Roostertail ?

D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Gentlemen I am the new and concerned owner of a beautiful offshore boat with a 270hp 2002 volvo 5.0gxi and the Sx outdrive.

When planeing the boat is shedding a roostertail and some spray is coming into the back of the boat so cant sit in the back seats. Adjusting the motor trim and the trimtabs, as well as the throttle speed in general, can have an effect, but, does not eliminate it all together, and I am thinking this is not normal.

Am wondering if a faulty seal in the exhaust path of the outdrive, or even worse freeze damage might be the reason ? Any thoughts or comments on how the exhaust path works and where exhaust gasses would normally exit when in neutral or in gear greatly appreciated.
 
S

spktho

Petty Officer 3rd Class
Joined
Apr 1, 2009
Messages
81
Re: Roostertail ?

Transom mounted transducer for the depth/fish finder?
 
WAVENBYE2

WAVENBYE2

Lieutenant Commander
Joined
Apr 28, 2007
Messages
1,636
Re: Roostertail ?

Do you have a hydrofoil on the sterndrive?
 
D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Re: Roostertail ?

There is a transducer and trim tabs. I am not sure what a hydrofoil is ? The spray seems to be from dead center and is a whole lot of water not as much as a jetboat but close. I thought unlikely to be the transducer because it is mounted on the side. But may be ? It will be coming off, I recently installed a new lowrance with a through-hull transducer mounting job in the bilge.
 
fuzzybob

fuzzybob

Petty Officer 1st Class
Joined
Oct 26, 2008
Messages
213
Re: Roostertail ?

Have you tried moving the trim angle up or down to get rid of the roostertail??
I see you've tried that.... should have read the post a little closer! :)
 
Last edited:
D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Re: Roostertail ?

Yikes.

If the motor mounted too deep this would be from factory that must be a bad template or something.

Is there any adjustment possible with mounting depth for a Volvo or is it determined by the cutout in the hull ?
 
bustermin

bustermin

Banned
Joined
Apr 13, 2009
Messages
315
Re: Roostertail ?

Deepblue22 said:
Yikes.

If the motor mounted too deep this would be from factory that must be a bad template or something.

Is there any adjustment possible with mounting depth for a Volvo or is it determined by the cutout in the hull ?
Click to expand...

You need to take a "Stright Edge" and see if the Cavitation Plate is level with the bottom of your transom. That is how you can tell if it is too low or not.

As far as an adjustment, I am not sure if you have one or not.
 
superpop

superpop

Master Chief Petty Officer
Joined
Mar 5, 2006
Messages
869
Re: Roostertail ?

Never seen anything like that but it looks like the drive is too low. On my boat, at full speed the cavitation plate rides on top of the water just a bit. From the pics and videos it looks like it is sitting too far into the water. Not an easy fix if that is the case, new transom and then raise the motor up if you have the clearance. Yikes.
 
superpop

superpop

Master Chief Petty Officer
Joined
Mar 5, 2006
Messages
869
Re: Roostertail ?

Exhaust exits out the exhaust bellow and some through the prop. That is not the problem, have you looked underneath to make sure there is nothing stuck to the bottom of the boat.
 
Mark42

Mark42

Fleet Admiral
Joined
Oct 8, 2003
Messages
9,334
Re: Roostertail ?

To me it looks like the trim tabs are too close to the outdrive and water is being deflected off the tabs onto the outdrive and splashing straight up. Usually trim tabs are mounted as far to the chines as possable because they have more leverage for reducing chine walking.

Try running with the trim tabs in full up position or remove them and see what the result is.

As far as the outdrive being too low, it should be easy to get a spec on the location of the outdrive from the keel from the manufacturer and check the dimension yourself, or go back to a dealer and measure the dimension on a boat on the lot yourself. It would be a serious mistake if the outdrive hole was cut in the wrong location.
 
D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Re: Roostertail ?

All: thanks for the replies. I'll take some measurements tonight and let you know.

I also wondered about the trim tab locations. I agree they should be way out to the side not close to center where they are in this application. I dont know if they came like this from factory or if they were installed after but they do have poor effect in their current location.

I spoke to the local Genmar dealer near where I live. Genmar makes or owns Larson and Seaswirl and a bunch of other quality brands. He did not know what was wrong but said it would be unlikely for the motor to be mounted wrong because Genmar is and has been ISO certified for a long time and that means every decision is tracked and signed off by an engineer, etc.
 
DRIFTER_016

DRIFTER_016

Petty Officer 1st Class
Joined
May 5, 2008
Messages
360
Re: Roostertail ?

Mark42 said:
To me it looks like the trim tabs are too close to the outdrive and water is being deflected off the tabs onto the outdrive and splashing straight up. Usually trim tabs are mounted as far to the chines as possable because they have more leverage for reducing chine walking.

Try running with the trim tabs in full up position or remove them and see what the result is.

QUOTE]

I have to agree that it does look like they are too close to the centerline.
Click to expand...
 
C

Campylobacter

Chief Petty Officer
Joined
Aug 4, 2007
Messages
503
Re: Roostertail ?

Maybe its just the camera angle in the videos but is the tail worse on the port side of the boat? Thats where it looks like most of the water is coming in.

If this is true, I was thinking possibly the transducer mounting bracket may be the issue (you said the transducer was removed, but the bracket might still be down a bit)

Also, the trim tabs do seem a bit close, have you tried them in the full up position (can they go higher than in the pic)? Perhaps with the kicker motor and the driver on the same side makes the starboard tab "dig" to keep the boat level, sending water laterally past the outdrive.
 
D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Re: Roostertail ?

I added some new pics to the photobucket link posted previously.

The cavitation plate appears to be approx 0.5 inch below bottom of boat. That would do it I guess ?

The trim tabs are positioned 13" from center of keel and 8" from edge of outdrive. This is within the bennett installation spec, although I will remove them to do a water test just in case.
 
Captain Caveman

Captain Caveman

Ensign
Joined
Mar 1, 2005
Messages
924
Re: Roostertail ?

Deepblue22 said:
He did not know what was wrong but said it would be unlikely for the motor to be mounted wrong because Genmar is and has been ISO certified for a long time and that means every decision is tracked and signed off by an engineer, etc.
Click to expand...

ROLF....! I'd be a rich man if I bet a nickel everytime an engineer proclaimed a fact and turned out to be wrong. I'm not knocking engineers, just the pompous ones. There are just as many engineers who make mistakes as any other profession.... I've just heard it so many times.... To be honest, no engineer wants to be wrong and fixing an error like this will be very costly to whomever has to open up their wallet. Of course he'll say that it is unlikely.

Anyway, to be honest the rooster tail doesn't look that bad. I've seen much worse but with outboards. Usually that is a mounting issue. Personally I wouldn't be too concerned about this unless you are dead set on getting the boat to be super efficient - most boats aren't though.
 
SeanT

SeanT

Senior Chief Petty Officer
Joined
Jul 8, 2009
Messages
661
Re: Roostertail ?

The problem is that engineers don't do anything themselves. They just sign off on work done by others. I should know, I am one.
 
D

Deepblue22

Seaman
Joined
Mar 31, 2007
Messages
51
Re: Roostertail ?

Went to lake today with trimtabs removed. No difference still got the roostertail.
 
You must log in or register to reply here.
Top