the kids like to fish, so Granny's old boat is getting more use these days.

Is there a good fix for this problem, without taking the boat all apart and reconfiguring everything, or is it a design issue, that will haunt this beast until the end?

Thanks for any feedback.
Charles

 

[79MERC1150]

Re: Hard Pull to the Right

The main question is if putting the lower unit deeper into the water will help fix the pulling problem, so that the cavitation plate is below the hull, and is there an extention availble for my engine that will extend the lower unit? There does not seem to be any way to lower the engine on the transom, and the powerhead would be too close to the water surface if the engine were lowered.

Thanks in advance,
Charles

 

[Bob_VT]

Re: Hard Pull to the Right

Try dropping the motor a notch on the transom if it is set that high. I raised a 115 up for more speed and could not make a left turn at all and had to fight the wheel...... dropped it a notch and evertthing went fine.

got a picture of the transom where the engine is mounted...... is it set at it's lower height...... no room on the top of the transom?

 

[79MERC1150]

Re: Hard Pull to the Right

Thanks. The engine mount does not appear to have any adjustment for height. The mount is bolted with four through bolts which are drilled through the transom, and two clamp bolts at the top that sandwich the transom between the mount and the bolts. Unless the transom were cut down some, I don't believe that there is a way to lower the engine into the water.

A local dealer suggested finding a junk motor on E-bay that has a longer shaft then mine does and tranfering the lower unit to my engine. He said that the Mercury's of that vintage that were used on pontoon boats were available with a longer shaft lower unit. They are not sure if lowering the engine will correct the problem, but if I am willing to buy the parts and pay for the labor, they put it together and we can give it a try.

Charles

 

[Bifflefan]

Re: Hard Pull to the Right

Read this

http://forums.iboats.com/showthread.php?t=331072

 

[79MERC1150]

Re: Hard Pull to the Right

Thanks, I took a look at that tread. We will be on the water again in a couple of weeks. I will take a socket and try different settings with the trim tab. We'll see how it turns out. Several mechanics have adjusted it over the years, but none have water tested it afterwards, so it probably just needs some fine tuning to get it right.
Charles

 

[79MERC1150]

Re: Hard Pull to the Right

We got back on the water yesterday. I moved the trim tab in small increments, noticing that the further to the right it was moved the less the right side pull is. Once the trim tab was set in the farthest right hand position, the pull was diminished to a slight drift to the right. Now the steering will drift right and the boat makes a large right hand circle. I guess that I had better get the engine safety kill switch fixed, just in case ever I fall overboard.

Looking closely at the engine, there is no was to move the engine up or down on the transom. The engine mounts with four through bolts, and two clamps at the top that fit over the top of the transom, and the clamp bolts compress the transom against the engine mount. Short of a jack plate, there does not seem to be any way to adjust the engine. I have been looking at a CMC power jack plate, and wondering if this would make the boat drive better, by pushing the engine farther back and lower in the water.

AS old as the boat is, I wonder if a jack plate would put more stress on the transom, and possibably cause a transom failure in the future. Everything is solid right now.

The boat planes faster and runs more level at all speeds with the tilt/trim all the way down. Any adjustments up, and the bow lifts up in the air, however the boat runs pretty flat with the trim down.

Looking at the design of the boat, I think that this right hand pull is a result of the weight distribution on the boat. The driver's seat is far right, and the passenger's seat is close to the middle. The weight of the console, the driver, and the batteries are all on the right, and while I weigh 230 lbs, my wife weighs 100 lbs.

I put all of our gear on the left side of the boat, and the right side pull, now drift almost went away.

Any suggestions are appreciated.

Charles