technically your both right in some aspect the trim tabs that are adjustable
are retracted once on plane creating less drag, there still is some due to
the added wetting surface but it is minimal, but some boats need tabs to get
up, w/out them it would not plane and it would than be a semi-displacement
boat and be very inefficient at high rpm's. it matters the application.

"Joe" wrote in message
...

"basskisser" wrote in message
om...
"Joe" wrote in message
...
"basskisser" wrote in message
om...
"Joe" wrote in message
...
I see you have decided not to argue against the facts for a
change.

There may be hope for you yet.

Idiot boy, do you not think that a PROPERLY TRIMMED boat, ie: weight
distribution, would out perform the exact same boat that was not
trimmed properly, but instead used trim tabs?

No, it would not. Equalization of weight would not outweigh the
advantages
of the lift provided by trim tabs.

Let me ask you a question, if a boat with trim tabs is able to plane
at
20
knots with the tabs adjust correctly, but must achieve 30 knots to
plane
without tabs, will adjusting the weight distribution in the boat
allow
the
boat to plane at 20 knots as it could with the tabs?

Again,dumb JoeTechnician, you were speaking of EFFICIENCY. I don't
give a damn about the speed at which the boat planes. I'm telling you
that if you stick a couple of plates in the ****ing water, and drag
them THROUGH the water, you are creating drag. You will use more power
to plane at 20 knots because you have to drag those plates through the
water. Does pulling a skier make your boat more efficient, too????

You can do the exact same thing with an aircraft, you can either
trim
it out by distributing the weight properly, which then you don't
need
to use tabs to trim it, or you can stick trim tabs out in the air.
Now, which would YOU think more fuel efficient??

Do you really think the dynamics of an aircraft flying through air is
the
same as a planing hull on water?

Never said they were the same thing, but, there is a direct
correlation between tabs on an aircraft, and tabs on a boat. Thusly:
they both create drag. They both create lift. BUT again, at a cost.
Same thing with an airplane, you generally use some tabs for takeoff,
because the lift is so much better. But, when you get up to altitude,
you certainly don't use the tabs because the efficiency of dragging
them through the air makes fuel consumption rates rise.


You're forgetting something, when tabs are deployed on an aircraft, and
produce lift, efficiency does not increase because the density of the air
is
equal on all sides of the aircraft. On a boat it is much different, water
is
approximately 800 times more dense than air and any reduction in wetted
surface will always result in increased efficiency. Properly activated
tabs
reduce the wetted area by providing lift at the stern, planing the boat,
and
lowering the bow reducing the hill of water the boat must overcome. Add to
this the more efficient prop angle which reduces prop slippage and energy
wasted pushing up instead of forward and the overall efficiency of the
boat
is greatly increased.

It's obvious that you have never owned a boat with trim tabs. I suggest
you
go along for a ride with someone who does have them and observe them in
action.

"Wildest Dream" wrote in message
et...
technically your both right in some aspect the trim tabs that are
adjustable
are retracted once on plane creating less drag, there still is some due to
the added wetting surface but it is minimal, but some boats need tabs to
get
up, w/out them it would not plane and it would than be a semi-displacement
boat and be very inefficient at high rpm's. it matters the application.


Of course they will not be efficient on every boat, nor at every speed, but
my contention is that they *can* reduce drag when used correctly on a
planing hull. Basskisser's contention is that they *can't* reduce drag since
they create some drag themselves. I have been very careful to always state
that to increase efficiency the tabs be used "properly" or "correctly" and
have provided real world scenario's, but he still argues that they can not
increase efficiency due to their drag. He is dead wrong.

All *planning hulls* will see *some* improvement in efficiency at various
speeds. This improvement will mostly be realized in slow to midrange speeds.

Here's an idea, ask your buddy Krause to use his flow meters and compare the
GPH with tabs and without at midrange power.

"Joe" wrote in message news:Pgstb.58486
All *planning hulls* will see *some* improvement in efficiency at various
speeds. This improvement will mostly be realized in slow to midrange speeds.

So, JoeTechnician, are you trying to say that trim tabs, when extended
into the water, don't create drag? My contention is a properly trimmed
boat, ie: weight distribution, etc. is correct, wouldn't need trim
tabs. Why would a company build a hull that was engineered to give a
unefficient ride?? I can see the use of trim tabs to get on plane, but
after that, they ARE creating drag, and a good bit. Do this, take a
plate of material the same size as the TWO trim tabs, fill your
bathtub full of water, and try to pull those through the water. Now
using some simple math, you'd see that at planning speed, that drag is
quite a bit.

"basskisser" wrote in message
om...
"Joe" wrote in message news:Pgstb.58486
All *planning hulls* will see *some* improvement in efficiency at
various
speeds. This improvement will mostly be realized in slow to midrange
speeds.

So, JoeTechnician, are you trying to say that trim tabs, when extended
into the water, don't create drag?

I never said they didn't.
I said "But, if the drag they do create is less than the drag they reduce
(stern
dive, pushing a wall of water against the bottom of the hull), and
inefficient prop angle (wasted energy pushing the bow up instead of the boat
forward) then the overall decrease in drag will result in increased fuel
efficiency."

And this is the case on a planing hull in slow to moderate speeds. I have
never seen a planing hull that didn't benefit from the addition of trim
tabs. Put them on a displacement hull and you'd probably *only* create drag.

My contention is a properly trimmed boat, ie: weight distribution, etc. is
correct, wouldn't need trim
tabs.

Distribution of weight will not create lift. It can help, but can not equal
the benefit of the tabs.

Why would a company build a hull that was engineered to give a
unefficient ride??

A planing hull can not be designed to operate efficiently throughout the
range of operation. They are designed to be efficient at higher speeds.

I can see the use of trim tabs to get on plane, but
after that, they ARE creating drag, and a good bit.

They may create some drag but this drag is reducing the overall drag of the
boat. At midrange power most boats can not stay on plane without them. If
you retract them fully at those speeds the stern drops,the bow rises, and
efficiency is lost.

Do this, take a plate of material the same size as the TWO trim tabs, fill
your
bathtub full of water, and try to pull those through the water. Now
using some simple math, you'd see that at planning speed, that drag is
quite a bit.

Tabs are not *pulled* through the water, nor angled down into the water at
the same angles as aircraft tabs. On my boat, you can barely tell the
difference in angle between full up, and the angle needed to hold plane at
slower speeds.

Again, I suggest you take a ride with someone who has them.

"basskisser" wrote in message
om...

My contention is a properly trimmed
boat, ie: weight distribution, etc. is correct, wouldn't need trim
tabs.

Very few boats are "properly trimmed" and have the appropriate weight
distribution for all speed ranges.

Why would a company build a hull that was engineered to give a
unefficient ride??

Because it provides a much more useable boat. It is VERY common to have a
stern heavy I/O. It is rather difficult to move the engine forward, and to
move the passenger seating far enough forward to balance the boat would
provide an unacceptable ride.

I can see the use of trim tabs to get on plane, but
after that, they ARE creating drag, and a good bit.

There is no doubt that the trim tabs drag, but they can reduce the amont of
drag that the hull creates and this will often be the dominant factor.

On many boats the trim tabs are essential for getting on plane. After
that, the trim tabs can be adjusted to provide the best ride and/or speed
(which usually is an indication of reduced drag and increased efficiency).

If you over extend the trim tabs you will force the bow down into the water
and increase the drag. If you retract the trim tabs, many boats will go
into a bow up position, which also increases drag. It isn't necessary to
understand which forces are acting against each other, just watch the
speedometer as you adjust the trim tabs.

Rod McInnis

How about the automatic trim tabs controller sold by bennett? Is this a
reasonable option or can they be dangerous should they fail at the wrong time?
There is no doubt that the trim tabs drag, but they can reduce the amont of
drag that the hull creates and this will often be the dominant factor.

On many boats the trim tabs are essential for getting on plane. After
that, the trim tabs can be adjusted to provide the best ride and/or speed
(which usually is an indication of reduced drag and increased efficiency).

If you over extend the trim tabs you will force the bow down into the water
and increase the drag. If you retract the trim tabs, many boats will go
into a bow up position, which also increases drag. It isn't necessary to
understand which forces are acting against each other, just watch the
speedometer as you adjust the trim tabs.

Rod McInnis

"Diver1055" wrote in message
...
How about the automatic trim tabs controller sold by bennett? Is this a
reasonable option or can they be dangerous should they fail at the wrong
time?

That's a good question. I know on my boat if I keep adjusting the tabs down
I will eventually get to a point where the bow plunges hard and the boat
will pull extremely hard one way or another to the point at which the boat
can not be controlled. I've only tried this at slow speeds, I'd hate to have
it happen unexpectedly at high speeds.

"Joe" wrote in message .. .
"basskisser" wrote in message
om...
"Joe" wrote in message news:Pgstb.58486
All *planning hulls* will see *some* improvement in efficiency at
various
speeds. This improvement will mostly be realized in slow to midrange
speeds.

So, JoeTechnician, are you trying to say that trim tabs, when extended
into the water, don't create drag?

I never said they didn't.
I said "But, if the drag they do create is less than the drag they reduce
(stern
dive, pushing a wall of water against the bottom of the hull), and
inefficient prop angle (wasted energy pushing the bow up instead of the boat
forward) then the overall decrease in drag will result in increased fuel
efficiency."

And this is the case on a planing hull in slow to moderate speeds. I have
never seen a planing hull that didn't benefit from the addition of trim
tabs. Put them on a displacement hull and you'd probably *only* create drag.

My contention is a properly trimmed boat, ie: weight distribution, etc. is
correct, wouldn't need trim
tabs.

Distribution of weight will not create lift. It can help, but can not equal
the benefit of the tabs.

No, proper hull design will "create lift".

Why would a company build a hull that was engineered to give a
unefficient ride??

A planing hull can not be designed to operate efficiently throughout the
range of operation. They are designed to be efficient at higher speeds.

I can see the use of trim tabs to get on plane, but
after that, they ARE creating drag, and a good bit.

They may create some drag but this drag is reducing the overall drag of the
boat. At midrange power most boats can not stay on plane without them. If
you retract them fully at those speeds the stern drops,the bow rises, and
efficiency is lost.

Do this, take a plate of material the same size as the TWO trim tabs, fill
your
bathtub full of water, and try to pull those through the water. Now
using some simple math, you'd see that at planning speed, that drag is
quite a bit.

Tabs are not *pulled* through the water, nor angled down into the water at
the same angles as aircraft tabs. On my boat, you can barely tell the
difference in angle between full up, and the angle needed to hold plane at
slower speeds.

Again, I suggest you take a ride with someone who has them.

Again, you are saying that you use trim tabs (creating drag) to push
the bow into the water, leveling the boat. My contention is that the
more wet surface of the hull, the more drag you are creating. Now, you
may like the nice level ride, but it is still creating drag. Twice.
One, the tabs are creating drag, two the bow is creating drag. Now,
does the efficiency improve? I'll agree, with a caveat. SOME boats may
actually see a gain in performance, with the prop angle closer to
horizontal, and the stern being up out of the ditch, but a good
planing hull may actually be less efficient. It's a boat to boat kind
of thing. Some may improve, some may not.

Again, you are saying that you use trim tabs (creating drag) to push
the bow into the water, leveling the boat.

No, you raise the stern, and lower the bow, but not to the point your
plowing it into the water.

My contention is that the more wet surface of the hull, the more drag you
are creating.

There's your hang-up, correctly deployed tabs *do* reduce the wetted surface
when correctly deployed at slow to medium speeds.

Now, you may like the nice level ride, but it is still creating drag.
Twice. One, the tabs are creating drag, two the bow is creating drag. Now,
does the efficiency improve?

No, at the slower to midrange speeds the drag the trim tabs reduce exceed
the drag produced by trim tabs themselves.
First the stern rises, then the bow lowers (not to the point of plowing)
reducing the wetted surface. Add to this the more efficient prop angle and
you will see an increase in overall efficiency. Again, they must be used
correctly.

I'll agree, with a caveat. SOME boats may
actually see a gain in performance, with the prop angle closer to
horizontal, and the stern being up out of the ditch,

So now you do agree that there can be an overall efficiency gain from the
drag produced by trim tabs.
Why didn't you start out your post with this statement?

but a good planing hull may actually be less efficient. It's a boat to boat
kind
of thing. Some may improve, some may not.

Your getting closer, but all planing hulls will benefit from the addition of
trim tabs to some degree.
Every planing hull will achieve plane faster and be able to cruise more
efficiently at slower speeds with trim tabs.