Assembly and Installation of the Radar Mast

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March 2005 --

It's up. I bought the adjustable mast kit from Garhauer back in 2002, and really didn't think it would take this long to get around to it. It sure feels good to get it done.

It's installed through the deck, and extends eight feet above deck level. When standing in the cockpit, it seems high,
but one can work on it when standing on
the stern rail seats.

There's the radome, of course, and a Shakespeare TV antenna with adjustable gain. I added a backup VHF Antenna from Digital Antenna, as well as a Furuno WAAS GPS antenna.

It was important to keep the GPS antenna away from the VHF antenna. Since the VHF antenna is really just a backup (and at the moment feeds the stereo) I didn't strictly adhere to the 1M distance, but I tried to keep the other antennas as far away from the GPS as possible. I have the Garman, which is mounted low on the centerline, as a trusted reference.
(Note: after testing, they read the same.)

The platform was made for a Raymarine system, but after three years I'd changed my mind and went with Furuno. I talked with Garhauer about replacing the stainless steel base plate,
or even purchasing an entire new assembly,
but oddly enough the folks there didn't recognize the part number for the radome, and it turned into a hassle,
so I wrote it off and decided to solve the problem myself.

I just made it work by drilling new holes
and attaching a good base of my own design. This actually worked out nicely, as the center of gravity of the Furuno radome allowed me to reverse the entire assembly and put the heel adjustment nut inboard, closer to the helm.

I made the base from Seaboard, from Tap Plastics.

It's a UV Stabilized Polyethylene, just like Starboard,
but costs a lot less. I liked this idea as
I could form the board to match the radome's molded base.

I moved the stern light up onto the pole, and inadvertently did another bonehead move.

The package said "waterproof", but it isn't waterproof if you mount it upside down!

It turns out that there was a tiny drain hole that I put on the *top*. Oh.
After a little work,
that hole is now sealed and there's a new tiny drain hole on the bottom.

I also mounted two Hella floodlights, separately wired, at the top.

They run to a Cole Hersee "on/off/on" switch mounted just inside the companionway.
Only one light can be on at a time, but I can live with that.

Before attaching the platform to the pole, I test fit it and slipped this piece of exhaust hose around it, so that it would be supported at the right location and wouldn't require a lot of lifting to slip the bottom bolt through.

I experimented with Dyna-Hair, a vinylester putty with long strands of fiberglass mixed in. This was really just to play with the stuff, in case it would come in handy for some other project where the material could have value.

Before putting the pole up, everything needed to be mounted and wired up.

There's a new GPS antenna, which connects directly into the Radar / Plotter.

I had originally thought that I'd use the Garman, which was wired into the ComNav / Nexus instrument system. The thought was to take the NMEA output from the Nexus system and use it to send Lat/Lon information to the Furuno. However, I also want NMEA to the Icom VHF, and someday to an Autopilot system, and that meant getting an NMEA multiplexor to provide enough connections. Suddenly the cost of all this complexity was getting pretty high. It was a lot cheaper to get a WAAS GPS antenna that plugs into the Furuno, and now I have redundant GPS systems.

Note that the wire from the GPS antenna is covered in flexible protection, which goes *through* the hole in the rail and protects from chafe and UV.

Note 3 months later: There's NO WAY I'll use the Faruno as my primary GPS. This system sucks 3A/H. Back to the Garmin!

Here's the assembly,
dry fit before getting out
the goopy stuff.

The lower ring is held in place with epoxy, and the upper ring is caulked in with 4200.

Note that the hole in the deck is a little wider, so that I can pack that groove with caulk to help maintain a flexible seal.

It was very important to get everything lined up right, both for structural integrity and to avoid getting too close the the exhaust hose through-hull.

So after spending two days thinking and measuring, I was sure I had it right and proceeded to rough up the area with a bronze brush, and seat the teak block in a huge glop of super thick West System epoxy / colloidal silica putty.

But the damn pipe had been sitting in the garage for two years, leaning up against the wall, and had a very subtle two inch bow in it.

All my measurements were wrong, but I'd already drilled a hole in the deck.

So three of the mounting lag bolts are in the teak block, but the back was hanging off the edge. I stuck a bolt in, and packed that entire area with an Epoxy / Fiberglass Chop / Colloidal Silica putty.

I think it's strong enough, especially with the steel braces that will be installed.
(More on that later.)

The pole then slides down into this Stainless Steel bushing, again from McMaster-Carr.
(part number 45735K311)


When the time came to install,
I made an incredibly bone-head move.

I did the planning using a couple of sections of ABS plastic pipe to stand in for the pole, because it was a lot easier to handle. I sliced off a small two foot piece and fit it under the deck to determine exactly where the hole should go, and where the block should be mounted.

The pole itself goes through the deck and is
bolted to the hull. Obviously, I wasn't going to
drill into the hull, so I took the old teak mounting blocks from the the old self-tending jib setup (removed in 2001) and shaped teak block that is really close to the angle of the hull, so that the mounting bracket is close to horizontal.

Then the little block was soaked in Smith's Penetrating Epoxy for about two days, and allowed to cure for the next two years.

That's a joke, sorta. It just took me two years to get around to the rest of the project.

Shakespeare provides an interesting tool to attach the coax to the antenna. I didn't use the coax provided, but put good Ancor wire on instead, and gold connectors. I put a little dielectric silicone on the connector
before attaching it.

I also used a threaded stainless steel antenna extension (cut down to fit)
on the nylon Forespar mount.

The coax goes through the pipe and down the bottom. Then I injected about half of a big tube of white marine silicone sealant into the joint.

The deck area is critical, since it needs to be really strong and also watertight. A lot of water flows around the deck at the stern, and pools up waiting to work down the deck drains.

I made a reinforcing plate (on the right) out of 1/2" prefab fiberglass from McMaster-Carr, that is epoxied to the underside of the deck, to make the deck thicker. On the left is another fiberglass ring that's painted with a dozen coats of polyurethane.


Way on the other side,
as far away from the GPS as possible, is a Digital Antenna backup VHF antenna in case something goes wrong with the masthead unit.

Right now it's hooked up to the Milltech AIS receiver.

It's mounted low and is braced to the steel rail using Dickinson universal rail mounts (2) mounted back to back and through bolted with 4 inch bolts.

The Seaboard plate is glued and sealed to the stainless base with 3M 4200 to keep water out and prevent corrosion. The bolts for the radome
pass through the steel plate.

The TV Antenna
has Bird Spikes glued on with 5200.
I finally found a use for 5200!

The spikes are from McMaster-Carr, part number 6200T51. They're UV Stabilized clear plastic. I expect they'll get ugly and yellow, but that's better than bird crap.
I need to climb up there and straighten the antenna
and add more spikes. Later.

Under the deck,
the pole is seriously braced by bolting it to the center bulkhead (which also supports the back stay) and to the side of the cockpit (hidden under the helm seat.)

These are custom braces from Garhauer, bolted onto one inch steel pipe. The other end is drilled and tapped, and bolted onto ordinary stainless 'rail mounts'
from Sea Dog.

Note how the wiring is covered in hose for chafe protection, and tie wrapped securely. The hose slips under the pole a bit,
to try and keep the wiring
away from the edge of the pole.


All the lights are mounted on little fiberglass pads, that were molded to the pole.

It turned out to be really difficult to handle,
although for some applications where a strong filler is needed it will work nicely.


It was too thick,
and left gaps.

I ended up making a putty of epoxy and colloidal silica and reforming the pads to fill the gaps, then grinding them into shape on the bench belt sander.

Here's a little detail on the radome cable.

The flexible cover extends down into the radar mast, to protect against chafe on the edge. It also goes all the way through the Seaboard and extends up to the radome, to protect against UV. The slit in the cover faces down so that water can drain out.

Then we raised the pole
and slipped it into place.

I stayed on the bottom to make sure that none of the wires were crushed.

Under the deck, the bushing is caulked through the fiberglass reinforced deck, and the pole slips through the bushing with about 1/32" of play all around.

One might as well plan on the pole flexing and moving a bit, which will break any solid caulked seal. So I wrapped butyl tape all around the area, pressing it firmly against the bottom of the deck and all around the pole.

Then a split piece of 3.5" PVC pipe was stuck around the butyl to hold it in place.

The big hose clamps gooshed it slowly all around the whole assembly.

I think I'll go back and stick some caulk over the bottom, to keep the butyl from drooping over time.

The Garhauer pole is open at the top, and I really want to seal it up to keep water from running down into the hull. It would eventually find its way to the bilge, but not after running
the length of the boat.

This 2.5" neoprene rubber plug
from McMaster-Carr (part number 2605K21)
was a bit too long to clear the cross bolt, so I cut it down with a hack saw. The through-bolt compresses the plug so that it fits really tight.


Above deck, the pole is braced to the new stern rail, with another side brace added for lateral support.

I'm trying to avoid having supports sticking up,
which can make it tough to move around . However, I might add one more brace near the top of the pole, because right now the top five feet are unsupported and the pole isn't totally rigid.

We'll see.

Then I injected Liquid LifeCaulk
into the joint. This stuff is really thin,
and dribbled all the way down the bushing until it hit the butyl.

I've experienced it turning Yellow in a year of UV, so after it set I wiped a thin top layer of regular Life Caulk over it.


I drilled new wiring holes myself because Garhauer provided one big hole for all the wires. I covered that hole and mounted a floodlight there, because it was just too big and I didn't want water getting in that easily. So all the wiring holes are sized to allow a tight fit for the flexible chafe protection -- and I might even go back and pack the holes with silicone.

After drilling, each hole was well polished with Emery Compound and White Rouge, to remove sharp edges.

I put the 36 inch davit on the mast.

The brackets that Garhauer provides are strong, and give the installer
(i.e. Me) flexibility in placing everything.
However, they're ugly.
One of these days, when I'm bored,
I'll whip up some little fiberglass covers for the ugly parts.

Anyway, there are a few other details to add. I need to adjust the TV antenna and add some more bird spikes, and stuff. But everything's wired up and works.

The boat's cleaned up and back in sailing shape,
and I just started sanding the toe rails for the spring varnish job,
so the left over details will happen when the time is right.

See what I mean?
A little cover of some sort will be nice.

Note that wherever I clamped stainless to stainless, I caulked it well with Polysulfide to avoid having areas where water can collect. Stainless will rust in the right conditions,
so this may help prevent that.