Trim Rite

[Eubie]

I bought an '87 17' Cobalt bow rider a few weeks ago from a yard sale believe it or not. It's got a Mercruiser 4.3 V6 175 hp. I'm usually the regular Jon Boat type of guy with a small outboard so today was my first time ever on this type of boat so go easy on me. <br /><br />I got it going around 20mph or so and noticed that it leans to the left just as it begins to plane when going straight (not turning at all with calm water). In other words the right side sits higher than the left when on plane. It's gets a little bit better when it's up around 35-40mph but you notice it. <br /><br />The guy I bought it from had trim tabs installed. These things are just plain ol Taylor Made Trim Rite tabs that you cannot adjust. I noticed when I bought it that the one on the right sits about a 1/2" lower than the other but didn't think that would make a difference since I have never had trim tabs.<br /><br />Could that 1/2" be the problem?

 

[rickdb1boat]

Re: Trim Rite

That would be the problem! Can you raise the right side or lower the left side so they are even? Better yet, if you can take them off or disable them, you will know right away if that's the problem. Gotta be...

 

[Eubie]

Re: Trim Rite

Whew, I was hoping it was something this simple and not something like my whole engine was sitting crooked or something. <br /><br />The tabs are screwed in so I guess the only way to find out would be to move the right one up or just remove them altogether. But I like how quickly the rear end comes up when accellerating (That's the whole idea )

 

[Jdeagro]

Re: Trim Rite

You are probably experiencing two problems. one is that the starboard trim tab is providing more lift because it is deployed more, and two the prop torque may be causing a list as well. Do you have a hydrofoil on the outdrive? <br /><br />In any case the very least you should do is make sure the tabs are the same on each side of the boat. I do not think these are available any longer, and if they do not have the same arc it means that one have taken set more than the other. This will make it difficult to adjust them equal. <br /><br />If the boat is prone to a torque list then a hydrofoil will likely exagerate the list as will cupped props. <br /><br />I suggest that you remove them, even if it is temporary (put the screws back in the holes just for a test run) and see how the boat runs. If you have a hydrofoil remove it as well. The boat wqill not plane as easily, but you will be able to determine what is causing the list.<br /><br />If the boat runs correctly, you have two choices, put the trim tabs back on but even on both sides ( the bottom of the tabs should be at least 1/2" up from the bottom edge of the transom). Secondly, try Smart Tabs, even if the list continues without the taylor tabs or other devices.<br /><br />Smart Tabs can be adjusted to eliminate the list.<br /><br />One last note: If the taylor tabs lift the boat too much when cruising, this bow down attitude can cause a list on a boat that is sensitive to a torque list. In other words even if the taylor tabs are the same on both sides the list may continue.

 

[Eubie]

Re: Trim Rite

Yes, I have a hydrofoil and was wondering if that could be it also. <br /><br />I was going to run down to the local boat store and look for something to plug the old holes once I move the starboard tab up a bit. What is a good hole plugger? Also, what is a good adhesive for when I put the screws in the new holes? It's some sort of silicone I think?<br /><br />Thanks for the replies....I've learned so much from the iboats forums.

 

[olgeezer]

Re: Trim Rite

Hey, Nautijohn, <br />I just put some Smart Tabs on my boat and I can't wait to try them out! They are very well made and easy to install. I had a "Happy Troller" on my outboard to slow me down for fishing and I liked the "quieting" effect it had on the boat but I couldn't steer it with the plate down. The lake I fish on is very rough so I am thinking the Smart Tabs will help keep the bow down and also slow me down a little bit more for trolling.

 

[Jdeagro]

Re: Trim Rite

Olgeezer;<br /><br />I am happy to hear you like the quality of the Smart Tabs. As for slowing your boat down for trolling it may not be noticable, however the steering will improve greatly. The boat will track much better at slow speeds, which will help when fishing.<br /><br />Let us know how they work once you get out on the water.

 

[Jdeagro]

Re: Trim Rite

Eubie;<br /><br />As most people know I am not a fan of hydrofoils, simply because they can cause more handling problems than they cure. To be fair you should also know I have a proprietary interest in Smart Tabs.<br /><br />Hydrofoils can be very effective at providing lift at high speeds, however this is not what your looking ofr. You want lift at slow speeds to help the boat plane easier. At Slow speeds the hydrofoils will seem to help but this is marginal by comparison to Trim Tabs, simply because of the amount of additional surface area. Smart Tabs provide significantly more surface area and are deployed to cup the water during acceleration. When cruising they are up or horizontal. <br /><br />Hrydrofoils (since they are rigid) continue to lift the stern more and more as the boat goes faster. This causes a bow down attitude when cruising. If the boat has a tendency to list to port, they will exagerate the problem. If the hydrofoil runs below water level at crusing speeds, then you have even more potential for handling problems. <br /><br />The hydrofoil s have been in the market for more than 20 years, and not one motor manufacturer has adopted the idea of redesigning the anti ventalation plate( cavitation plate) to increase the lift with a larger surface. They know that the dinamics of hydrofoils is tricky, and that you should not lift the boat by the motor, that job belongs to the boat hull.<br /><br />Lifting a V bottom boat from the center ( motor) will likely cause a "teeter totter" effect especialy in turns.<br /><br />My advice? You already have two extra lifting devices on your stern, plastic trim tabs, and a hydrofoil. You have handling problems, that are driving you to look for more help. Get rid of the foil, get rid of the plastic tabs, and see what the boat does. Then, move to Trim Tabs. For a performance guaranty (to your satisfaction) get Smart Tabs ST1290-60. Fix it once, and enoy the boat. <br /><br />Fill the holes with 3M 5200. <br /><br />For more info contact www.nauticusinc.com

 

[Hooty]

Re: Trim Rite

Must be a V bottom boat. It wants to fall off the V and on to the flat part of the bottom. Trim tabs should help, so will a little negative trim.<br /><br />c/6<br />Hooty

 

[Eubie]

Re: Trim Rite

Thanks for all of the responses. <br /><br />I moved the right trim rite tab up about a 1/2" and now they match practically perfect. I took it out today and the damn thing raised up like crazy on the right. I got so pissed I almost turned around and went to a boat dealer and traded it in. haha. <br /><br />But, this is when I trim the lower unit ALL the way down so I experimented with trimming it up a bit. I have a trim needle on my dash so I trimmed it between a 1/4 and 1/2 from the DOWN position and wouldn't you know it. It ran perfectly. No leaning anywhere and the turns were so much better. Before with it trimmed all the way down the handling was really crappy at high speeds. <br /><br />So now I won't worry about it so much.<br /><br />Also, I filled the old holes with wood dowels coated with Marine-Tex and resessed the dowls a bit and filled the 1/4" with Marine-Tex. I wasn't quite sure if I could use the 5200 I had.

 

[richg99]

Re: Trim Rite

It would be pretty rare to run the boat with the trim all the way in, except for your initial hole shot. Sounds like it was trimmed in too far and you had a "bow steering" probably caused by the off center tab and the too excessive trim-in. Glad it is all fixed now. RichG