Which way should that little tab point?

[stevens]

Hi guys,<br /><br />I recently swapped propellers and had to take off the little trim tab above.<br /><br />Now the boat leans more to the left than before, especially when accellerating.<br /><br />It's an Alpha drive with a regular RH turning Ballistic (soon to be Turbo) prop.<br /><br />I am thinking I'll put a different tab back on, but which way should I point it? As a rudder pointing left (as in making a right hand turn), or pointing right (left hand turn)?<br /><br /><br />

 

[cuzner]

Re: Which way should that little tab point?

You should point it slightly in the opposite direction your boat is pulling. You may have to adjust it a bit till you get it right.<br /><br /> Jim

 

[Dunaruna]

Re: Which way should that little tab point?

You point the trailing edge TOWARDS the pull. If it's pulling left, Turn the trailing edge towards the left.<br /><br />Aldo

 

[stevens]

Re: Which way should that little tab point?

Thanks, but that is the point. I haven't noticed any particular sideways pull. If anything, it pulls to the right at slow speed, but that could equally well just be the wind. At higher speeds I think maybe there's a tendency to veer left. I then compensate by turning the wheel slightly to the right.<br /><br />The main problem is that the boat simply leans to the left and even more so when I accellerate.<br /><br />Which way do these tabs usually point when used with a regular RH prop?

 

[Dunaruna]

Re: Which way should that little tab point?

Every boat/prop combination is different, there is no hard and fast rule. <br /><br />My rudder is pointing straight ahead.<br /><br />I read your other thread, my suggestion is - plan to get wet. You will probably need to do some trial and error adjustments on both the tabs and the fin.<br /><br />Aldo

 

[stevens]

Re: Which way should that little tab point?

Thanks - the water is still only about 14 degrees Celsius. I was hoping to avoid the getting wet part....<br /><br />I guess I'll just have to check some more before deciding how it should be angled, or put the tab on straight and see how it goes.<br /><br />By the way, I just ordered the tab from the local shop, a long-time licenced Mercruiser dealer. Would you believe they had never sold any such tab before? They usually just used a saw on the standard tab or put on a flat one.<br /><br />The guy even sounded surprised there was a tab for raked-back props, and was only convinced when I gave him the parts number 822777Q1/A1 and he found it in his ordering system.

 

[QC]

Re: Which way should that little tab point?

I don't think the "lean" is from the trim tab. I think it is from the propeller design and you are just experiencing more torque effect in the opposite direction of the prop spin. I beleive that little trim-tab is to assist with hard (or unsafe) steeering torque, not propeller torque specifically. If I recall, you have hydraulic steering, right? If steering is not hard to control in either direction, I would still forget the trim tab. My .02 . . .<br /><br />BTW, this is when SmartTabs fail IMHO. If you had adjustable tabs, you could simply adjust for the lean and have some fun . . .

 

[stevens]

Re: Which way should that little tab point?

Yes, still hydraulic power steering that feels the same in both directions. Just a leaning boat, for a number of reasons.<br /><br />Yes, I see the benefits of adjustable tabs in this situation. However, I am hoping to address the problem once and for all and be done with it...

 

[QC]

Re: Which way should that little tab point?

Get a duo-prop . . . that'll fix it <br /><br />My boat exhibits a variety of listing conditions depending on RPM and trim tab position. If I am pushing on the throttle pretty hard for a short burst and then back off, she'll list to the starboard side pretty hard and pretty quickly until she starts to fall of plane. I have just learned to anticipate that stuff to the point where my corrections are fairly automatic.

 

[stevens]

Re: Which way should that little tab point?

Every boat/prop combination is different, there is no hard and fast rule. <br />

Is this really true? I would think that RH props would tend to produce torque (and list/drift)in one direction, and LH in the other? Wouldn't that also mean that the little trim tab would usually also be set towards the same side for the same rotation direction?<br /><br />Please, someone tell me it is so, and maybe you'll save me from swimming in this freezing cold water with a wrench between my teeth.

 

[Solittle]

Re: Which way should that little tab point?

Stevens - Get out your wet suit unless you can put it stern in to a beach or dock. It is a trial and error thing. It would be best to have the typical load on board when you do it.

 

[Dyna]

Re: Which way should that little tab point?

Is that trim tab a pain to adjust or replace? I have an 83 mercruiser I/O & the bottom of mine is broken off. The boat pulls slightly to the left. Would replacing it cure this?

 

[stevens]

Re: Which way should that little tab point?

No, it is fastened with just the one bolt you see in the picture, so replacing it should be a breeze (unless you have to swim to do it).<br /><br />If the boat pulls to the side, that tab is there to fix exactly that. At $12, it must be one of the cheapest replacement parts for the boat.<br /><br />I always thought this was a sacrifical zinc anode, but all the trim tabs listed at mercurypartsexpress.com are made from aluminum. If so, why do we change it every year?<br /><br />See:<br /><br /> http://www.mercurypartsexpress.com/...OneKey=74&key=10050&level=3&store=Accessories

 

[Dunaruna]

Re: Which way should that little tab point?

Stevens, they often serve two purposes, a rudder tab AND an anode. Aluminium is sacraficial (it's not very noble ).<br /><br /> http://www.protroll.com/blkbox8.html <br /><br />Aldo

 

[stevens]

Re: Which way should that little tab point?

Yes, you are of course right. But, isn't the outdrive itself, and very often the propeller, made from aluminum too? Apart from being painted, wouldn't these parts then corrode just as quickly as that trim tab anode? I don't see the point of an aluminum anode sitting on an aluminum drive, but I may be missing something here.<br /><br />Thanks for the link, by the way. I have never heard of an electronic fish attractor before. Do they really work? On any particular type of fish?<br /><br />Edit: follow-up in this post:<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=012718

 

[Dunaruna]

Re: Which way should that little tab point?

Well, a lot of fins are zinc but some are alloy. Here's where it gets interesting, not all aluminium is the same. Each manufacturer has their own perculiar blend - AKA, composite alloy. same with props. This means that the sacraficial anode (and/or fin) needs to match the outdrive and prop otherwise the wrong part of your boat gets sacraficed.<br /><br />If your fin is being eaten away over time, that's probably a good thing. It's protecting the prop and outdrive.<br /><br />As for the fish attractor, I heard they work with salmon. <br /><br />I find the subject very interesting, who would have thought that an out of balance sacraficial system could repel fish.<br /><br />Aldo