I have a trim tab off my starboard engine that I'm going to replace. Do I need to coat the threads with a antisieze or just screw the bolt on? Also wonder if you have to run them on a twin engine boat, My old fountain lighting with Bravo one drives didn't have them but it did have a tie bar between the drives. Just thinking out loud! Thanks Tom
trim tab/sacrificial anode
- Thread starter tomyoung
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journeyman
GreatGrady Captain
If you're talking about the bolt that holds the zinc to the tab, then yes, antiseize is probably a good idea.
As far as whether you need tabs vs twins... Tabs are used to adjust the attitude of the boat while running. Bow down, a list to either side etc. Adjustment of the engine(s) trim, though it may help a little with boat attitude, is used to adjust for speed and economy in different conditions
As far as whether you need tabs vs twins... Tabs are used to adjust the attitude of the boat while running. Bow down, a list to either side etc. Adjustment of the engine(s) trim, though it may help a little with boat attitude, is used to adjust for speed and economy in different conditions
I have lost my tab twice and I am confused here. It seems to me putting a dab of loctite on it is preferable and not antiseize stuff. Zinc is way softer than stainless and from my experience vibration and such just rattles that thing off.
Also its purpose as a sacraficial annode against galvonic corrosion is important. I don't see why anyone would not have it installed?
Also its purpose as a sacraficial annode against galvonic corrosion is important. I don't see why anyone would not have it installed?
SmokyMtnGrady said:
Loctite or a similar products is a good idea. There are several types, some less permanent that others ( I can't remember which color is what)
It is not a good idea to not have sacrificial anodes. There is always some electrolysis going on and in some cases, you don't see it until major damage is done.
One thing that is important is that the zincs have to make good electrical contact with whatever they are attached to. For some applications, a ground wire may be used, don't disconnect it. be carful when painting things like trim tabs and outdrives. If there is not a good electrical connection, the annode won't do its job
journeyman
GreatGrady Captain
Bob, I guess I got confused. Tom's post had "Trim Tab" as a header. I assumed he was talking about the zincs on them. I too have lost a couple of motor zincs and wound up using Loctite. They make anodes for twins with no tab as twins are counter rotating, but you're right, they are necessary.
Doc Stressor
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Torque tabs are a more appropriate name for the sacrificial elements that are located on the anti-ventilation plates of outboards and outdrives. They are there to compensate for the lateral force generated from the propeller as it drives the boat. When they are adjusted properly the steering wheel should be easy to turn in either direction. They have little effect with counter rotating twin engines except to help protect the lower unit from galvanic corrosion.
They are typically made from an aluminum alloy that is "less Noble" than the alloy used for the lower unit. The electrical connection to the lower unit is mainly through the stainless steel bold since the contact area with the anti-ventilation plate is typically painted. You need to tighten that bolt to the proper torque specs in order to have it bond correctly. Using anti-seize can cause problems because of dissimilar metal like copper in many of these products. These products are formulated for all sorts of applications. They are basically solid metal particles suspended in grease. The ones with powered aluminum, graphite, and molybdenum are safe, but vibration can cause them to loosen up and unthread over time.
I don't use any lubricant or sealing compound and I've never had a problem removing the bolt or had one fall out. If you are paranoid, I guess that you could use a little Loctite on the upper threads. This stuff is basically a type of plastic glue. It will help hold the bolt in place but it might act as an insulator if you use too much.
They are typically made from an aluminum alloy that is "less Noble" than the alloy used for the lower unit. The electrical connection to the lower unit is mainly through the stainless steel bold since the contact area with the anti-ventilation plate is typically painted. You need to tighten that bolt to the proper torque specs in order to have it bond correctly. Using anti-seize can cause problems because of dissimilar metal like copper in many of these products. These products are formulated for all sorts of applications. They are basically solid metal particles suspended in grease. The ones with powered aluminum, graphite, and molybdenum are safe, but vibration can cause them to loosen up and unthread over time.
I don't use any lubricant or sealing compound and I've never had a problem removing the bolt or had one fall out. If you are paranoid, I guess that you could use a little Loctite on the upper threads. This stuff is basically a type of plastic glue. It will help hold the bolt in place but it might act as an insulator if you use too much.
Guys, I see some of these zinc tabs come with a fin and some without. I had to trim my fin back little to install a Permatrim. With hydraulic steering is the fin of any use and when this one is used up could I go with the finless zinc tab? Cheers, trapper
Doc, the as annode touches the lower unit and that connection is unpainted right? Electrolysis occurs with dissimilar metals. So you got the bolt, the magnesium alloy of the lower unit (Yamaha) and the zinc. I am confused as to your post. Are you saying the annode function is really just between the zinc piece and the SS bolt and the motor is pretty much "neutral"? I just replaced mine and I need to look again at it. I thought the contact surface between the zinc and motor was unfinished but I could be mistaken.
As mentioned, many types of anti-seize actually contain trace amounts of metals. Don't use it as you could actually cause some corrosion. Plus, you don't want to diminish the metal-to-metal contact. A LITTLE bit of loctite is fine - with some manufacturer's, they put it on the threads to begin with.
Your Bravo drives did, indeed, have anodes under the anti-ventilation plate - but they were flat since you have power steering. With twin engines, you can certainly use the flat style.
Be wary of the anode composition you get. But it's best to find out what locals are using with a similar setup as you. DO NOT simply make a choice based on the old adage of "Salt=Zn, Fresh=Mg". In many cases, the best composition is Al.
Also be sure you're buying it from a reputable place - don't buy anodes based on cost alone. If you don't want to get Yamaha anodes (which are Al), Performance Metals makes an excellent anode.
Your Bravo drives did, indeed, have anodes under the anti-ventilation plate - but they were flat since you have power steering. With twin engines, you can certainly use the flat style.
Be wary of the anode composition you get. But it's best to find out what locals are using with a similar setup as you. DO NOT simply make a choice based on the old adage of "Salt=Zn, Fresh=Mg". In many cases, the best composition is Al.
Also be sure you're buying it from a reputable place - don't buy anodes based on cost alone. If you don't want to get Yamaha anodes (which are Al), Performance Metals makes an excellent anode.
The previous owner Mike Higgins had a extra set of anodes in the boat along with a lot other spare parts. So I will replace said part. The boat is trailered now and washed after every use. I will be watching for any galvanic action. Thanks for all the tips and Info! Tom
Fishtales
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I take a fine wire brush and hit the mating surfaces of both the zinc and mating area to ensure good contact. I've never added a lubricant nor loctite to the threads and never have had an issue removing or losing. Generally my dealer replaces them every three years. I've been doing it every two. The 'U' strap zincs at the bottom of the motor seem to get the most wear, but the fins do as well. I have twins and both have the fins. Don't forget your internal zincs. These have to be changed periodically as well.
The one that seems to need replacing every year is the thruster. Maybe because it sits 100% in the water.
I doubt your going to have a problem trailering - not to say you should not stay on top of. It is those of us in the water 100% of the season (time related) that really need them to be in top shape.
The one that seems to need replacing every year is the thruster. Maybe because it sits 100% in the water.
I doubt your going to have a problem trailering - not to say you should not stay on top of. It is those of us in the water 100% of the season (time related) that really need them to be in top shape.
If you have twin outboards and one is counter rotating, you can install finless anodes as you noted. Of course you can use finned ones too but the fin on the counter-rotating motor bends in the opposite direction.trapper said:
Parthery
GreatGrady Captain
This is an item that is worth buying the factory Yamaha one. The cost is only a little more (and on Amazon you can do well on these) but the quality is better.
I bought a couple at West...one cracked as I was putting it on and the second one broke apart after 2-3 trips.
Finally - make sure to put the rubber cap back in after you tighten the bolt. That way when it does break and you have to replace it again, you will have the bolt.
I bought a couple at West...one cracked as I was putting it on and the second one broke apart after 2-3 trips.
Finally - make sure to put the rubber cap back in after you tighten the bolt. That way when it does break and you have to replace it again, you will have the bolt.