1991 OUTRAGE 19: Engine Mounting Height Affects SONAR Performance

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Author Topic:   1991 OUTRAGE 19: Engine Mounting Height Affects SONAR Performance

seasled posted 07-01-2006 05:06 PM ET (US)
I have a 1991 Outrage 19,that I just re-powered with a 2005 Johnson 150. The engine is mounted in the second set of holes in the top of the stern backets. There is about one inch of space between the top of the transom and the bottom of the brackets. At speeds over 30_MPH I get a lot of spray, so much that I lose my high speed reading on the depth finder. I have The manual for the engine. It says that generaly that the anti-ventilaion plate must be in alignment with the bottom of the hull. It is. It also says that most v-hulls can perform well with the anti-ventilation plate one inch above the bottom of the hull. Any advice would be helpful. Thanks
Tom W Clark posted 07-02-2006 10:30 AM ET (US)
Your motor is just fine where it is.
You need to adjust the transducer for your depth sounder.
Sal DiMercurio posted 07-02-2006 10:37 AM ET (US)
There's no connection between the engine and your fish finder. The transducer for the fish finder depth finder is mounted on the bottom of the transom and the the engine is well behind the transducer and away from the transom. You are losing your reading on the fish finder because your transducer has to be lowered to approx 1/4" - 3/8" below the bottom of the boat. No, the anti-vent plate above your prop shouldn't be level with the bottom of the boat, it needs to be above the water when the boat is on plane, and the way to check that is to have someone look at the anti-vent plate while you run the boat. If it's going through the water instead of above the water, your engine would be to low and needs to be raised. With your engine mounted on the second set of holes as it is now, you should be fine. Again, your engine has nothing to do with losing the signal on your fish finder, just lower the transducer a bit until it holds the signal at all speeds. .
Sal
seasled posted 07-03-2006 01:10 PM ET (US)
Hi guys. I understand what you are saying about the transducer. But I did not have sounder problems with the ole engine. I think I am going to raise the engine one hole and try it.
seasled posted 07-03-2006 01:14 PM ET (US)
When running the boat I did look over the transom and the anti-ventilation plate wasn't even visable. The water was almost up to the second small set of fins on the lower unit.
Sal DiMercurio posted 07-03-2006 05:24 PM ET (US)
The bottom plate is the anti-vent plate and that is the one that needs to be above the water while on plane. Isn't your transducer mounted off to the starboard side away from the engine? The engine can't bother the water going to the transducer because the engine is behind the transducer by at least 10". Sounds like your transducer was somehow raised up and now gets air bubbles when you are on plane. No matter how you look at it, it has to be lowered. Is there a thru hull fitting in front of the transducer? If so, thats your culprit.
Sal
aja posted 07-05-2006 10:34 AM ET (US)
It sounds like your engine is fine mounted where it is, but one thing I didn't hear mentioned is what the engine and transducers look like when this is happening. Our engine was mounted too low when we bounght out 1992 OUTRAGE 19 II and it threw a large rooster tail when up to speed. I quick look at the engine when it was running like this made it obvious what the probem was. As to your transducer, I have had a few Eagle/Lowrance fishfinders and the transducers always had some means to kick back/up if they hit something solid. Maybe in your case the transduced got bumped while the engines were being switched? Regardless it should be level with the bottom of your hull so it stays entirely in the water while planing. Look at both of those things and hopefully the solution will be fairly obvious if you see just what is causing the problem while at speed.
jimh posted 07-05-2006 11:06 PM ET (US)
There is information on SONAR transducer mounting in the REFERENCE section. See:
http://continuouswave.com/whaler/reference/sonarTransducer.html
Sal DiMercurio posted 07-05-2006 11:25 PM ET (US)
Mounting the bottom of your transducer to be level with the bottom of the boat will result in loss of signal at planeing speed.
The bottom of your transducer must be mounted "below" the bottom of the boat approx 1/4", or you will get aireatted water flowing to the transducer resulting in signal loss.
The transducer "must" be mounted not level with the bottom of the boat, but below the level of the water flowing from the bottom of the boat, there is a difference.
A good way to check that is to use a 2x4 or 8' straight edge & run it from the bottom of the boat out past the transom & check that the bottom of the transducer is 1/4" below the top of the straight edge.
There's no way the new engine can have anything to do with loss of signal.
Sal
aja posted 07-06-2006 10:01 AM ET (US)
Just to clarify my commet regarding Sal's, I was referring more to the angle of the transducer than the depth. I completely agree that it should extend below the hull so it remains in the water stream, but if tilted up/back can cause all but the leading edge to come out of the water when planing. All of the external transducer mounts I have seen have had some sort of break-away mechanism would allow them to kick up if the they hit something solid (or you grabbed and pulled them hard), hopefully before being torn off the transom. Not that any of this is the definate cause of the issues described, but just something to be aware of...
seasled posted 07-18-2006 04:18 PM ET (US)
I tried the boat out on the river and guess what,perfect high speed signal. The only thing differrant. no trolling motor on the port side transom and no battery in theport side splash well. I did raise the engine To the third hole up and no more spray. Thanks for the support. saesled

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Author	Topic: 1991 OUTRAGE 19: Engine Mounting Height Affects SONAR Performance
seasled	posted 07-01-2006 05:06 PM ET (US) I have a 1991 Outrage 19,that I just re-powered with a 2005 Johnson 150. The engine is mounted in the second set of holes in the top of the stern backets. There is about one inch of space between the top of the transom and the bottom of the brackets. At speeds over 30_MPH I get a lot of spray, so much that I lose my high speed reading on the depth finder. I have The manual for the engine. It says that generaly that the anti-ventilaion plate must be in alignment with the bottom of the hull. It is. It also says that most v-hulls can perform well with the anti-ventilation plate one inch above the bottom of the hull. Any advice would be helpful. Thanks
Tom W Clark	posted 07-02-2006 10:30 AM ET (US) Your motor is just fine where it is. You need to adjust the transducer for your depth sounder.
Sal DiMercurio	posted 07-02-2006 10:37 AM ET (US) There's no connection between the engine and your fish finder. The transducer for the fish finder depth finder is mounted on the bottom of the transom and the the engine is well behind the transducer and away from the transom. You are losing your reading on the fish finder because your transducer has to be lowered to approx 1/4" - 3/8" below the bottom of the boat. No, the anti-vent plate above your prop shouldn't be level with the bottom of the boat, it needs to be above the water when the boat is on plane, and the way to check that is to have someone look at the anti-vent plate while you run the boat. If it's going through the water instead of above the water, your engine would be to low and needs to be raised. With your engine mounted on the second set of holes as it is now, you should be fine. Again, your engine has nothing to do with losing the signal on your fish finder, just lower the transducer a bit until it holds the signal at all speeds. . Sal
seasled	posted 07-03-2006 01:10 PM ET (US) Hi guys. I understand what you are saying about the transducer. But I did not have sounder problems with the ole engine. I think I am going to raise the engine one hole and try it.
seasled	posted 07-03-2006 01:14 PM ET (US) When running the boat I did look over the transom and the anti-ventilation plate wasn't even visable. The water was almost up to the second small set of fins on the lower unit.
Sal DiMercurio	posted 07-03-2006 05:24 PM ET (US) The bottom plate is the anti-vent plate and that is the one that needs to be above the water while on plane. Isn't your transducer mounted off to the starboard side away from the engine? The engine can't bother the water going to the transducer because the engine is behind the transducer by at least 10". Sounds like your transducer was somehow raised up and now gets air bubbles when you are on plane. No matter how you look at it, it has to be lowered. Is there a thru hull fitting in front of the transducer? If so, thats your culprit. Sal
aja	posted 07-05-2006 10:34 AM ET (US) It sounds like your engine is fine mounted where it is, but one thing I didn't hear mentioned is what the engine and transducers look like when this is happening. Our engine was mounted too low when we bounght out 1992 OUTRAGE 19 II and it threw a large rooster tail when up to speed. I quick look at the engine when it was running like this made it obvious what the probem was. As to your transducer, I have had a few Eagle/Lowrance fishfinders and the transducers always had some means to kick back/up if they hit something solid. Maybe in your case the transduced got bumped while the engines were being switched? Regardless it should be level with the bottom of your hull so it stays entirely in the water while planing. Look at both of those things and hopefully the solution will be fairly obvious if you see just what is causing the problem while at speed.
jimh	posted 07-05-2006 11:06 PM ET (US) There is information on SONAR transducer mounting in the REFERENCE section. See: http://continuouswave.com/whaler/reference/sonarTransducer.html
Sal DiMercurio	posted 07-05-2006 11:25 PM ET (US) Mounting the bottom of your transducer to be level with the bottom of the boat will result in loss of signal at planeing speed. The bottom of your transducer must be mounted "below" the bottom of the boat approx 1/4", or you will get aireatted water flowing to the transducer resulting in signal loss. The transducer "must" be mounted not level with the bottom of the boat, but below the level of the water flowing from the bottom of the boat, there is a difference. A good way to check that is to use a 2x4 or 8' straight edge & run it from the bottom of the boat out past the transom & check that the bottom of the transducer is 1/4" below the top of the straight edge. There's no way the new engine can have anything to do with loss of signal. Sal
aja	posted 07-06-2006 10:01 AM ET (US) Just to clarify my commet regarding Sal's, I was referring more to the angle of the transducer than the depth. I completely agree that it should extend below the hull so it remains in the water stream, but if tilted up/back can cause all but the leading edge to come out of the water when planing. All of the external transducer mounts I have seen have had some sort of break-away mechanism would allow them to kick up if the they hit something solid (or you grabbed and pulled them hard), hopefully before being torn off the transom. Not that any of this is the definate cause of the issues described, but just something to be aware of...
seasled	posted 07-18-2006 04:18 PM ET (US) I tried the boat out on the river and guess what,perfect high speed signal. The only thing differrant. no trolling motor on the port side transom and no battery in theport side splash well. I did raise the engine To the third hole up and no more spray. Thanks for the support. saesled