Best way to attach harware to cabin top

[Doug J]

As I'm installing new hardware to my boat, traveler track, genoa tracks, fairleads etc. I'm hearing differences of opinion regarding the correct way to seal the holes.I'd be interested to hear the opinions of all of you!What type of sealant? 3M 4200 or silicone?Should the sealant be allowed to cure a little before all is tightened down?Should the holes be oversized, filled with epoxy, then re-drilled to the smaller correct size?For those of you that have installed a lot of hardware, what method did you use? Have you developed any leaks yet?What works good, what doesn't?

 

[John S]

Mounting Techniques

Sounds like you have some good recommendations already. One thing, the power from your sails will be transmitted through your traveler, I backed mine up with an aluminum plate running the width of the cabin on the overhead. If you are going to go to the trouble of oversized/epoxy/redrill technique, you should back up whatever it is your are mounting with a metal plate below. Just what I have done.... John S

 

[CP-Mike]

My procedures and recommendations

When you drill the holes, make them just a little bit bigger than the bolts you're putting in them. Then take masking tape (that blue 3M stuff) and cover the underside of the hole. Also try to put some masking tape around the hole on the topside to prevent spills from messing up your deck. Mix up a small batch of marine epoxy and pour it into each hole. If the level of the epoxy goes down in the hole, make sure it's not dripping into the interior and add more until it stops going down. The point here is to completely coat any exposed laminate or core that your bolt hole could allow water to access. Now keep poking the epoxy with a stick or something every few minutes. Once you feel it thickening, quickly remove the tape from the underside and let the epoxy drain out. If it needs some coaxing, you can blow down the hole from above. Now let the epoxy cure. If you had let it thicken just the right amount, the hole should have been closed up just enough so that when you try to put the bolt in, it can't spin very easily. I highly recommend 3M 4200 for sealing deck hardware. Why? It's permanently flexible, so it won’t crack, it's durable, it's UV resistant, it won't shrink as it cures, and when you do need to re-bed the hardware or remove it outright, it IS possible to get the damn stuff off your boat. 3M 5200 is easier to get; most Home Depots have it. But don't do it! Once it's on, forget about getting it off. Also it doesn't have the UV inhibitors that 4200 has. Silicone is easy to get off. Unfortunately, that's the only thing it does well....coming off that is. Silicone is easily broken down by salt water and UV rays. Unless you want to be re-bedding all your deck hardware every 8-12 months, don't use silicone. Now that you've got the holes themselves sealed, bust out your caulk gun and 4200. Squeeze some out onto each bolt, then with a gloved hand, work the sealant into the threads. Then put some down into the hole itself, and try to mush it around with a stick or something. Put sealant on the deck around the holes and under where the deck hardware will go. Use some more of that 3M masking tape to keep it from oozing out all over your deck. Now put your hardware into place and put the bolts through it. Go to the underside, and around where each bolt comes out of the ceiling, put a rough bead all around each bolt. Now put on your backing plate (you did remember to make one of those, right? ) or washers or whatever you're using, and tighten down the nuts onto the bolts and washers / backing plate. Sealant should be oozing out from under the backing plate/washers as well as out from under the deck hardware. Since you used masking tape, cleanup is a breeze. Let the sealant dry, then take a utility knife and cut around the inside edge of the tape. Then just pull up the tape, and the sealant will come with it (except for where you cut, of course). The trick is in selecting the correct location for the masking tape, back before you put the deck hardware on. I've never heard of letting the sealant cure a bit before tightening down. I don't really see the point, either. You want the sealant to be squeezed into wherever there's an open gap, and it can't do that if it's viscous. But maybe someone else can weigh in on this aspect.All that is what I have done, and so far no leaks or loose hardware. Hope it helped.

 

[Moe16696]

More thoughts...

Agree with not using 5200.Backing the machine screw or bolt with a plate or fender washer is important, and if there's a fiberglass liner under the deck, you'll have to drill down through it too, then use the hole below as a guide for a hole saw large enough to slip a fender washer through. White plastic filler plugs to cover the hole are available in a limited number of sizes at Lowes and Home Depot, so you may have to go a little larger than the fender washer you intend to use for backing. Where you're going to install a larger backing plate, you may have to install a large deck plate nearby in the fiberglass. Don't count on wood screws to hold anything but the lightest loads, such as cushion snaps, and even then a little epoxy through the hole and on the screw threads may be needed.

 

[Doug J]

oversized/epoxy/redrill technique

John S,So do I understand you correctly, you did use the epoxy technique?I was afraid that would be the recommended method. Sounds like a lot of work.I was hoping I could simply use 4200, with holes just the right size for the screws, let it settup a bit with finger tightened screws, then tighten them down.I already mounted the geoa tracks, only used silicone. I'll remove and re-do. Want to make sure I do it right.

 

[John S]

Cabin Top Hardware

No. I did not use the oversize holes with epoxy. Although that might be the BEST way to do it, I have found drilling slightly oversize, sealing, and clamping with a backing plate is sufficient for most applications. But there is a problem. Some areas are hollow and flexible (like the cabin top in places). I feel that not filling the void is OK if you are using the bolted down item in a shear direction (along with a backing plate). Otherwise, mix up a lot of epoxy. Having said that, sometimes you can see someone elses installation and see if what they did stands the test of time. In the case of my traveler, which is mounted on the bridge deck, which is hollow and flexible, I used the backing plate and sealant alone and it works OK so far (1 year). John S

 

[CP-Mike]

Epoxy

You don't really need to seal the holes with epoxy, it just waterproofs the core of your deck if you do. If water gets down in there and is allowed to fester, it's going to be a huge mess. at worst, you'll suffer delamination, where the outer and inner layers of fiberglass seperate, and at worst, you can have core failure, and your deck could collpase around the hardware. If you're careful to inspect your sealant a few times each season, you can probably keep water penetration to a minimum. When I was new to boat repairs, etc, I was hella scared of epoxy...like it was some mystical substance that mere mortals shouldn't mess with. As a result, I was very hesitant to even attempt to use it. But once I read about it and started using it, I realized that epoxy should be embraced by the fiberglass boatowner. It's wonderful stuff. So if you're in a similar situation, and you're not really comfortable using epoxy, I say read up on it and get comfortable, because you're missing out. System Three has a great trial kit that you can buy for $25 that has a good-sized sample of a few of their main epoxy-based products, everything you need to get started with epoxy and/or fiberglassing, as well as a well-written Epoxy Book that talks all about how to use epoxy, etc. The kit also comes with a $20 rebate coupon off your next purchase of epoxy. Go to www.systemthree.com and click on "SilverTip Trial Kit". That's what I used to learn about epoxy and fiberglassing, and as I'm sure you can tell, I really recommend it.

 

[Doug J]

Thanks to all!

I appreciate all the recommendations!There are probably others out there that will hopefully find this information helpfull as well.

 

[Ben]

drilling through non-wwoden cores

I was under the impression that the epoxy technique is used only when you drill through wooden cores??? Is it really needed when the drilling is done in places where there is no wooden core???ThanksBen

 

[Doug J]

Wood Core

Hello Ben!Yes, my question relates to wood core decks. It's my understanding that if there is no wood core, the epoxy is not needed. But at this point I also understand 4200 should still be used, opposed to silicone..The epoxy idea is to to try to keep any water from ever reaching the wood.Seems like some go that extra step while others don't.I would bet the factories of production boats do not put epoxy in the holes they drill!

 

[Steve Paul]

Seal those holes

I agree with cp-mike. Even glass cores have layers. Keeping water out of layers is important to the integrity of your hull. Delamination starts with moisture and goes on from there. Seal your holes just to be sure, it's not that difficult and just makes sense.Steve

 

[Ben]

Go for it Doug!

Go for it Doug! I played a lot with epoxy buliding kayaks and small sailing dinghies...It is very easy to work with it if you plan and prepare.Good luck!

 

[Night Sailor]

Maybe I'm just lucky... or lazy...

For bolts and screws into cored wood or uncored solid glass I've always just used silicone applied generously and tightened immediately before it cures. I've never had it leak. For large holes in solid glass I've done the same thing. Never a leak. For large holes in sandwiched or cored areas, I coat the inside of the hole and any voids with liquid expoxy and let it cure. Then I install the hardware with a generous amoount of silicone and tighten it down. In six boats over fifty years I've never had this process produce a leak. The first thing I did when I took delivery of my M26X in 1997 was remove ALL deck hardware including windows. I cleaned all surfaces with acetone, the bedded everything with silicone. After seven years I still don't have the first leak.GE or DAP brands of pure silicone, 35 or 50 year quality is what I use.I advise never using 3M5200 or polyurethane goop unless you are sure the item will never have to be removed for repair or replacement elsewhere.Hope this helps.