Re: Trim Tabs
Bob in Calif.,<br /><br />Sorry for the delay, I am little busy now that everybody is getting there vessels ready for the boating season!<br /><br />Please keep in mind folks that I work for Bennett Marine and we manufacture trim tab & hatch lift systems, so I am little bias in my opinions. I have to tell you this up front, so everyone will be on the same page and understand where I am coming from. <br /><br />I believe the "automatic" trim tabs you are referring to are what we Self Adjusting trim tabs, which are essentially fixed trim tabs fitted with spring type mounting systems or trim tabs made with a flexible material. They rely on pressure from the water flow to decrease their angle of deflection as speed is increased. Because of this, they cannot be maked to clear the water flow and will always cause drag regardless if you need them or not. They are not adjustable and the amount of lift they provide at different speeds is unpredictable. They can also provide too much lift in conditions where it is not needed or wanted, such as in a following sea. There is also no way to tailor the boats attitude to changing conditions and they cannot be used to alter the lateral trim of the vessel. Being in the down position at all times can have an adverse effect on the boats steering in reverse, as well as being more susceptible to damage from trailer bunks or dry storage, so to make along story short they are not the end all be all for a trim tab system! <br /><br />Our hydraulic adjustable trim tabs do a much better job of this than the Self Adjusting type could ever do. The following are a few beneficial effects that adjustable trim tabs provide to a vessel:<br /><br />1. If the boat shows a tendency to porpoise at higher speeds, a very slight deflection of the tabs will smooth the ride out.<br /><br />2. If you run with unequal passenger distribution you can lower one trim tab to even out the boat.<br /><br />3. If your boat leans to one side due to prop. Torque you can level the boat side to side.<br /><br />4. You can keep the boat on plane at lower speeds. This is particularly useful when running in choppy water.<br /><br />5. Since you can plane at lower speeds you can tow tubes, skiers etc. through a much wider speed range. Plus at lower speeds you can hold your bow down, and see where you are going.<br /><br />6. Hole shots are faster.<br /><br />7. At lower speeds you can use the trim tabs to hold the bow down, and use the power trim to get the most thrust from your prop. This is much more efficient then forcing the prop into the water at an angle as you would when using the power trim to correct bow up.<br /><br />Now, as for a trim tab suggestion for you vessel, I would have to first ask you to check your Available Mounting Area (determined by starting 3-4 from the chine and measuring to within 8 of the outdrive/keel) and get back to me with your findings, so we will know how much room we have to work with. With out this information and just taking a stab in the dark, our M80 Sport Tabs,
http://www.bennetttrimtabs.com/m80.htm, would most likely do the trick! They have an 8" Span (side-to-side) by 10" Chord (fore-to-aft) length and are designed to fit most trailered vessels, because of the small footprint they take up on the transom. To keep the capabilities of the trim tabs high, we designed them with 1" Drop Fins on the sides to capture escaping water on each side to provide more lift relative to its dimensions. If you look closely at the planing surface you will also see a downward taper towards the trailing edge, which allows faster boats to apply a little trim at high speeds and more trim at slower speeds. At any rate, please take a look at your transom and get back to me with your findings as soon as you can!<br /><br />I look forward to your reply.<br /><br />Sincerely,<br />MJ Thomas<br />Bennett Marine, Inc.<br />Client Services<br />
www.bennetttrimtabs.com<br />trimtabs@earthlink.net
