Filing cutting Trim anode fin Mercruiser MC1

Hello All,

Quick Question:

Have a Merusier 120 coupled to an MC1 outdirve. just got a turningpoint 4 blade 19 pitch prop and it doesn't clear the trim tab/anode. Can I file/cut the fin and not cause havoc in the boats handling?
Great lakes fresh water/trailered boat.

Hull is a a 16'9" modified v bow rider (1981 Four winns marquios 170).

thanks

Re: Filing cutting Trim anode fin Mercruiser MC1

merc120_81 said:

Hello All,

Quick Question:

Have a Merusier 120 coupled to an MC1 outdirve. just got a turningpoint 4 blade 19 pitch prop and it doesn't clear the trim tab/anode. Can I file/cut the fin and not cause havoc in the boats handling?
Great lakes fresh water/trailered boat.

Hull is a a 16'9" modified v bow rider (1981 Four winns marquios 170).

thanks

Click to expand...

Howdy,

That trim-tab is adjusted to prevent torque steering at a particular (or desired cruising) speed. Making it smaller would just make it a little less effective, requiring a slight adjustment.

I don't think it would make a huge difference unless you cut a LOT off. (which might make it "stall" and not work at all.)

You could also take the prop to a prop shop and have them slightly reduce the diameter.

I suspect that a much larger (diameter) prop will reduce your top speed significantly due to the additional drag and blade area.

You don't have a huge amount of excess HP to play with....

What pitch/dia prop do you have on it right now?

Re: Filing cutting Trim anode fin Mercruiser MC1

Yes, if it is just a little bit that you need for clearance, then probably OK to file/cut. You may also want to see if there is an 'offset' tab available for your ourdrive. Typically, those are needed for the 'high rake' props.

Re: Filing cutting Trim anode fin Mercruiser MC1

I did the exact same thing when I put my Turning Point prop on. I had to cut about 1/4 of it back to get the clearance I needed. It did not make one bit of difference in handling in my case. The only reason I did it was because I was impatient though, I agree with tpenfield, if you have the time to wait I would get the offset tab or merc. also make a completely flat one as well.

Re: Filing cutting Trim anode fin Mercruiser MC1

I had a michigan wheel 14.75" 21 Pitch on the boat before. I don't really care too much about top speed. I actually care about two things, going slow to troll and yanking my kids around the lake on tube, knee boards, or wake board.

I always had the tab set to streight inline before, and don't recall torque steer beeing an issue, perhaps because the tab was doing its job.....

Thanks, all, I am looking to aqquire the offset tab. Does anyone know, if MC1 aplha1 M MR annodes are completely interchangale, (same size bolt, and hole they go in to?

Re: Filing cutting Trim anode fin Mercruiser MC1

sweet addication: Where you happy with the turningpoint and what was your previous prop?

Re: Filing cutting Trim anode fin Mercruiser MC1

merc120_81 said:

I had a michigan wheel 14.75" 21 Pitch on the boat before. I don't really care too much about top speed.

Click to expand...

The offset tab (if you can find one) or trimming will probably do the job.

You do need to consider what your engine will turn at full throttle. All engine manufacturers suggest selecting a prop that will give you an RPM either in the WOT "range" or at the top of the range. I think the 120 (2.5L) was rated at 3900-4300 RPM

If you were turning in the lower part of the recommended range with the 21p prop you have now and you still probably can get a WOT (wide-open-throttle) RPM in the recommended range, then the 4 blade 19p prop will work well. It will be a tad slower but you should get a markedly better hole-shot.

Re: Filing cutting Trim anode fin Mercruiser MC1

merc120_81 said:

sweet addication: Where you happy with the turningpoint and what was your previous prop?

Click to expand...

I am very happy with my Turning Point prop. I went with a 14.25 X 23 stainless, the prop it replaced was a 14.25 X 21 aluminum.

Re: Filing cutting Trim anode fin Mercruiser MC1

merc120_81 said:

Does anyone know, if MC1 aplha1 M MR annodes are completely interchangale, (same size bolt, and hole they go in to?

Click to expand...

yes

the offset, or h.p. trim tab anode should be available at any merc dealer

if your engine is equpped with power steering the position of the tab will have very little to do with steering torque