Reinforce keel question

I'm ready to fiberglass-coat the hull of my Ches 17 LT kit and was hoping to hear some feedback on whether it might make sense to first reinforce the keel knuckles by applyling a length of 6" fiberglass tape and perhaps leveling the edges of that tape with a glass microspheres filler.  Would this extra step be overkill and add more weight to a procedure that is already covered?  I'm reasonably careful with my equipment, but cannot help imagine the wear & tear against a wooden hull along sandy shorelines.  Thanks for your thoughts on this.  I'm a boat-building nubie, and consequently drawing advice from local "experts".


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RE: Reinforce keel question

Reinforcing's a fine idea, but I'd put the main glass on first, then the reinforcing patches. Easier to fair in that way, just scrape the edges at the "green" stage (pliable, leathery but not tacky) and then a quick hit with a sander when it's fully cured.

Have fun,



RE: Reinforce keel question

if you really want wear protection from things like sandy shorelines, skip the extra fibreglass and install dynell rub-strips as part of your build.  they are neat, light,  easy to install and they work.

unfortunately....regular glass does not have particularly good abrasion resistance.  so putting on more of the wrong material just makes for a heavier boat with little extra protection for all the work.

i put on several hundred miles of paddling each season on my wooden fleet and have a lot of experience with general abrasion from sandy/gravelly shorelines..  every boat gets the dynell treatment right out of the shop.



RE: Reinforce keel question

Helpful ideas, thank you.


RE: Reinforce keel question

ááI have a few questions pertaining to the dynel that maybe someone could answer. I was able to obtain a sq/yd of it from the person that I purchased my fiberglass from.áThe dynel has a course texture, similar to canvas, is the weave filled in after the installation ? If so this will require a heavy or many light coats. Every time that I have seen it used it is black, is there a reason for this or could it be painted to match the color of the paint on a stitch and glue hull. Thanks Tom a very course texture

RE: Reinforce keel question

   Per the linked instructions, 2 layers of the dynel cloth are laid down with epoxy wetting. Then an epoxy and graphite mix is applied in thin coats to fill the weave and skim coat the dynel. The grphite adds strength, flexibility to the expoxy and like graphite adds some lubrication of slippreyness to the dynel patch.

RE: Reinforce keel question

A clickible link to the instructions:

Bow and Stern Rubstrips

FYI to make ative link, highlight the words for the link, click on the chain link on the option line for the editing post and fillin the web address. You may need to adjust the "HTTP:" as needed to match the web address.

RE: Reinforce keel question

áááThanks for that information George. Tom

RE: Reinforce keel question

I reinforced the keel of a skiff I built with Dynel, but it adds a good bit of bulk that needs to be faired. I don't think I used peelply, and not sure how well it would work.

I later used Kevlar on another job, and was really impressed by how thin I could laminate it.

In retrospect, I wish I had used Kevlar on my skiff. It should be a lot more abrasion resistant, lighter, a lot stronger and should be easier to deal with. The Dynel you would have to paint, but if you were careful cutting and laminating Kevlar, finishing bright might look cool.

It is expensive, but how much are you going to use, anyway?

I'm still learning, every step of the way. I just wish I had learned this one sooner.





RE: Reinforce keel question

a couple comments that may be useful. 

let me begin with the obvious....abrasive events (like hitting a rock or running a boat up on sand or gravel) will leave an unsightly mark on almost every shiny surface.

so trying to deal with abrasion and having that area have the same look as  every other part of the boat where your not interested in those marks is sort of like spitting into the wind. 

if you want the most pristine looking, shiny boat, just don't hit anything and don't worry about doing anything about abrasion other than the normal build.   (after each can refinish the boat :)

the idea with dynel patches (or rubstrips in general) is to recognize that certain areas deal with most of the abraison....on kayaks that's the bow and stern knuckles.  so a dynel patch (or other patch approach) limits the application of abraision resistance methods to these areas becuase materials with great abrasive properties aren't typically 'good looking' and may have other characteristics that are not particularly desirable for the rest of the boat (e.g., thick, heavy, etc).

in the dynel patch approach, graphite is used in the mix for two major reasons.  one...most folks don't like the color of raw from an optics perspective....a black patch is nicer than a yellow patch.   but if you can find another additive that works for can color it any way you want.  second, graphite has ablative properties (think a pencil) where when it gets scuffed/ doesn't obviously appear to have been scratched any more than when you say a used pencil is 'scratched'.  the graphite has a flat appearance....not most abrasive events don't change its appearance.

so the  balancing act, from my perspective, is to find an artful way to pull this all together that works for you....

when i started building, i did not have patches.  everthing was shiny.  and the bow and stern knuckles kept getting scratched.  nothing that put the boat in danger....just didn't look nice...and i was getting tired of refinishing.   for me, over time, i just found this, on balance, worked better given my paddling habits and standards for what i wanted my boat to look like.




RE: Reinforce keel question

On my C 17 the varnish gets scratched on the hull when air hits it. It gets scratched when there is sand on the cradles on the roof rack. It gets scratched when I go through the skinny water, rocks, oysters, a lemon line, etc. Keel strips would help on launching, boat ramps, etc. but things get scratched in other places.  In many of our streams there are deadfall in the water. Limbs and other stobs reach up to scratch the hull between keel and chine. Can't seem to help it. It's only "bad" if it gets through the glass/epoxy. Of course I could hold back and baby it............but that's not what you do with a speedy crusier like the C-17.

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