Topic: Transducer location on a party barge

[chuck41]

My party barge has only one available mounting location for the transducer.  On a welded bracket at rear of left pontoon.  Unfortunately the lower unit of the motor is just to the right of that location and directly in line with it extending about 10 to 12  inches below the pontoon.  That has never been a problem with a normal depth unit but the side image system sends information horizontally that a normal system doesn’t. Will that cause a significant problem? 

I am about to have the boat fitted with a third pontoon and the motor will then be mounted at the end of that pontoon.  Should I make some kind of arrangements to have that modified to hold the transducer in front of the lower unit of the motor?

[ITGEEK]

chuck41:
If you want your sonar and side imaging to work as best as possible,
you need a clear line of sight of the transducer to both sides and straight down.
Also, you don't want the transducer too close to your propeller, because the
propeller will churn up air bubbles which will cloudy up your images.
While on dry land, you should be able to see a clear line of sight to both sides
of the transducer with your motor down at the normal operating angle.

My advice would be to fabricate or get someone to fabricate a
new mounting bracket.  Keep in mind also, that you don't want the
transducer hanging down too far, or it might hit something.

Good Luck.

[Humminbird_Greg]

chuck41,
Will this new third pontoon be located any farther aft?  What I’m getting at is if it does not stick back any farther than the other two pontoons than you could possibly get blockage from both the left and right Si sonar beams from the existing pontoons if the transducer gets mounted on the new pontoon.  Lowering the transducer farther down in the water could bypass this but it would also expose the Si to damage from underwater objects.

If the new pontoon is father aft than the other two pontoons than it may be a good location for the Si transducer, if there is room for it.  You may be able to mount it on the third pontoon but I would caution you about mounting it directly in front of the lower unit/propeller as we have heard from some who did that at higher boat speeds the transducer causes an air pocket to form which does not allow cooling water to flow into the water intake and/or causes the propeller to spin out.  You won’t know if this is a problem until you mount and test the transducer.  Now if the transducer was mounted just to the outside of the propeller you should not have this problem.

An (expensive) option would be to mount an Si transducer on both the left and right pontoons and use an AS-Si-LR-Y cable to connect them both to your 798 unit.

[chuck41]

You have confirmed my fears. Will check it out before the toon upgrade and go from there. Pontoons don't give you many options. No hull to shoot through or space to move from side to side. Might have to move motor back further than I had planned so I can shoot just in front of it.

[rnvinc]

You have confirmed my fears. Will check it out before the toon upgrade and go from there. Pontoons don't give you many options. No hull to shoot through or space to move from side to side. Might have to move motor back further than I had planned so I can shoot just in front of it.

Seems like Greg's suggestion of a port and starboard HDSI with the AS SILR Y cable would be easier than moving the motor...

I use this xducer setup sometimes in my xducer experiments...it works fine...and the unit doesn't even know it's using 2 separate xducers...

Rickie

[chuck41]

Good idea. I am having a custom built pontoon/motor mount installed on the boat. To modify that at this point would be relatively easy. If that looks like too much problem I will condiderbbuying a second transducer. Problem is the right pontoon has an access ladder on it. Putting an expensive transducer under that ladder could be a very risky proposition. Guys climbing in the boat with 50 or more lbs of scuba gear hanging on them might not be too careful about that transducer under the ladder.