Garmin 740s install diary

[hart]

So I pulled the trigger on a Garmin 740s this week. While waiting for it to arrive I'm laying the groundwork in the boat. And for kicks I've decided to keep a diary of sorts for my and others future reference:

I'll be using a Ram Mount to hold the unit on the pedestal. I figure this way it will be easy to remove from the boat when not on board and it will swivel so I can view it from the windward side when heeling over. Currently I have a compass mounted on top of the pedestal:


B and Andy sailing by Brian Hart, on Flickr

I kinda hate to lose it but I think I'll put the Ram Mount on top of the pedestal and ditch the compass for a bulkhead mounted one. Alternately I could mount the Ram off to the side and keep the compass but I think the 740s will stick too far out into the cockpit space if I do that. I'll have to measure for sure once it gets here.

As part of the install I've gone ahead and run new beefier power cable up to the pedestal and I'm installing a 6 fuse block inside the pedestal so I have room to add a few other items - at the moment a 12v power outlet and the charging station for my wireless WHAM VHF mic. Later I might add some cockpit LED lighting and maybe a washdown pump wired to the pedestal. I've used 5200 to secure a wood block inside the pedestal that I will screw the fuse block too. I like fuse blocks - no more mess dealing with inline fuses.

I'm going with an in-hull puck transducer in my "X" and trying to decide where to put it. After searching the site I think I'm going to place it under the galley, more or less as far forward as the cable will reach. It seems like there's a good spot to make contact with the hull under there (and not the water ballast tank). Anybody that's done this already want to chime in with any helpful hints?

I'll also be running a signal cable to tie my Uniden VHF in with the 740s via the NMEA 0183 input/outputs so I can take full advantage of the DSC capabilities in my radio. I would have done that today but I forgot to buy the cable.

I'll post pics too once there's something to post. Right now all that's visible is some cable in the bilge and the inside of the pedestal so nothing exciting yet.

[hart]

Well UPS didn't show up for the weekend. Argh. Prepping for the transducer install. I'm going with the Airmar P79 (the in hull puck as mentioned). Here's part of the install guide:

Mounting Location
About Fiberglass Hulls
The fiberglass hull below the transducer must be solid. Since the
hull absorbs acoustic energy, transmitting through the hull
reduces the transducer’s performance. Fiberglass hulls are often
reinforced in places for added strength or to reduce weight. These
cored areas contain balsa wood or structural foam which are poor
sound conductors. Do not locate the transducer over coring.
Placement
CAUTION: Do not mount the transducer near water intake or
discharge openings or behind strakes, fittings, or hull irregularities
that will disturb the water flow.
Choose a location:
• Where the fiberglass is solid (no air bubbles are trapped in the
fiberglass resin) and where no coring, flotation material, or dead
air space is sandwiched between the inside skin and outer skin
of the hull.
• Where the hull below the transducer will be in contact with the
water at all times.
• Where the water flowing under the hull is smoothest with a
minimum of bubbles and turbulence (especially at high speeds).
• Away from interference caused by power and radiation sources
such as: the propeller(s) and shaft(s), other machinery, other
echosounders, and other cables. The lower the noise level, the
higher the echosounder gain setting that can be used.
• Where the transducer beam will not be blocked by the keel or
propeller shaft(s).
• Where the deadrise angle does not exceed 22°.
• Where there is space inside the vessel for the height of the unit,
tightening the locking ring, and installing the transducer.Mounting Location
About Fiberglass Hulls
The fiberglass hull below the transducer must be solid. Since the
hull absorbs acoustic energy, transmitting through the hull
reduces the transducer’s performance. Fiberglass hulls are often
reinforced in places for added strength or to reduce weight. These
cored areas contain balsa wood or structural foam which are poor
sound conductors. Do not locate the transducer over coring.
Placement
CAUTION: Do not mount the transducer near water intake or
discharge openings or behind strakes, fittings, or hull irregularities
that will disturb the water flow.
Choose a location:
• Where the fiberglass is solid (no air bubbles are trapped in the
fiberglass resin) and where no coring, flotation material, or dead
air space is sandwiched between the inside skin and outer skin
of the hull.
• Where the hull below the transducer will be in contact with the
water at all times.
• Where the water flowing under the hull is smoothest with a
minimum of bubbles and turbulence (especially at high speeds).
• Away from interference caused by power and radiation sources
such as: the propeller(s) and shaft(s), other machinery, other
echosounders, and other cables. The lower the noise level, the
higher the echosounder gain setting that can be used.
• Where the transducer beam will not be blocked by the keel or
propeller shaft(s).
• Where the deadrise angle does not exceed 22°.
• Where there is space inside the vessel for the height of the unit,
tightening the locking ring, and installing the transducer.

Full guide is here: http://www.airmartechnology.com/uploads ... 217-01.pdf

One thing I find very interesting is that they no longer recommend epoxy or 5200 etc for the installation. They recommend you seal the base with a water tight silicone such as GE Silicone I or II and fill it with just under 3 ounces of mineral or Propylene glycol. Well that's easy enough.

[hart]

Ok, the fuse block is in and ready to go:


Fuse block in helm by Brian Hart, on Flickr

I left room on the wood to add a terminal block later for a planned cockpit lighting mod.

And the Ram Mount is installed and waiting on the 740s:


Ram Mount by Brian Hart, on Flickr

You can also see the 12v outlet I added to the pedestal in the middle right of this photo. I've got to clean up the wiring a little bit and organize it with some cable ties but that's not worth a photo.

[hart]

Well it finally arrived yesterday. The 740s unpacked includes the unit, the bail mount, flush mounting gasket, templates for bail mounting or flush mounting, the power/data harness, quick start guide, and owners manual:


Untitled by Brian Hart, on Flickr

Here's the In-Hull transducer - it's an Airmar P79 model. You get the transducer and cable (not sure of the length but I bet it's 25 or 30 feet) the mounting bracket, O-ring, and a collar so you can adjust the dead rise angle to fit your boat. The Garmin Bluechart G2 Vision card comes in a sleeve as pictured:


Garmin In-Hull Transducer, Airmar P79 and Bluechart G2 Vision card by Brian Hart, on Flickr

The transducer includes detailed mounting instructions, the same ones I linked to in an earlier post. Airmar now reccomends mounting the 'ducer with GE Silicone I or II and using Propylene Glycol (an RV/Marine Antifreeze) to fill the reservoir with. I've read mineral oil works but will soften some adhesives. I'm not sure about silicone but I think I'll go with the antifreeze to be on the safe side.

Today I'll do the actual install so more pictures and a post coming later.

[Divecoz]

ahhhhhh you did nothing to seal or protect that mounting board?

[hart]

The piece of wood? No. I figured it wouldn't get too wet in there, was I wrong? As it turns out it fell off anyway. Guess I didn't leave it clamped long enough. I'm rethinking that one. I may just screw the fuse block through to the pedestal and put some finish washers/sealant on the outside. I also now have a piece of starboard I could use instead. More on that later with pics.

[hart]

I'm all but finished.

The Ram Mount and the Garmin bail mount don't match up at all. So I ended up making a bridge piece out of starboard:


740s mounting bracket. by Brian Hart, on Flickr

I wanted the ram mount so I could swivel the unit side to side, move it up and down, and tilt it. It's very versatile. They make a smaller one and perhaps it would be a better choice on our pedestal but hind sight is 20/20. We'll see how it works out this weekend on the B.E.E.R. Cruise.


I ended up mounting the transducer just aft of the head. I did that for a couple reasons. 1. To get it away from the electrical wiring I've got running back to the motor and to the pedestal. Apparently electrical interference can cause problems with the transducer. 2. It's an easy spot to get to in case I messed something up and have to redo it. 3. I wanted to make sure I was far enough back I didn't have any problems with the hull leaving the water when planing and that I wouldn't get any interference from dirty water coming off the keel. As it turns out this is where the P.O. had installed the original transducer. I never knew that until today. That one worked fine so I think this one will too.


Untitled by Brian Hart, on Flickr


It's ALIVE!


Untitled by Brian Hart, on Flickr

All that's left is to close up the pedestal and install the G2 Vision Card, and add the antifreeze to the transducer once the silicone has fully cured. And with that it's time to move on to other projects to get ready for B.E.E.R. Can't wait to test it out. I'll post reports from the B.E.E.R. Cruise on my facebook page if you're interested: http://www.facebook.com/HartVoiceOvers