More of that dang boating stuff here...

As I've put a number of hours on "Her Idea" (a Four Winns 195 Sundowner with
4.3L OMC Cobra), I'm coming to realize that there's quite an art to trimming the
drive (not the trim tabs, which I don't have) for conditions. I should mention
that I have one of those funky rubber "wings" bolted to the outdrive.

I've been coming out of the hole (lightly loaded) with the drive all the way
down, then bringing it up until the RPMs increase to the max (typically from
3800 to 4200) then bringing the throttle back to 4000 for cruise.

If there's much of a chop, or a lot of wakes, I've been bringing the bow back
down a bit to reduce pounding.

This seems to work reasonably well. Is there anything else I should be
considering?

Joe Parsons

On Fri, 05 Sep 2003 01:10:49 GMT, Joe Parsons
wrote:

More of that dang boating stuff here...

As I've put a number of hours on "Her Idea" (a Four Winns 195 Sundowner with
4.3L OMC Cobra), I'm coming to realize that there's quite an art to trimming the
drive (not the trim tabs, which I don't have) for conditions. I should mention
that I have one of those funky rubber "wings" bolted to the outdrive.

I've been coming out of the hole (lightly loaded) with the drive all the way
down, then bringing it up until the RPMs increase to the max (typically from
3800 to 4200) then bringing the throttle back to 4000 for cruise.

If there's much of a chop, or a lot of wakes, I've been bringing the bow back
down a bit to reduce pounding.

This seems to work reasonably well. Is there anything else I should be
considering?

Joe Parsons

Sounds like you did it right! )
If you are concerned about fuel consumption, you may wish to throttle
back a little more, but don't drop off plane. If not, enjoy!
noah

Ah, very interesting.

I'm beginning to experiment with more of the top end on my boat and have
discovered something that I wouldn't mind hearing a bit about (if you don't
mind me muscling in on your thread).

Running at about 20-28 knots my trim tabs do a fine job of keeping my bow
down to where I want it. At these speeds the trick seems to be to keep the
bow down. The port side wants to be especially high, I assume from engine
torque.

But once now I've opened it out and the bow has flattened right down on its
own, with no high side. I tried to lift it with the tabs and had the tabs
all the way backed off but the bow was still quite low.

I ran out of room (and courage) before I got to play with the drive trim.

I've played with the drive trim in the marina to see what it does (drives go
up, drives go down, drives go up, drives ... etc.) and I've read the manual
so here's what I figu

Once I get past the part where the tabs help keep it down, I can back off
the tabs and start to use the drive trim to get the bow up.

Does this sound about right?

Also, will I be able to level the bow (if one side wants to stay low) with
the drive trim?

I guess I'm asking, will the drive trim behave "sort of" like my trim tabs?

Boats are *so* not cars.

On Fri, 05 Sep 2003 13:50:15 GMT, "Paul" wrote:

Ah, very interesting.

I'm beginning to experiment with more of the top end on my boat and have
discovered something that I wouldn't mind hearing a bit about (if you don't
mind me muscling in on your thread).

Running at about 20-28 knots my trim tabs do a fine job of keeping my bow
down to where I want it. At these speeds the trick seems to be to keep the
bow down. The port side wants to be especially high, I assume from engine
torque.

But once now I've opened it out and the bow has flattened right down on its
own, with no high side. I tried to lift it with the tabs and had the tabs
all the way backed off but the bow was still quite low.

I ran out of room (and courage) before I got to play with the drive trim.

I've played with the drive trim in the marina to see what it does (drives go
up, drives go down, drives go up, drives ... etc.) and I've read the manual
so here's what I figu

Once I get past the part where the tabs help keep it down, I can back off
the tabs and start to use the drive trim to get the bow up.

Does this sound about right?

Also, will I be able to level the bow (if one side wants to stay low) with
the drive trim?

I guess I'm asking, will the drive trim behave "sort of" like my trim tabs?

Boats are *so* not cars.


Paul, the drive trim will 'only' raise the bow, if one starts with the drive in
it's normal position, all the way down. Any raising of the drive will raise the
bow, assuming you are on plane.

Lets pretend the water is smooth and we are on plane with the trim tabs up all
the way and the drive trimmed down all the way. Trimming the drive up will now
raise the bow. Trimming it up enough will cause the boat to 'porpoise' if there
are any waves. I will trim the drive up a little, after I'm on plane. As Joe
said earlier in this thread, the engine rpm's will increase a little. The boat
becomes more 'efficient', so to speak.

Now, let's leave the drive trimmed all the way down for a moment, and focus on
the trim tab. I'm assuming you have two controls, one for each tab. If the boat
is on plane and you lower both tabs, you will lower the bow. In very smooth
water, this would not be very efficient, unless -- you have a lot of weight
(mother-in-law) in the stern of the boat causing the bow to be too high. If this
is the case, the trim tabs can be used to 'raise the stern', i.e. lower the bow.

When going from 'no wake' to get on plane, forcing the stern up with the trim
tabs can get you on plane more quickly, especially if you have a lot of weight
in the stern. "Forcing the stern up" would be the same as lowering the bow and
is accomplished by lowering the trim tabs.

Now, let's assume you're on plane, everything is fine, and your mother-in-law
moves to the starboard side of the boat. The port side is riding higher. By
lowering the starboard trim tab, a little, you can raise the starboard side of
the boat, thus 'trimming' it. BE VERY CAREFUL DOING THIS! The trim tabs have a
tremendous effect on the boat, and the effect occurs very rapidly when at speed.
Use only small corrections with the trim tabs when on plane, or you can flip
things right out of the boat, like people!

Hope this helps somewhat!

John
On the 'Poco Loco' out of Deale, MD

You're so welcome. Good boating!


On Fri, 05 Sep 2003 17:43:21 GMT, "Paul" wrote:

Wow, thanks for the detailed explanation, very much appreciated. That's a
keeper.



"JohnH" wrote in message
.. .
On Fri, 05 Sep 2003 13:50:15 GMT, "Paul" wrote:

Ah, very interesting.

I'm beginning to experiment with more of the top end on my boat and have
discovered something that I wouldn't mind hearing a bit about (if you
don't
mind me muscling in on your thread).

Running at about 20-28 knots my trim tabs do a fine job of keeping my bow
down to where I want it. At these speeds the trick seems to be to keep
the
bow down. The port side wants to be especially high, I assume from engine
torque.

But once now I've opened it out and the bow has flattened right down on
its
own, with no high side. I tried to lift it with the tabs and had the tabs
all the way backed off but the bow was still quite low.

I ran out of room (and courage) before I got to play with the drive trim.

I've played with the drive trim in the marina to see what it does (drives
go
up, drives go down, drives go up, drives ... etc.) and I've read the
manual
so here's what I figu

Once I get past the part where the tabs help keep it down, I can back off
the tabs and start to use the drive trim to get the bow up.

Does this sound about right?

Also, will I be able to level the bow (if one side wants to stay low)
with
the drive trim?

I guess I'm asking, will the drive trim behave "sort of" like my trim
tabs?

Boats are *so* not cars.


Paul, the drive trim will 'only' raise the bow, if one starts with the
drive in
it's normal position, all the way down. Any raising of the drive will
raise the
bow, assuming you are on plane.

Lets pretend the water is smooth and we are on plane with the trim tabs up
all
the way and the drive trimmed down all the way. Trimming the drive up will
now
raise the bow. Trimming it up enough will cause the boat to 'porpoise' if
there
are any waves. I will trim the drive up a little, after I'm on plane. As
Joe
said earlier in this thread, the engine rpm's will increase a little. The
boat
becomes more 'efficient', so to speak.

Now, let's leave the drive trimmed all the way down for a moment, and
focus on
the trim tab. I'm assuming you have two controls, one for each tab. If the
boat
is on plane and you lower both tabs, you will lower the bow. In very
smooth
water, this would not be very efficient, unless -- you have a lot of
weight
(mother-in-law) in the stern of the boat causing the bow to be too high.
If this
is the case, the trim tabs can be used to 'raise the stern', i.e. lower
the bow.

When going from 'no wake' to get on plane, forcing the stern up with the
trim
tabs can get you on plane more quickly, especially if you have a lot of
weight
in the stern. "Forcing the stern up" would be the same as lowering the bow
and
is accomplished by lowering the trim tabs.

Now, let's assume you're on plane, everything is fine, and your
mother-in-law
moves to the starboard side of the boat. The port side is riding higher.
By
lowering the starboard trim tab, a little, you can raise the starboard
side of
the boat, thus 'trimming' it. BE VERY CAREFUL DOING THIS! The trim tabs
have a
tremendous effect on the boat, and the effect occurs very rapidly when at
speed.
Use only small corrections with the trim tabs when on plane, or you can
flip
things right out of the boat, like people!

Hope this helps somewhat!

John
On the 'Poco Loco' out of Deale, MD


John
On the 'Poco Loco' out of Deale, MD

Joe Parsons wrote:

More of that dang boating stuff here...

As I've put a number of hours on "Her Idea" (a Four Winns 195 Sundowner with
4.3L OMC Cobra), I'm coming to realize that there's quite an art to trimming the
drive (not the trim tabs, which I don't have) for conditions. I should mention
that I have one of those funky rubber "wings" bolted to the outdrive.

I've been coming out of the hole (lightly loaded) with the drive all the way
down, then bringing it up until the RPMs increase to the max (typically from
3800 to 4200) then bringing the throttle back to 4000 for cruise.

If there's much of a chop, or a lot of wakes, I've been bringing the bow back
down a bit to reduce pounding.

This seems to work reasonably well. Is there anything else I should be
considering?

Joe Parsons



I used to start off with the drive all the way down and then trim up
until the prop would ventilate and then trim back down a little. I
recently replaced my propeller with a nice stainless steel one and it
WON'T ventilate. So now I trim up until the bow gets a little "bouncy"
and then trim back down a little. My stinkin' trim gage doesn't work
anymore so I can't use that. It's hard to trim it right if the water's
rough.

I'm new to boating and learning about trimming my outboard also. Have a
1981 16' tri hall with 90 horse outboard. Not happy with the hole shot to
pull skiers out of the water. Has a 17 pitch prop. Was told that a stainless
steel prop will have a better hot shot, with same pitch. Is that true?

Steven

"mike hicks" wrote in message
news:CSb6b.46373$xf.10838@lakeread06...
Joe Parsons wrote:

More of that dang boating stuff here...

As I've put a number of hours on "Her Idea" (a Four Winns 195 Sundowner
with
4.3L OMC Cobra), I'm coming to realize that there's quite an art to
trimming the
drive (not the trim tabs, which I don't have) for conditions. I should
mention
that I have one of those funky rubber "wings" bolted to the outdrive.

I've been coming out of the hole (lightly loaded) with the drive all the
way
down, then bringing it up until the RPMs increase to the max (typically
from
3800 to 4200) then bringing the throttle back to 4000 for cruise.

If there's much of a chop, or a lot of wakes, I've been bringing the bow
back
down a bit to reduce pounding.

This seems to work reasonably well. Is there anything else I should be
considering?

Joe Parsons



I used to start off with the drive all the way down and then trim up
until the prop would ventilate and then trim back down a little. I
recently replaced my propeller with a nice stainless steel one and it
WON'T ventilate. So now I trim up until the bow gets a little "bouncy"
and then trim back down a little. My stinkin' trim gage doesn't work
anymore so I can't use that. It's hard to trim it right if the water's
rough.

On Sun, 07 Sep 2003 05:08:03 GMT, "Steven Carlson"
wrote:

I'm new to boating and learning about trimming my outboard also. Have a
1981 16' tri hall with 90 horse outboard. Not happy with the hole shot to
pull skiers out of the water. Has a 17 pitch prop. Was told that a stainless
steel prop will have a better hot shot, with same pitch. Is that true?

Steven

Probably. The stainless will "flex" less than an aluminum prop.
A better idea is to find out what pitch prop is the "right" one for
your engine and load. You'll need to know your WOT rpm's under normal
load.

I used to use a 21" pitch for general boating, and switch to a 19" for
water skiing. Both props gave proper rpm under the given load, and
the 19" gave good acceleration for skiing.

Good luck,
noah

A friend had a new 19 pitch and with that one on, checked the tach and
speed. Boat topped out at 37 mph with a rpm of 4300. Then the tach quit
before checking with the 17. The rpm I'm told should be around 5000 to 5200.

Thanks,

"noah" wrote in message
...
On Sun, 07 Sep 2003 05:08:03 GMT, "Steven Carlson"
wrote:

I'm new to boating and learning about trimming my outboard also. Have a
1981 16' tri hall with 90 horse outboard. Not happy with the hole shot to
pull skiers out of the water. Has a 17 pitch prop. Was told that a
stainless
steel prop will have a better hot shot, with same pitch. Is that true?

Steven

Probably. The stainless will "flex" less than an aluminum prop.
A better idea is to find out what pitch prop is the "right" one for
your engine and load. You'll need to know your WOT rpm's under normal
load.

I used to use a 21" pitch for general boating, and switch to a 19" for
water skiing. Both props gave proper rpm under the given load, and
the 19" gave good acceleration for skiing.

Good luck,
noah

your only going to gain 400 rpm, 200/in. something wrong w.ur engine.



"Steven Carlson" wrote in message
news:Ewb7b.397185$Ho3.59951@sccrnsc03...
A friend had a new 19 pitch and with that one on, checked the tach and
speed. Boat topped out at 37 mph with a rpm of 4300. Then the tach quit
before checking with the 17. The rpm I'm told should be around 5000 to
5200.

Thanks,

"noah" wrote in message
...
On Sun, 07 Sep 2003 05:08:03 GMT, "Steven Carlson"
wrote:

I'm new to boating and learning about trimming my outboard also. Have
a
1981 16' tri hall with 90 horse outboard. Not happy with the hole shot
to
pull skiers out of the water. Has a 17 pitch prop. Was told that a
stainless
steel prop will have a better hot shot, with same pitch. Is that true?

Steven

Probably. The stainless will "flex" less than an aluminum prop.
A better idea is to find out what pitch prop is the "right" one for
your engine and load. You'll need to know your WOT rpm's under normal
load.

I used to use a 21" pitch for general boating, and switch to a 19" for
water skiing. Both props gave proper rpm under the given load, and
the 19" gave good acceleration for skiing.

Good luck,
noah