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Discussion Starter · #1 ·
Hey folks,
when washing down my boat after the trip on Sunday, one of my HOs noticed that the fin that counteracts prop thrust on my outboard is missing - there's just a big bolt and a hole where it used to be. A couple questions:

1) what is that thing called - because I assume I need to get a new one.

2) I can't imagine how it could have accidentally fallen off or otherwise been taken off the motor unless SOMEONE actually did it. I always rinse my motor thoroughly and think I would have noticed if it was loose enough to be in danger of falling off. I'm worried it was stolen off my motor by someone who needed a new one. That would have had to happen either in the locked parking lot at stingrays (where I'm currently storing it) or in the parking lot of Kiptopeke Inn, where it was parked overnight from thursday until sunday this past week.
 

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Its a sacrificial zinc. it helps to keep the rest of the metal on your motor from corroding.
Of course Yamahas are the most expensive(about 45.00). I replace mine every year.
I doubt it was stolen but who knows. It may have vibrated loose.

Jeff
 

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Called a Tab-Trim (by yamaha) They are Zinc ( not Skip of course)and do corrode and may have correded off or stolen. Since my engine is out of the water when not running I have not had to replace mine in >3 years. The corrosion usually starts at the bottom and mores up but they often corrode aroung the screw also. Heck it might have been stolen, but they do fall off at times.

Jim
 

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Sacrificial anode or trim tab is what I call it. Sometimes the bolt that holds them on vibrates loose. I check mine by hand when I'm back there because I found it loose once. Mine is almost 6 yrs old but I need a new one this year. If your boat stays in the water they corrode faster of course. My boat is on a trailer.
 

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Discussion Starter · #7 ·
Thanks guys. Glad to know they can fall off, but sounds also like there might be some demand for a relatively new one. Also glad I know what to order :)
 

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I would be surprised if someone swiped it, but I guess you never know. I had mine come off last year on my Optimax. Not that hard for it to vibrate loose and it's something you never really think to check.
 

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Just a stoooopid question, I'm sure. Josh said he just had the bolt hole and giant bolt remaining. Can they corrode and fall off leaving the bolt? Sounds to me like some "Good Samaritan" was kind enough to put his bolt back. Probably just me, the skeptic.
 

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Just a stoooopid question, I'm sure. Josh said he just had the bolt hole and giant bolt remaining. Can they corrode and fall off leaving the bolt? Sounds to me like some "Good Samaritan" was kind enough to put his bolt back. Probably just me, the skeptic.
Mine did. Not sure about the Yammy but on an Optimax the bolt sits is recessed into a hole about 2.5" deep with a cap over it. Pretty hard for it to fall out.
 

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To remove it- you must take off a plastic cap - then use a deep socket or socket with an extender.Often the zinc will break when taking them off , after they have been on for awhile.

Very,very unlikely a thief would take one and then put the plastic cover back on.Check your bolt threads- there might be some zinc part left from it breaking off.

As you saw - you do not need it for the engine to work and leaving it off one trip does not hurt anything.You might notice the steering is stiff on turns at high speed.The zinc helps offset the pull of the prop.
 

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Discussion Starter · #19 ·
Thanks all - I'm more pursuaded it just fell off. A drop of lock tight will go on it when the new one arrives. And thanks skip for the install directions, because I was quite sure that plastic cap had to come off, but afraid to pry at it without knowing. Skip - how does the plastic cap come off?

As mentioned above, I do not think it came off when I ran aground on a sand bar. We were coming off plane and I was trimming the motor up before we hit bottom, and I did not have any prop or other damage so I do not think I could have damaged the zink that is above the prop.
 

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Last week at the CBBT I noticed that ours was loose on the 225F. I could not tighten it as, I believe, it requires a Metric socket. FYI, you will also need a socket extension to get to the bolt head.

Good luck.

GT
 
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