[Rdrdon]

On my 1996 Shabah 5.7L Alpha One, I'm replacing my trim tab anode because I saw that it doesn't have a "fin" that sticks down, I assumed it had eroded or was knocked off in one of my many escapades of trimming the submerged trees in Lay Lake. Besides, I needed something to do with the boat until it gets warm enough to put it in the water, right?
Once I got it off, it looks like it was made that way, flat, no fin, but all the manuals & parts lists show the fin type. The guy who had the boat says it always had the flat one.

I'm confused, is it supposed to have the fin, or flat? What's the difference?

[lomitabob]

The important part is the zinc which is sacrificial and helps protect the matallic parts of the drive from corrosion. The fins can be used to help straighten out a drive if it tends to push to one side when underway by turning it to one side like a rudder. It is like a trim tab for the outdrive. If you can cruise in a straight line without correcting then you do not need the fin.

[Rdrdon]

Maybe it will help, then. My boat tends to "walk" side to side, especially at slower speeds. I have a hydrofoil which seems to help get up on plane, but I'm considering trim tabs, the problem is where to put them. The Shabah doesn't seem to have a lot of room on the outer part of the stern, and it's not really flat on the bottom.

[lomitabob]

Do a search for "smart tabs" There is a lengthy discussion about the different options available

[AirNavy]

The anode you are talking about isn't supposed to have a tab on it on an Alpha One. If you look closely, you'll see that there is no room for a tab as the prop would hit it.

[Rdrdon]

Actually I put it on & it has less than 1/4" of clearance, not sure what will happen if the prop flexes, though it would seem that it would only flex axially and not longitudinally. Should I take it back off?

[AirNavy]

I'm in no way qualified to tell you what to do with your boat, but I know I wouldn't feel comfortable with a clearance of less than 1/2" on mine. There is a lot of "slop" built into the drive so the propshaft and everything attached can wiggle around quite a bit. Another option to consider if you are trying to correct for some of the prop walk at slow speed would be to look at adding trim tabs to your hydrofoil. I currently have a hydrofoil as well (no tabs added), but as soon as I can figure where to mount some Smart Tabs without having to relocate all of the stuff on my transom, the hydrofoil will go away.

[jgreen]

Hi guys, if I can throw my .02 in, I had the same question on my old Sea Ray with Alpha drive. The dealer told me that they didn't use the finned part on any drive with power steering. Does that make sense?

[jeffryb]

When I bought my Mariah it came with a quicksilver alum. 19p prop with a trim tab. I bought a SS prop 21p last year and it recommended a new anode and it has no tab, so probaly depends on what size prop and pitch. I switch props of and on and I use the diff. tabs for each prop and the boat handles just fine with each one. Hope maybe this Help's.

[Rdrdon]

I've been told by a couple of "boat" people now that it's not needed if you have power steering, but it can't hurt anything.