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bligh

bligh

Guru
Joined
May 29, 2013
Messages
1,531
Location
USA
Vessel Name
Concerto
Vessel Make
1980 Cheoy Lee
New radar mast.
I need one as I dont have one at all.
I was thinking of consolidating all my electronics on it;
GPS receivers, VHF antennas, radar, satellite receiver (if I choose to keep or replace mine), Anchor light, steaming light, rear camera, FLIR (haha-not on my budget).
Here is the mast I am looking at;
product_range_4d52bc0ad4515.jpg

Scanstrut – Tapered Mast

2 Questions;
Is it a good idea to consolidate the electronics like this? Will they all work properly?

What is involved in mounting this mast on my pilothouse and making it stable? There has never been one located there before. I'm good at cutting and drilling, but if fiberglass resin work is involved, I'm not interested.
 
You shouldn't have to do any fiberglass work to install something like that. You will have to back it up inside the cabin top with a good sturdy backing plate. My first choice would be a G10 fiberglass plate. You can get them at most plastic supply places or eBay. Sealing it might be a challenge if you've got a lot of curve to your cabin top. My preference is for mastic tape instead of goopy stuff. Looks like it'd be a nice retrofit project.
 
Rick,
I am not positive, but I think my cabin top is balsa cored fiberglass. I would think that even with a backing plate, I would risk crushing the balsa core with the boats and potentially expose the balsa core to moisture intrusion.
I'm hoping a NT owner can verify this for me though.
 
bligh, I think that people use metal sleeves just a tad shorter than the thickness of your cabin top to prevent the crushing that you speak of. This procedure, of course, requires great attention to the sealing. Try http://www.pbase.com/mainecruising/boat_projects for deck attachment procedures. George
 
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bligh said:
Rick,
I am not positive, but I think my cabin top is balsa cored fiberglass. I would think that even with a backing plate, I would risk crushing the balsa core with the boats and potentially expose the balsa core to moisture intrusion.
I'm hoping a NT owner can verify this for me though.
Click to expand...
You can also overdrill and fill the holes with thickened epoxy. Let that cure then drill out to correct size. For example: 3/8" bolt I'd drill to 1", fill then re-drill for the 3/8" bolt once cured. That should prevent crushing the core.

Update: I forgot, you don't have to drill a full 1" hole. Once you get the 3'8" drilled you can remove the material from inside the hole leaving as much of the original fiberglass in place as possible. Stick an allen key in your electric drill and insert that in the hole to route out the core then fill with thickened epoxy. I did that trick on a searchlight install on a balsa cored anchor platform once.
 
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Well. Howabout this;
I can remove the balsa core from inside above the headliner along with the thinner, inside layer of fiberglass, then use a g10 plate to fill where I removed the balsa core. Then I can drill all the holes I need through the fiberglass and the g10. Then I can fasten it on that way. (I also need holes for the cables to run through to serve the electronics..)
 
Wow. that g10 stuff is pricey. I think I could get stainless steel cheaper.

1.000" (thick)
18.00" X 24.00" $253.94
 
She-Kon said:
Once you get the 3'8" drilled you can remove the material from inside the hole leaving as much of the original fiberglass in place as possible. Stick an allen key in your electric drill and insert that in the hole to route out the core then fill with thickened epoxy. I did that trick on a searchlight install on a balsa cored anchor platform once.
Click to expand...

:thumb:I will remember that one.:thumb:
 
bligh said:
Well. Howabout this;
I can remove the balsa core from inside above the headliner along with the thinner, inside layer of fiberglass, then use a g10 plate to fill where I removed the balsa core. Then I can drill all the holes I need through the fiberglass and the g10. Then I can fasten it on that way. (I also need holes for the cables to run through to serve the electronics..)
Click to expand...

That should work. You could also look at using aluminum plate. As others have mentioned you need to be very diligent with sealing all the bolt holes, plates and wire runs. Hopefully all the wires can run through the mast.

You also need to consider how close to each other your VHF antennas are going to end being.
 
bligh said:
Wow. that g10 stuff is pricey. I think I could get stainless steel cheaper.

1.000" (thick)
18.00" X 24.00" $253.94
Click to expand...
Wow! That's waaaaaaaaay toooooooo much! I'd think 1/4" and 10" x 10" (size same as base of mast) would be 'nuff! It's just a backing plate for strength. You could replace the core with marine plywood much easier.
 
bligh said:
Teach me OBIWAN.
Click to expand...

It's not an exact science. But as I recall most manufactures recommend 2m of separation. But if you can mount one higher than the other that can help if you have to mount them close together on the horizontal plane. BillyIII will know all this stuff off the top of his head.
 
Capt.Bill11 said:
It's not an exact science. But as I recall most manufactures recommend 2m of separation. But if you can mount one higher than the other that can help if you have to mount them close together on the horizontal plane. BillyIII will know all this stuff off the top of his head.
Click to expand...

And of course very few people use both their VHF antennas at the same time. :) In theory perhaps having them too close together can cut down on even received signal strength, but practically speaking I do not think it would make a dime's worth of difference.

Of course, there are some electronics experts on the forum that may correct me on all this, since I am not an expert. Just an old ham radio operator for many years.
 
You could very well be right. But I thought the issue wasn't just if by some odd chance you were using both radios at the same time. But the fact that if one antenna, even if it is not being used, is to close to the other one that is broadcasting the unused one could cut down on the range of the one in use.

At least that is what I've been told and read over the years.
 
Capt.Bill11 said:
Y But I thought the issue wasn't just if by some odd chance you were using both radios at the same time. But the fact that if one antenna, even if it is not being used, is to close to the other one that is broadcasting the unused one could cut down on the range of the one in use.

At least that is what I've been told and read over the years.
Click to expand...

Yes, I agree with you on that. If they are the proper distance apart then the one could absorb some of the energy of the other. I was being a bit facetious in my post -- sorry about that. You are correct.
 
Just remember.... replacing the core with something more solid still requires some kind of overlap or structural bonding between the existing roof structure and the square you insert.

Otherwise the leverage of the mast might just pop your new square free and the only thing holding then will be the upper skin.

There's more going on than just compression of a sandwiched core.
 
psneeld said:
Just remember.... replacing the core with something more solid still requires some kind of overlap or structural bonding between the existing roof structure and the square you insert.

Otherwise the leverage of the mast might just pop your new square free and the only thing holding then will be the upper skin.

There's more going on than just compression of a sandwiched core.
Click to expand...

Very good point. The backing plate needs to be significantly larger than the pad of the mast it is backing up. Especially because the glass skin you will be bonding the backing plate to will more than likely be pretty thin.

In fact you may be better off not digging out the core. But through bolting down through the top, core and lower skin to a large are pad. Just be sure to dig out the core around the bolt holes, and any other holes you make, and fill the pockets you create with epoxy.
 
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Capt Bill..... You are correct, the backing plate does not need to be 1" thick as the OP suggested but definitely needs to be bigger than the mast base. In this application it should be as big as he aesthetically can make it. Within reason of course.

Sent from my Nexus 4 using Trawler
 
There are several ways to do it...any of them are fine as long as "cored roof" crush is prevented and adequate backing prevents pull through. (assuming the top skin is strong enough to take the weight and not oil can/flex/deform, etc.....)

Major surgery isn't necessary and epoxy/reinforcing in itself used correctly is adequate.

The trick is to use the right combo...certainly not ALL of the suggestions combined.
 
Very nice mast. I wouldn't mount vhf antennas on it if you run with 2 vhfs at the same station. If you have 1 on fly bridge and 1 in PH, no problem. Many of us use 2 or more at one pilotting station and the separation in 2 antennas that close together(on mast) would be a recipe for splashover.
 
I'm using EDSON mounting plates, device matching plates and Aluminum masts on my Gulfstar. I'll have the ability to have 4 if I cut the Aluminum supplied masts in half. My application will require 3 masts one centered the other 2 offset one on each side.
Bill
 
Way too complex. The reason for the balsa core is rigidity. Don't remove it. Aluminum is cheap, thin and easy to work for a backing plate.

If truth be known... My mast, much higher (more leverage) than the one shown only has a teak plate on the outside and was found to have no backing plate. It worked for twenty some years until I put on a backing plate. No epoxy around the bolts either (gasp). No leaks, no cracks, no crush.

I am also in the process of building a new mast. But I am just designing it and will have it fabricated by an aluminum shop. The off the shelf options are a bit limiting.

There is significant camber on the pilothouse roof. Go up there with a straight edge.

I will drill oversize holes from the top and fill with epoxy and redrill as I have with everything thing else I have rebedded since ownership. Gravity is your friend when using this method.
 
Good post Northern Spy...

Bligh - Sorry to insult your experience if you are already pretty good at this kind of stuff...if not ...remember when drilling holes in a pretty good camber that depending on how you drill, vertical or 90deg to the surface will determine the hole spacing on the backing plate...

More than once I have forgotten or tried to use prefabbed stuff and couldn't line up the bolt holes.
 
I'm thinking of going the same route, but was wondering if the self leveling mast mounts are better?

-Josh
 
Thanks for all the comments. I'm actually changing to a different mast, but the install should be the same. I think I'm going to have a yard install it. I'll discuss the final details of the install with them and I'll do the all the prep for them. Then run all the electronics myself. I'll problem leave the final wiring to to the panel to an aybc electrician.
 
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