Protecting a Wooden Keel Strip

[Don Silsbe]

There has been an interesting thread within a thread going on.  I thought this topic deserved its own separate thread.  The subject is how to adequately protect our wooden keel strips.  I hope we can share our own experiences and thoughts here.  They might be easier to find, when we get to that point on our next build.

 

On my Bay River Skiff and Two Paw 8, I have chosen the “no protection” approach.  My TP8 is showing wear.  I expect the BRS might as well.  I’m currently working on a non-B&B boat, which is posted on the general boatbuilding forum.  

 

Alan has taken an interesting no-wood approach.  I’ll paste that video link later.  It will be interesting to see how that holds up with use.  My experience with fiberglass is that it has lousy abrasion resistance.  I want to do something different.

 

I have been told that Dynel offers excellent abrasion resistance.  I do know from personal experience that it is an epoxy sponge.  I plan to use that only on the keel and skeg of my current build.  We’ll see how that goes.  I’ll track the abrasion performance here, but construction details will be on the other thread.

 

What about hollowback?  How do you attach it without compromising your moisture barrier?  Is graphite in the epoxy very effective?  Kevlar? Carbon fiber?  Let’s chew on this bone awhile!

[Pete McCrary]

I thought of solid or hollow back half oval OR “flat” stock, brass or ss.  But I wanted a 5/8” x 1/8” it to cover the 3/4” yellow pine keel for Seabiscuit, my Spindrift 10.  Hard to find and too expensive.

 

So, I’m going with a white oak 5/8” x 1/8” (maybe 5/32”?) cut from a 3/4” quarter-round 8’ molding purchased from Lowes.  The yellow pine keel strip will be glued in place, and the white oak strip bedded (on its top) with 5/8” x #8 SS FHWS counter-sunk (flush) at 6” spacing.  If it gets torn up, I’ll just replace it.  The 8’ molding cost $9.44.  Might even get two strips out of the 8’ molding?

 

I’m considering installing it bare (i.e., no finishing).  White oak holds up well in moisture and any finish would quickly be stripped off by beach sand, gravel, etc.

[Don Silsbe]

@Pete McCrary— I just learned that that is called a wormshoe.  I thought about that, too.  

[Steve W]

I used White Oak for the keel strip on Suzy J, my Spindrift 11N. I haven't used her heavily, but she has been beached enough the epoxy and paint coating has been compromised. White Oak, being closed cell has held up. The closed cell properties can make gluing reliably difficult they say, but I've not experienced this. As a precaution, I took a cheap harbor freight saw blade and knocked a tooth out to make a really rough cut on the glued edge. I did not use any fasteners but I did glue it down while the cloth was not fully cured.

 

I did the exact same thing on Skeena, my Core Sound 20.3. The only thing different is I had to put a screw in the front and back to hold it down as I found straps didn't seem to work well while gluing. I shallow V cut the strip on the glued side with the same crappy blade I used on the Suzy J. The Epoxy on the hull cloth was definitely cured a few days, but the bond seems excellent. I piled cinder blocks along it on plastic to hold it down between the screws.

 

Because of the weight of the boat and it being on a trailer, I did radius the top to match hollow-back and I used short screws and 4200 to bed it. It has held up really well, although I decided to use wide bunk boards that support the longitudinal bulkheads (and the released centerboard) while trailering, so it doesn't get as much torture as originally planned with keel support.

 

I hope this helps you make a decision. They are all compromises.

 

Take Care,

Steve

 

 

[Hirilonde]

I spent much of the last 5 seasons running my Lapwing onto a coarse sand  landing.  I used solid bronze half round over a Poplar keel.  The keel takes no abrasion notable for the 5 years and I have yet to have to touch up the paint. I pre-drilled and dry fit the entire keel strip, removed and and bedded the entire length in BoatLife LifeCaulk. My boat is trailered, but left outside for all 5 seasons. No issues of any kind.

[Mark Rendelman hull 24]

In the construction of my mk3 keel I used a keel strip of laminated mahogany 3/4 wide with a 3/4 oval brass cap purchased from on line metals not to bad of a price if you keep the length short I needed 18’ so I ordered 3lengths 6’ long.

[Jknight611]

I think I did my keel strip totally different from anyone else on my CS20.3.  I clamped a packing tape covered 1X4 to each side of the keel, the filled the gap with unidirectional glass with epoxy and graphite in the epoxy slurry.  I wanted to experiment with a keel strip with no screws.  So far it seems to be working, although I suspect it would/may crack it point loaded, but sand an shells seem to have no problems.   All a compromise, I suppose. 

[Don Silsbe]

It is my understanding that traditional wormshoes are expendable, sacrificial pieces.  They do not get glued down, but are screwed into bedding compound.  When they wear out, they are replaced.  If I used wood instead if Dynel, I’d bed it in some polysulfide, and screw it in place.  I’d paint it, too.

 

But what about Dynel?  Anybody?  Eric Blake from the Brooklin Boatyard recommends it for sheathing hulls when abrasion is an issue.  I thought it might be a candidate for keel strip abrasion.

[Don Silsbe]

This is Alan’s solution.  The wear strip discussion starts at about the 9:30 mark.

 

[Don Silsbe]

I’d be cautious about buying oak from Lowes.  All I’ve ever seen there was Red Oak, which is notorious for being porous. 

[Jknight611]

Lou Sauzedde (tips from a shipwright)  did a YouTube video a while back on the difference in red/white oak using rubbing alcohol.   That being said I trimmed my boat’s cabin with red oak, has enough epoxy to protect it from a nuclear blast.  I find white oak is ridiculously expensive in our area, and the quality is suspect.  

[Pete McCrary]

Don — Can you give me a reference to the origin of “wormshoe”?  You reminded me that I had previously heard the word (at least a nautical word with “shoe” in it).  But I can’t find it.  An interesting word as many nautical terms are.

[Aphers]

Has anybody thought about using plastic keel strip? Obviously not as durable as bronze etc but lighter, cheaper, no corrosion or rot, and perhaps the low friction would be handy at times.

[Don Silsbe]

Here’s my plan, as of Oct 2, subject to change without notice.  I’m going to make my keel and skeg out of all Poplar, per the original plan.  I’m going to lay down one or two layers of Dynel onthe bottom face only.  This is new.  I’ll use tough fumed silica as filler for the weave.  If it performs poorly, I’ll take my power planer or belt sander and eliminate it, replacing it with a 3/8” thick “wormshoe”, the full length of the keel.  I might add a brass strip to the stem, because the dock at my boat launch is rubber and aluminum.

 

Comments?

[Don Silsbe]

@Pete McCrary— here’s a page from the CLC Annapolis Wherry build manual. (My next build)

[Don Silsbe]

@Jknight611—. I’m ok with it above the waterline, especially on a trailerable boat*.  But it definitely has no place below the waterline.  
 

* I would also never use it where the cabin meets a deck.  Bad memories!

[Don Silsbe]

@Aphers— clever idea!  Worth considering.

[Don Silsbe]

@Jknight611— white oak is abundant in our forests in the Appalachian foothills.  You need to snag a few boards when you pass by.

[Wommasehn]

why not the „Rope Trick“ or maybe modified as a „webbing trick“ , that‘s some hefty strap soaked in epoxy?

Should be easily replaceable if necessary.

[Don Silsbe]

This is what I’m trying to avoid.  This is the skeg on my Two Paw 8.