Keel protection

[Frank Olsen]

I'm in the process of refitting and repairing some minor damage from skipping over a submerged rock and want to add something better than the multi layers of glass cloth/epoxy that was my current keel protection, especially for beaching. The fiberglass held up fairly well but abraded away in several spots exposing raw wood. Luckily no structural damage to the keel, only to the rudder. My current moorage dries out every day and even though it's a silty bottom in still gradually erodes the epoxy glass as it settles in about 3"

I've considered:
1) extra wood strips and more glass. Cheap, easy to apply, but probably needs constant
repair after contact.
2) UHMW polyethylene. Extremely tough, slippery and anti-fouling, but, not glueable to the
epoxy, and I'm not crazy about exposed screws into the keel.
3) added strips of G-10. Very tough, glueable to epoxy, but, expensive.
4) strips of kevlar or carbon fiber cloth or combination of both.

Any other ideas, pros and cons, opinions, or comments?

Thanks,
Frank (Pahi31 "Mikyla")

[boatsmith]

Kevlar strips are the most impact and abrasion resistant. David www.boatsmithfl.com

[Bertrand FERCOT]

For my Tiki30 and 46 I glued on the glassed keel a square hard wood without screws + glass cloth around and I screw on top of this a stainless steel strip, so if a strong grounded happened, the screws will not damage the keels

Bertrand

[Ann and Neville Clement]

We had to remove the stainless strips we put on Peace. The screws we used were not the same kind of stainless steel as the strip so they corroded away and the strip started to tear off. It was a worry until we hauled three years ago and removeed the strip, removed the stubs of the screws, filled the holes with epoxy, and sealed the keels again. This haul out we are happy to say all is well.

If I had it to do over again (God forbid!) I would just want three more layers of fiberglass above and beyond the design. The stuff is tough.

ann and Nev

[Frank Olsen]

Thanks all, Bertrands method with the extra strip of wood to hold the screws gives me an idea. Instead of a stainless steel strip screwed to the sacrificial wood use UHMW polyethylene which probably has as much hard grounding resistance, maybe better, plus it's so slippery and antifouling. This solves my reluctance to screw into the actual keel.

Frank

[Bob Bois]

We were of the mind to use a sacrificial hardwood shoe covered by extra layers of glass. However, the hardwood shoe covered by strips of Kevlar might just be foolproof, right? Kevlar wouldn't be too expensive for such a limited use?

[Ralf]

On my T30 in progress, after glassing the hull and keel as to plans I glued on a 2.5cm thick hardwood keel shoe which I consider sacrificial. I fastened it with clamps, lead and rope (spanish windless? is that what you call it?) until the glue set. Later I painted it over just like the rest of the hull under the waterline.
My objetive was not to use any screws under the waterline for 2 reasons:
1. possible corrosion, 2. the impossibility to plane the wood down when it needs to be replaced which will sooner or later happen.

I think it would be possible to screw and glue a ss strip on top of such a hardwood shoe if one makes sure that the srews do not penetrate into the glass under the hardwood and if ss strip and screws are of the same type of stainless steel (probably the 316type). The reason why I did not do this is that I was not sure about the quality of the ss available here.

See a picture here: http://wharrambuilders.ning.com/photo/keel-shoe?context=user

Ralf

[Frank Olsen]

David, do you just laminate kevlar tape to the keel or are you using some preformed kevlar strips? If you're using tape how many layers, and do you mix any fiberglass cloth with it? I see from your website the T30 is shown beached, is that keel protected with kevlar? By the way, what a beautiful boat and nice website.
Thanks for all the info and advice you provide,
Frank

boatsmith said:

Kevlar strips are the most impact and abrasion resistant. David www.boatsmithfl.com

[boatsmith]

Raka sells rolls of kevlar tapes that you can just laminate onto the stems and keels. I hadn't heard about the kevlar when we did our tiki 30. We staggered 3 layers of 1708 fiberglass instead. It has proved very satisfactory. The kevlar tape has a tendency to fuzz when sanded or torn and I believe it would be appropriate to laminate a layer of fiberglass over it.
David
www.boatsmithfl.com

[Polinesio - Tarcisio Silva]

For my Tiki 21' Polinesio I use the bretrand's method, glueing an extra laminated keel and glassed it. Then screw and glued on a brass strip 1/8 x 3/4. So the keel skin is not affected by screws. This system perform very well since 2000, every time on the water and very many, many beaching. And sometimes grounding.
For paint the botton we beach the boat (very charged - we living aboard) and lift the hulls from the tide line using wood handspike... Nine years with no problems.
Bravo! it function pretty well.

[Budget Boater]

1. Get some hardwood strips (or whatever material tickles your fancy) cut to the right width and thickness that you want.
2. Clamp it onto the keel
3. Drill 1/8" (3mm) holes every two feet through the hardwood and into the keel (should about 1.5" (38mm) deep into the keel) along the centerline
4. Remove the hardwood
5. Drill out the pilot holes left in the keel with a 3/8" (10mm) drill bit to an approximate depth of 2" (51mm)
6. Mix up some unthickened epoxy and inject it into the holes until they fill to the top (It will disappear as it soaks into the wood grain.)
7. Have a couple of beers.
8. Mix up some thickened epoxy and slowly inject into the holes making sure the air escapes. Do this until the thickened epoxy is overflowing the hole slightly
9. Wait 2-4 hours. Take a razorblade and cut off the excess (muffin tops) thickened epoxy from the keel
10. Wait one day. Drill proper sized pilot (less than 1/4" (6mm)) holes for your fasteners in the center of the thickened epoxy to a depth of 1.5" (38mm). DO NOT EXCEED 1.5" depth Put a drill stop on your drill bit to ensure that you do not drill too deep. And make sure that you drill straight.
11. Drill fastener pilot holes in your wood strips.
12. Attach wood strips to keel with STAINLESS STEEL WOOD SCREWS

Doing it this way will ensure that your plywood keel will not absorb water and that you can remove and replace the keel strip after you trash it.

[Ann and Neville Clement]

Putting screws into ply or Douglass Fir is a worry because of rot and also because those screws are into a fairly soft material. We worried about screwing cleats onto the ends of the crossbeams. What worked for us was to predrill the holes and they were long holes and long, strong screws too. Then I filled the holes to the tip top with liquid epoxy and just screwed the screws in. This pressureized the liquid epoxy right into the wood and last time we went through the Canaveral Barge Canal Nev and I got it quite wrong so the boat pulled HARD on that cleat and actually broke the cleat after bending over the top ends of the screws. I was astonished to see that the lower end of the screws were undamaged and there was no damage to the wood at all. We removed those damaged screws using a pair of pliers and put in a new cleat. No boat damage at all.

[Frank Olsen]

Thanks to all who commented. I've decided on a couple layers of Kevlar cloth tape topped off with a layer of glass. A couple layers of Kevlar; 1 layer 2" wide plus a layer 6", so to protect against the abrasion up the sides of the keel when the boat dries out and settles into the gritty mud daily, or I beach in the gravel. That will cost about $60 US for the Kevlar and less than $10 for the glass, plus epoxy. I might add an epoxy glued (no screws) sacrificial strip of wood to the keel before the Kevlar. Still pondering that.

Since the anti-fouling paint erodes off the bottem 3" off the keel, because of the daily drying, I'm going to try a couple layers of epoxy mixed with copper powder just on the bottom 3 o 4". Even as that abrades away it should stay anti-fouled. Hopefully it'll last longer than the bottom paint that only lasts a couple months at the keel.

I'm many months away from re-launch but after a year or so in the water I'll post on how well it works or doesn't.

Thanks,
Frank