smart tabs on a heavy boat

[thunder]

my boat is a gradywhite 205 overnighter chevy 350 2 big batterys fuel tank oh ya people i tried a se 300 hydrofoil nothing, alot of guys said smart tabs will work great, there web site says it will help greatly,i was wondering if any one with a heavy boat uses them the has no leaks,holes, soggybottom it's a heavy butt boat thanks MIKE

[freebie]

what is the boat doing that makes you think you need them. a boat that big I would think you need real trim tabs. bennet is the best.

[thunder]

the boat does'nt plane fast or at all

[freebie]

mercruiser? it should plane no problem with that motor in there unless you have a running issue. are you trimming the drive down enough? maybe try to move some more weight forward but I don't think that's the issue

[thunder]

boat runs great it's that little bit change in weight if some one goes up front the boat goes about 40 i'm looking at lenco and bennett

[Raider Ronnie]

Tabs are meant to level ride (list) not so much jump on plane quicker.

[numbskull]

Provided the engine is trimmed correctly, I would consider a different prop with less pitch and larger blades (or more blades).

[Van]

If a 20 footer needs trimtabs, there is something strange going on.
Gradys are a heavy boat but still should not need trim tabs.
Tabs can bring your bow up or down.

My hydfrofoil on my 21 proline with a 175 works great and can change the pitch while underway. But I'm pushing with an outboard.

You say your'e doing 40 mph but not at plane?
You may have a prop issue. Its a easy and cheaper fix.
Maybe look into that first.

[Mr. Sandman]

Originally Posted by numbskull

Provided the engine is trimmed correctly, I would consider a different prop with less pitch and larger blades (or more blades).

Bingo! we have a winner!

You have the wrong prop. Prop selection is a compromise that allows for decent low mid range performance with near peak at cruise. If you are far off it will not even plane. For example, many big boats with twin outboards (or inboards) can not plane on one engine because the props are selected assuming the other engine is operating, take it away and the single prop cant even push the boat on plane. (hence the "need" for trips and quads in those go fast tournamnt boats)

[Fish On]

Jim sounds like you've studied hydrodynamics ;-)

[Pete_G]

If you decide to try trim tabs I'd go with real trim tabs. I've always felt there's no hard and fast rules with trim tabs and that they are useful on almost any boat, and necessary on some. Some boats (deep v's for example) are optimized for some things but can end up lacking in some ways because of it.

I use them regularly on a deep V at night to help me hang on plane at a slower speed when the boat is heavily loaded or viz is low and I want to be on plane. Otherwise I would have to move faster then I would like to or fall off plane and go slower then necessary with my bow pointed skyward.

Also I often drop them (especially when heavy on fuel, passengers, and ice it makes a big difference) to get on plane quicker.

On many hulls, especially go fast centers dropping the bow into choppy seas is standard procedure and achieving that via engine trim isn't the best way to do it.

I avoid correcting list with a tab if I can move weight or passengers instead as you can feel the drag of the single lowered tab.

The 24 foot center I generally run would really be a mess without them, especially at battle weight with a crew, ice, and a full tank of fuel. Once it is lightened up after burning off some of the tank, its behavior in rough seas, ride quality, and fuel efficiency are still greatly effected by the trim tabs. It was built for them; if they are fully up, at any speed and fuel load it will not plane happily. It'll get up, it just doesn't feel right, it feels uneasy and the bow porpoises along. Trimmed properly, and speed and fuel efficiency noticeably climb (despite the same throttle setting). You can literally feel the boat get "happy" when it's trimmed right. The engines start to sing and all is right with the world. If you're really sensitive to your boat even a person or two moving to the bow might want to make you back off a touch on the trim.

It's important to note some boats respond to and/or need them more then others, but I think it would be rare to find a boat (and it's passengers) that wouldn't benefit from them. Maybe Grady has an opinion on how helpful tabs are on that hull?

As suggested though a starting point might be taking a look at the prop.

[thunder]

thanks guys,i went with lenco's with auto retrieve,shut the power off and they go up, it's like having a new boat,the boat rides better,turns flatter,going slow it's flat,planes real fast,nice level ride going 30mph through 3 footers like a knife,well a big fat grady knife thanks again for all the help

[MrHunters]

i got the lenco's auto retrieve is a nice feature

i would forget always.

[KeyWest225]

Looks like I stumbled across the right post! I too am having problems with porpoising. I have a 23 deep V with a 225 Verado. That's a lot of weight in the stern, not to mention my batteries are also mounted back there too. I have the Lenco tabs. I have been searching all over the web, including the forums and have learned different techniques to deal with it but the one that most intrigues me is worth bringing up here. Although tabbing the bow down helps, the boat still wants to porpoise. Somebody suggested that my prop is too far below the waterline - ie my engine is mounted too low. I checked and there are 3 other holes on the bracket that will allow the engine to be raised. I am thinking this is my next step. Anybody know more about this than I do? Thx

[Roger]

Originally Posted by KeyWest225

Although tabbing the bow down helps, the boat still wants to porpoise. Somebody suggested that my prop is too far below the waterline - ie my engine is mounted too low.

That's been my experience - outboard too low. With the engine in neutral trim, you should barely need any tabs, or none, to avoid porpoising in flat water.

With an IO, engine height is not an option - obviously. They're left with motor trim, trim tabs, prop selection, etc as the alternatives.

[thunder]

the trim tabs work great but now i'm thinking about the prop,it says 5052-17 on the side,i cant even find it on the web it's a s/s prop the rpm and speed is close the motor does'nt overrev but with a 350 i think it should have some more get up and go

[Roger]

Originally Posted by thunder

the trim tabs work great but now i'm thinking about the prop,it says 5052-17 on the side,i cant even find it on the web it's a s/s prop the rpm and speed is close the motor does'nt overrev but with a 350 i think it should have some more get up and go

Huh? Close to what?

[Slipknot]

Originally Posted by KeyWest225

Looks like I stumbled across the right post! I too am having problems with porpoising. I have a 23 deep V with a 225 Verado. That's a lot of weight in the stern, not to mention my batteries are also mounted back there too. I have the Lenco tabs. I have been searching all over the web, including the forums and have learned different techniques to deal with it but the one that most intrigues me is worth bringing up here. Although tabbing the bow down helps, the boat still wants to porpoise. Somebody suggested that my prop is too far below the waterline - ie my engine is mounted too low. I checked and there are 3 other holes on the bracket that will allow the engine to be raised. I am thinking this is my next step. Anybody know more about this than I do? Thx

I don't know any more about that issue than you, but it sounds logical. And I think I will raise my 9.9 honda on my skiff up an inch since I get porpoising also. I look at the motor and the fins just above the water inlets is about an inch + below the lowest point of the hull on my skiff. Also I don't believe it is sitting 90 degrees to the plane of the hull so I might need a slight wedge also.
I am gonna give this a try before next time I go out.

[macojoe]

Are you guys running a tac?? If you are reaching the WOT RPMs from the motors company then you are fine, if you are to low or high tghen you need to get the right prop!
If no tac then get one!

[numbskull]

Originally Posted by macojoe

Are you guys running a tac?? If you are reaching the WOT RPMs from the motors company then you are fine, if you are to low or high tghen you need to get the right prop!
If no tac then get one!

Not exactly. His problem is prop pitch. A lower pitch and larger diameter would give him more bite at low rpm, but similar top rpm numbers. His top end performance (ie speed and fuel efficiency) would suffer SLIGHTLY......but his boat would run better and plane more easily. Being able to remain on plane at lower speed and higher bow trim is a HUGE advantage when the going gets tough....and well worth giving up a little high end performance unless you plan to cover very long ranges at very high speeds on very nice days only.

[macojoe]

I had much the same issue with my V20, I had a 15 x 15 1/2 prop and it worked great for the heavy loads I use to have, much of the other V20's have 17 pitch. I also had Hydrofoil and no tabs

Good Luck