Announcement

Collapse
No announcement yet.

Installing an Additional Set Of Trim Tabs - 3788

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    Installing an Additional Set Of Trim Tabs - 3788

    Since the trim tabs in the 3788 are undersized I decided to install an additional set of 12x18 tabs to help bring the bow down a bit more and gains some additional performance. Below are a few photos and a description of the process.

    The first step is to layout where the tabs will go and drill the holes. I taped the backing plates to the hull and used them as drilling templates. Incidentally, notice that my boat does not have the u-bolts that are normally installed in the transom. When I bought the boat one of the u-bolts was leaking. I had them both removed and the holes filled.




    After the fastener holes were drilled, the tabs planes were installed.




    The next step is to determine where to drill for the actuator attach bolts, as well as for the pipe that threads into the actuator and goes through the transom. I ran into a bit of a problem here. Bennett has a PDF on their site with full instructions and drilling templates. Unfortunately, the scaling of the printer resulted in undersized templates. Make sure that you check this before you drill! In my case I laid the holes out using the actuator, a ruler, and a compass.




    Here are the tabs and actuators installed.




    The pipes that thread into the actuators go through the transom. Elbows from the Bennett kit are threaded onto the pipes. The Bennett hydraulic tubing is attached to the elbows and other fittings via compression fittings.




    The new hydraulic tubing is attached to the existing tubing using Tee fittings.




    After it's all done, the hydraulic system is bled by holding the switches in the up and down position for 15 seconds a number of times. The reservoir is serviced and the connections are checked for leaks.

    Finished installation.




    I want to thank Tom from Bennett Trim Tabs, known in this forum as "Tabman" for all his advice.
    Last edited by Jim_Gandee; 02-04-2018, 07:56 PM.
    1999 3788, Cummins 270 "Freedom"
    2013 Boston Whaler 130 SS
    Anacortes, WA

    #2
    Awesome. On my list for the next hullout. Can't wait to here your before/after results.
    1997 3788/Cummins 6BTA 5.9 M2s (Sold)
    2003 Silverton 42c/Cummins 480CEs
    2014 Sea Fox 22 Center Console
    2006 Boston Whaler 13 Sport

    Vero Beach, Fl.

    Comment


      #3
      Try www.zipwake.com. We did last summer on our 2452 and very happy with it. Works perfectly.

      Comment


        #4
        Can you post the be Bennett parts numbers? Sure would help when I order.
        1997 3788/Cummins 6BTA 5.9 M2s (Sold)
        2003 Silverton 42c/Cummins 480CEs
        2014 Sea Fox 22 Center Console
        2006 Boston Whaler 13 Sport

        Vero Beach, Fl.

        Comment


          #5
          "p91473" post=693365 wrote:
          Can you post the be Bennett parts numbers? Sure would help when I order.
          2 ea. TPA1812DF 18 x 12 Drop Fin Trim Plane Assemblies

          2 ea. A1101A Standard Actuators

          1 ea. H1170B Dual Actuator Hardware Kit (contains the tees and hydraulic connections for the additional actuators).

          1 ea. T1125-20 Hydraulic Tubing. Note that some suppliers sell this by the foot as p/n T1125. I ended up using about 3' but I recommend that you get at least 5', just in case.

          Incidentally, there's no need to buy fasteners. Between the fasteners included in the trim plane assemblies and the dual actuator hardware kit, there are more than enough fasteners to do the job.
          1999 3788, Cummins 270 "Freedom"
          2013 Boston Whaler 130 SS
          Anacortes, WA

          Comment


            #6
            Great Job! I am delighted I could help!
            sigpic"Like" Bennett Marine on Facebook

            Comment


              #7
              "ILGVARS" post=693353 wrote:
              Try www.zipwake.com. We did last summer on our 2452 and very happy with it. Works perfectly.
              I have no doubt that these will work. The issue is that most of our boats have Bennett Trim Tabs already installed and they work well. In my mind it is a lot easier to add an additional set of tabs to an existing Bennett system than to retrofit a boat with a totally new system.
              1999 3788, Cummins 270 "Freedom"
              2013 Boston Whaler 130 SS
              Anacortes, WA

              Comment


                #8
                Last weekend I took the boat out for the first time after installing the additional trim tabs. The performance of the boat was improved and I was quite pleased.

                In the past I was getting 15-16 knots at 2200 RPM. With the extra tabs I got 17-19 knots. In both cases the bottom was clean. Moreover, the boat had full fuel and water tanks. With the stock factory tabs the speed with full tanks was usually 15 knots. Keep in mind that I did not correct for current or cruise for a long time. I just cruised for 1/2 hour each way, between Anchor Cove in Anacortes and Eagle Harbor in Cypress Island.

                As expected, trim tab actuation is a bit slower than before (same pump with 2 additional cylinders). While the actuation speed is a bit lower, the actual trim tab effect is unchanged. I believe the reason is that the additional tab area makes up for the slower tab speed.
                1999 3788, Cummins 270 "Freedom"
                2013 Boston Whaler 130 SS
                Anacortes, WA

                Comment


                  #9
                  Well done, must have been a very satisfying project.
                  "Impasse". 2001 3988
                  Cummins 330's
                  Puget Sound

                  "You don't want to be the richest guy in the nursing home..."

                  Comment


                    #10
                    I'd like to revive this thread. I don't see pics as they were probably lost in the sitentransition.

                    Our 2001 3788 with heavy Zodiac center console off the back really weighs the back down. OEM tabs don't lift the back enough, so along with a bigger anchor and 300' chain, I would like to either get larger trim tabs or have zipwake installed. Does anyone have actual experience with zipwake on a boat like the 3788?

                    I saw the zipwake at the recent Seattle boat show and was intrigued with the design. I've got a haulout scheduled the 14th of this month and need to decide which way to go. Norton, can you repost your pics and or chime in with your recommendation?

                    Thanks!
                    2001 3788 w/ 330 Cummins
                    Seattle, WA

                    Comment


                      #11
                      Interesting concept but one thing I noticed on the website was the boats were moving right along, possibly at higher speeds than your normal cruise. Another concern I would have is damage from no see em types of debris. A trim tab would tend to skim over most stuff, but a vertical, just like an outboard or outdrive, might sustain damage. Interesting concept, I didn’t look at the price. You might contact tabman here. He works for Bennett and can advise you about some trim tab options. I’ve found his advice to be more in the line of counciling than sales pitch.
                      P/C Pete
                      Edmonds Yacht Club (Commodore 1993)
                      1988 3818 "GLAUBEN”
                      Hino EH700 175 Onan MDKD Genset
                      1980 Encounter Sunbridge "Misty Blue" (Sold)
                      MMSI 367770440
                      1972 Chevrolet Nova Frame off Resto-mod in the garage
                      Boating on the Salish Sea since 1948

                      Comment


                        #12
                        I copied and pasted my original post from 2015 below and added the photos back in.



                        Installing an Additional Set Of Trim Tabs - 3788-gctid693259
                        11-12-2015, 05:15 PM
                        Since the trim tabs in the 3788 are undersized I decided to install an additional set of 12x18 tabs to help bring the bow down a bit more and gains some additional performance. Below are a few photos and a description of the process.

                        The first step is to layout where the tabs will go and drill the holes. I taped the backing plates to the hull and used them as drilling templates. Incidentally, notice that my boat does not have the u-bolts that are normally installed in the transom. When I bought the boat one of the u-bolts was leaking. I had them both removed and the holes filled.

                        Click image for larger version

Name:	Laying out tab location (600x338).jpg
Views:	1
Size:	47.3 KB
ID:	409407


                        After the fastener holes were drilled, the tabs planes were installed.

                        Click image for larger version

Name:	Tabs Installed (600x338).jpg
Views:	1
Size:	55.8 KB
ID:	409408


                        The next step is to determine where to drill for the actuator attach bolts, as well as for the pipe that threads into the actuator and goes through the transom. I ran into a bit of a problem here. Bennett has a PDF on their site with full instructions and drilling templates. Unfortunately, the scaling of the printer resulted in undersized templates. Make sure that you check this before you drill! In my case I laid the holes out using the actuator, a ruler, and a compass.

                        Click image for larger version

Name:	Laying out actuator location (600x405).jpg
Views:	2
Size:	35.3 KB
ID:	409409


                        Here are the tabs and actuators installed.


                        Click image for larger version

Name:	Installed tab assemblies (600x338).jpg
Views:	1
Size:	53.5 KB
ID:	409410

                        The pipes that thread into the actuators go through the transom. Elbows from the Bennett kit are threaded onto the pipes. The Bennett hydraulic tubing is attached to the elbows and other fittings via compression fittings.

                        Click image for larger version

Name:	Hull penetrations (600x246).jpg
Views:	1
Size:	23.3 KB
ID:	409411


                        The new hydraulic tubing is attached to the existing tubing using Tee fittings.

                        Click image for larger version

Name:	Tee into existing hydraulic line (338x600).jpg
Views:	1
Size:	30.9 KB
ID:	409412


                        After it's all done, the hydraulic system is bled by holding the switches in the up and down position for 15 seconds a number of times. The reservoir is serviced and the connections are checked for leaks.

                        Finished installation.

                        Click image for larger version

Name:	All tabs (600x338).jpg
Views:	1
Size:	50.6 KB
ID:	409413


                        I want to thank Tom from Bennett Trim Tabs, known in this forum as "Tabman" for all his advice.

                        Attached Files
                        1999 3788, Cummins 270 "Freedom"
                        2013 Boston Whaler 130 SS
                        Anacortes, WA

                        Comment


                          #13
                          Originally posted by ILGVARS View Post
                          Try www.zipwake.com. We did last summer on our 2452 and very happy with it. Works perfectly.
                          Those are really nice..... unfortunately they are really expensive when compared to a bennet system for my boat... I’d love to have a set, though ...
                          BJ
                          OMEGA
                          5788

                          Comment


                            #14
                            Originally posted by Norton_Rider View Post
                            Last weekend I took the boat out for the first time after installing the additional trim tabs. The performance of the boat was improved and I was quite pleased.

                            In the past I was getting 15-16 knots at 2200 RPM. With the extra tabs I got 17-19 knots. In both cases the bottom was clean. Moreover, the boat had full fuel and water tanks. With the stock factory tabs the speed with full tanks was usually 15 knots. Keep in mind that I did not correct for current or cruise for a long time. I just cruised for 1/2 hour each way, between Anchor Cove in Anacortes and Eagle Harbor in Cypress Island.

                            As expected, trim tab actuation is a bit slower than before (same pump with 2 additional cylinders). While the actuation speed is a bit lower, the actual trim tab effect is unchanged. I believe the reason is that the additional tab area makes up for the slower tab speed.
                            I love what you did... it looks great!

                            I had to increase my tabs, too, as they were undersized, in my opinion. Unfortunately, I wasn’t able to add another set to the center of my stern as my stern thruster was in the way. Instead, I increased the width and length of my tabs from 42 x 12 to 48 x 18 inches... it made a huge difference. The only thing I have to be sure I do before docking, each time, is fully retract my tabs so I don’t accidentally pull them off if I have an emergency that I have to reverse quickly.. Like you, my performance increased and the boat’s ride did, too....

                            ~BJ
                            BJ
                            OMEGA
                            5788

                            Comment


                              #15
                              Found a pic of my larger tabs as I was installing them...

                              ~BJ
                              BJ
                              OMEGA
                              5788

                              Comment

                              Working...
                              X