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Tabs will help, but using tabs while running is not very efficient. Porpoising is usually caused by too much weight aft. Performance boats with too much engine usually have this problem, and putting the tabs down just a little will help.
 

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Tabs will help, but using tabs while running is not very efficient. Porpoising is usually caused by too much weight aft. Performance boats with too much engine usually have this problem, and putting the tabs down just a little will help.
curious as to why you say tabs aren't efficent? I thought that was the purpose of trim tabs? mine are pretty much all the way down when I run wot and still get up around 50mph. infact once i get over 2400rpm I have to start moving them if I want to see over the bow.....28'cc (triton 2895) seems pretty efficient to me:huh:
 

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Discussion Starter · #7 ·
thanks for the feedback....weight in the back is definatly a factor....i notice it more when i have a full tank(have to keep it around a half) i already planned on putting them on this year, so hopefully it will help with the porpoising too.
 

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curious as to why you say tabs aren't efficent? I thought that was the purpose of trim tabs? mine are pretty much all the way down when I run wot and still get up around 50mph. infact once i get over 2400rpm I have to start moving them if I want to see over the bow.....28'cc (triton 2895) seems pretty efficient to me:huh:
Trim tabs are like brakes in the water, they create drag. Anytime you put something in the water like that it will slow you down. They are designed to either level the boat, from too much weight on one side or the other or from prop torque. Also to help plane the boat, but once your on plane you should lift them. Why would you run wot with them down, other than maybe correcting the porpoise problem.
 

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my old 22 wa did not have tabs..with the 225 i got up on plane quickly and only porposed when trimmed up too much.. my new ride(yet to get wet) is a 20 foot v20 with bennett trim tabs and a 225 zuk...what do i need these tabs for..i have plenty of power to get up on plane and as stated.. if down they create drag..when would i use them (other than uneven load) and why:confused:
 

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maybe try a hydrofoil wing on your motor. i tried one on my 13' whaler and it was great. i know your boat is larger but maybe it will help. also try to redistribute weight in the boat front to back and side to side. will probably help a lot.
 

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Your Hydrasport should not be porpoising.. First what Hydrasport is it? Seahorse or a Vector?

What year is the boat? What engine is on it..? Who made the prop on it? What size, dia and pitch? What rpm will the engine turn wide open trimmed up? Engine mounting bolt position?

Porpoising, yes can be caused by too much weight aft...AKA heavy NEW engine, but it's just as likely the engine is mounted too low on the transom in combo with a prop that can't carry the bow of the boat. Simple as that..........or as complicated as bad stringers in the boat letting the bottom flex.
 

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Trim tabs are like brakes in the water, they create drag. Anytime you put something in the water like that it will slow you down. They are designed to either level the boat, from too much weight on one side or the other or from prop torque. Also to help plane the boat, but once your on plane you should lift them. Why would you run wot with them down, other than maybe correcting the porpoise problem.
I get the "drag" part but if I raised them once on plain the bow would come right up:huh:
 

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A lot of misinfo out there about tabs and trimming...if your engine trims well...tabs won't be much more help. Tabs are good for any side to side trimming but the bow trim is primarily done with the motor....inboards are a different story.

Trim tabs may increase a bit of drag...but if they give the boat better trim they can increase speed and/or efficiency (even when down). If you have to use too much tab to get the desired effect...usually you need bigger tabs.

Bottom line is that I doubt tabs will help with your porposing...if engine trim won't help...unless you just can't get your bow down...try getting some weight forward first..then try tabs or like Dunk mentioned by having someone eyeball the mounting height.
 

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Discussion Starter · #15 ·
Thanks again for the feedback, I plan to get tabs put on anyway...to help stabilize the boat side to side, help navigate some head winds, etc.
I agree with the weight issue...as I stated earlier, when I have a full tank it seems to happen more often...it is mounted on the middle hole of the bracket(that may be an option also)....the engine is a 2003 175 Yamaha, I'll have to check the prop size and pitch(more good information...thank you).....I may be blowing this up a little....it doesn't happen all of the time, depends on wind direction, sea conditions, weight, etc....was my 1st season with an outboard...as usual, we learn as we go.:thumbsup:
 

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Trim tabs are like brakes in the water, they create drag. Anytime you put something in the water like that it will slow you down. They are designed to either level the boat, from too much weight on one side or the other or from prop torque. Also to help plane the boat, but once your on plane you should lift them. Why would you run wot with them down, other than maybe correcting the porpoise problem.

No way - if the tabs give you a better running angle then you are going to be MORE efficient.

I can tab 2-3mph with my boat when I am at 4200rpm. Small engine trim and tab adjustments help me get "dialed in" to the best possible trim angle for any given sea state.
 

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No way - if the tabs give you a better running angle then you are going to be MORE efficient.

I can tab 2-3mph with my boat when I am at 4200rpm. Small engine trim and tab adjustments help me get "dialed in" to the best possible trim angle for any given sea state.
Same happened with my 37' diesel boat. The boat was designed for gas but had an additional 2-3 thousand pounds withthe diesels. If I trimmed most of the way down...the boat ran a solid 2 knots faster.

I've seen it many times on heavily loaded boats...some of the old big Sea Rays I ran benifited the same.
 

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Trim tabs were the best thing I have put on my 17 mako. On the recommendation from Dunk, I installed the next size up from what was recommended. The difference in the ride is unbelievable.
 
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