Trim tab use

[Firemedic181]

Wondering what your thoughts on tab use is. I have always thought the bow should be up and out of the water as much as possible while underway, was reading an article that stated trim tabs should be down and the bow down in the water while underway, this confuses me.
Our boat is 2000 410 sundancer.

 

[Creekwood]

It depends on the boat I think. You use the tabs to find the most efficient running angle (fore/aft) and level (side to side) for your hull and the speed you are running at. There is an optimum that you will be able to feel, especially with a 410 with gas engines. Where the boat is running the fastest and smoothest at a given engine RPM, and isn't bow high (I doubt you can over trim down and plow the bow on a 410DA with your tabs, but that is an issue on smaller boats). For some boats, its very little tab. On my little 330, I have a lot of chain in the anchor locker that helps keep the bow down, so at cruise (30 to 32 mph), I am running with as little tab as possible (used for leveling, not keeping the bow down). At slower speeds (barely on plane - maybe down to 20 mph?), I use more tab to keep the bow down.

If its rough and you are running on plane into large waves, bow down with more trim can reduce pounding, but at the cost of efficiency. Barely on plane, you will need full tabs to hold the bow down to prevent squatting and keep the boat more level for visibility over the bow.

With your boat, its possible you may need full tabs when on plane if the boat won't stay bow down on its own. Some of the large aft cabins like to run full tabs all the time because they barely can get on plane.

 

[Stee6043]

I like to run as level as possible, to heck with MPG's!

I don't have a trim level indicator but I suspect I have 50% tab in, or slightly more, every time I'm on plane. Full tab when it's choppy...

 

[Firemedic181]

It depends on the boat I think. You use the tabs to find the most efficient running angle (fore/aft) and level (side to side) for your hull and the speed you are running at. There is an optimum that you will be able to feel, especially with a 410 with gas engines. Where the boat is running the fastest and smoothest at a given engine RPM, and isn't bow high (I doubt you can over trim down and plow the bow on a 410DA with your tabs, but that is an issue on smaller boats). For some boats, its very little tab. On my little 330, I have a lot of chain in the anchor locker that helps keep the bow down, so at cruise (30 to 32 mph), I am running with as little tab as possible (used for leveling, not keeping the bow down). At slower speeds (barely on plane - maybe down to 20 mph?), I use more tab to keep the bow down.

If its rough and you are running on plane into large waves, bow down with more trim can reduce pounding, but at the cost of efficiency. Barely on plane, you will need full tabs to hold the bow down to prevent squatting and keep the boat more level for visibility over the bow.

With your boat, its possible you may need full tabs when on plane if the boat won't stay bow down on its own. Some of the large aft cabins like to run full tabs all the time because they barely can get on plane.

Thanks for the reply, I’ll be testing it out to see what the best efficiency is for us and of course conditions will warrant how we run as well.

 

[jmauld]

I like bow down. Smoother ride and it helps keep the exhuast fumes out of the cockpit.

 

[jmauld]

I’m also thinking that I will order an automatic trim controller at some point this year. I just need to finish up a few other projects before jumping into the next one.

 

[Creekwood]

I’m also thinking that I will order an automatic trim controller at some point this year. I just need to finish up a few other projects before jumping into the next one.

I have Bennett ATC. It’s awesome. That’s why I know how tabs are set when on plane. I set the level when I am on plane based on tabs fully up. Once set the ATC will try to hold it at that angle and level. So when I slow down they automatically deploy to try to hold that level.

 

[jmauld]

I have Bennett ATC. It’s awesome. That’s why I know how tabs are set when on plane. I set the level when I am on plane based on tabs fully up. Once set the ATC will try to hold it at that angle and level. So when I slow down they automatically deploy to try to hold that level.

Is this the one that you have?
https://www.boemarine.com/catalogsearch/result/?q=AP000A1BC