Running with trim tabs down

BahamasBlair said:
Guys,
On my 340, I always run with the tabs down at least half way if I have a full take of gas (225 gals). That extra weight seems to make the boat heavier in the aft sections. I get around 3 extra MPH for the same amount of throttle which translates into a bit of fuel economy. Once I get down to a half tank of fuel, I tend to run without the tabs and use them only to balance the boat if we have crosswinds.
Also, at any speed below 3300 rpm the boat runs better with tabs down regardless of how much fuel we are carrying. Hope this helps a bit.
Click to expand...

Ditto, and it frustrates me that I do not have a way to monitor tab position on my 02 340. This will be something I will want to add.
 
With the diesel trim tabs, when I push the buttons I can feel the boat movement Port and Starboard. With the factory tabs and the buttons its almost inpossible to know were the tabs are because they do not react much or at all.
 
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How are the trim tabs used
with the rocker switch??

Pressing the top of the rocker switch will bring the trim tabs up??
and pressing the bottom of the rocker switch will bring the trim tabs down??
 
I must be missing something here. I run tabs when running into currents or chop. I always monitor my RPM's, MPH, and MPG on the Smartcraft gauges while underway. I'm always looking for the most efficient speed, for where I want to get and when, in order to save fuel (depending on conditions). I almost always see the speed drop, and a corresponding down-tic in MPG when running tabs (at a moderate or aggressive angle).
 
billnpat said:
How are the trim tabs used
with the rocker switch??

Pressing the top of the rocker switch will bring the trim tabs up??
and pressing the bottom of the rocker switch will bring the trim tabs down??
Click to expand...

I think it is the opposite...........
 
We have a '05 340, 6.2 with Vdrives & run trim tabs down when on plane. It lowers the nose enough that the increase in drag of the tabs is negated by the better angle of the hull & props. I'm usually heavy with water & fuel. My go fast setting is 4000 rpm...smartcraft indicated this is best while 1600 is best low speed. A buddy of mine bought an '04 340 with 8.1s a couple of weeks ago & it was noticably quicker acceleration, top speed, greater fuel burn, quicker response at idle going from forward to reverse & back. For our situation I still prefer our 6.2s...fresh water operation, no great distance to travel, save 20K at purchase & ease of maintance.
 
Skuza said:
This really puzzles me. I adust the tabs almost every time I go out trying to find max speed which I think would be max efficiency. Never have I found full down tabs to be most efficient. It labors the engines and plows the water. Yes it smashes the waves a little better than banging over the top of them but I rarely am in such conditions. What am I missing here???
For a reference I managed 26mph at 3400rpm full of fuel and water this past weekend.
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You're not missing anything. Your conditions sound normal. Take extreme conditions - heavy boat, big seas... Now your might want them down more.

Just from reading these posts and some past experience, it seems that boats with engines on the smaller end of the spectrum than the average for their boat find tabs down to be more useful.
 
allan1 said:
With the diesel trim tabs, when I push the buttons I can feel the boat movement Port and Starboard. With the factory tabs and the buttons its almost inpossible to know were the tabs are because they do not react much or at all.
Click to expand...


Thanks for the info. I've always felt the factory tabs on the 340 were too small. Gotta get those big tabs asap. :grin:
 
Im under the assumption that when trim tabs are down in fact they are facing down
and when up meaning straight out, RIGHT ?
...Up is flat out, straight out, there is NO up :smt021 , just straight out and down.....:thumbsup:
 
Billnpat:

Your are 100% correct. Trim tabs do not go up any further than even with the bottom of the boat. Up is up and down is down.
 
allan1 said:
Billnpat:

Your are 100% correct. Trim tabs do not go up any further than even with the bottom of the boat. Up is up and down is down.
Click to expand...

Thanks :thumbsup:
 
This is an interesting thread. By the time I get to about 2000...2500 rpms I need my tabs fully down to plane, and I have to keep them down, even after I reach 3200 to 3500 rpms. The slightest touch on my tab control raises my bow..but I am stearn heavy with gen, and a/c unit.
 
Rum Runner said:
This is an interesting thread. By the time I get to about 2000...2500 rpms I need my tabs fully down to plane, and I have to keep them down, even after I reach 3200 to 3500 rpms. The slightest touch on my tab control raises my bow..but I am stearn heavy with gen, and a/c unit.
Click to expand...


Agree:thumbsup: great thread:thumbsup:
 
Chris R said:
I must be missing something here. I run tabs when running into currents or chop. I always monitor my RPM's, MPH, and MPG on the Smartcraft gauges while underway. I'm always looking for the most efficient speed, for where I want to get and when, in order to save fuel (depending on conditions). I almost always see the speed drop, and a corresponding down-tic in MPG when running tabs (at a moderate or aggressive angle).
Click to expand...

You're not missing anything. That's the way a properly balanced boat should run- without tabs.

It's especially common for larger mid-cabin boats to need tabs in flat water. All that iron well aft of the boat's COG because of the V-drives...
 
Yachtmaster. said:
Thanks for the info. I've always felt the factory tabs on the 340 were too small. Gotta get those big tabs asap. :grin:
Click to expand...


I had called Bennett a few months ago about tabs for our 340 Dancer. I was told the stock tabs are for ride adjustment and that if I was interested in fuel economy I should get bigger tabs. I was told Sea Ray sizes the tabs for WOT so they are small.
 
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