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



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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.

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.


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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.

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

Tabs will help get the bow down faster, not the same as "reducing lift" but the
result is the same, at least it seems to me it is.

So I guess, from the other posts, I was wrong & my friend was right. I hate
it when I have to admit I'm wrong.


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

Tabs will help get the bow down faster, not the same as "reducing lift" but the
result is the same, at least it seems to me it is.

So I guess, from the other posts, I was wrong & my friend was right. I hate
it when I have to admit I'm wrong.

Welcome to the club - I've made an entire career out of being wrong. :)

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.

"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.

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.

"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.