Sportsman/Fisherman 180 - Trim Tabs

[corinthmistral]

Good evening. I am a reasonably experienced boater but trim tabs are completely new to me, so apologies for what may be stupid questions.
I have a GW 180 (2008) with a Yamaha F150 and factory fitted Bennett trim tabs. I use the motor trim all of the time and am getting pretty conversant with that - usually have it trimmed down at low speeds, accelerate onto the plane and then trim up to get her riding smoothly and economically (I can usually see the motor gain 200rpm when she is trimmed comfortably.) The exception is in larger seas, where she starts porpoising - then I usually trim down and the porpoising stops. So, two questions for the learned forum:
1. am I correct in trimming down to stop porpoising?
2. are trim tabs on a 180 necessary? when/how should I use them, and can they be used to stop porpoising? If so, where should I set them and where should I simultaneously set the the motor trim?
Thanks in advance for the education.

 

[seasick]

Many old salts will say that other than correcting for leaning, you don't need tabs. In your case, I would first try trimming the motor down to reduce purposing. Of course all boats are different so experimenting is best. It can be easy to over deploy tabs especially if you don't know how far the tabs have been deployed.
Note that tabs add drag and drag burns more fuel. In certain cases tabs can help get a hull on plane faster but would then be retracted partly or entirely after planing is achieved

 

[corinthmistral]

Many old salts will say that other than correcting for leaning, you don't need tabs. In your case, I would first try trimming the motor down to reduce purposing. Of course all boats are different so experimenting is best. It can be easy to over deploy tabs especially if you don't know how far the tabs have been deployed.
Note that tabs add drag and drag burns more fuel. In certain cases tabs can help get a hull on plane faster but would then be retracted partly or entirely after planing is achieved

Thank you. That’s very helpful.

 

[DennisG01]

Tabs are an excellent "tool" to have. They can have a huge impact on getting you onto plane faster... running on plane at a slower speed... correcting listing (more noticeable in a small boat with where people sit)... stopping the porpoising... keeping the bow planted in chop for a smoother ride... once you understand them and get comfortable using them, you'll never want a boat without them.

The trick is to think what you want the BOW to do and each rocker button controls that. The port rocker button controls the port bow and vice versa. Even though the button actually controls the opposite side tab... Newton's Third Law of Motion. So think about what you want each side of the bow to do and push the buttons accordingly. Push the top of the button to push the bow down - push the bottom of the button to raise the bow. It might make more sense if you think of the last one as pulling the top of the button to pull the bow up - sort of like an airplane stick... push forward to go down, pull back to go up.

As you start playing with them, you'll inevitably hold the button too long and the boat will lean one way and then the other. You'll get the hang of it the more you use them... just like engine trim.

In a chop, you can trim your motor down to keep the bow planted... but with tabs, you can leave the motor in a more neutral trim angle (better, more efficient thrust) and instead, use the tabs to calm the bow. You'll find that you won't scrub speed off as much using tabs as you would be lowering the engine. In other words, tabs are BETTER FOR FUEL ECONOMY.

 

[corinthmistral]

Tabs are an excellent "tool" to have. They can have a huge impact on getting you onto plane faster... running on plane at a slower speed... correcting listing (more noticeable in a small boat with where people sit)... stopping the porpoising... keeping the bow planted in chop for a smoother ride... once you understand them and get comfortable using them, you'll never want a boat without them.

The trick is to think what you want the BOW to do and each rocker button controls that. The port rocker button controls the port bow and vice versa. Even though the button actually controls the opposite side tab... Newton's Third Law of Motion. So think about what you want each side of the bow to do and push the buttons accordingly. Push the top of the button to push the bow down - push the bottom of the button to raise the bow. It might make more sense if you think of the last one as pulling the top of the button to pull the bow up - sort of like an airplane stick... push forward to go down, pull back to go up.

As you start playing with them, you'll inevitably hold the button too long and the boat will lean one way and then the other. You'll get the hang of it the more you use them... just like engine trim.

In a chop, you can trim your motor down to keep the bow planted... but with tabs, you can leave the motor in a more neutral trim angle (better, more efficient thrust) and instead, use the tabs to calm the bow. You'll find that you won't scrub speed off as much using tabs as you would be lowering the engine. In other words, tabs are BETTER FOR FUEL ECONOMY.

That is super helpful and clearly explained. Thank you. Next time out I shall have a play with them.

 

[REBThunderroad]

I have a 2006 GW 180 and 2005 Marlin 300. On the Marlin I rarely if ever use the tabs and run the boat primarily with engine tilt and trim.

The GW 180 is a different animal...It runs bow high to get on plane and with a 7.5 foot beam is tipsy loaded. Saying that I use tabs more on 180...

You are correct to trim down during porpoise. You may find that running slight tabs (both of them) on the 180 keeps the bow down a bit with people on the back.

If I have 6 people on board I get on plane with tilt trimmed down and tabs all the way down to pop up on plane. You will use tabs a lot on 180 for different conditions but they are a great tool.

 

[Recoil Rob]

I put them on mine last year, wouldn't be without them, especially since I have a (heavy) Honda 150 hanging off the back. I trim motor down most of the way and tabs down about half to get on plane. I adjust motor trim till I get optimum speed for rpm and the trim the boat with the tabs.