That entirely depends on the boat. For my boat, the answer is a resounding yes. I’ve also been on boats (an under-powered single I/O for example) that needed tabs up.

 

This is interesting since we have "pretty similar" boats and I've never used my tabs to get on plane. My 400 planes so much better than my 340 did I never thought to try for better/faster

 

I absolutely need tabs down to get on plane, she pops right up while with them up, it takes a while.
I probably depends on how much weight is up front vs passengers in the back etc.
I get up on plane pretty quickly even with 6-8 people in the back

 

Generally speaking, yes, tabs are going to help get on plane faster and even keep the bow from bouncing around in a chop as it keeps the bow planted better so it slices through the water. Whether they're really "needed" on a particular hull is dependent on hull design, conditions and even owner preference. But they can only help - it's just that "how much" is a huge variable based on lot's of variables.

Best thing to do? Go try them! Deploy them all the way and advance the throttle all the way and see the difference. Again, there's lot's of variables here, but once you're on plane, it's generally advisable to retract them somewhat - sometimes leaving them all the way down puts too much hull in the water and will cause listing once on plane. Sometimes this happens with too much outdrive down trim, too (again depending on hull and other variables). But... just like using your drive trim will affect hole shot - tabs will help in the same way.

Since you have outdrives... you can fine tune better than v-drives and get better fuel economy. Basically, you want to the outdrives trimmed parallel with the hull or slightly "up". This frees up the hull and gets it further out of the water (less drag). Then fine tune with the tabs as they won't scrub speed as fast as the drives do when you trim the drives down.

To sum up... go out and play! Real, live experience is the best thing!

 

As Dennis points out it depends on the boat. The deployment strategy for an outdrive setup is different than with fixed propellers be they Vee drive, classical inboard, or pods. With fixed position props tabs are almost needed to improve time to planing. With sterndrives not so much.

When getting a sterndrive boat on plane the drive is trimmed all the way down (about 6:00 on a trim gauge). As power is applied the nose comes up and once it is up, and the boat is beginning to plane, the trim is backed off (about 7:00-8:00). This will result in a slight increase in RPM.

With the B3 drive trimmed all the way down the force from the props is actually pushing on a line that is slightly pointed up into the hull. Although the gauge shows a 6:00 orientation it is closer to a spot between 6:00 and 5:00. In effect the props are trying to push the nose up. When the boat does reach plane the props are now oriented pointing up even more. By backing off the trim, the props are now more in a parallel line with the hull, the load is reduced, rpm rises, and things are running more efficiently. Trim tabs are now only needed to fine tune and to level the hull port/stbd. With our single engined 280 I found using the tabs to get on plane actually made it harder, probably because of the drag they created was greater than any lift force.

With fixed attitude props, trim tabs are needed much more. Since the props have a fixed attitude in relation to the hull, they are positioned for when the hull is in an orientation when it is on plane so that they run most efficiently when being used as intended. The getting on plane part is less of a priority, so the props may not be in the best position for doing that. Here is where the tabs can become very important in improving reaching planing speeds.

 

I had a bayliner 2355 that really needed tabs to get up. My current boat, with tabs down, just burns gas, churns water and flounders. With tabs up she comes up nice.

 

Another option with Bravo III drives is to adjust the trip limit insert from the standard aft position to the forward position. This allows the drive to be further down when trimmed all the way down. The benefit is improved stern lift and hole shot, though the trade-off is that you have to be more cognizant of trimming the drive(s) up as soon as you get on plane. Otherwise (just like tabs fully down), you’ll be subject to bow steering as there will be too much bow in the water unless the drive(s) are trimmed up.

On our 240 DA, with full fuel and 6 adults in the cockpit, I use my tabs to lift the stern and get on plane faster. My biggest reason for doing so is that I try everything I can to avoid plowing through the lake. Alternatively, I can have 2 or 3 people move to the cabin and it makes a big difference.

As others have said, go out on a quiet day and play around and see what you find works best for you. Tabs are a very useful tool and when used judiciously don’t make a huge impact on fuel economy.