Sealing Holes

[Jazzmanic]

I know this topic has been discussed many times and I've been scouring the forums using the search function but I'm asking a one simple question.

It turns out I didn't do a very good job last spring of attaching my radar arch, (read-it leaks). I want to redo it and do it the right way, taking my time and doing everything necessary to avoid leaks. After reading posts by Dr. Bob and Sea Wolf Joe, I want to make sure the holes I drilled into the roof are sealed to avoid any water intrusion into the cored roof.

My question: What is the best sealant to use for this purpose? I will be cleaning out the balsa core in the existing holes with a dremel tool (Xmas present ) then I want to seal the hole, let it cure and redrill the proper bolt size.

Should I use WestSystems epoxy system? System 3? Or MarineTex? I'm looking for simple but bullet-proof.

Peter

[Larry H]

Peter,

You can undercut the balsa in the holes by using a small hex key or bent nail chucked in an electric drill to remove the balsa back 1/4 to 1/2 inch from the holes in the fiberglass. This avoids enlarging the hole in the fiberglass skin. Then tape off the bottom of the hole and fill with epoxy. After cure, drill out the holes to the original dimension.

Seal the arch and bolts with 4200 or similar. (Not 5200!!)

System Three has dual caulking tubes of various formulations, which should be easy to use.

Link:
[/url]http://www.systemthree.com/p_u_cartridge.asp[url]

Also check this thread:

http://www.c-brats.com/viewtopic.php?t=8109

Dr Bob or others may have more advise.

[Sea Wolf]

Peter-

Larry H has answered your questions fully. Good job!

Joe.

[matt_unique]

I built two wooden boats using System 3 epoxy and had a good experience with the durability of this product. I plan to use System 3 for my Tomcat installations.

[rogerbum]

I installed my own last year and on a 22, the roof isn't cored - at least not out at the place where a radar arch would typically be installed (e.g. on the flats outside of the center rising portion). Mine just had fiberglass there.

There's several places where the installation could conceivably leak -
1) under the base and through the large hole cut for the wiring
2) from the top down - e.g. water getting into the arch and coming in. This could happen if the cable from the radar doesn't have a low spot in it prior to entering the arch - e.g. water can wick down the cable.
3) Through the holes that are drilled to bolt on the arch.

You might want to see if you can determine the path. Water with a fluorescent dye can sometimes be helpful for that.

I installed mine with liberal amounts of 5200 and have had no problems. I also put liberal amounts on each bolt and made sure I had good size fender washers on the inside to spread out the load. So far, so good.

[Larry H]

A warning,

5200 is an ADHESIVE. If you ever plan on removing the part use 4200, a sealant-adhesive. Tough, but removable. Removing hardware mounted with 5200 can result in damage to the fiberglass. They now make a solvent to remove 5200.

[Jazzmanic]

Roger, on our 2005 CD22, the roof is definitely cored with balsa. I think my problem is that I didn't liberally use the sealant. Unfortunately, I used 5200 so I'll see how hard/easy it is to get off using the Debond stuff.

I also asked one of the guys at the Tanner Radar Arch booth at the boat show and he told me that they bed their radar arches using Sikaflex 291. It's a bedding compound, not an adhesive, which makes sense. I think he was horrified when I told them I used 5200. So that's what I'll use when I reinstall, if I can ever get the arch off the roof.

Matt & Larry, which System 3 product did you use? I look on their site and there seemed to be lots of choices. I like the idea of getting the cartridge and not having to mix.

Peter

[Larry H]

Peter,

My use of system three was big boat construction where I bought 5 gal jugs of resin and hardener and mixed my own.

I just purchased some of the gel glue in the tube and I am going to try it out. I would call System Three and ask them which product to use. If you give me a couple of days I will call them and find out. I want to know for myself. Those tubes look like a winner. Just use a small amount and cap off the rest.

Perhaps Dr. Bob (thataway) will tell us his preferred product.

[thataway]

Probably the Marine Tex is the easiest and cheapest It has a filler in the epoxy material, and you don't have to mix the epoxy with various fillers. Although the ratio is 5 parts of epoxy to 1 part of hardner, the epoxy seems to be very tolerant of the hardner and epoxy ratio. It is easy to drill into, to sand, and to screw into. You don't have to buy pumps, or fillers etc.

System 3 I believe uses 2:1 by volume, and West Systems comes in several various ratios depending on use--the fast set is 1:1 in the half pint size. I buy the 104 resin in the gallon size, and the hardner in the appropiate size, and keep slow, regular and fast hardner, and the appropiate pumps on hand. I also use cabosil (fumed silica) and medium density filler for this type of application. I use West, because I have used it for many years, and I am familiar with its properties--not because it is any better. There are a lot of "tricks" and there will be a learing curve for any resin used. But the MarineTex is very easy. I use a tooth pick to push the epoxy into the hole, and undercut area. I usually use a Dremel tool for the undercutting and balsa removal--it seems to give a bit smoother area where it cuts the balsa.

I use 4200, unless it is a plastic I am bedding, then I use Boat Life, Life Caulk--which is a urethane/silicone combination.

There seems to be some variation from year to year and model to model as far as the balsa core. My CD 25, has balsa only on the side, not on the center of the roof. My Tom Cat has it both on the sides and center.

[Holoholo]

Bob, I used 5200 a few days ago for putting down the tank strips to the floor and noticed that you recommended 4200. What is the difference between the two?

Vern

[CAVU]

Peter,
I had good luck removing a small fitting that had been put on with 5200 by using a short piece of spectra fishing line(very thin and strong.) I used it to basically saw under the fitting and cut the adhesive. You will still have a hard time removing all the old bedding but with the metal base removed the debonding agent can work much better and there is less chance of damaging the gel coat.

[Jazzmanic]

You guys are the best. I think I even have an unused, unopened box of MarineTex.

Bob, I think you're probably right about the center of the roof not being cored. Where I drilled the holes for the radar arch was on the sides.

Thanks for the tip using Spectra fishing line Ken. I might give that a shot. It looks like we might have a nice weekend, a brief respite if you will, from this cold damp winter. I might try to do it this weekend. Wish me luck.

Peter

[dogon dory]

Sorry, Folks - Post Deleted By Author

[doc]

[Larry H]

Vern,

5200 is an adhesive, that is , a glue. Use it to put stuff together when you don't want to take it apart again.

4200 is a sealant, with good adhesion, but stuff sealed with it can be taken apart again.