Jump to content

Glassing the keel?


Mike Henderson (Oregon)

Recommended Posts


Hi Mike,

Been following your photos of your Weekender as you have been building.

Wood moves, it expands/contracts with the seasons and humidity/temp changes. It has moisture content in it. Even kiln dried wood has moisture left in it. As you go thru the seasonal changes and just one freeze/thaw cycle the layers of wood in the keel will move/ expand/contract and separate slightly. The moisture trapped inside the layers of the keel by the glass will not have any place to go and it will collect in the small voids. This is when rot begins. Wood moves, that is a simple fact of life, on a boat some species of wood and cuts of wood move more than others, regardless of adhesives, epoxy, glass or other treatments. Moisture gets trapped from condensation, freezing/thawing and the simple fact that the wood picks up moisture from the air. Eventually it begins to decay/rot.

But regardless of my opinion and experience or others, it is still your choice. Stevensons do not recommend glassing the keel for a number of reasons, but they don't really express them in the video or the builders manuals. But on the Vacationeer they recommend using thicker glass mat to add strength and allow a better finish to the keel and hull. Larger boat, different criteria, but the points are still valid.

The glass on the plywood/hull allows the plywood to have a good finish without checking. The plywood is dimensionally stable and doesn't have the issues that solid wood has thru the seasonal changes.

So glass on the hull prevents checking, allows you to have a nice finish. On the keel it can trap moisture and not allow you to see when there are problems developing. Either you put so many layers on the keel that it really locks things tightly and you build with woods that won't want to cup and move or in my opinion, you are better off just painting it and checking it regularly for hairline cracks as the wood expands and contracts. It will take abuse, I would rather know what is wrong or going wrong than to all of a sudden realize that there are major problems and have to remove the glass and start major repairs.

Now, there are other opinions, equally valid for the contributors. These are mine based upon repairing a ton of boats that have had rot problems and finding out what works and what doesn't from professional builders and repair shops.

The paint on the keel will crack with the movement of the wood, that is your indication that it has happened and allow you to make a relatiavely simple repair before things get too bad. I would rather have that occur and be aware than to let things go, hidden by the glass and then have major repairs. Just my opinion Mike.

Link to comment
Share on other sites

Thanks Barry. I hadn't thought of plywood being so different than regular wood but I can see this point now. What are your thoughts regarding Kevlar tape to protect the bottom of the keel? Is it the same as glassing the whole thing? Would it pose the same risks as glassing the entire keel? (In your opinion)

I'm wondering where my photos are. I think I have one in the gallery but all it shows me is an "x". I used to have more posted somewhere but I think I took them out. Maybe not.

Anyway, I do appreciate the time and thought you put into your responses to everyones questions.

Link to comment
Share on other sites

I'm also a "no glass" advocate on the keel, and Barry has covered the reasons. There's a particular spot I'm worried about with a glassed keel, and that's near the front where the stem meets the keel. There is end grain exposed to the water at that point, and a tiny hole or crack in the glassing will allow water to be trapped in the end grain (it soaks up water faster than any other part). You also have a lot of wood movement different directions at that point ... wood generally moves more in width than it does in length. The stem pieces are growing almost fore and aft, and the keel wood is expanding and contracting up and down, so there's movement right at that joint.

Still, plenty of people have glassed their keels and haven't had any problem. So its "builder's choice".

On the kevlar strip, my opinion is you won't have much wood movement along the edges of the board, so you can glass on the bottom of the keel. Its going up the sides that might give you trouble, if you have any at all.

Link to comment
Share on other sites

I am using Kevlar tape rather than fabric, as are all the others that I know that put Kevlar on their keels in the Northwest. It has woven edges and comes in various widths and drapes beautifully even in the heavier weights. I plan on using 3" wide tape on the stem and down the first 6-8' of the keel. Two layers on the front and down to about the 4' back from the junction. Then the longer piece over that. I will bring it up just to the bow eye.

I've never had a problem with using the Kevlar tape, but I know that there are a couple of builders that use kevlar fabric instead and were very unhappy with the results. Most of the keel problems exhibit themselves at the stem junction and at the stern post. And even with the Kevlar tape on the bottom, we've seen when there are problems with underlying wood on a lot of the boats that I've had experience with.

Link to comment
Share on other sites

Mike,

I use Fiberglass Supply.

http://www.fiberglasssupply.com/Product_Catalog/Reinforcements/reinforcements.html

Scroll down the list until you reach the Kevlar Tapes. In the past I have just purchased the roll for about $95 but you can purchase it by the yard.

I'm using just about 10 yards of tape on the Weekender.

C63-8815

Cut per yd., Up to 3 yds., 3" Wide X 5 oz., Kevlar Tape

$ 3.20 Specify Yardage

C63-8814

Cut per yd., 4 yds. to 15 yds., 3" Wide X 5 oz., Kevlar Tape

$ 2.62

Specify Yardage

Link to comment
Share on other sites

Jan,

I had ordered the Style 7533 Volan flat

C31-1526

Cut per yd., 16 yds. & Up, 5.6 oz. X 60" Plain Weave, Volan

$ 6.08 per yard.

This is 20" wider than the width specified for the Weekender by Stevenson's in their bill of materials. But I plan on glassing then entire hull from the keel up to the upper rail. Then after painting and finishing, applying the lower rub rail.

I want the integrity of a solid glass surface. I will also apply a strip of the Kevlar tape along the middle 60" of each chine over the glass.

Link to comment
Share on other sites

Barry-Thanks for the fabric info, I don't know much about glassing yet, but I have to plan ahead, so I can have the right things before I need them. I hate waiting on supplies. So you are going to glass "from the keel" up. at what point are you going to end below the fillet? And the kevlar on the keel edge and chines. I like the rub rail idea too. It will be very neat and tidy looking. What about the upper rail?

Hopefully I can contribute, even a small fraction of what you do, when I am done. Maybe I'll have something in the sail sewing section. (seamstress) :)

Link to comment
Share on other sites

Ok Jan,

I plan on running the glass down over the fillet on the keel. My top rail is finished brite and it a double 1X2 sandwich with the plywood let into the inside 1X2. It is attached and I will run the glass up to the bottom edge of the top rail and end it there.

The kevlar on the chine is because the beaches here in Puget Sound country are not nice sand in most areas. They are rock. So I would imagine that as in the past, with several of my smaller boats, that I will be beaching it. I found that the Kevlar on the chine where it contacts the beach helps to protect the glass and paint.

[attachment over 4 years old deleted by admin]

Link to comment
Share on other sites

Okay..

I am not going to glass the sides of the keel.

I am going to Kevlar the end though. The Kevlar tape (11 yards) came in the mail on Friday. I'm going to use two layers on the keel and one on the chine as Barry suggested.

The plan is (unless someone makes a better suggestion) is to lay the tape up on the boat before I do any fairing with the micro ballons that I am about to order. Here's a question...Do I fair (fill the weave) of the Kevlar with the micro ballon mix or do I use something else? Something harder?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...


×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.