User manual STANDARD HORIZON P79

[. . . ] However, carefully selecting the transducer mounting location can minimize the affect of vessel generated noise from the propeller(s) and shaft(s), other machinery, and other echosounders. The lower the noise level, the higher the echosounder gain setting that can be used. Placement Choose a location where: · The water flowing across the hull is smoothest with a minimum of bubbles and turbulence (especially at high speeds). · The hull below the transducer will be in contact with the water. · The transducer beam will be unobstructed by the keel or propeller shaft(s). [. . . ] Mount on the side of the hull where the propeller is moving downward. Outboard and I/O--Mount just forward of the engine(s). Inboard--Mount well ahead of the propeller(s) and shaft(s). Step-hull--Mount just ahead of the first step. AIRMAR ® AIRMAR ® A B C active face Figure 2. Establishing a performance baseline 2 Figure 3. Testing the transducer at the selected location AIRMAR base ® AIRMAR keel keel direction arrow ® hull flange guideline perpendicular to keel parallel to waterline deadrise angle keel direction arrow Figure 4. Aligning the flange of the base (4°­12° deadrise angle shown) Observe the echosounder's performance, and compare it to the baseline. Look for a stable depth reading that is similar to the baseline. If you are testing a fishfinder, compare the thickness and intensity of the bottom trace. If the performance is close to the baseline, this is a good mounting location. Remember, some energy is lost transmitting through the hull. If the test reading differs markedly from the baseline, you will need to find another location to install the sensor. If there is no reading or it is erratic, the transducer may be positioned over coring which is absorbing the acoustic energy. If no other spot is available, check with the boat manufacturer to be certain coring is present before proceeding with the instructions for "Installation in a Cored Fiberglass Hull" on page 4. Caution: The base must be liquid-tight. DO NOT use an epoxy adhesive, polyurethane based sealant, or the previously recommended Boatlife® Life Seal® or 3MTM 4200. 6. When you are satisfied that the location of the transducer is optimal and the orientation of the base corresponds to the deadrise angle of your boat, apply a bead of silicone sealant (such as GE Silicone I or Silicone II) to the underside of the flange of the base. (Follow the sealant manufacturer's instructions for its use. ) Press the flange firmly in place to form a liquid-tight seal. Slide the transducer into the locking ring. Turn the housing until the rib that most closely corresponds to the deadrise angle of your hull is aligned with the angle indicator on the locking ring. To secure the housing to the locking ring, insert the two screws (see Figure 6). Do not over-tighten the screws. Installation 1. Measure the deadrise angle of the hull at the selected location using a digital level, or bubble level and protractor (see Figure 4). [. . . ] Sand the inside surface of the outer skin using a miniature disk sander. Slightly undercut the surrounding coring if possible. Clean and dry both the inside surface of the outer skin and the housing with a weak solvent, such as alcohol, to remove any dust, grease, or oil. Fill the gap between the base and the hull with casting epoxy or resin following the manufacturer's directions for its use. [. . . ]