scross":3nr2di9k said:
You can NOT use a SPACER BELOW THE LOWER HINGE of the actuator, since this will lift the LEVERAGE CONTACT POINT higher on the RIVETED/RIGHT ANGLE on the trim tab. This position will damage the RIVETED/RIGHT ANGLE & ACTUATOR over time with the chance of TRIM TAB LOSS in the future.
scross":3nr2di9k said:
YES, the DROP FINS MUST BE IN LINE WITH THE WATER FLOW to work as designed. If not, they will act like “rudders” and cause undue STRESS/DRAG on the trim tabs & vessel to the point of TRIM TAB LOSS & ACTUATOR DAMAGE.”
Both of these statement are conflicting with the information that I received from Bennett. I installed drop fins on my C26 6 months after purchasing the boat in 2016 for a couple reasons. The bow rode to high when I had passengers in the cockpit and I did not get enough response from the trim tabs to assist in bringing the bow down. The trim tabs were mounted to high on the transom and there was a loss of travel depth because of this.
I spoke with Oliver at Bennett, a veteran customer service rep that said the tab size (C26 and C28) 12X12 are to small for that boat. He was very knowledgable about the drop fins because of work he had done with Bayliner back in the late 80"s. Bayliner too rode high and Bennett made drop fin trim tabs known now has Bayliner trim tabs. Olivers advise to me was install the drop fins. I explained the angle of the transom to him. He said on a boat that has a WOT of 20Kts the efficiency loss of having the drop fins run at the angle of the transom will not be NOTICED. If the boat WOT was 30+Kts you may see a slight difference in performance. If it is 40 Kts you want them to be run-in straight (parallel ) with the keel. Olivers other suggestion was to install a spacer between the mounting surface of the Plane and the mounting surface of the hinge bracket at the base of the trim ram. This will extend the ram travel and eliminate the need to lower on the transom or install a spacer at the transom. "This as worked for years and we have had no issues with this spacer being used in this location"
I took his advise and installed the drop fins at an angle and installed the spacers. I used the trim tabs in this configuration for a season and found a significant change in the bow attitude. I was able to bring the bow down and found the boats handling and performance to be enhanced.
I'm not sure what the MJ Thomas is talking about. The integrity of the mounting location is not compromised and the load is the same why would this Cause a failure? I installed this when the boat had 120 hrs on it. It now has 650 hrs on it. I have used the boat in the open waters of Lake Michigan, the Gulf of Mexico, and many bays with choppy conditions. I use the trim tabs at full extension anytime the boat is operated above 2250 which is more than 50% of the time. I see no issues with the integrity of the install. It is a five minute install. There is nothing wrong with the transom mounted plate just a lot of extra work. It is usually used by manufactures when building the boat because of transom angles or mounting location the ram.
Having the drop fins run parallel with the boat? I did make a set of custom drop fins that would run parallel with the keel. I did not want to use the original ones because the configuration would take away from my plane surface. I made new one that would outside the running surface of the 12X12 planes. This increased the planes surface area and increasing the effects of the trim tabs. The benefits of having them run parallel were not noticed has far has change in handling or performance. The only thing I noticed was the wake was cleaner. That was it!
My advise from my experience try to get the Bennett drop fins to run close to parallel to the keel without absorbing the plane surface. It will not make a difference in performance or handling on a inboard diesel Ranger or Cutwater. I have seen many installed and talked to many that have installed them running off center to the keel and say it handles fine.The benefits of installing them will be good. I operated the boat both ways and found the efforts were not warranted.
My final trim Tab modification was to install larger planes. The only reason I did this was to eliminate the chance of damage to my Trim tabs when I am having the boat lifted out of the water with a fork truck. The only benefit of the 18 X12 larger tab on my C26 or a C28 is you do not have to worry about the drop fin getting hit by a fork. The 18 X12 plane is equal to the 12X12 with a drop fin.
I highly recommend the installation of dry fins on the Fluid motion boats by design they ride bow high stern heavy. The same way the Bayliner did.
18 X 12 trim tab
Almanac":3nr2di9k said:
How much down trim are you guys running at cruise? Are you maxing it out or just bringing the bow down? Do the drop fins give you more trim or just... more efficient somehow?
This is the link to the photos of my drop fin modifications it should answer some of your questions. More trim better efficiency at any speed above hull speed.
gallery2.php?g2_itemId=48595
