End pour

Just did the end pours on my SW Hybrid sport. I used West Epoxy, with 1/2 fast hardener, and 1/2 slow hardener, with  light weight filler.  I left is very viscous, and poured it in the bow.  It appeared to be kicking off, so I left for awhile.  When I came back, it had expanded to at least double the original volume.  It looked like expandable foam.  I was able to break off the piece that expanded way out, so it is about 7" deep.  I mixed just epoxy, and poured it in to fill around where it had pulled away. 

The second pour, I used wood flour, and left it even thinner.  That expanded about 50% above what was poured in.  I left it as it is.  My concern now is that the pours appear to be very pourous, just like expanded pour in foam.  When I drill for the handle toggles, I will super saturate the complete hole from one side to another, so it doesn't absorb water.

I have never seen epoxy expand like that, it really looks like foam.  I will probably send an inquirey to West and see if they can tell me what went wrong.  It won't be a big problem, but I am real curious why it happened.


20 replies:

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RE: End pour

Dave, nothing went wrong, you have to keep it cool.  If you make a large amount of epoxy and put it in a small container it will generate a lot of heat and boil and you end up with foam.  That's why the instructions should say that the tip of the boat should be in cold water or something to keep it cool.

How many oz. did you pour in the end?

An alternative is to epoxy carved wood blocks into the tips.  Saves on weight, saves on epoxy, and you don't have to tip the kayak up vertically.

Kim

RE: End pour

Dave,

I had a similar experience with my first end pour on my MC 156.5.  I mixed up three batches, adding each one as it was reay.  About the time I put the third one end, the first started to cook off.  this was behind a cardboard dam with the boat on the floor.  All that gas generated by the cookoff has to go someplace.  I was there to scrape off the excess as it bubbled up so there were no epoxy monuments to deal with.  When I did the other end of the boat I mixed smaller batches and added a little at a time.  letting each batch cook off before adding the next.  All worked out better that time.  As far as the final result, I have had no trouble with either pour, including dropping the boat on the bow where the first pour was installed.  Check for air pockets when you drill your end loop holes and fill any you find.  Otherwise, all should be OK

RE: End pour

Wondering what type of filler you used...? I just bought some micro balloon microspheres and planned to do the same thing. So glad you posted. So does the cold water thing work Kim? Have you used this method?

RE: End pour

I epoxy a carved wedge of wood in the two ends.  It's easlier, saves on weight, you don't have to tip the kayak up, and you don't have to worry about the epoxy overheating.

If your going to do an end pour then you should at least add filler.  I use saw dust which works well.

Kim

RE: End pour

I used West Epoxy with Microlight in the first pour.  It is a low density fairing filler.  On the second pour I used wood flour.  Both had the similiar results.  The front pour was about 8 oz of resin, and the stern was about 10 oz, due to the extra beam, it took more to fill to about 6 inches.  The bow expanded to more than double, which I was able to break off.  The stern  didn't expand nearly as much.  I used the West because I was not sure I had enough Mas, and I had plenty of West, and wanted to use it up. I think the thing to do, is what PAG said, several smaller pours.  I have used alot of epoxy over the years, I have mixed epoxy, then not used it and left it in the pot, and it never expanded like this did.    

RE: End pour

On my first build, a SW17, I carved cedar blocks, epoxied into place, instead of doing an end pour. On my current build, a SW17 Hybrid, I thought that the End Block would be too complicated where the shear clamps meet, so I did a different kind of end pour. I made V-shaped wedges of minicell foam, to use as "dams", and filled the ends with epoxy thickened with microbaloons.  The pours expanded about 1/4", easily ground down to level when cured.

RE: End pour

For those of you putting wooden wedges in the bow and stern instead of doing end pours, what do you do with the inside of the blocks once drilled to prevent them from getting soaked and rotting?

Thanks,

Gero 

RE: End pour

with a wooden end pour, you would protect the wood by coating it with epoxy.

there are two techniques that can be used here.  one is the drill/fill/drill technique and the other is painting with epoxy.

the drill/fill/drill approach is a bit more complicated but tougher/more resillient.  executed properly, it also is a very nice detail on a varnished (not painted) hull.  in this case you would drill a 3/4 inch hole for the grab/loop toggle.  you would then put the boat on it side so the hole is vertical and tape the bottom of the hole with duct tape... and fill that hole with wood flour-thickened epoxy (not too thick -- syrup/ketchup consistency).  after it cures, you would then redrill it with a 1/2 inch drill leaving a 1/8 inch ring of epoxy to protect the wood.

the other, easier, approach is simply to drill it with the 1/2 inch bit and 'paint' the inside of the hole with unthickened epoxy.  i use a q-tip to paint the epoxy on the inside of the hole.  you would probably want at least two seperate passes of epoxy to ensure you sealed the exposed wood.

i use the first technique on all varnished hulls...and the second technique on painted hulls.  they both do the job.

 

RE: End pour

 Pouring in "lifts" will solve the form "blow out" problem. 

RE: End pour

 Is there any good reason not to do an end pour before the deck is permanently  mounted to the hull? My plan would be to fabricate a dam and pour strengthened epoxy in small batches or  fabricate a cedar block completely excised in epoxy. I am building a Shearwater Sport. I am trying to avoid having to stand the boat on end twice to do a traditional end pour.

 

RE: End pour

i can't think of a 'good' reason to do an end pour after the deck is on when, in most cases, it can be done competently and with more precision before the deck is attached.

i have built a number of kayaks and assisted on a great many others.  all with pre-poured end pours.  as you said, you build a little dam and fill it.  and you need not make that dam any bigger than is necessary to accomodate the toggle line holes.

between the glass on the hull and the fillet in the bow and the hull coming together with the deck piece, the bow is plenty strong for normal use.

why won't i do a traditional end pour (standing the boat on its end)?

- you can't see what you are doing so you will invevitably make a larger pour than you need to which simply adds weight

- you will end up with some epoxy not where you want it....(not much)....but invitiably it will, on its way to the end, be either on the deck or the hull...vs just in the end.

- in order to get it to pour, it has to be a very liquid mixture which is heavier than what you need.  with a pour that is created prior to the deck going on, you can make your end pour light and peanut butter consistency with something like microballoons.

less material...and less dense material....is what you get by not doing a  traditional end-pour.  all of these properties are just fine if all you are trying to do is make sure when you drill a toggle line hole that the hole does not open  up into the hull.,

howard

RE: End pour

Interesting thread. I've filled ends both ways and have a pretty strong preference for blocks of lightweight wood like white pine. 2x4 bits are great for this.

Here's a twist: drill your toggle hole over sized, say 3/4 then insert a length of that clear plastic hose into the hole and center it with duct tape, which would also seal one end of the hole. Pour ketsup thick epoxy in the open side (boat on it's side of course) and it fills the over sized hole. Fiddle it with a small stick to make sure the bubbles are popped and hole filled all the way around. Center the upper end of the hose and tape it in place until epoxy is cured.

Take some locking pliers and twist the hose round and round to deform it. Epoxy won't bond to the plastic so it will pull right out. Use mould release if you're nervous.

This saves having to align two holes drilled from either side and saves a few minutes overall. It bugs me to do an extra drilling step. Not really all that important but little things bug me ;-)

When ever I have a drill-fill-drill step I try to insert something in the mix so I won't have to drill later. Some of you "detail oriented" folks might agree with me.

RE: End pour

So here's my 2 cents worth: First, I do end pours AFTER the deck is installed, just to create an additional bond between deck and hull at the bow or stern. Second, I do fairly minimal pours, just enough to do the job, not create a solid block of epoxy, and falling far short of where I have already drilled for the toggle loops. So how do I stop water from getting into the toggle holes when the boat is in use? Before I do the end pours, I will have already epoxied in a section of half-inch PVC pipe, then trimmed and sanded it flush to the bow. In fact, I install that pipe and trim it flush even before I fiberglass the outside of the hull. I just glass over the openings and don't worry about it, then later, when I'm sanding and smoothing the outside, I trim away the glass that has covered the ends of the pipe. The pipe ends show through as elegant inlays. The rope loop goes through the pipe. Any water that goes in one side just flows right through to the other side. I've done six boats this way, bow and stern, and never leaked a drop of water. IMO, putting in enough epoxy to create a block to drill through is a waste of material and just adds weight to the boat.  

RE: End pour

Jim,

are you doing the PVC on S&G boats?  If so, does the pipe going through the plywood, I'm assuming with a good fillet on the inside, provide enough structural strength when you're hauling or carrying a boat with some gear in it?  This being said with the understanding that the fiberglass and epoxy on the hull are already providing strength to the hull.

Thanks,

Gero

RE: End pour

I agree with the statement by Howard that if all that one wants is to make sure that the boat does not leak at the toggle hole, than many of these techniques will work.  I am very glad that I wasted a few ounces of resin and placed a "heavy" traditional pour with no lightening agents.  When attempting to go against a tidal current between bridge abutments in a reversing falls in Maine this summer, one of our Shearwaters slammed into the wall.  The noise was surprisingly loud and I thought there was going to be plenty of damage, but less than an inch of the bow was missing with the tip of the end pour showing but not damaged.  I'll stick with the reinforced end in future builds.  There are some knowledgeable boat builders that claim that a wood end pour will pick up moisture over time and be just as heavy as resin after awhile.  

RE: End pour

   You mght find the epoxy with micro ballons is just as strong as all expoxy but it will be more flexible and this might provide a "stronger" nose or tail piece.

West Systems Fillers

I would look at using the 406 Colloidal Silica.

RE: End pour

  Gero -- I've used the PVC on 4 stitch'n'glue boats and 2 cedar strip boats. Yes, there is a fillet on the inside of the hull, but not a particularly beefy one. I use the rope loops to carry the boats, with all gear inside them, but by all gear I mean seats, pfd's, paddles, a light jacket, a couple of bottles of water and lunch (not much weight). I also use the rope loops as fore and aft tie-downs when I car-top the boats, and there is a LOT of tension there. I have never had a problem with anything pulling out or loosening at all. It is completely solid and reliable. Hope this helps.

RE: End pour

Oh, and one other thing: I've settled on locating the PVC 1.5 inches from either the bow or stern, and that seems to look good and work well.  

RE: End pour

i thought i would throw a couple quick pictures i took of an end-pour installed on my recently completed night heron as it illustrates a couple points that folks were making,

in the first picture you see a 'pre-poured' end pour with a mixture of epoxy and micro-balloons.  now this went in at a peanut butter consistency and only weighs between 2 and 3 oz (two pumps).  from a volume perspective its not quite half an 8 oz plastic cup worth of material.   that said, while light, it is extremely tough....and inert to water.

in the second picture you see the toggle hole.  so the end-pour only extends about 1/2 to 3/4 inch beyond the toggle hole.

no problem totally supporting the boat with the toggles though i would still recommend carrying your boat by holding the hull.  i use these toggle holes also for my bow and stern tie-downs.  15 years of building include running into a couple things.  never had a problem.

end pours are not really a place where throwing in a lot of extra epoxy makes a material difference in durability for the types of impacts you would expect to have on a sea kayak.  if you are putting so much epoxy in that you are getting heat expansion...i think you are over-doing it.  that said, to get it where you need it with confidence an end-pour that is poured after everything is already closed up almost inevitably put more material than you need.,,,which is why i don't particularly like the approach.

 

 

 

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