"whale tails" or cavitation plate foils
 

So, a buddy and I were talking -- he said I wasted my money on trim tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their cavitation
plates larger.

What's the general opinion on them?

-j



--- AntiSpam/harvest ---
Remove X's to send email to me.

"whale tails" or cavitation plate foils
 

Josh Assing wrote:
So, a buddy and I were talking -- he said I wasted my money on trim tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their cavitation
plates larger.

What's the general opinion on them?

Interesting question. I researched this when I bought my 14'
Princecraft with a 25 Johnson a couple of years ago.

There are two types that I'm aware of - Doelfin and Permatrim. Doelfin's
work like an airplane wing providing lift to the stern under power
forcing the bow down. Doelfins basically work with the water without
impeding the water flow.

The Permatrim devices work a little differently in that they work with
the water off the prop creating lift by retaining the water that spins
off the end of the prop and creating stern lift pressure that way.

I tested boats with both types and I can't really see where they make
much of a difference on boats with electric trim control. On small
boats, like my Princecraft, there is a difference because the running
trim angle is fixed and allows for quick bow lift and a pretty solid
running angle. Both types exhibit an odd tendency to dig in a sharp
turn which can bury the stern and on the boats I tested, prop cavitation
in turns where I wouldn't have expected a non-equipped prop to cavitate.

In my opinion, for boats with fixed trim, I can see where they would be
advantageous. With electric trim, not so much.

As to stress on the outdrive - it's negligible and not something that I
would worry about.

Boat trim is all about the proper application of power - meaning that
prop sizing, fixed trim angle and engine leg size are the real important
criteria. Can you adjust for any of these if they aren't correct with
one of these devices? I would say yes, but I wouldn't be the first one
on the block to buy one if I was having trim angle problems on take off.

I'd try something else first.

"whale tails" or cavitation plate foils
 

Thanks for the information.

so I guess it "depends" but probably "not worth it"

I always thought trim tabs are a better way to go than adding the fins.

-j

On Mon, 19 Feb 2007 16:28:34 GMT, Short Wave Sportfishing
wrote:

Josh Assing wrote:
So, a buddy and I were talking -- he said I wasted my money on trim tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their cavitation
plates larger.

What's the general opinion on them?

Interesting question. I researched this when I bought my 14'
Princecraft with a 25 Johnson a couple of years ago.

There are two types that I'm aware of - Doelfin and Permatrim. Doelfin's
work like an airplane wing providing lift to the stern under power
forcing the bow down. Doelfins basically work with the water without
impeding the water flow.

The Permatrim devices work a little differently in that they work with
the water off the prop creating lift by retaining the water that spins
off the end of the prop and creating stern lift pressure that way.

I tested boats with both types and I can't really see where they make
much of a difference on boats with electric trim control. On small
boats, like my Princecraft, there is a difference because the running
trim angle is fixed and allows for quick bow lift and a pretty solid
running angle. Both types exhibit an odd tendency to dig in a sharp
turn which can bury the stern and on the boats I tested, prop cavitation
in turns where I wouldn't have expected a non-equipped prop to cavitate.

In my opinion, for boats with fixed trim, I can see where they would be
advantageous. With electric trim, not so much.

As to stress on the outdrive - it's negligible and not something that I
would worry about.

Boat trim is all about the proper application of power - meaning that
prop sizing, fixed trim angle and engine leg size are the real important
criteria. Can you adjust for any of these if they aren't correct with
one of these devices? I would say yes, but I wouldn't be the first one
on the block to buy one if I was having trim angle problems on take off.

I'd try something else first.


--- AntiSpam/harvest ---
Remove X's to send email to me.

"whale tails" or cavitation plate foils
 

Short Wave Sportfishing wrote:
Josh Assing wrote:
So, a buddy and I were talking -- he said I wasted my money on trim tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their cavitation
plates larger.

What's the general opinion on them?

Interesting question. I researched this when I bought my 14'
Princecraft with a 25 Johnson a couple of years ago.

There are two types that I'm aware of - Doelfin and Permatrim. Doelfin's
work like an airplane wing providing lift to the stern under power
forcing the bow down. Doelfins basically work with the water without
impeding the water flow.

The Permatrim devices work a little differently in that they work with
the water off the prop creating lift by retaining the water that spins
off the end of the prop and creating stern lift pressure that way.

I tested boats with both types and I can't really see where they make
much of a difference on boats with electric trim control. On small
boats, like my Princecraft, there is a difference because the running
trim angle is fixed and allows for quick bow lift and a pretty solid
running angle. Both types exhibit an odd tendency to dig in a sharp
turn which can bury the stern and on the boats I tested, prop cavitation
in turns where I wouldn't have expected a non-equipped prop to cavitate.

In my opinion, for boats with fixed trim, I can see where they would be
advantageous. With electric trim, not so much.

As to stress on the outdrive - it's negligible and not something that I
would worry about.

Boat trim is all about the proper application of power - meaning that
prop sizing, fixed trim angle and engine leg size are the real important
criteria. Can you adjust for any of these if they aren't correct with
one of these devices? I would say yes, but I wouldn't be the first one
on the block to buy one if I was having trim angle problems on take off.

I'd try something else first.

Maybe we're talking different crafts here, but my little ChrisCraft
169 (18 ft) with alpha drive and 3.0 GM engine, had a fin bolted onto
the cav. plate. OK, well I hit a stump , pr something and wrecked the
lower unit. I found a salvage leg, and bolted everything up. the
salvage unit didn't have a fin on the plate, and I had thought of
transfering the fin over, but boating season was running short, and I
wanted to head to the lake really bad. so away we went. I really
couldn't tell much performance difference between the two, except
accelerating performance took a little bit longer to drop the bow, but
nothing I couldn't live with. PLUS, really slow speed steering seemed
to be effected, that it didn't want to go straight as well, not bad
but seemed to be noticable.

I'm not going to install the fin and my 23 ft. marquis with 350 chevy
and MR drive doesn't have a fin , and it's been doing well since 1977
without one, and I doubt I'll install one on it either.

I suppsoe they ahve their place, but I haven't found it on my stuff.

"whale tails" or cavitation plate foils
 

"Josh Assing" wrote in message
...
So, a buddy and I were talking -- he said I wasted my money on trim tabs.
I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their
cavitation
plates larger.

What's the general opinion on them?



Our 19 ft CC with 125hp I/O (no power trim) has a Stingray hydrofoil, and
without it, the prop cavitates very easily in a high power turn. A bit lower
planing speed and less bow rise with it, but the reason I keep it on is
mainly cavitation prevention.

"whale tails" or cavitation plate foils
 

Josh Assing wrote:
Thanks for the information.

so I guess it "depends" but probably "not worth it"

I always thought trim tabs are a better way to go than adding the fins.

That's a completely different discussion.

Side to side stabilization is much very different than reducing bow lift
while getting the boat on plane.

"whale tails" or cavitation plate foils
 

Bob Smith wrote:
"Josh Assing" wrote in message
...
So, a buddy and I were talking -- he said I wasted my money on trim tabs.
I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and if
something that simple really helped, manufactures would make their
cavitation
plates larger.

What's the general opinion on them?

Our 19 ft CC with 125hp I/O (no power trim) has a Stingray hydrofoil, and
without it, the prop cavitates very easily in a high power turn. A bit lower
planing speed and less bow rise with it, but the reason I keep it on is
mainly cavitation prevention.

I would suspect that the angle of your drive in the turn and prop
selection has more to do with the cavitation problem than the plate.

"whale tails" or cavitation plate foils
 

"Short Wave Sportfishing" wrote in message
...
Bob Smith wrote:
"Josh Assing" wrote in message
...
So, a buddy and I were talking -- he said I wasted my money on trim
tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and
if
something that simple really helped, manufactures would make their
cavitation
plates larger.

What's the general opinion on them?

Our 19 ft CC with 125hp I/O (no power trim) has a Stingray hydrofoil, and
without it, the prop cavitates very easily in a high power turn. A bit
lower planing speed and less bow rise with it, but the reason I keep it
on is mainly cavitation prevention.

I would suspect that the angle of your drive in the turn and prop
selection has more to do with the cavitation problem than the plate.



Angle is not adjustable, since our outdrive (VP 270) needs to be locked in
the "down" position when operating. All three of our props (14x19SS, 14x17
aluminum, 15x15 aluminum) exhibit the same cavitiation upon cornering w/o
the fin. I'm not pro-fin or anti-fin, I just know that this one needs to
stay on our boat.

"whale tails" or cavitation plate foils
 

Bob Smith wrote:
"Short Wave Sportfishing" wrote in message
...
Bob Smith wrote:
"Josh Assing" wrote in message
...
So, a buddy and I were talking -- he said I wasted my money on trim
tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and
if
something that simple really helped, manufactures would make their
cavitation
plates larger.

What's the general opinion on them?
Our 19 ft CC with 125hp I/O (no power trim) has a Stingray hydrofoil, and
without it, the prop cavitates very easily in a high power turn. A bit
lower planing speed and less bow rise with it, but the reason I keep it
on is mainly cavitation prevention.
I would suspect that the angle of your drive in the turn and prop
selection has more to do with the cavitation problem than the plate.

Angle is not adjustable, since our outdrive (VP 270) needs to be locked in
the "down" position when operating. All three of our props (14x19SS, 14x17
aluminum, 15x15 aluminum) exhibit the same cavitiation upon cornering w/o
the fin. I'm not pro-fin or anti-fin, I just know that this one needs to
stay on our boat.

Interesting.

That's the great thing about boats - every single one of them is
different in some way.

I'm a small boat guy and I get to play and test a lot of small boats -
in the 16 to 22 foot range - mostly fishing boats on pre-delivery runups
for some local dealers.

You can test two identical boats except for color and each of them will
handle differently by comparison. Some will turn a little tighter, plane
a little faster, higher top end, etc.

It's definetly a curiosity.

"whale tails" or cavitation plate foils
 

"Short Wave Sportfishing" wrote in message
m...
Bob Smith wrote:
"Short Wave Sportfishing" wrote in message
...
Bob Smith wrote:
"Josh Assing" wrote in message
...
So, a buddy and I were talking -- he said I wasted my money on trim
tabs. I
said I did not.

The conversation revolved around the use of whale tails (foils on the
cavitation plate).

I said that they could help; but would add stress to the outdrive, and
if
something that simple really helped, manufactures would make their
cavitation
plates larger.

What's the general opinion on them?
Our 19 ft CC with 125hp I/O (no power trim) has a Stingray hydrofoil,
and without it, the prop cavitates very easily in a high power turn. A
bit lower planing speed and less bow rise with it, but the reason I
keep it on is mainly cavitation prevention.
I would suspect that the angle of your drive in the turn and prop
selection has more to do with the cavitation problem than the plate.

Angle is not adjustable, since our outdrive (VP 270) needs to be locked
in the "down" position when operating. All three of our props (14x19SS,
14x17 aluminum, 15x15 aluminum) exhibit the same cavitiation upon
cornering w/o the fin. I'm not pro-fin or anti-fin, I just know that this
one needs to stay on our boat.

Interesting.

That's the great thing about boats - every single one of them is different
in some way.

I'm a small boat guy and I get to play and test a lot of small boats - in
the 16 to 22 foot range - mostly fishing boats on pre-delivery runups for
some local dealers.

You can test two identical boats except for color and each of them will
handle differently by comparison. Some will turn a little tighter, plane a
little faster, higher top end, etc.

It's definetly a curiosity.

Isn't a good deal of that weight variation in fiberglass hulls?