Bennett SLT-10 Self-Leveling Trim Tabs - Vertical Mounting

[gsbarry]

I've done some reading already on here about other's experience with trim tabs in general, but am looking for some further feedback on trim tab selection more specific to my application. Here are some pics of my transom, to give you an idea of what I'm working with, which is a 2105 Bayliner 175 runabout (which is about 2k lbs.). The transom has an overhang, which based on my initial measurements indicates the trim tab actuator/piston would be mounted pretty much vertical (I've seen some pics of installs that are vertical, but not sure if they were SLT's). The boat performance I'm looking to improve is bow rise out of the hole, and reduced porpoising while on plane in chop. I'm looking for opinions as to whether the Bennett self-leveling trim tabs (the SLT-10's) will likely work well or not given my application. I contacted Bennett and haven't really been getting a clear answer. They indicated that vertical mounting on the SLT actuators results in too much downforce on the trim tabs which produces poor performance. I asked about actuators that have less spring force (which I've read about on a few other posts), and it seemed like he was avoiding my question, or just simply didn't know/understand what I was talking about. They did recommend that I mount the trim tabs more inboard (pic with blue lines) which would allow for the actuator to be slightly less vertical, although not all that much by my rough measurements, at the expense of side to side stability. I realize the controlled systems will be superior to the self-leveling system, but I would like to avoid the added cost if the self-leveling system will still have ~60% of the performance improvement of the full control system. Price wise, we're looking at $150 for SLT-10's vs $500 for M80's (which is the hydraulicly controlled sport tab for sized for my application). If I hear that the SLT-10's simply will not work in this application, then I'll have to bite the bullet on the M80's I suppose, but open to hearing suggestions on other models/brands in a similar price range.

 

[dingbat]

Get the tabs too close to the keel and you end up with a stability issues. Boat wants to teeter tooter, port to starboard and back

Unless your a fair weather, lake boater that doesn't do "conditions", self adjusting tabs are not going to cut it.

 

[JASinIL2006]

My boat has a similar transom (see picture below; not my boat, but the same model) and I was able to install Nauticus SmartTabs on it. I contacted Nauticus customer support and they said the tab's pistons could be mounted to the bump-out portion of the transom, but we might have to adjust the pistons to a lower pressure setting due to the placement.

I installed the tabs as shown in the picture and they work great. My boating is all lake/river boating, and the tabs were installed to eliminate chinewalking and bowrise on takeoff, which the tabs do remarkably well. I'd install yours as far outboard as you can.

 

[gsbarry]

Get the tabs too close to the keel and you end up with a stability issues. Boat wants to teeter tooter, port to starboard and back

Unless your a fair weather, lake boater that doesn't do "conditions", self adjusting tabs are not going to cut it.

This boat is fresh water only. While I don’t go out on really nasty days, I’d like to improve porpoising in chop on moderately windy days.

 

[gsbarry]

My boat has a similar transom (see picture below; not my boat, but the same model) and I was able to install Nauticus SmartTabs on it. I contacted Nauticus customer support and they said the tab's pistons could be mounted to the bump-out portion of the transom, but we might have to adjust the pistons to a lower pressure setting due to the placement.

I installed the tabs as shown in the picture and they work great. My boating is all lake/river boating, and the tabs were installed to eliminate chinewalking and bowrise on takeoff, which the tabs do remarkably well. I'd install yours as far outboard as you can.

View attachment 406249

Is the pressure on the Nauticus pistons adjustable (meaning is there a valve you could bleed off or maybe even add gas pressure)? Or would you have had to buy new pistons if that was needed?

 

[dingbat]

This boat is fresh water only. While I don’t go out on really nasty days, I’d like to improve porpoising in chop on moderately windy days.

Purposing is caused by too high of a trim angle. Trim down to stop proposing.

The boat’s weight and deadrise are not conducive of rough water performance.

If you want to increase performance in adverse conditions, investigate high lift props.

 

[JASinIL2006]

Is the pressure on the Nauticus pistons adjustable (meaning is there a valve you could bleed off or maybe even add gas pressure)? Or would you have had to buy new pistons if that was needed?

There are adjustments on SmartTabs. there are five different holes where you can attach the piston to the tab. If that isn’t enough adjustment, they allowed me to exchange pistons to a softer version at no additional cost. They were very helpful and accommodating.

 

[Scott Danforth]

you will need the shorter cylinders from Bennett on that transom as its similar to my old searay that I put bennett sport tabs on. I am not sure if the shorter cylinders are available with the self leveling if the feedback sensor fits in them. However the self leveling system is only so-so based on the issues that @alldodge had with the self leveling system. just get the bennett sport tabs and then have them swap out the cylinder for the short ones

 

[gsbarry]

you will need the shorter cylinders from Bennett on that transom as its similar to my old searay that I put bennett sport tabs on. I am not sure if the shorter cylinders are available with the self leveling if the feedback sensor fits in them. However the self leveling system is only so-so based on the issues that @alldodge had with the self leveling system. just get the bennett sport tabs and then have them swap out the cylinder for the short ones

Thanks Scott. I think I’ve convinced myself to spend the extra money and go with sport tabs. Out of curiosity, what were the issues alldodge had with the SLT’s?

 

[Scott Danforth]

what were the issues alldodge had with the SLT’s?

Here is his thread.

I installed the sport tabs on my SeaRay and never looked back. I did change from their switch to a nicer looking switch that matched the other dash switches.

 

[MikeSchinlaub]

Use a big plate on the inside when you mount it. I would assume they come with one, but you never know. Also, if the bolts are really long, don't stack a ton of washers to make them shorter.

@Scott Danforth you forgot to link the thread.

 

[gsbarry]

Here is his thread.

I installed the sport tabs on my SeaRay and never looked back. I did change from their switch to a nicer looking switch that matched the other dash switches.

Where did you source your new switch from? I was looking around for a third party tab position indicator gauge, the added cost of the Bennett one seems ridiculous for something fairly simple like that.

 

[dingbat]

Where did you source your new switch from? I was looking around for a third party tab position indicator gauge, the added cost of the Bennett one seems ridiculous for something fairly simple like that.

Not as simple as you believe.
Your paying for the two (2) LDTs (linear displacement transducers) that get installed in the cylinders to provide position feedback to the switch

You operate tabs by feel.
No reason to know tab position unless you like lighted gadgets

 

[Scott Danforth]

Where did you source your new switch from? I was looking around for a third party tab position indicator gauge, the added cost of the Bennett one seems ridiculous for something fairly simple like that.

A pair of Carling switches and wired per the Bennett manual

 

[Scott Danforth]

@Scott Danforth you forgot to link the thread.

Oops.

Bennett Trim Repair And Auto Pro Install

The port side trim cylinder needs repaired. It is cracked on the left side top and leaking fluid. The boat is a 1994 model so its kind of old. Looks like I can get the upper actuator hinge, just looking for the best repair and not necessarily the cheapest. Most the time I don't even use the...

forums.iboats.com

 

[gsbarry]

Oops.

Bennett Trim Repair And Auto Pro Install

The port side trim cylinder needs repaired. It is cracked on the left side top and leaking fluid. The boat is a 1994 model so its kind of old. Looks like I can get the upper actuator hinge, just looking for the best repair and not necessarily the cheapest. Most the time I don't even use the...

forums.iboats.com

That’s an interesting saga alldodge went through. Definitely makes me not want to ever upgrade to auto trim pro.

 

[gsbarry]

After more consulting with Bennett I decided to go with the Bolt 9x12” edge mount setup. Should arrive next week. The easier install, similar price, and up fins vs drop fins are what led to my decision. Bennett indicated that with the drop fins on the sport tabs one might have to shim the mount if your transom is not perfectly perpendicular to the boats through-line (i.e. not good if the drops fins are slightly askew).

 

[gsbarry]

I got the Bolt trim tabs installed this weekend. It all went pretty smooth overall. The most time-consuming part was cleaning up all the excess 5200 that squeezed out upon tightening the fasteners. I used a generous amount of 5200 to help deter leaks in the 24 holes that were drilled. On the upper hinge mounts I went with stainless through bolts instead of the supplied screws, as the transom was not very thick on the bump-out section, along with stacked washers, and lock washers. The port side was pretty tough to reach behind the gas tank, but I was just barely able to do it. A helper would have been great to hold the bolts in place while putting on the nuts. Instead my "helper" was a piece of duct tape holding the allen key on the bolt on the transom side while I turned on each nut. The reach was tough enough that I had to do it all by feel, but I got it done with a little patience. The starboard side was much easier as there wasn't much interference. The wiring and the helm control were pretty straightforward and went quickly.

 

[gsbarry]

I was able to get out on the water this past weekend and I was pretty happy with the performance of the trim tabs. I won't go so far as to stay it was night and day, but the performance improvement was certainly noticeable. For my application the most useful performance improvement was the overall stability of the hull in choppy conditions. I probably would not have stayed out very long without the trim tabs, but with them the ride was comfortable enough to enjoy. Hole shot was improved somewhat, although it wasn't bad before.