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Capt-Rum

Tracking fins

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Capt-Rum

Question, the fins on my 08 are not straight? Are they supposed to be? I climbed under the boat for the first time and saw this. What's up.

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radioman

I have had 3 BU's in the last three years . none of them have been in line, must not matter

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bsoss

Maybe it's by desing. I would think that they may straighten out under load, thus keeping tension? Maybe an ME on the board can comment on the the hydrodynamics of it.

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98mallybu

you mean they are mounted at a slant right? They definitely should not be bent or curved.

I've heard two theories but I'm not sure if they are true, good question for a bu' dealer

1. To oppose rudder load (rudder is mounted slightly off to the side to stay in clean water, but creates hard pull to the right)

2. To help oppose the twist the prop puts on the boat and help keep the boat level instead of leaning to the right hard

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99response

I've always thought rudder load was due to uneven pressures on either side of the rudder cased by prop wash and rudder shape, this pressure delta causes the boat to pull right. Higher fluid velocities on the starboard side of the rudder cause lower pressure (remember bernoulli?) and cause the rudder to turn to the right under load.

As for opposing the torque created by the prop, I dunno about that

Something can be said for keeping a "clean" fluid path to the prop (new Volvo IPS drives), maybe that tracking fin offset maintains that.

-Chris

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dmer8282

I would take them off and glue them back on straight.

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UWSkier

They're laser aligned to be that way. I'd leave them alone. I've never seen a boat with them perfectly straight. It's to help with tracking in a straight line. You can thank your slalom friends for that.

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BillFooter

If the fins are perfectly in line they will make lots of noise. Something to do with hydrodynamic harmonics.

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dalt1

I just noticed this myself last week while polishing the bottom of my 06 VLX. I was wondering the same thing. They are mounted about 1/4" towards the starboard side at the front of the fin. Both front and back fin seem to be the same.

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Capt-Rum
I would take them off and glue them back on straight.

Guess I'll leave them alone. Maybe ask the dealer.

dmer8282, I suppose you would suggest wood glue too!

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SmoothWaterMan

The tracking fins are slanted 1/8-1/4" right at the front of the fin (Aligned to the right may be a better description) to provide a more level boat to compensate for the prop rotation.

Built that way. On purpose.

Peter

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dmer8282
I would take them off and glue them back on straight.

Guess I'll leave them alone. Maybe ask the dealer.

dmer8282, I suppose you would suggest wood glue too!

Wood glue or some spray adhesive, yea.

BTW, mine or a little off too.

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