Re: Trim tabs versus Trim and tilt
Karl Paoletti,<br /><br />I am Thomas and I work for Bennett Marine in the Client Service Department. <br /><br />I have copied below a brief outline for using trim tabs to their fullest extent on a vessel. Honestly, we all use the outdrives tilt/trim to change the running attitude of the vessels we pilot, but it really wasnt designed to do this. The outdrives tilt/trim ability was intended to position the prop at the appropriate angle to provide the most efficient use of its thrust, which is to propel the vessel thru the water. Any time you tuck the drive under or tilt it out you are using some of the props thrust to lift the stern or bow, which from holeshot would be advisable but even then as soon as you are on plane you start to tilt it out to gain as much thrust from it as possible. Any time the power trim is used to adjust your running attitude the prop will operating at an angle to the water flow. This increases prop slippage & wastes RPMs, since you are now asking it to provide both thrust & trim the vessel. Trim tabs unburden the prop of trimming the vessel and allow you to achieve the optimum running attitude and maximum the efficiency of your engine over a greater range of conditions. After you read over this outline you may have a few more questions, so feel free to contact me here or at
trimtabs@earthlink.net. <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 /><br />One Step at a Time<br />The key to obtaining optimal results from trim tabs is to operate them in short bursts and let the boat react before making another adjustment. The amount of time between corrections is influenced by the size of the trim tabs and the boats speed. This will help avoid overtrimming or ending up with one tab too far down when correcting lateral trim. You will quickly become acquainted with a boats particular traits.<br /><br />Take Off <br />Properly sized trim tabs can significantly reduce the time needed to get up on plane. They also allow a boat to keep its bow down and stay on plane at lower speeds. <br /><br />As the throttle is advanced the stern of the boat begins to squat, lifting the bow. As the boat accelerates, push the bow down position of the helm control in short bursts. The boat reacts by the stern lifting, the bow coming down, speed increasing, and reduced engine laboring. If you over do it and deflect the tabs too far the boat will end up over trimmed. When over trimmed, the steering becomes over sensitive and wants to pull off course to port or starboard. If this occurs, operate the control "bow up" until the desired attitude is established.<br /><br />Getting the Most from Power Trim<br />Adjust the trim tabs to achieve the desired running attitude. Then use the power trim to position the propeller thrust parallel to the water flow. If necessary, re-adjust the trim tabs to fine-tune the attitude. By observing the boats speed and engine RPMs the best combination of trim tabs and power trim will be apparent. Trim tab angle indicators and a power trim angle indicator are particularly useful in duplicating effective settings.<br /><br />Trimming to Sea Conditions<br />When running into a head sea you want to trim the bow down so the sharp forward sections of the boat do their work cleaving the waves. This provides the most comfortable ride and minimizes stress on the boat (and passengers). In a following sea the tabs should be fully retracted for maximum steering response.<br /><br />Correction of a List<br />Using the trim tab controls you may operate one trim tab independently and correct for a list. This list may be caused by uneven weight distribution, prop torque or wind,<br /><br />You may find it easier to correct the boats fore and aft attitude before you correct the athwartship trim.<br /><br />Correction of Porpoising<br />Operate the tabs in very short bursts of about half a second. Continue until porpoising subsides. The objective is to have only a very slight amount of tab deflection, just the amount needed to cure the up and down motion of the bow.
