[Daz (Taylor Maid)]

:wave:

Hi, I'm new to the forums, but been a boat owner for 18 months.

I have a quicksilver 640 and have noticed that when cruising in a straight line on flat seas, it tends to wander to the right every so often. Does anyone know why this might be? It will stay in a straight line for 300 yards or so and then just start turning to the right.

I am thinking it could be air in the hydraulic steering and the problem gets worse at higher speeds. I have tried moving things about on the boat for balance, but to no avail.

I hope someone can shed some light on this as I am finding it extremely frustrating.

 

[maverick]

It could be due to prop torque. As the prop turns in one direction it will have a tendency to turn the boat. There is a way to compensate for this by adjusting the little rudder type thingy on the bottom of the outboards cavitation plate. If you do adjust this only do it a little at a time as a small amount of adjustment can make a big difference.

Someone will probably be along with a more descriptive answer

Or you could fit an autopilot :idea: more toys to play with :blink:

Martin

 

[Daz (Taylor Maid)]

Maverick - Thanks for the quick reply. I did wonder if it could be prop torque, but still cannot work out why it will stay straight for a while and then just suddenly start turning. Some days seem to be worse than others.

When I had the boat delivered I was told it would stay straight even if I took my hands off the wheel due to hydraulic steering!!!!!

 

[Afishionado]

Well lets torque about this! Torque! Talk! Geddit? Ok I'll get me coat!

A revolving object has an affect on the item it is revolving on. A sort of twisting motion. This is called TORQUE. So with your prop whizzing round and round there is a subtle force in the opposite direction. Also there is the 'paddle wheel' affect of the prop turning horizontally to the direction of motion, so if say the prop turns clock wise (viewed from the back of the boat looking forward) there is a paddle wheel affect that pushes the stern to the left.
Either both or one of these characteristics is likely to be the cause.
To compensate for this on O/B's there is a small skeg immediately behind the prop. It is usually made from Zinc so that it acts as a corrosion protection for the engine. It is fixed by one central bolt, which when slackened off allows you to rotate the skeg like a mini rudder to correct the swing out of the stern. Or the little zinc skeg might have corroded away (ie doing it's job) and need replacing.


Also there are other factors like wave form, wind affect, and you steering one handed with a gin and tonic in the other hand 0)

 

[kveite]

I think it isn't the paddle wheel effect, this effect is the greatest at low speeds when you rev up the engine/prop. I use this effect a lot when docking old flat bottom sailing ships with leeboards.

How is the balance of your boat? When the balance is off center the boat can sway when it reaches planing speed or drops back to a displacement speed.

 

[YAZAMAAN]

hi guys had this problem with our raider , when at high speed you had to really fight with the wheel!! altered the little rudder type thing as maverick said now flat out you can let go of wheel and its virtually straight , hope this works regards steve

 

[Daz (Taylor Maid)]

Thanks for the tips guys - I will try adjusting the skeg/rudder thingy. I also have to fight the wheel at high speeds Yazamaan, so it looks like it could well be the same thing. How much did you adjust it by??

The balance of the boat does not seem to bad as she sits pretty level in the water.

 

[Salar]

Try adjusting tilt as well. This can affect stability, and if it leans to one side on the plane it can veer. I had a similar problem with an Alaska, which was cured by adjusting fore-and-aft tilt.

 

[gibberfish]

Incorrect trim can cause your problem (chine riding?), as can poor adjustment of the engines trim fin. One other thing to consider is do you have any mounting brackets or plates hanging down off the transom? Even a badly mounted transducer can cause a boat to heel at speed.

 

[TomBettle]

I agree with gibberfish in as much as anything, no matter how small, will cause a surprising amount of drag and act as a mini trim tab or rudder (hence the tiny little one attached to the outboard)

 

[YAZAMAAN]

hi daz kept adjusting a notch and trying till we got it right it certainly made all the difference to our boat, hope it works for you nothing to lose by trying it can soon be put back to where it was regards steve
p.s let us know how you get on

 

[oakley_ten]

I reckon you have one leg shorter than the other, so you need to lean a bit the other way - that'll sort it!