trim tabs, how big is too big?

[Sea Hawk]

I have a 23' Chris Craft Sea Hawk (walk-around). Dry weight is about 2500lbs. It holds 80 gallon of fuel, and I usually boat with 2 other 200+lbs. men. It is powered by a 1995 mercury 225 (carborated) outboard. All told, Baot, motor, men, fuel and gear = approx. 4000+lbs. I want to select the best trim tabs I can for my boat. I fall into two categories according to the manufacturer's specs. Boats 16' thru 25' call for a 12" wide tab while boats 22' thru 30' call for an 18" wide tab. Both sets extend 9" off the transum. What are the advantages and disadvantages of going with one size vs. the other. Drag? Overkill? performance?

 

[Boatist]

Re: trim tabs, how big is too big?

Sea Hawk<br />I am not sure I can answer your question but will tell you I have a 21 foot Aluminum runabout with a 8 foot beam. Dry weight 2800 Lb usually 3 or 4 adults and 34 gallon of fuel. Two anchore, tools fishing tackel ect. <br /><br />I put on Benett Hydrolic trim tabs and it is best thing I have added to my boat. I selected the 18 inch wide by 12 deep chord per side. With out tabs boat planes at about 19 with tabs down can stay on plane to 9 mph. On the days where have the 1 to 2 foot chopp the tabs smooth the ride out real nice. Offshore in the 6 to 8 foot swells every 8 seconds allows me to slow way down and stay on plane. I would recommend you get the dual rocker switch control instead of the joy stick.<br /><br />I hope Tabman replies as to size because he is a expert and help lots of people with benett tabs even after the warranty has run out. For that reason I will always install benett on my boat. Too big a tab I do not think will hurt anything but run all the way down at high speed would burry the bow and be danerous. I got the 12 inch chord because I felt that has more effect to smooth ride out. As bow pushes up tab goes down and try to push bow back down.<br /><br />If you water ski or swim around the boat the tab are sharp so need a good swim platform.

 

[Sea Hawk]

Re: trim tabs, how big is too big?

Thank you Boatist. I kinda figure the bigger the better, but I just wasn't sure about the safety of the larger tabs. Like you said, don't want to burry the nose, or tilt her too far left or right accidentaly and shoot someone overboard. Hopefully I'll hear from Tabman and get my answers. Thanks again and happy cruising.

 

[Tabman II]

Re: trim tabs, how big is too big?

Sea Hawk,<br /><br />I am Thomas and I work for Bennett Marine in the Client Service department. <br /><br />Your 23’ vessel by our General Sizing Recommendations falls in the 24 x 9 trim tab range, but depending on the Available Mounting Area (determined by starting 3-4" from the chine and measuring to within 8" of the outdrive) you may have to step down in size (22 x 12, 20 x 12, or 18 x 12). So, the next thing for you to check is the Available Mounting Area. In general, the largest trim tabs that will comfortably fit on the transom will be the most efficient, but protrusions (transducers, speed wheels) &/or obstructions can influence your choices. The closer you can stay to the 24 x 9’s the better the performance will be for slow speeds and hole shot, just like Boatist stated. Speed capabilities also play a part in your trim tab choice, so please let me know what she can do and how you drive her. Some vessels have plumbing troubles because of their design, but we have a few tricks that will normally cover any situation you run up against. It really is just a matter of looking at the installation and explaining to me your woes. So, take a look at your transom and get back to me with the measurement & speed information.<br /><br />I look forward to your reply.<br /><br />Sincerely,<br />MJ Thomas<br />Bennett Marine, Inc.<br />Client Services<br />trimtabs@earthlink.net

 

[Sea Hawk]

Re: trim tabs, how big is too big?

Tabman, <br /> Thank you for replying. My top speed with just me and little fuel and gear, and perfect wind, tide and water conditions is about 47mph. With gear, fuel and company, I generally cruise at about 4500 rpm. whitch runs me about 35-37mph. My main woe is simple. I get tired of telling guys to stay put on the boat. I feel like a kindergarden teacher. "you sit here. And you sit here. And don't let me catch you two on the same side of the boat." Yada...Yada...Yada... I just want to be able to trim the boat out once everyone is comfortable. I also would like to be able to plane at lower speeds. I run the Delaware river and bay most of the time and it can get pretty nasty when she wants too. Getting beat up in the chop all day is no fun. I would like to get better hole shots, but it's not a priority for me. I took the measurements you mentioned and found that I can fit the 24x12 tabs. But, as you also mentioned, my transducer is in the way. Could it be moved into the 8" space between the tab and the outdrive?

 

[Tabman II]

Re: trim tabs, how big is too big?

Sea Hawk,<br /><br />I would stay out of the 8" area, since the transducer may introduce air into the prop and cause ventilation (baaaad transducer!). Could you install 18 x 12's and not have to move the transducer? If so, then this is the route I would take to reduce the amount of holes in your transom. If you are really worried about not having enough trim tab performance because of the reduced size, then you can order them with our 3" Drop Fins. The 3” Drop Fin is an addition that can be added to a trim tab to increase its performance by channeling the water flow under the tab and holding it there to produce the maximum lift capable of a given trim tab. They are 3” fins that angle 90 degrees down on the sides, forcing the water flow to run the full length. These will help bring the trim tabs back to the 24 x 9 size our guidelines suggest for your vessel. Please take another look at your transom and let me know your findings.<br /><br />I look forward to your reply.<br /><br />Sincerely,<br />MJ Thomas<br />Bennett Marine, Inc.<br />Client Services<br />trimtabs@earthlink.net

 

[Sea Hawk]

Re: trim tabs, how big is too big?

Tabman,<br /> I rechecked my transom and found that the 18" tabs would work great. Even the 20" tabs would fit quite well without having to move anything. I was just wondering a few things. First, What difference would using an 18" or 20"x12" tab make as opposed to the 24"X9". I realize that the 20X12 has a bigger overall (square inch) size. How Would performance be affected by having more tab sticking out the stern as opposed to across the transom? Second, in your opinion, what are the biggest pros and cons for using hydrolic tabs over electric tabs. I am not new to boating, but I am clueless about trim tabs. I never had them on any boat I have ever owned. I have seen the difference they make on other boats similar to mine and do intend to have a set on my boat by spring. I just don't know much about what to look for and what is available. Any input would be greatly appriciated. Thanks again for taking the time to help out.<br /><br />Ted Christopher<br />A.K.A. Sea Hawk<br />New Castle, DE

 

[Boatist]

Re: trim tabs, how big is too big?

Sea Hawk<br />I recommend the bennet hydrolic ones with the dual rocker switches. I had them on my boat for 23 years now. I had one problem, when I got them came with a Joy Stick control and it got kinda of flaky after about 10 years so replaced with the dual rocker which I like much better. I check the oil every year or two and that is all I have done. I will like to see Tabman's reply as to 9" verses 12" cord. I have the 18 wide by 12 deep ones 1981 model.

 

[Tabman II]

Re: trim tabs, how big is too big?

Sea Hawk & Boatist,<br /><br />Our sizing guidelines are geared toward installing 9" Chord vs. 12" Chord, since the largest trim tabs that will comfortably fit on the transom will be the most efficient (working off of more water flow. With wider Span tabs you will not have to deflect them as much to gain the lift you need (better lift/drag ratio). Our 12" Chord tabs are for installations that can't fit the suggested Span tab (transducer, speedo in the way) &/or one that needs extra lift because of slow speed &/or stern heavy. <br /><br />Electro-hydraulic trim tabs systems are superior to the Electro-mechanical style in many ways and we should know, since we abandoned the Electro-mechanical type in the Sixties in favor of the more reliable Electro-hydraulic. One of the reasons is our Hydraulic Power Unit (HPU) can be mounted in the best possible environment for longevity and service, inside of your vessel instead of on the transom in the water. <br /><br />We offer a 5-year warranty on the complete trim tab system to include the control, wiring harness, HPU, tubing, actuators, fittings, and the trim planes. Our warranty is very easy to access, since we want you to CONTACT US FIRST before spending any time trouble shooting the system because we will most likely be able to pinpoint the problem &/or provide you with information to find it quickly and easily. Also, our warranty is an exchange of parts and depending on the situation we can even ship the part out before receiving the faulty one back to get a client back on the water quickly! <br /><br />Our electro-hydraulic system doesn't rely on a seal at the bottom of the cylinder body to keep water out, unlike the electro-mechanical type. The seal is made at the piston face, which makes them impervious to damage caused by fouling of the shaft (I.E. barnacles, marine growth...), so leaving the tabs extended will not damage the system &/or void the warranty. See, when the seal fails on the electromechanical type the watertight integrity of the system is compromised and water in an electric motor equals failure. Also, our actuators only need two (2) o-rings seal the system, unlike the leading electro-mechanical system which has a total of seven (7). <br /><br />Really, this is getting very close to spamming and I don't wish to do that, so please contact me at trimtabs@earthlink.net and I will be happy to provide all the information regarding the pro's & con's.<br /><br />Sincerely,<br />MJ Thomas<br />Bennett Marine, Inc.<br />Client Services<br />www.bennetttrimtabs.com

 

[Solittle]

Re: trim tabs, how big is too big?

Sea Hawk - My input is that bigger is not always better. Seems to me that the bigger ones are going to by hyper sensative. With trim tabs - a little does a lot. I run a 6,000 lb CC with modest tabs that work great.

 

[Tabman II]

Re: trim tabs, how big is too big?

Sea Hawk,<br /><br />Solittle does have a point! Trim tab systems can be "touchy" if they are too large, but very few vessels fall into this family since they normally only get heavier with age. In fact, if you take a look around at your local marina or boat yard you will find very few vessels tabbed per OUR sizing guidelines from the manufacturers. We like to have a little more to work with in the end, since the system is adjustable and you can dial in just what you need for the situation at hand. For this reason we offer trim tabs in so many different sizes and configurations to ensure you get the best trim tabs set to fit your vessel and needs. <br /><br />If you have anymore questions, feel free to contact me.<br /><br />Sincerely,<br />MJ Thomas<br />Bennett Marine, Inc.<br />Client Services<br />trimtabs@earthlink.net