1980 Munro 16ft Fiberglass - Nose Dives
 

Regardless of the angle that I position my motor (manual tilt
adjustment) the front end of the boat dives low. Even when in the boat
by myself the front end will not lift upwards much when accelerating and
the motor is tilted up all the way. It has never even come close to
porpoising at all. What can cause this behavior?

I've looked for excess weight up front to no avail, and also made sure
the drain is not plugged. This ob motor (40hp) originally came with
fins which I removed before having ever used them. My thought is that
they would make this nose diving problems even worse. What am I missing?

Thanks for any advice.

1980 Munro 16ft Fiberglass - Nose Dives
 

AMD Rules wrote:
Regardless of the angle that I position my motor (manual tilt
adjustment) the front end of the boat dives low. Even when in the boat
by myself the front end will not lift upwards much when accelerating and
the motor is tilted up all the way. It has never even come close to
porpoising at all. What can cause this behavior?

I've looked for excess weight up front to no avail, and also made sure
the drain is not plugged. This ob motor (40hp) originally came with
fins which I removed before having ever used them. My thought is that
they would make this nose diving problems even worse. What am I missing?

Thanks for any advice.

The boat was kept on a trailer, probably, and has now developed a
concave "hook" in the hull shape. Check the shape of the keel as viewed
along the bottom from the back.

Rob

1980 Munro 16ft Fiberglass - Nose Dives
 

My 2 cents- 40 hp is not enough to properly plane a 16 ft fiberglass boat.
The hydroplane fin(s) will help the boat to plane better, and help eliminate
wasted "rooster tail" energy by directing it rearward instead of upward.


"AMD Rules" wrote in message
...
Regardless of the angle that I position my motor (manual tilt
adjustment) the front end of the boat dives low. Even when in the boat
by myself the front end will not lift upwards much when accelerating and
the motor is tilted up all the way. It has never even come close to
porpoising at all. What can cause this behavior?

I've looked for excess weight up front to no avail, and also made sure
the drain is not plugged. This ob motor (40hp) originally came with
fins which I removed before having ever used them. My thought is that
they would make this nose diving problems even worse. What am I missing?

Thanks for any advice.

1980 Munro 16ft Fiberglass - Nose Dives
 

Stanley Barthfarkle wrote:
My 2 cents- 40 hp is not enough to properly plane a 16 ft fiberglass boat.
The hydroplane fin(s) will help the boat to plane better, and help eliminate
wasted "rooster tail" energy by directing it rearward instead of upward.


Its actually the opposite problem. It planes too easily, and goes
beyond. Its lots of power to get the boat moving well, but I can't keep
the nose up enough for my liking and I believe it begins to drag and
slow it back down a bit.

I will mount the fins to see if I can better direct the energy rearward.
Your advice is appreciated.

1980 Munro 16ft Fiberglass - Nose Dives
 

On Tue, 22 Jun 2004 14:13:31 GMT, "Stanley Barthfarkle"
pulled up to the drive-thru window and hollered:

I agree. 40 hp is JUST enough to get a plane depending on motor
condition and loading. Also may have waterlogged foam under the deck.

My 2 cents- 40 hp is not enough to properly plane a 16 ft fiberglass boat.
The hydroplane fin(s) will help the boat to plane better, and help eliminate
wasted "rooster tail" energy by directing it rearward instead of upward.


"AMD Rules" wrote in message
.. .
Regardless of the angle that I position my motor (manual tilt
adjustment) the front end of the boat dives low. Even when in the boat
by myself the front end will not lift upwards much when accelerating and
the motor is tilted up all the way. It has never even come close to
porpoising at all. What can cause this behavior?

I've looked for excess weight up front to no avail, and also made sure
the drain is not plugged. This ob motor (40hp) originally came with
fins which I removed before having ever used them. My thought is that
they would make this nose diving problems even worse. What am I missing?

Thanks for any advice.

1980 Munro 16ft Fiberglass - Nose Dives
 

If it were "planing well", and if it had plenty of power, it would have no
trouble in holding it's bow out of the water. It's doesn't sound like
"over-planing" to me, it sounds like it's underpowered. Planing a 16 foot
aluminum jon-boat with a 40 hp I would believe, but a 16 ft fiberglass boat
is pretty heavy. How much does the boat weigh loaded?




"AMD Rules" wrote in message
...
Stanley Barthfarkle wrote:
My 2 cents- 40 hp is not enough to properly plane a 16 ft fiberglass
boat.
The hydroplane fin(s) will help the boat to plane better, and help
eliminate
wasted "rooster tail" energy by directing it rearward instead of upward.


Its actually the opposite problem. It planes too easily, and goes
beyond. Its lots of power to get the boat moving well, but I can't keep
the nose up enough for my liking and I believe it begins to drag and
slow it back down a bit.

I will mount the fins to see if I can better direct the energy rearward.
Your advice is appreciated.

1980 Munro 16ft Fiberglass - Nose Dives
 

NerfHerder wrote in message . ..
On Tue, 22 Jun 2004 14:13:31 GMT, "Stanley Barthfarkle"
pulled up to the drive-thru window and hollered:

I agree. 40 hp is JUST enough to get a plane depending on motor
condition and loading. Also may have waterlogged foam under the deck.


I appreciate all the comments thus far. The boat really does plane
well with one or two people. Its not going to win any offshore speed
records, but it is definitely up on a plane as can be heard by the
cange in the motor frequency. The 40 hp has enough power to waterski
behind, mind you at a reduced speed of approx 23 to 25mph WOT.

I will hook up the whale tail fins and see if that improves it. I
would check the hull shape but without a trailer, it will be
difficult. I suspect the hull may be warped in the rear from polonged
storage.

Lastly, is placing a wedge between the transom and the motor an
option to raise the trim further, or would that be deemed dangerous
and inappropriate? I am not seeing a large rooster tail with it
trimmed all the way up (manual pin).

1980 Munro 16ft Fiberglass - Nose Dives
 

Adding wedges is a reasonable option if you need more trim "in". I did it on
one boat and it helped a lot. Trim tabs might also help.
--
RichG manager, Carolina Skiff Owners Group on MSN
http://groups.msn.com/CarolinaSkiffOwners
"AMD Rules" wrote in message
om...
NerfHerder wrote in message
. ..
On Tue, 22 Jun 2004 14:13:31 GMT, "Stanley Barthfarkle"
pulled up to the drive-thru window and hollered:

I agree. 40 hp is JUST enough to get a plane depending on motor
condition and loading. Also may have waterlogged foam under the deck.


I appreciate all the comments thus far. The boat really does plane
well with one or two people. Its not going to win any offshore speed
records, but it is definitely up on a plane as can be heard by the
cange in the motor frequency. The 40 hp has enough power to waterski
behind, mind you at a reduced speed of approx 23 to 25mph WOT.

I will hook up the whale tail fins and see if that improves it. I
would check the hull shape but without a trailer, it will be
difficult. I suspect the hull may be warped in the rear from polonged
storage.

Lastly, is placing a wedge between the transom and the motor an
option to raise the trim further, or would that be deemed dangerous
and inappropriate? I am not seeing a large rooster tail with it
trimmed all the way up (manual pin).

1980 Munro 16ft Fiberglass - Nose Dives
 

RichG wrote:
Adding wedges is a reasonable option if you need more trim "in". I did it on
one boat and it helped a lot. Trim tabs might also help.

I was thinking about wedges in the opposite direction. Requiring more
front end lift.

1980 Munro 16ft Fiberglass - Nose Dives
 

Oh, of course. I read your posting and still didn't read it well enough.
Sorry.

I'm guessing the motor does NOT have hydraulic tilt/trim. You say you have
already moved all the pins as far as they go. I don't see any reason why
adding the wedges " in the opposite direction" could hurt anything. It will
only put your engine at too high of a "normal" angle to the transom.

However, if you really have a "hook" in the hull, then one device ( the
wedge) is trying to overcome another problem(the hook) and you have to be
losing power along the way.

p.s. don't let anyone tell you a 40 hp won't plane a 16 foot well. I have a
16 ft Carolina Skiff STD ( admittedly a light boat hull) and it planes like
the devil. I added Smart Tabs to flatten any excessive bow lift.
--
RichG manager, Carolina Skiff Owners Group on MSN
http://groups.msn.com/CarolinaSkiffOwners


"AMD Rules" wrote in message
...

I was thinking about wedges in the opposite direction. Requiring more
front end lift.