Mounting an ATU to a steel hull

[Orchidius]

Hi there,

So I'm looking at ways to install the whole HF-rig I've had laying in the basement for a few months now. The transceiver is dealt with, and now I'm turning my attention to the ATU unit. I've talked to a few people who are all a lot smarter than I am, and the consensus seems to be that the ATU should not be mounted outside as was my original plan, but moved indoors somewhere.

Since it's a small boat, this has given me a bit of a headache, but I did manage to find a spot. The issue is that it's in one of the cockpit lockers, and there are no GRP/wood surfaces to mount the ATU to. It's got to be mounted either directly to the steel hull or directly to the steel stern (well, I guess that's hull too).

How would you go about this? Use construction adhesive (like liquid nails) to glue a piece of hardwood to the hull and then screw the ATU onto that?

[Orchidius]

Nobody?

[Wotname]

Presumably welding on mounts isn't practical in your circumstances ??????

What's wrong with through bolting it?

There must be (or should be?) some way to bolt on some timber framing, mount some plywood to the frames and mount the ATU on the ply.

Or just sikaflex the ATU to the hull and hope for the best

[Orchidius]

The issue is that I'll be mounting the ATU directly to the steel hull, directly at the waterline... Through-bolting or making holes of any kind isn't really an option as you can imagine.

Welding isn't either, installing it means hanging upside down in the locker with barely enough room to get your head in the right spot while leaving enough room for your arms to move around.

My initial idea of using "sikaflex" to glue some ply/hardwood onto the steel surface of the hull and then screwing the ATU onto that ply/hardwood doesn't sound so crazy then?

[Wotname]

Originally Posted by Orchidius

The issue is that I'll be mounting the ATU directly to the steel hull, directly at the waterline... Through-bolting or making holes of any kind isn't really an option as you can imagine.

Welding isn't either, installing it means hanging upside down in the locker with barely enough room to get your head in the right spot while leaving enough room for your arms to move around.

My initial idea of using "sikaflex" to glue some ply/hardwood onto the steel surface of the hull and then screwing the ATU onto that ply/hardwood doesn't sound so crazy then?

Come on, be more adventurous ; Put some decent weight at the bow to left the stern up a few inches, drill the holes, fix the ATU and make sure you seal the bolts really well. Retrim the boat and away you go...

OK, I probably wouldn't do it either

Well, gluing some wood to the steel would work - at least for a while.

Can't the ATU be mounted on the underside of the deck or the underside of the cockpit floor or similar??

[Orchidius]

If I had a picture you'd understand, but I can't take a picture because it's such a cramped space .

The underside of the deck is also steel btw, with a teak deck on top (FML). There is a fiberglass bulkhead in the locker, but that's a good 4ft futher aft (away from the antenna) and I might have to recruit a kid or a midget to install it there.

[Wotname]

Originally Posted by Orchidius

If I had a picture you'd understand, but I can't take a picture because it's such a cramped space .

The underside of the deck is also steel btw, with a teak deck on top (FML). There is a fiberglass bulkhead in the locker, but that's a good 4ft futher aft (away from the antenna) and I might have to recruit a kid or a midget to install it there.

There is a saying in general aviation circles (where space is always tight) that goes "if you see it or touch it but not necessarily at the same time, you have access; if you can see it and touch it at the same time, you have good access".

Good luck with it and keep looking; there is always a solution!

[Orchidius]

Another idea that was mentioned is to glue some metal profiles directly to the steel hull using two-component epoxy glue. Superstrong apparently, but nobody knows how it'll stand up to the test of time...

[ka4wja]

Full disclosure up front, I don't have a steel boat!!

But, I have had good luck with epoxy sticking to alum and even glossy-painted (powder-coated) alum...
So, I'd try some epoxy....glue a piece of wood, etc. to whatever steel structure is best / has best access and allows the remote ATU to be placed close to the external ant / stay...

Originally Posted by Orchidius

Another idea that was mentioned is to glue some metal profiles directly to the steel hull using two-component epoxy glue. Superstrong apparently, but nobody knows how it'll stand up to the test of time...

My USCG doc number board (a big piece of teak) is epoxied to the gel-coat on the inside of my hull, and has been in place for > 15 years, across the Atlantic a few times and thru THREE Cat 3 Hurricanes in S. Florida....and it's still solidly in place....


So, go with the epoxy....

Fair winds...

John
s/v Annie Laurie

[Cadence]

Originally Posted by Orchidius

Hi there,

So I'm looking at ways to install the whole HF-rig I've had laying in the basement for a few months now. The transceiver is dealt with, and now I'm turning my attention to the ATU unit. I've talked to a few people who are all a lot smarter than I am, and the consensus seems to be that the ATU should not be mounted outside as was my original plan, but moved indoors somewhere.

Since it's a small boat, this has given me a bit of a headache, but I did manage to find a spot. The issue is that it's in one of the cockpit lockers, and there are no GRP/wood surfaces to mount the ATU to. It's got to be mounted either directly to the steel hull or directly to the steel stern (well, I guess that's hull too).


How would you go about this? Use construction adhesive (like liquid nails) to glue a piece of hardwood to the hull and then screw the ATU onto that?

Liquid nails will hold to about any surface. Save a buck from buying an adhesive that state "marine".

[Viking Sailor]

Hang a "L" bracket from the underside of the deck using bolts. Mount the ATU to the bracket and run the antenna feed line from the ATU up through the deck to the antenna.

[a64pilot]

I don't know about liquid nails, but 5200 will hold it, it being a wood shelf etc.

[hpeer]

I mounted a GPS antenna on steel plate with 5200. And the Chimney cover for my kero heater. Both seem to be doing fine.

The antenna tuner isnt very heavy I think.

Getting lots of surface area for the bond should help.

Good luck.

[jldunn86]

3m products...
SMC/F/G PNL ADHES 200ml
This stuff is double tough...

[Cheechako]

under an aft berth? Do you have any kind of bulkhead in the cockpit lockers or lazzarette? Bolt it to a bulkhead or divider without screwing thru the stern. Or, can you put it on the stern above the waterline?
A bracket using Plexus?