Cavitation plates (foils vs. whale tail) along with tabs.
 

I've read thru past posts, and searched the web. The world seems divided into
two camps

"trim tabs are a better choice"
"whale tails/foils are cheaper and do more for hole shot"

After reading, it seems there's two types of cavetation plate 'add ons' -- foils
that hydrodynamically lift the stern, and "whale tail" types that use prop wash.

My boat has trim tabs, but am looking for better hole shot, I've played around
with props already. before I make holes in my cavetation plate I wanted to know
if one or the other types of tails are worthwhile and if anyone can sum up
pros/cons between the two.

Lastly - will they really help more than the tabs did for hole shot? The boat
is a 92 22' cuddy cabin runabout with a single 350ci engine.

Cavitation plates (foils vs. whale tail) along with tabs.
 

That would be a stern drive unit then, eh?

You should not need any add on devices with a 350 with a boat that small.
Again, assume it is at least a 260 HP engine, eh? HP is so much more useful
than CID when looking at hole shot.

I just switched to a four blade prop to improve hole shot, acceleration, and
to maintain plane at lower RPM with my outboard engine. I assume I'll lose
some top speed but that is OK as long as I can turn the right RPM at WOT .

As your boat has tabs I seriously doubt you will much improve hole shot by
adding a hydrofoil device to the cavitation plate.

If your engine is producing sufficient HP, if your boat is not overloaded,
if your drive is properly proped, and if you are a good boat operator you
should have good, if not oustanding, hole shot.

If you do not have good hole shot and you are a competent operator with an
engine in good tune, I would revisit the prop selection issue.

Good luck.

Butch
"Doug" wrote in message
...
I've read thru past posts, and searched the web. The world seems divided
into
two camps

"trim tabs are a better choice"
"whale tails/foils are cheaper and do more for hole shot"

After reading, it seems there's two types of cavetation plate 'add ons' --
foils
that hydrodynamically lift the stern, and "whale tail" types that use prop
wash.

My boat has trim tabs, but am looking for better hole shot, I've played
around
with props already. before I make holes in my cavetation plate I wanted
to know
if one or the other types of tails are worthwhile and if anyone can sum up
pros/cons between the two.

Lastly - will they really help more than the tabs did for hole shot? The
boat
is a 92 22' cuddy cabin runabout with a single 350ci engine.

Cavitation plates (foils vs. whale tail) along with tabs.
 

On Sat, 10 Mar 2007 00:20:32 GMT, "Butch Davis"
wrote:

That would be a stern drive unit then, eh?

You should not need any add on devices with a 350 with a boat that small.
Again, assume it is at least a 260 HP engine, eh? HP is so much more useful
than CID when looking at hole shot.

I just switched to a four blade prop to improve hole shot, acceleration, and
to maintain plane at lower RPM with my outboard engine. I assume I'll lose
some top speed but that is OK as long as I can turn the right RPM at WOT .

As your boat has tabs I seriously doubt you will much improve hole shot by
adding a hydrofoil device to the cavitation plate.

If your engine is producing sufficient HP, if your boat is not overloaded,
if your drive is properly proped, and if you are a good boat operator you
should have good, if not oustanding, hole shot.

If you do not have good hole shot and you are a competent operator with an
engine in good tune, I would revisit the prop selection issue.

Couldn't have said it better.

Cavitation plates (foils vs. whale tail) along with tabs.
 

You shouldn't have a hole shot problem with a 350 in a 22' boat unless; 1
the engine is not running properly, 2 the boat is atypically heavy for a 22'
cuddy, or 3 your expectations for a 22' cuddy cabin hole shot are
unrealistic. The last one being if you want it to stand on it's tail when
you floor it you need a big block :-)

What brand boat? What's your top speed at wot? How long does it take to
get onto plane from a dead stop at wot? Any idea how heavy your boat is?
What's your typical crew and equipment load?

I disagree that whale tails offer any better hole shot than tabs. Both
apply downward force against the water and as a consequence lift the thing
they are bolted to, your boat. How much either does it depends on the
surface area, the angle of attack, and the weight of the boat. The whale
tail is not particularly influenced by the prop because when the outdrive is
trimmed down the prop remains at the same angle as the whale tail. And the
prop outflow is mostly behind the whale tail. The big advantage of trim
tabs is that their position is independent of the prop. And you can run
tabs hard down as long as you want where an outdrive should be trimmed to
the center range for extended runs to avoid increased ujoint wear.

If you have read around the web I suspect you have also come across comments
that suggest whale tails offer the most improvement on underpowered boats
and are less noticable on boats with bigger engines.

"Doug" wrote in message
...
I've read thru past posts, and searched the web. The world seems divided
into
two camps

"trim tabs are a better choice"
"whale tails/foils are cheaper and do more for hole shot"

After reading, it seems there's two types of cavetation plate 'add ons' --
foils
that hydrodynamically lift the stern, and "whale tail" types that use prop
wash.

My boat has trim tabs, but am looking for better hole shot, I've played
around
with props already. before I make holes in my cavetation plate I wanted
to know
if one or the other types of tails are worthwhile and if anyone can sum up
pros/cons between the two.

Lastly - will they really help more than the tabs did for hole shot? The
boat
is a 92 22' cuddy cabin runabout with a single 350ci engine.

Cavitation plates (foils vs. whale tail) along with tabs.
 

"trim tabs are a better choice"
"whale tails/foils are cheaper and do more for hole shot"
Lastly - will they really help more than the tabs did for hole shot?

I wouldn't think that tabs or hydrofoil would do much to help the hole shot,
since they don't deflect much water until the boat gets up to speed, but
either will allow you to plane somewhat faster and maintain a plane at a
slower speed.
If you want a better hole shot, changing the prop pitch will have much more
effect. Everyone says that you should select a prop that produces a WOT rpm
near the top of the recommended range, but I have a different theory. I
have a prop that produces a WOT rpm that is several hundred rpm over the
"desired" range, and it gives me a much better hole shot, as well as the
ability to bust over a wave or leap off of a wake that I encounter. I don't
do a lot of long-range high-speed cruising, so the reduction in
efficiency(mpg) is not as important to me as performance at lower speeds.
Think of it this way......if you had a car with a 5-speed transmission that
was stuck in one gear, would you rather have it stuck in 5th gear to get the
best performance at the highest speed, or have it stuck in third or fourth
gear for all-around performance? Boats have a similar scenario, except for
the prop slippage issue during the hole shot that you can reduce by
selecting a larger diameter or four-blade prop.

Cavitation plates (foils vs. whale tail) along with tabs.
 

What prop do you have now? 3 or 4 blade? pitch etc?

I have a 22' blue water w/ 240hp engine (v8, 350) & tabs. The tabs help get on
plane -- perhaps that's what you mean rather than "hole shot"?

In order to get teh boat on plane, you had to get going fast, otherwise, it
would 'settle down' and come off plane at lower speeds. The tabs helped there.
I've thought about using a whale tale, but decided not to to avoid extra stress
on the outdrive.

I'm with the others (but I know a lot less than they do) on working more with
your prop.


On Fri, 09 Mar 2007 14:20:55 -0800, Doug wrote:

I've read thru past posts, and searched the web. The world seems divided into
two camps

"trim tabs are a better choice"
"whale tails/foils are cheaper and do more for hole shot"

After reading, it seems there's two types of cavetation plate 'add ons' -- foils
that hydrodynamically lift the stern, and "whale tail" types that use prop wash.

My boat has trim tabs, but am looking for better hole shot, I've played around
with props already. before I make holes in my cavetation plate I wanted to know
if one or the other types of tails are worthwhile and if anyone can sum up
pros/cons between the two.

Lastly - will they really help more than the tabs did for hole shot? The boat
is a 92 22' cuddy cabin runabout with a single 350ci engine.


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