scross
Well-known member
- Joined
- Jan 30, 2015
- Messages
- 2,094
- Fluid Motion Model
- C-28
- Hull Identification Number
- FMLC2831A717
- Vessel Name
- R-25 Classic - Sold
- MMSI Number
- 367719470
We do longer duration cruises and end up packing the cockpit and transom areas with lots of extra weight in gear and coolers. Plus we have an extra two house batteries in a port side cockpit locker. Add to that a heavy dinghy and motor hanging off the swim step. It all adds up to being pretty tail heavy.
The 12” chord 18” wide Bennett trim tabs worked ok but not great in gating the nose down at higher speeds. In reading through the online materials about the trim tabs two things stuck out.
First, I needed to add drop fins to the trim tabs make them more effective. I’ve already left comments on that install in another thread.
viewtopic.php?f=5&t=17040&p=111440&hilit=Drop+fins+angle#p111440
Secondly, my boat had the trim tabs installed in a way so that, with the tabs fully retracted, the negative reflex of the tab was far to great. If you measure from a line flush to the hulls bottom, the trailing edge of the trim tab is suppose to be 5/8 inch above that line. This is per Bennett’s installation instructions. My measured reflex at the trailing edge was closer to 1 1/8 inch. I was losing effective movement of the trim tabs because they were just angled upward at the trailing edge too much.
So, I bought a pair of special order 1/2 inch Bennett spacer blocks - part number A1124.
gallery2.php?g2_itemId=77509
Not very expensive but it took two months to get them. The install was relatively straightforward:
1. Remove the three screws holding the upper part of the trim tab piston to the hull.
2. Using a wedge to break the old sealant, separate the piston assembly from the hull.
3. Remove the hose fitting from the piston using 7/16 and 1/2 inch wrenches.
4. Using needle nose pliers pull the hose out an inch to install the spacer through the hose and next to the hull.
5. Reattach the hose to the piston assembly using the two wrenches.
6. Finally apply sealant to both sides of the spacer and tighten everything up using the supplied longer screws.
gallery2.php?g2_itemId=76522
gallery2.php?g2_itemId=77503
gallery2.php?g2_itemId=77506
Took about 15 minutes per side. Some of the hydraulic fluid will leak out but the system is self bleeding and a couple of cycles should get any air bubbles out.
As measured after the spacer installation, my reflex at the trailing edge of the trim tab is now 5/8 inch. Just where it should have been per Bennett Marine. See page 1 of the installation instructions.
https://bennetttrimtabs.com/wp-content/ ... lation.pdf
Looking forward to better performance from the trim tab system when the boat’s back in the water!
The 12” chord 18” wide Bennett trim tabs worked ok but not great in gating the nose down at higher speeds. In reading through the online materials about the trim tabs two things stuck out.
First, I needed to add drop fins to the trim tabs make them more effective. I’ve already left comments on that install in another thread.
viewtopic.php?f=5&t=17040&p=111440&hilit=Drop+fins+angle#p111440
Secondly, my boat had the trim tabs installed in a way so that, with the tabs fully retracted, the negative reflex of the tab was far to great. If you measure from a line flush to the hulls bottom, the trailing edge of the trim tab is suppose to be 5/8 inch above that line. This is per Bennett’s installation instructions. My measured reflex at the trailing edge was closer to 1 1/8 inch. I was losing effective movement of the trim tabs because they were just angled upward at the trailing edge too much.
So, I bought a pair of special order 1/2 inch Bennett spacer blocks - part number A1124.
gallery2.php?g2_itemId=77509
Not very expensive but it took two months to get them. The install was relatively straightforward:
1. Remove the three screws holding the upper part of the trim tab piston to the hull.
2. Using a wedge to break the old sealant, separate the piston assembly from the hull.
3. Remove the hose fitting from the piston using 7/16 and 1/2 inch wrenches.
4. Using needle nose pliers pull the hose out an inch to install the spacer through the hose and next to the hull.
5. Reattach the hose to the piston assembly using the two wrenches.
6. Finally apply sealant to both sides of the spacer and tighten everything up using the supplied longer screws.
gallery2.php?g2_itemId=76522
gallery2.php?g2_itemId=77503
gallery2.php?g2_itemId=77506
Took about 15 minutes per side. Some of the hydraulic fluid will leak out but the system is self bleeding and a couple of cycles should get any air bubbles out.
As measured after the spacer installation, my reflex at the trailing edge of the trim tab is now 5/8 inch. Just where it should have been per Bennett Marine. See page 1 of the installation instructions.
https://bennetttrimtabs.com/wp-content/ ... lation.pdf
Looking forward to better performance from the trim tab system when the boat’s back in the water!