would be interesting to see a picture of your boat/affected area.

you may get better result by re-thinking your landing approach or boat type if it is getting this much wear.  i have a west river 180 and did about 700 plus miles on it last season with dynel rubstrips and was fine....and this is my second season.  that said, i don't actively run the bow up onto the shore or drag it other than what is absolutely required to to have a safe landing.  i can get my legs outs while still seated and will often brace and lift the boat out (not drag it).

any possibility of better describing how you managed to wear through things.  the dynel is pretty good stuff....but at the same time, it won't protect you from dragging the tips on a routine basis.   is a plastic boat is in order?

howard

Howard,

Here's a first time builder question on the above topic that may help Corrotman too.  I'm getting ready to epoxy the bottom of my dory real soon (like tomorrow or Monday hopefully) and want to build it to take the kind of abuse I've given all my boats.  I've been reading up on graphite in the last, or last 2, coats of epoxy on the bottom and up to the water line.   What's your thoughts on graphite for Corrotoman or my situation?   Thanks!  Curt 830/997-8120

I've got graphite/epoxy on all my boat bottoms. It works well but is not a panacea.  It works by taking the hardness of fully cured epoxy (which is about as hard as formica) and making it slippery. That way when your boat hits a rock or whatever, it slides over it. The rock does not get a chance to get a purchase and dig in to start a scratch.

Graphite/epoxy is also easy to repair when the rocks do get through (and eventually they will).

The more graphite that you add, the slipperier the bottom. But the more you add, the softer the bottom, so it's a balancing act. For what I encounter, a 50-50 mix by volume works well.

A brass strip is much tougher and I have one of those on the skeg for my sailing dinghy, too. The problem (but not a big one) with brass strips is attaching them. You may have to add internal structure.

Good luck,

Laszlo

to Curt, the dynel rubstrips get a final coat or two of graphite mixed with epoxy.  that said,  the graphite epoxy mix helps and is effective for certain kinds of ‘abuse’.  but i suspect ‘abuse’ may mean very different things to different people.

so lazlo's comments are particularly important here.

it's important to define 'abuse' and approach it appropriately.

as an example, i went for years with no rub strips on my kayaks and it was not a problem until I joined a group of paddlers that routinely launched from concrete boat ramps and other hard surfaces.

there were a number of folks in the group who have plastic sea kayaks and while they are great paddlers, it was pretty clear they were willing to expose the ends and keels of their boats to a kind of 'abuse' that i never did previously. to be a member of the group, i did not think they weren't going to wait for me to always find the gentle spot to land the boat. i also did not want to get upset when people in the group tried to help and maybe didn't handle the boat as gingerly as i would on my own.

prior to joining them, i had only launched from sand, mud, pebbles, grass or, if from a hard surface (e.g., concrete boat ramp), I was very careful (read slow) to avoid abraiding the ends and the glass only ends held up fine.

once i got involved with the group, i wore through my glass to the wood in about 4 paddles; mostly from concrete boat ramps. I realized i had to change....and that is when i put the dynel strips on at the most likely impact points (bow and stern knuckles). I have three layers of dynel.

my sense after two seasons, is that when i inspected the bow knuckle this morning, is that i have gone about half way through the dynel.

so what would I take from this?

the dynel and black graphite does a great job of getting the boat through sand, small rocks and the occasional light scrape on concrete (e.g., the equivalent of hitting  30 grit sandpaper with over 200 lbs per square inch of pressure for a half second....which i figure is what it’s like to drive your bow up on a concrete boat launch). but i don't think any material/approach we have talked about is going to hold up well if dragging your boat up a concrete boat launch is the kind of 'abuse' you expect to expose your boat to. the only material i have seen that seems to manage that kind of abuse reasonable well is a plastic boat and or sacrificial/replaceable wood or plastic strips.

so as mentioned above, if rubbing against concrete is the abuse you expect, you really need to have some material that can be sacrificed and easily replaced when worn through.

on flat bottom boats, they often will put one inch untreated (no coatings) marine grade lumber ‘rub rails’ that screw into the bottom of the hull.  at the end of a season or two, they are removed and new ones are screwed in their place.  on glass/kevlar kayaks, around here a very common approach is a product called KealEazy  http://www.keeleazy.com/page1/page1.html  which is a sacrificial plastic kind of material that seems pretty durable (you can read their website where they discuss what its made of in more detail)   fwiw...the folks who use the keeleazy really seem to like it and it is very popular on high end manufactured kayaks around here...but i have not figured how to put it on a homebuilt boat in a way that i like.

not sure that helps, but i don’t want to give the sense that the graphite epoxy will perform better than it really will.    my thinking is it’s great for ‘light abuse’....but it’s not going to help for routine scraping/sanding action against hard surfaces.

Just thought i would take a quick snapshot to accompany last comment.

you can see here how graphite/epoxy has quickly scraped away leaving the dynel to take the brunt of the action.  in spring, i will put another layer or two of dynel over the rubbed out spot and fair back in with graphite epoxy.  these stips are about 20 inches long but all the wear is happening in about an eight inch area right at the knuckle.

fwiw...almost no wear on the rear rub strip....becuase i am pretty careful to lift the boat and not drag it.

   Drift boats use UHMV and similar products to protect from rocks encountered. I believe it is available in 1/8 inch which might be formable enough to use. It is very durable and slippery. 

Barry

barry makes a great reference.

i think the term is UHMW (not v) (Ultra High Molecular Weight) plastic.

a quick google search shows a lot of options.

i suspect KeelEaze is made of this....i have also seen it used as toe-rails (in lieu of wood) on high end composite sailboats.

definitely would consider this (you can shape/drill/countersink this material) if i needed to do rubstrips on a boat that i was going to drag up a ramp.

Even in my plastic kayak I usually lay parrallel to the boat ramp to get in/out. If you run the boat up on many of the ones around here you end up with narrow bow and narrow stern supported and tippy mid section capsizing at the ramp. Some of our ramps are a little steep. Hang out with the fiberglass kayakers and the boat handling will be a little more gentle.