Trim Tabs ???

[Bobnfl]

I have a 2006 nitro 750 bass boat with a 90hp mercury optimax. The motor has a ss 22p prop on it and turns 5700rpm's. the boat is underpowered and it is slow getting out of the hole. I have tried 4 blade props but they do little good. will trim tabs or a hydrofoil fin work? which one would be better. By the way WOT is 51mph by gps. Help please.
Bob

 

[Silver Heels]

Re: Trim Tabs ???

I am not well versed on bass...mine is a 20 ft cuddy...but it seems to me like you might simply be over-propped at a 90 horse with 22p. Decrease the pitch and you'll get on plane sooner. For what its worth, I have trim tabs. They seem to help a little with getting on plane sooner. To get max speed, they are trimmed up all the way, so they don't help there. On my boat, their big attraction is fine tuning for load and sea conditions once I'm up on plane, so they may be of little value for what your after. Many on this forum swear by them as the end all be all for any boat handling problems...I'm sure they'll chime in soon.

 

[iconracing]

Re: Trim Tabs ???

i have them and i didnt see much improvement 19ft runabout 4.3 mercruiser

 

[Boatist]

Re: Trim Tabs ???

I do not know your boat or motor.
For the best hole shot you want a prop that will let your motor reach it's max RPMS
at full throttle when you have a light load.
A 4 blade prop shoud have a faster hole shot and get on plane faster but loose up to 3 MPH in top speed.

I have Bennett trim tabs on my 21 foot I/O and love them.
It gives me complete control of the boats trim at any Speed with any Load and any Sea condition.

Trim tabs will decrease your top speed 1 to 3 MPH. The tabs have some drag even all the way up. Also they will lower the bow some even all the way up.
With a lower bow you have more hull drag. More drag means lower Mile per gallon also.
These negitive things are very small and not much to pay for the great improvement in the way the boat rides and how you can control the ride.

One place where they will improve Miles per Gallon is in rough seas where it is not safe to go over 15 MPH and your boat will not plane until 20 MPH.
In this condition you put the tabs down until you reach plane at 15 MPH.
The bow comes down and you stop plowing, the bow is cutting the waves and you reduce the throttle to stay at the safe speed of 15 mph.

I will never have another boat with out Helm Contolled Trim Tabs and will never have a Hydro Foil.

 

[joe009]

Re: Trim Tabs ???

all the above info is good and true.foils will get you on plane faster.imo i have all three,tilt,tabs, foils

 

[ziggy]

Re: Trim Tabs ???

i have all three,tilt,tabs, foils

. tabs and a hydrofoil... i think yer supposed to have one or the other. bet they're working against ea. other.

op, before ya do tabs. get the prop right. ya want one that ya can reach your wot spec. on the high side w/ your normal load and trim. a 4 blade will add lift to the stern and make for a better holeshot, though you'll likely loose a little speed...

if ya still have issues, then ya might pursue tabs of some kind.

 

[Chris-R]

Re: Trim Tabs ???

Get your prop right before doing anything else. a 3 blade prop will give you more speed at WOT than a 4 blade prop, everything else being equal. If that doesn't do it, and it sounds like it won't, then try a hydrofoil. I have a hydrofoil on my boat and it gets up on plane very quickly and without a problem. The hydrofoil makes a big difference and I wouldn't be without it. Trim tabs are great as well and I've had them on previous boats that I owned in the salt water and would never buy a big boat without them but for your size boat, you may want to try the hydrofoil first.

 

[Tabman]

Re: Trim Tabs ???

Boatist is spot on in regards to the benefits of Helm Controlled Trim Tabs. I would like to point out that if Trim Tabs are installed with the proper amount of negative angle when fully retracted they should not scrub any speed off the top end and not hold the bow down when not in use. Negative angle is the amount the Trim Tab is angled above the bottom of the hull when retracted. Additionally on some of our Trim Tabs designed for faster boats the we call for the leading edge where the Trim Plane is attached to the transom to be mounted slightly above the bottom of the hull. Combined with the proper negative angle this allows the Trim Plane to ride above the water flow when the boat is planing, thus creating no lift when retracted.

In some instances where this is occurring we can help the boat owner modify the stroke of the actuators so that they retract further, increasing the negative angle, raise the Trim Planes above the water flow so they are not affecting the boat's trim when fully retracted.

 

[Philster]

Re: Trim Tabs ???

The OP has an underpowered boat.

Accessories won't make it accelerate faster. 99% of the problem is the engine/prop.

Optimax engines are 2-strokers, right? 2-strokers light up faster than the
4-strokers, and a 4-blade prop was tried, and he is at max operating RPM... right at the top of the range actually.

Doesn't seem to be much room for improvement. Can't drop pitch.

I'd like to hear more about the experiments with 4-blade props. I believe a four-blade prop (the right one) is the best answer, as it should get more accel and bite from that 2-stroker and knock off just a little RPM, dropping him right in the middle of the max RPM range. This is the meat of the issue: Getting a good/responsive 4-blade SS prop.

 

[lakegeorge]

Re: Trim Tabs ???

I'm still trying to figure out why Bass boats need to go 70 mph? The Bass aren't going anywhere and 15 seconds longer to get to the fishing spot won't change anything.

I watched the pros on Lake Lanier last month and some of them didn't fish in one spot for over 2 minutes and then off they went at 70 mph. It was really funny.

 

[rwidman]

Re: Trim Tabs ???

I'm still trying to figure out why Bass boats need to go 70 mph? The Bass aren't going anywhere and 15 seconds longer to get to the fishing spot won't change anything.

I watched the pros on Lake Lanier last month and some of them didn't fish in one spot for over 2 minutes and then off they went at 70 mph. It was really funny.

Yes but think about how cool they look going 70 mph in that little boat with the rooster tail and all!

 

[QC]

Re: Trim Tabs ???

The OP has an underpowered boat.

How is a 51 MPH boat underpowered?

Accessories won't make it accelerate faster. 99% of the problem is the engine/prop.

Trim tabs will absolutely, 100% bring the bow over faster and can thus improve acceleration. I'll test this with you anytime you want. You bring the stopwatch to Havasu, and I'll bring the boat, fuel and beer, oh, and I already have the trim tabs . . .

Optimax engines are 2-strokers, right? 2-strokers light up faster than the
4-strokers, and a 4-blade prop was tried, and he is at max operating RPM... right at the top of the range actually.

Doesn't seem to be much room for improvement.

Yes two stroke, what about vents?

Yes but think about how cool they look going 70 mph in that little boat with the rooster tail and all!

Yeah, they do look cool, just like a Displacement hull does at hull speed with no wake . . . or a blow cat flying a hull, or a 12 Meter with a full Spinnaker, or a 5 bhp tinny on plane, or a Squirt boat with a place diverter, or an Offshore racer with a surfacing drive . . .

 

[Philster]

Re: Trim Tabs ???

Um, HE called it unpowered. To him, slow out of the hole is underpowered. I didn't recommend a new engine. I went to the prop:

Vents: Sure, didn't I refer to the prop as room for improvement?

I have this thing about trim tabs. Maybe it's me. I am hung up on hating them. I'll give you that. I like to exhaust everything else before trim tabs are resorted to. Call me crazy.

I like to eliminate variables: In this case, the prop. Because it runs like the dickens at 5700 RPMs and good top speed, in my mind this thing has hole shot potential. Again... I look to the prop first because he has enough juice... and it's a 2-stroker.... so I have a hard time believing we should jump on some trim tabs first. Last? Yes... last, but they're on the list of things to try.

For me, that's an improvement.

 

[Philster]

Re: Trim Tabs ???

How is a 51 MPH boat underpowered?


.

When the operator doesn't like the hole shot, or is getting passed by identical boats doing 58.

Anything under 60 is underpowered. Damn Max HP ratings!

 

[Bobnfl]

Re: Trim Tabs ???

The only thing wrong with my boat is it is a little slow getting out of the hole. I tried 4 blade props 21p & 20p both showed little or no improvement with higher than recommended rpm. so I am looking at a hydrofoil or trim tabs. which is better for hole shots? oh by the way my prop does have 5/16" vent holes in it and according to a prop specialist the prop I have is ideal for my boat.My boat is rated for 75hp to 135hp. that is why I am saying that it is under powered. and by the way even though it my run 51mph I cruise at 40 to 45mph.
Good Fishing Bob

 

[QC]

Re: Trim Tabs ???

Vents: Sure, didn't I refer to the prop as room for improvement?

Yeah, but vents seem to me to be the way to achieve a little better hole shot without losing the top end.

I have this thing about trim tabs. Maybe it's me. I am hung up on hating them. I'll give you that. I like to exhaust everything else before trim tabs are resorted to. Call me crazy.

You're eff'n crazy and you need to take me up on my challenge. Personally, I hate hydrofoils, but have loosened up to the fact that they may be OK on certain (read very small) hulls. Tabs, on the other hand, should be standard equipment on all V-hulls over 15 ft. and they should absolutely be on your boat . . .

 

[Philster]

Re: Trim Tabs ???

Got me some tabs: Bennet Dual Ram Hydraulic

Don't use them. Don't need them.

But, I am getting over my anti-tab issues. Not for me, but they must be needed for some. Never needed them on a variety of boats over the years.

 

[Tabman]

Re: Trim Tabs ???

OK, let's think about Trim Tabs like flaps on an aircraft. Flaps are used to create more lift on takeoff and retracted to reduce drag at higher speeds. Trim Tabs accomplish the same thing and opposed to a hydrofoil are not always causing drag.

Also a hydrofoil is "coupled" to the motor's trim and changing the trim for best speed can affect trim when using a hydrofoil. Trim Tabs allow you to trim the hull's attitude when needed and the power trim is used for trimming the propeller for maximum efficiency.

I'll admit I'm biased, but having spend many years working with Trim Tabs and boat owners I know that they are the most effective way to pop a boat on plane faster. I agree that getting the right prop on the boat is key, but if you take a look at Flat's Fishing Boats (the gurus of skinny water hole shots) you will find that virtually every one of them is fitted with Trim Tabs.

 

[QC]

Re: Trim Tabs ???

Don't use them. Don't need them.

I'll bet I could make your boat faster with proper use. I could show you about 15 different conditions where'd I could improve the ride, safety and handling of your boat simply with tab adjustments. All V-hulls can benefit, and I don't sell them . . . maybe I should . . .

 

[Philster]

Re: Trim Tabs ???

I need to avoid trim tab threads like the dreaded oil threads.

When you come out to the East Coast, let me know and I'll take you for a spin, and you can learn me good.

I never want a boat that needs trim tabs to survive a hole shot or to make time-to-plane bearable. If it comes to that, I'm not owning a boat.