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Old 06-20-2014, 10:56 AM   #1
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Trawler mast

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;

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.
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Old 06-20-2014, 11:14 AM   #2
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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.
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Old 06-20-2014, 01:20 PM   #3
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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.
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Old 06-20-2014, 01:32 PM   #4
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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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Old 06-20-2014, 03:02 PM   #5
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Quote:
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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.
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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Old 06-20-2014, 03:13 PM   #6
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I concur with She-Kon about the G-10 for a base. A somewhat better price than outfits like Jamestown Distr. etc. can be had from Cross Nail Laminates in PA, who can also cut to size. Here's the link:

G10/FR4 Properties, Technical Specifications | CNLAP
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Old 06-20-2014, 04:36 PM   #7
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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 Compass Marine How To Articles Photo Gallery by Compass Marine How To at pbase.com for deck attachment procedures. George
Which article are you referring to?
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Old 06-20-2014, 04:53 PM   #8
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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..)
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Old 06-20-2014, 04:57 PM   #9
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Wow. that g10 stuff is pricey. I think I could get stainless steel cheaper.

1.000" (thick)
18.00" X 24.00" $253.94
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Old 06-20-2014, 04:59 PM   #10
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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.
I will remember that one.
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Old 06-20-2014, 05:01 PM   #11
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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..)
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.
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Old 06-20-2014, 05:09 PM   #12
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You also need to consider how close to each other your VHF antennas are going to end being.

Teach me OBIWAN.
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Old 06-20-2014, 05:12 PM   #13
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Wow. that g10 stuff is pricey. I think I could get stainless steel cheaper.

1.000" (thick)
18.00" X 24.00" $253.94
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.
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Old 06-20-2014, 05:27 PM   #14
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Teach me OBIWAN.
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.
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Old 06-20-2014, 05:34 PM   #15
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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.
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.
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Old 06-20-2014, 05:49 PM   #16
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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.
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Old 06-20-2014, 05:57 PM   #17
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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.
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.
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Old 06-20-2014, 07:27 PM   #18
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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.
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Old 06-20-2014, 08:37 PM   #19
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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.
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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Old 06-20-2014, 09:15 PM   #20
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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.

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