Bennett SLT6 trim tabs? Anyone running them?

[erictetterton]

So I’m running an Alweld 1448LA with a 25hp Yamaha 4 stroke. I have a Atlas micro hydraulic jack plate. 3 blade SRA3 prop. Boat has manual trim tabs welded on from the factory, but the boat still porpoises on occasion when entering a headwind, making running a hassle due to having to stop and re-adjust the manual trim of the motor. I’m wondering if the Bennett self leveling trim tabs may offer an advantage over the manual ones that came stock on the Alweld? I’ve been reading a lot about them and most seem to like them. The only negative I’ve heard is that on lighter boats, the spring is too stiff, causing the tab to bury the bow of the boat in the water, causing loss of top end speed. On my current setup, I’ve adjusted them to a fairly neutral position, but no matter what, the boat will porpoise. I feel that the self leveling tabs will give me more control of the boat, while also helping the boat get on plane faster. Any feedback would be appreciated. They are only $86 by the way. I was originally going to go with the electric tabs for ultimate control and adjustability, but at over $500 and I would have to run more wires, I thought I would explore this option first.

https://bennetttrimtabs.com/springloadedtrimtabs/

 

[CedarRiverScooter]

It's hard to see the tabs in your photos, so I may be off base here, but it looks to me that they would be more effective if they were larger. Maybe you can just add some material with stainless steel screws, overlap needs to go with the water flow.

 

[erictetterton]

It's hard to see the tabs in your photos, so I may be off base here, but it looks to me that they would be more effective if they were larger. Maybe you can just add some material with stainless steel screws, overlap needs to go with the water flow.

Yeah the tabs present from the factory are something like 2” by 8”. The Bennett tabs are 6” by 8”. I definitely think the bigger tab will give a more effective result.

 

[gatorglenn]

Your problem isn’t the taps. It’s the long shaft motor on that transom. With the jackplate all the way up , in the pic. The prop to pad is still to low.


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[erictetterton]

Your problem isn’t the taps. It’s the long shaft motor on that transom. With the jackplate all the way up , in the pic. The prop to pad is still to low.


Sent from my iPad using Tapatalk

Jack plate all the way up, the cavitation plate is 2” above the bottom of the boat. It’s just high enough that I can still run it wide open without prop blowout (thanks to the SS SRA3 prop). So no, the jack plate is not my problem. My motor not having electric tilt/trim is. I have a 21” transom and a long shaft motor plus a jack plate. I’m paired appropriately.

 

[turbotodd]

Problem is the hull.

They put those "tabs" on it to band-aid a hull design problem. There's many ways to deal with that, from a manufacturing standpoint. They found the cheapest and easiest. Seen more than a few guys beat a hook into the last few inches of the hull to stop this exact issue (porpoising)-but I refuse to go beating on a good hull and would rather work at it in other ways.

You're correct in that PT&T will fix it. What you have is a classic issue of a well-set up rig for one particular water condition with no way to adjust for changing conditions; and that's where PT&T comes in nicely, gives you the ability to change the angle of the motor to account for differences in water conditions and loading conditions among other things.

Have never used tabs, and never had a need to on the little tin boats. I usually set up on the conservative side of things rather than working toward max speed because achieving max speed usually means there's a compromise somewhere else.

The SRA prop is a little aggressive for a 4 stroke, IMO. I found it to have a little too much rake which causes it to have a little more "bow lift" than I like to see on "most" aluminum hulls; which leads to porpoising in certain conditions without a way to adjust the trim angle. SRA is really better suited for a modified 2 stroke, or more specifically, that's been my personal experience with 'em.

Another option. If one trim hole is too low and the next is too high, put a couple spacers on the pin, or one long one, which gives you a halfway between scenario. I've used that option before and it works pretty good, but again, will NEVER take the place of PT&T.

Could you drop the motor a half inch and run a less aggressive prop on it? Or is that out of the question?

Another option. Bob's tilt & jac, if your pockets are deep enough

 

[gatorglenn]

Your problem isn’t the taps. It’s the long shaft motor on that transom. With the jackplate all the way up , in the pic. The prop to pad is still to low.


Sent from my iPad using Tapatalk

Jack plate all the way up, the cavitation plate is 2” above the bottom of the boat. It’s just high enough that I can still run it wide open without prop blowout (thanks to the SS SRA3 prop). So no, the jack plate is not my problem. My motor not having electric tilt/trim is. I have a 21” transom and a long shaft motor plus a jack plate. I’m paired appropriately.

Ok, just going off the pics. It looks to be 3” below. One thing you can try, is to put a bead of jb weld on the edge of the transom. This will do the same thing as beating a hook in the bottom, as mentioned. Try 3/8” if you get no porpoising. File it down 1/8” at a time, until it starts again. Then you can have that bead welded on. At the size you need. Put the bead between the bottom straights on each side of the motor. But not in the middle in front of the motor.

For years Ranger has been putting a pair of angle wedges on the mod V boats. For this same problem, instead of redesigning the hulls. But those wedges are to much. So a lot of guys are filing them down to a bead. This is something I have do for someone on there Crestliner mod v. So it’s very inexpensive but it does work.


Sent from my iPad using Tapatalk

 

[erictetterton]

Problem is the hull.

They put those "tabs" on it to band-aid a hull design problem. There's many ways to deal with that, from a manufacturing standpoint. They found the cheapest and easiest. Seen more than a few guys beat a hook into the last few inches of the hull to stop this exact issue (porpoising)-but I refuse to go beating on a good hull and would rather work at it in other ways.

You're correct in that PT&T will fix it. What you have is a classic issue of a well-set up rig for one particular water condition with no way to adjust for changing conditions; and that's where PT&T comes in nicely, gives you the ability to change the angle of the motor to account for differences in water conditions and loading conditions among other things.

Have never used tabs, and never had a need to on the little tin boats. I usually set up on the conservative side of things rather than working toward max speed because achieving max speed usually means there's a compromise somewhere else.

The SRA prop is a little aggressive for a 4 stroke, IMO. I found it to have a little too much rake which causes it to have a little more "bow lift" than I like to see on "most" aluminum hulls; which leads to porpoising in certain conditions without a way to adjust the trim angle. SRA is really better suited for a modified 2 stroke, or more specifically, that's been my personal experience with 'em.

Another option. If one trim hole is too low and the next is too high, put a couple spacers on the pin, or one long one, which gives you a halfway between scenario. I've used that option before and it works pretty good, but again, will NEVER take the place of PT&T.

Could you drop the motor a half inch and run a less aggressive prop on it? Or is that out of the question?

Another option. Bob's tilt & jac, if your pockets are deep enough

Thanks for the reply, the SRA prop took the performance of my motor to a whole new level while using the jack plate. The stock aluminum prop wouldn’t bite when I jacked the motor up. I agree, it caused too much bow rise and now I have the porpoise issue with a headwind. Trimming the motor between the two settings would be an easy solution that I could easily try. The only problem that is still present is the ever changing water conditions and weight distribution. The ultimate fix would be that bobs jack plate with t/t but that price tag is out of my league for this setup. I was considering this $85 solution because it would be a simple/cost effective fix. There are lots of fixes to this problem and yes, I agree that the hull design is is the issue.

 

[erictetterton]

Your problem isn’t the taps. It’s the long shaft motor on that transom. With the jackplate all the way up , in the pic. The prop to pad is still to low.


Sent from my iPad using Tapatalk

Jack plate all the way up, the cavitation plate is 2” above the bottom of the boat. It’s just high enough that I can still run it wide open without prop blowout (thanks to the SS SRA3 prop). So no, the jack plate is not my problem. My motor not having electric tilt/trim is. I have a 21” transom and a long shaft motor plus a jack plate. I’m paired appropriately.

Ok, just going off the pics. It looks to be 3” below. One thing you can try, is to put a bead of jb weld on the edge of the transom. This will do the same thing as beating a hook in the bottom, as mentioned. Try 3/8” if you get no porpoising. File it down 1/8” at a time, until it starts again. Then you can have that bead welded on. At the size you need. Put the bead between the bottom straights on each side of the motor. But not in the middle in front of the motor.

For years Ranger has been putting a pair of angle wedges on the mod V boats. For this same problem, instead of redesigning the hulls. But those wedges are to much. So a lot of guys are filing them down to a bead. This is something I have do for someone on there Crestliner mod v. So it’s very inexpensive but it does work.


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I like that idea. I’ll consider doing that to see if it helps. Thank you

 

[DaleH]

In response to your initial inquiry, the Bennett self-leveling tabs or SLTs are a similar product to the Smart Tabs of which member Richg99 here has installed on many small tin boats.

See his experiences - link below - as he likes the 'gas shock' system of the SmartTab vs the heavy 'mechanical spring' system of the Bennett Marine SLT tabs. Just my guess, but I bet Bennett (who makes both hydraulic & electric tabs) were losing a bit of the market by not having a low-cost non-powered tab option, so they came up with their own, but had to use the spring to get around the patent on the gas shock.

https://www.forum.tinboats.net/viewtopic.php?f=3&t=45624&hilit=smart+tab

I myself would definitely NEVER use SMartTabs or any "auto" tab on a saltwater boat or one where you need to run rivers with holes and rapids (in case of a following sea condition) but for flat water use ... I can see the advantages vs. no tabs or just a foil.

 

[thill]

I have used Smart tabs and the Bennett tabs on a number of boats, both my own and customer's. (I own a small marine repair shop, and have owned a LOT of boats)

I like the Smart tabs A LOT. They make an amazing difference in the handling of smaller boats especially. Like night and day- really! Some boats really don't need them, but when you start tweaking the performance like the OP of this thread, they are gold.

In my opinion, the Bennet SLT tabs LOOK more impressive, with the thick cylinder, and they work okay, but are not as good as the Smart Tabs.

The biggest reason is that you order the cylinders with the pounds of pressure you designate with the Smart Tabs. With an aluminum boat, for instance, you may need 30# cylinders to keep the nose stable, without plowing, whereas you might need 80# of pressure on a 17' fiberglass center console. With Smart tabs, you order the cylinder that fits your boat.

The Bennetts only come in one size and cylinder pressure, the last time I bought a pair. A one-size-fits-all approach, which is less effective, in my opinion.

In response to DaleH's comment about following seas - Both brands come with locking pins. You pull up on the tab and stick in the pin to lock them up. I've very rarely used them, and I've probably been out in rougher seas than most people on this board, as have you, looking at that tuna pic. But that being said, I avoid nasty inlets on the outgoing tide in my little boat!

-TH

 

[erictetterton]

So far I am impressed with them. I am still tuning them to find the best performance with my setup. I agree that being able to order different springs in different poundage would be nice. Mine came with 57# springs. The SLT 10 comes with 90# springs. One thing that I have considered is trimming a coil off of the original spring if your bow plows down too much and your adjustment plate is maxed out. You could also find a replacement spring at Lowe’s or online. It’s 4&1/8” x 1&1/8”. For $85, you can’t go wrong with these in my opinion.