Monday, April 23, 2007

Inertia Sold and That Damn Keel Joint

It's been some time. So much to do - and so little time. Life proceeds apace. I'm working very hard towards a life more dedicated to sailing and boating and writing or failing that, bottom painting. I've cleaned out all the crap in my house (or a large portion of it) and Inertia, and put both up for sale.

Happily and sadly, Inertia has been sold. It means that I can buy the Pierson 424 I've been lusting after. Why the 424? It's reasonably priced, pretty well put together and has a good reputation for cruising. Since a plan is forming to sail ultimately to Scandinavia and take a couple of years to do it, a boat that is comfortable and strong is just what the doctor ordered. Oh, and it has to be less than $90,000. Much less.

In the meantime, I've waxed and painted Inertia so that she looks very nearly pristine. She will be transported to Wisconsin to her new owner. I feel as if I'm letting my child go. Or a really good friend. I will take pictures of her departure and share them when it happens. It should be interesting.

So, back to the interesting stuff. Every sailboat with external ballast will have a crack that forms around the hull to keel joint. Famous for this is Ericsons and Beneteaus. It's not a structural problem or even a design one. It's really only a aesthetic problem. But anytime you use a filler to fix it, next year at haulout there it is again!

Don't mistake this for an ever-widening crack. That indicates the either a failure of bolts or hull form. My repair won't fix that. And losing your keel while sailing is very bad. End of the world (for you) bad.

So when I got Inertia, I decided to fix the crack once and for all - remember a fiberglass hull, no matter how strong, flexes. And because it does, any joint between it and something else will also flex, especially a heavily loaded one like the hull to keel joint. Hence, the crack.

You'd think off the bat that the manufacturer should use something like 3M 5200 and slather it on all over the keel before bolting it on. At first blush, it sounds good. But if you ever have to remove the keel (like after a really hard grounding), you're screwed. Really, thoroughly screwed. So it's not a good idea. Even using any other adhesive isn't good. There is a school of thought that says sealing the joint will promote chloride stress corrosion ( stainless steel under stress immersed in warm, oxygen depleted water ). True, all those could exist except that 'warm' in this case is relative - it's a worry in steam generators for power plants, or pressurized water nuclear plants. A little out of the range of temperatures you or I are likely to sail in.

So the solution I came up with is to make a flexible seal all around - using my favorite adhesive/sealant - 3M 5200. I'd be lost without it! Popular belief is that it's impossible to remove. It isn't. It's difficult, but not as difficult as silicone. More to the point, silicone will virtually guarantee that whatever you're trying to seal will leak and will leak forever. Think of capillary action. But more on that later.

The first thing to do if you're going to fix this clean up both the joint and the surrounding area, about an inch to each side of the joint. Clean it down to the fiberglass or gelcoat. Make sure it's all dry and clean.



Next, run a piece of blue painter's masking tape about 1/2" to 1" parallel to and on either side of the joint. Get a pack of inexpensive sqeegees. Evercoat makes a three pack. They're flexible and cheap. Good thing, because they're one use.



Finally, with a caulking tube of 3M 5200 or 4200 in the color of your choice (I use black), put a bead all along one side of the joint in the keel. Don't be afraid to use more than you need. With the sqeegee spread the 5200 evenly and smoothly from front to back. The bead should be spread evenly between the tape filling to the thickness of the tape.

Make sure it's over 50 degrees F. 5200 behaves very poorly below that. You'll have about 15 minutes before it skims over, so work it quickly. Unless you're racing and are particular about the surface smoothness, don't worry too much. Pretty smooth is smooth enough.

Before the 5200 sets, pull the tape away carefully. Now do the other side. And resist the urge to touch it to see if it's dry. It isn't. If your joint was cleaned deeply do this in layers. Put a bead in, wait until it sets ( four or more hours ), and put another bead. If you make it too thick all at once it will a; run and b; bubble as it sets creating something like a foam. It's still watertight, but I don't like it.


That's it. Wait 24 hours, and paint away! The joint will flex with the boat and next year when you haul, it'll still be tight. It isn't forever. It will eventually start to pull away. But after 6 years in the water, Inertia's needed only some minor repair (that's what the pictures are from).

Silicone in boats. Silicone has really one use in a boat and that's tacking wires or hoses to some structure. I use it to tack the wires going up the mast to the mast so they don't rattle. I also use it to tack wires that run along a stringer so I don't have to drill through it. Finally, I use it to hold cotter pins to the fitting they're in. Just a dab at the end and you don't have to bend them all the way open - just spread them a little and put a dab between the legs.

Why not on a port? Because although it bonds tightly, it is not very UV resistant and will eventually pull away a little bit from the glass making a capillary action pump - more water will leak than it did before it was put on. I hate seeing a boat with layers of silicone around the ports. It stops the leak, but makes it worse so the owner puts more on, which works for a bit, and then it gets bad again. And so on and so on.

Use it with head or kitchen fittings if you must, but not outside.

The new boat promises so many more projects! I can't wait. And I can't wait for this summer - this year, maybe I'll be the mama boat!

See you all on the water!

5 comments:

GlynWild said...

http://www.gaw-associates.com/inc/blog.html

Seems we have a similar background and hobby. The link to my BLOG is above, knock off the last two pipes to get to my website and full CV.

gregg said...

What do you know about a product called 'G flex' by west systems?

Cap't Bob said...

Hi Gregg,

G-flex is a good epoxy for quick repairs - there are two kinds, thickened and non-thickened. I'm going to use some today, as a matter of fact.

They aren't for biggish jobs like keel repair if that's what you're getting at.

It's a good product in a convenient size. Because it's easy to mix (1:1) and has a fairly long working period you can get a lot done with a little bit.

Recommended.

Captain Bob

Dave Hollis said...

West System technical support explicitly recommended using the thickened G-Flex for this exact repair on my 30 ft Lancer.

Cap't Bob said...

Hi Dave,

There are two points of view here. If all you have is a hammer, every problem looks like a nail. This, I think, is the case with West and West products.

It really depends on the amount of movement the seam experiences. In the case of fin keels, there's relatively lots of movement. It doesn't necessarily represent structural weakness but there's a lot of weight at the end of a arm and it will move as the hull pounds.

If you're rebedding the entire keel, use 5200. When set up, the keel bolts can all fail and the keel will stay on.

If you just have the annoying seam where the keel meets the hull and you know it doesn't move much, use the thickened G-Flex as a fairing compound (to be honest, if I were going to fair the crack with something else, I'd use a compound especially for that, either West epoxy with 404 to thicken it or West fairing compound). On average, the longer the keel, the less movement.

In the case of my Ranger and Ericson, there was enough movement to cause any stiff compound to eventually crack and fall out. The 5200 never fell out.

3M 5200 has a large ability to stretch and compress and bonds quite tightly to almost anything. These two features is what I believe make it a great product for this particular application.

That said, if G-Flex has worked for you, great. I would never discount another boater's successful experiences. That's the great thing about boating - there are a bunch of ways to achieve the same goal.

Good luck, Dave!