Best/first electronics for our 27' Ericson

Hello everyone,
This is my first post to the forum as my family and I just purchased our first sailboat a 1976 27' Ericsson. As we paint the keel, install the through hole transducer and all around cleaning while preparing the boat to move, I have a couple of questions. First off sorry if the questions seem naive, so here we go. While getting the cockpit ready for sailing, so I've decided to add an angle guard for our electronics with a Navpod for security, so I would love to pick-up a Garmin GMI 20, and chart plotter. I am starting with the depth sounder/ speed detector. First, how is speed detected is it internal GPS? Or do I need to add a speed impeller? Second, if I rely on a GPS, once I go blue water will I loose signal and need a mast mounted GPS antenna or is the typical unit coming with a sufficient GPS? This will be the last item I add to the boat before we switch marinas. Also lastly if anyone out there has a Gamrin Depth sounder and chart plotter they would like to sell let me know we have just begun the search. Thanks and we are so happy to be apart of the Ericson family.
Regards,
Chris

Welcome to the forum. All questions answered, really a useful place for us all.

GPS gives speed by calculation, and it works fine 1,000 miles offshore (Racers require a paddle wheel- type speed indicator to give speed through the water--GPS is always speed over ground).

For depth sounding a transducer is needed, but not a hole in the hull--new models shoot sonar through the fiberglass.

Many inexpensive units are both GPS chartplotters and fathometers ("fishfinders").

I'm pleased with the Garmin 50s GPS/fathometer described HERE, but there are many to choose from.

Thanks, great link too

Christian Williams said:

Welcome to the forum. All questions answered, really a useful place for us all.

GPS gives speed by calculation, and it works fine 1,000 miles offshore (Racers require a paddle wheel- type speed indicator to give speed through the water--GPS is always speed over ground).

For depth sounding a transducer is needed, but not a hole in the hull--new models shoot sonar through the fiberglass.

Many inexpensive units are both GPS chartplotters and fathometers ("fishfinders").

I'm pleased with the Garmin 50s GPS/fathometer described HERE, but there are many to choose from.

Click to expand...

I appreciate it. I was curious mostly about the GPS. I have the through hole and transducer already and it's set for Garmin. A little more pricy but I like Garmin.
Regards,
Chris

The GPS satellites cover the whole globe. It doesn't make any difference whether your antenna is on the mast or the rail, as long as it's out of the way of the running rigging. Mine is on the little port quarter deck, outside the coaming. Not sure if the 27 has that.

Some of the other satellite services, such as SPOT tracker have more limited coverage off shore, but they cover all of the US coastal waters.

I used a "shoot through the hull" depth transducer on my boat, the first year, because I hadn't hauled it out yet, and the approaches to the marina were really, really shallow. There were a number of times, when I needed it most, that it seemed to get confused (from too many reflections/diffractions?) and the display would go blank. I've never had a problem since installing the through-hull.

I did also install a through-hull for the paddlewheel speed sensor. (There was already a hole for an old non-functioning transducer.) One extra thing that often comes with those is a water temperature sensor.

Oh, but to answer your actual question, it appears that the unit that the Garmin unit uses a single through-hull sensor that measures both depth and speed, and uses a paddlewheel for speed.

For the record, my Airmar in-hull transducer also measures water temperature.

+1 on the Garmin 50

This spring I installed a Garmin DV50 and wired it to my old Airmar sounder, no need for the expensive water proof box if you do your connections in a dry area. No need for an external antenna as the GPS has it built in. It accepts Blue Chart G2 maps.

Great device.

Great thanks!

Terrific, thanks everyone.
I just completed my basic sailing "light air" certification course today. I celebrated by signing up for Intermediate Keel boat course in a week. Great feeling, we sailed 420's all weekend. We couldn't get heavy air signatures even though we were sailing with 15 knts for 4 hours this morning because the Norfolk Navy Sailing class doesn't typically sign off on that section of our "Red Book".
Regards,
Chris