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Free Range Human, Sailor, Writer, Artist, Videographer  

Saturday, July 26, 2014

GPSMAP 640/ Depth Finder Swing Mount

I set out to design a swing arm for my Garmin GPSMAP 640 that would include the depth finder. There are, no doubt, more expensive and modern solutions available, neverthelessI like the look of wood on a boat. Especially if it lives out of the weather.   
First Off  -  I am Not a Carpenter!

Garmin GPS MAP 640 w/ Depth Finder Swing Arm

 Considering the cost of the GPS, the risk of damage to the unit is an important concern.  The design is a simple "T" made from 1 x 4 fir, ship lapped and epoxied, then attached to a solid brass door hinge mounted on a home made magazine rack.  Be sure to leave space between the companion way access and the edge of the GPS and plan your wire and cable route carefully.  It would have been better, in this instance, to mount the arm on the starboard side to be closer to the panel box and transducer however, the magazine rack is on the port side and readily available.   Note how the GPS cable extends into the companion way creating a possibility of snagging it on something.  So far it has not been an issue. 

 The ship lap does not extend to the end of the vertical piece. There is no reason for this, I just liked the idea of an undisturbed edge.   I'm sure anyone with average skills can produce a better looking result but this side of the mount is not visible from the cockpit.  If anybody notices it - Well, the Complaint Department is located at the end of the plank, starboard side, should anybody  want  to comment about my  carpentry skills. 

SV HideAway GPS / depth finder swing mount

The arm swings fully back on its hinge and is held in place by a line from the back of the mount to a wood inspection hole cover.  The line is loose to allow some movement if bumped.

Yes, those are hinge screws protruding on the face of the unit.  They have been filed smooth and are not visible when the arm is deployed. (Comments are accepted at the Complaint Desk above.)

Solid brass door hinge - reversed pin -note angle
The magazine rack follows the slope of the cabin wall.  In order to compensate I angled the hinge to produce a level arm.  Some day I may finish the end of the arm, but not today.

Line from back of display keeps the unit to front
 The line holding the arm to the front has a bit of slack that serves as a sort of warning should you collide with it.  The mount looks crooked in this photo, but if memory serves I made the correction later.   On a small sailboat such as HideAway, level and plumb are more concepts than reality.

Line from back of display secured 
 When not in use the line used to hold the arm open is employed along with a shorter line to hold the arm inside the cabin.  That way the arm does not swing wildly about during launching and it keeps the expensive stuff out of the weather.

In the interest of maximum security, I thru bolted  the GPS mount with stainless steel bolts rather than using wood screws.   I let the bolts run long so I could attach the swing arm control lines.

GPS Mount is Thru-Bolted
 The electrical wires and cables are not contained. I routed them under the sink top edge, around the back to the panel box or in the case of the depth finder, along and under the settees.  Since I installed the depth finder on the starboard side, the depth finder cable and wiring had to run through five bulk heads.  A real pain to accomplish, however the potential hole-in-boat problems, the vanity sink drain and the transducer, are isolated from other storage areas and have good access in case of an emergency.  See the Video Here

GPSMAP 640 Swing Mount w/ Depth Finder 

The GPSMAP 640 plastic mount has a interesting feature.  The mount swivels at the center.  (See the knob in the center of the mount.) The knob allows the unit to turn when you bump it saving damage to the GPS and mount.  A nice feature on a rough day. 

This is a simple woodworking project that someone with little carpentry skills, that would be me, can complete to a reasonably functioning level.  The swing mount has been in service for more than a year without difficulties or safety issues.