Boat Builder Central - Builder Forums

Posted: **Fri Jan 24, 2020 4:54 am**

I just needed to get that out. This is fustrating.

Boat is a C17 and I have a build thread C17 in New Zealand.

Photos will follow when I edit this post on my iPhone.

I spend 4 hours last night laminating two layers of my transom (12mm x2) and stringers. This is my second attempt at stringers.

First I thought I would show my method in case there is something I am missing.

I dispense epoxy into a cup (WEST with slow hardener, using pumps this time, and I checked the first few batches on a digital scale to confirm the pumps are on ratio.)
Then I mix for about 1 minute, maybe 2, scraping sides and stick etc.

The cup is paper lined with a 'bio plastic' called Ingeo, it is not waxed.

Then pour into a bigger plastic mixing container.

I then brush this on with a chip brush wetting the entire surface.

I then get some more epoxy thickened with Cabosil (Wood flour is not available commericially in NZ.)

Brush that on one surface until it looks like this.

Photo clamping board with glue.

Then put one over the other and weigh down.

I followed this exact same procedure for my stringers, and one of them (call this bad stringer) has a good half metre near the front where there is daylight between the layers! I drilled small holes visible here and in the end I could get a saw blade through! I then got my holesaw and took some plugs out of both stringers.

The plugs on here from my 'bad stringer' show delamination between the layers of plywood. This is the same stringer with the daylight near the front. I could pull these apart by hand.The epoxy on the left plug shows no sign of being in contact, it was smooth.

The plugs on the right from my 'good stringer' show a nice solid bond, but who is to say that there isn't voids in that stringer somewhere?

My options at this point are

A) to attempt a repair, cutting out the whole front of the bad stringer and regluing, taking several plugs out of both stringers checking and epoxying back etc, then when I finally put this in the boat wrapping the whole stringer with so much biaxial that it won't matter what it is made of.

B) Buy some more plywood and try again, but if I do this I really need to rethink my lamination. How does one ensure that the stringers are bonded everywhere? And if not, how close to everywhere do I need to be? Obviously rocks every half metre or so isn't cutting it.

If it makes a difference, I have far more glass than I need (it was economic to buy a 100m roll of double bias) but am curently out of plywood, except scraps.

Posted: **Fri Jan 24, 2020 5:03 am**

If I take the repair and install approach, how much glass do I use in case of unseen voids?

Posted: **Fri Jan 24, 2020 5:07 am**

What my stringers look like.

Posted: **Fri Jan 24, 2020 5:37 am**

: shopping.png (3.18 KiB) Viewed 830 times

When laminating plywood pieces like the stringers and transom with thickened epoxy, try using a notched spreader.
Bob

Posted: **Fri Jan 24, 2020 5:44 am**

Actually I did that right after the second photo.

I think it is the way I weighted the stringers. Rocks every half metre doesn't cut it. If I rebuild from scratch (I am still waiting for advice here) I will need to do something different there. Buy a 2 by 4 and screw the stringer to it? Seems a bit of a waste but I have already mucked up two lots of stringers.

Posted: **Fri Jan 24, 2020 6:06 am**

Looking at the picture of the transom lamination, and the amount of thickened epoxy looks a little skimpy. When spread with the notched trowel you should get approx 1/8" high raised lines of thickened epoxy over the whole area. When you apply the weight to hold it down, there should be a very small amount of "sqeezeout" at the edges.

Posted: **Fri Jan 24, 2020 6:17 am**

So I’ll bite...

Three things come to mind
1. Wood sucked epoxy out of joint
2. Not enough glue
3. Not enough pressure.

2 and 3 seem most likely based on what you’re saying.

2. You want glue to squeeze out before you apply much pressure. Epoxy is a “gap fill” glue and wants a bit of space. This means you need a thicker cover than if you were using LPU (if I recall you’re a woodworker type). This also means you don’t want too much pressure on the glue up.

3. Just use screws. Get some drywall screws, drill a pilot every 18”. One row in middle. One row 2” in from each edge between the middle row. (You need more rows for transom). Slap a healthy layer of glue, assemble you’re pieces, then HAND SCREW the center row in until the screw head just snugs up the joint. Once the center is done hit the edge rows. at 6hr take a razor blade and clean the squeeze out from the edges. Once the glue has about 18hr setup remove screws, drill out the screw hole and fill with thickened epoxy.

That’s just what I’d do. I can’t remember if it was Jacques, Cracker Larry or someone else that told me how to do it that way. I’m sure someone will point out a flaw though.

Posted: **Fri Jan 24, 2020 6:47 am**

Rmarsh wrote: ↑Fri Jan 24, 2020 6:06 am Looking at the picture of the transom lamination, and the amount of thickened epoxy looks a little skimpy. When spread with the notched trowel you should get approx 1/8" high raised lines of thickened epoxy over the whole area. When you apply the weight to hold it down, there should be a very small amount of "sqeezeout" at the edges.

I see what you mean looking at that photo. That was about half the glue I used for the transom clamping board. The other half I mixed up after the photo. It was hard to coordinate photos with clean gloves. Obviously there were places in the stringers needing more glue (or better use of the glue I had!

)

I would say about 300ml (10 fluid ounces) epoxy for the glue for the transom clamping board plus fillers. About two lots of WEST five pumps each.) And another 200ml to wet out both sides.
The clamping board is roughly 1.8m by 0.3m (6' by 1') so that's ball park within gougen estimates of glue use. Of course they have better technique.

I will probably use more glue next time regardless.

Posted: **Fri Jan 24, 2020 6:50 am**

Jaysen wrote: ↑Fri Jan 24, 2020 6:17 am

3. Just use screws. Get some drywall screws, drill a pilot every 18”. One row in middle. One row 2” in from each edge between the middle row. (You need more rows for transom). Slap a healthy layer of glue, assemble you’re pieces, then HAND SCREW the center row in until the screw head just snugs up the joint. Once the center is done hit the edge rows. at 6hr take a razor blade and clean the squeeze out from the edges. Once the glue has about 18hr setup remove screws, drill out the screw hole and fill with thickened epoxy.

That’s just what I’d do. I can’t remember if it was Jacques, Cracker Larry or someone else that told me how to do it that way. I’m sure someone will point out a flaw though.

Thats fairly labour intensive, but not as much as cutting stringers three times.

I did actually consider screws, but I was worried about using too much pressure. Hand screw into a pilot hole would work.

Posted: **Fri Jan 24, 2020 6:54 am**

I must admit that I really don't have the heart to cut new stringers right now, even if I had the wood to hand. What I really want to do is rescue them somehow.

I'm going to sleep on it. Tomorrow I will start working on the jig. If anyone else wants to chime in with advice I'm all ears. The stringers won't be going in the boat for a few months in any case.

Posted: **Fri Jan 24, 2020 8:41 am**

..and confirm; your pieces have been pre-wetted ? i.e. coat of epoxy on both pieces prior to spreading the glue ?

Marc

Posted: **Fri Jan 24, 2020 9:11 am**

OneWayTraffic wrote: ↑Fri Jan 24, 2020 4:54 am I just needed to get that out. This is fustrating.

Boat is a C17 and I have a build thread C17 in New Zealand.

Photos will follow when I edit this post on my iPhone.

I spend 4 hours last night laminating two layers of my transom (12mm x2) and stringers. This is my second attempt at stringers.

First I thought I would show my method in case there is something I am missing.

I dispense epoxy into a cup (WEST with slow hardener, using pumps this time, and I checked the first few batches on a digital scale to confirm the pumps are on ratio.)
Then I mix for about 1 minute, maybe 2, scraping sides and stick etc.

The cup is paper lined with a 'bio plastic' called Ingeo, it is not waxed.

Then pour into a bigger plastic mixing container.

I then brush this on with a chip brush wetting the entire surface.

C9DCDEC7-1E4F-4014-9FC6-F755D894CB61.jpeg

I then get some more epoxy thickened with Cabosil (Wood flour is not available commericially in NZ.)

Brush that on one surface until it looks like this.
AE901D4D-D348-48F3-8A5F-3A523775FF3D.jpeg
Photo clamping board with glue.

Then put one over the other and weigh down.
4BD99848-333D-4137-9333-21C08620D0C6.jpeg
I followed this exact same procedure for my stringers, and one of them (call this bad stringer) has a good half metre near the front where there is daylight between the layers! I drilled small holes visible here and in the end I could get a saw blade through! I then got my holesaw and took some plugs out of both stringers.

The plugs on here from my 'bad stringer' show delamination between the layers of plywood. This is the same stringer with the daylight near the front. I could pull these apart by hand.The epoxy on the left plug shows no sign of being in contact, it was smooth.2F765C77-934B-488F-9F85-3670B19D32C0.jpeg

The plugs on the right from my 'good stringer' show a nice solid bond, but who is to say that there isn't voids in that stringer somewhere?
3E58DFB1-F7E4-4133-8B61-4B56F2342B48.jpeg
My options at this point are

A) to attempt a repair, cutting out the whole front of the bad stringer and regluing, taking several plugs out of both stringers checking and epoxying back etc, then when I finally put this in the boat wrapping the whole stringer with so much biaxial that it won't matter what it is made of.

B) Buy some more plywood and try again, but if I do this I really need to rethink my lamination. How does one ensure that the stringers are bonded everywhere? And if not, how close to everywhere do I need to be? Obviously rocks every half metre or so isn't cutting it.

If it makes a difference, I have far more glass than I need (it was economic to buy a 100m roll of double bias) but am curently out of plywood, except scraps.

Okay, I have some advice.

1. That is NOT cabosil. The white stuff looks like qcel or balloons which is used as fairing compound and does not have the same properties as cabosil or aerosil which is never white when applied. The balloons are ez to sand and don't have the same mechhanical properties. Take a picture of the bag. I have never seen white cabosil.

2. The thickened mixture is too runny. It should be like peanut butter. When you clamp; a good job should have minimal squeezeout. Balloons are a bit like marshmallows and they never firm up.

3. Both sides of the boards must be troweled out with a trowel for consistency. You can use a 1/16th" u trowel. A bigger trowel will require LOTS more glue. If you only have a 1/8 trowel; trowel on side out perfectly.

4. After prewetting the plywood; you wait until gel time. Otherwise troweling the thixo is impossible. The wood will be really sticky. That is a good thing. Do not mix the resin until the thing is tacky because troweling takes time to do right. Troweling over wet epoxy is a no-no here.

5. It takes quite a bit of epoxy, more than what it looks like you used, but less if you mix it a bit thicker.

6. This work is finicky, but not too hard. Ask a lot of questions; there is a lot of experience on the forum and people are glad to help.

7. I worked with a guy years ago who told me to do it right or don't bother. Sometimes, it is better to fail twice and teach yourself to be careful than mush on with errors. At the beginning of my build we struggled for a couple months learning to vac bag. I build a couple of large 33 foot long panels that cost about $1500 each that I rejected. I recommend you suck it up, accept the error, and make new stringers. They are the backbone of the boat and you will always be glad you did them right.

8. If you continue to use the wrong glue; the entire boat will have weak glue joins. So, please make sure and review this issue. It looks like you are using a fairing filler. By the way, I did the same thing on one of my bottom to hull joins and used ballons. Fortunately, I stopped doing that. The possibility exists that the material is cabosil, but it really looks like marshmallowy balloons.

Posted: **Fri Jan 24, 2020 9:16 am**

ps. Once you stick two sides together with 1/16th trowel each side and the proper glue; they will almost not be able to be pulled apart wet. They will slide, so consider spot screws. Things like to slide after you pour a beer amd are not looking.

Don't stand on them.

If you put weights on them; place the weights on a couple of 2x4s to balance the loading below.

Again, glue squeeze must be minimal when done right.

Another way to do this job is to put a piece of 1708 fiberglass in between the stringers instead of glue. The wetted 1708 is about the ideal size for a glue joint. About 40 mil Or one millimeter is a good joint. The 1708 method is done if you want to use mechanical fastenings and thus avoid squeezing the glues. I don't prefer the method here unless you screw things together.

Feel free to pm me any more questions as I check the forum daily, but don't read all the posts.

Sorry if I wasn't clear enough before.

Posted: **Fri Jan 24, 2020 9:41 am**

Also, consider this failure a win if we identified a filler error now. If I am wrong; I would be surprised.

Posted: **Fri Jan 24, 2020 10:21 am**

Also, to keep them from sliding apart you can use wooden dowels to keep them lined up.
After cutting and shaping, clamp them together and drill some holes for dowels. Precoat the wood ( I also don't think you used enough nor thick enough) let gel, mix up some more epoxy and thicken it appropriately, spread, then insert the dowels in the first piece and then put the second on top lining up the dowels.

I used screws to clamp some items together along with weights spread out.

Have you gone around to any commercial woodshops and requested their sawdust? From there if you have a sieve you can use it to get the fine particles. Can't recall who it was on here but that's what they did. From a 5 gallon bucket of sawdust they got about 2 lbs of woodflour.

Posted: **Fri Jan 24, 2020 12:05 pm**

fallguy1000 wrote: ↑Fri Jan 24, 2020 9:41 am Also, consider this failure a win if we identified a filler error now. If I am wrong; I would be surprised.

I am glad that at least that is not the problem. I'm using a 20L bag of WEST 406. I used it without issue on my dinghy.
It’s recommended for everything except fairing.

Posted: **Fri Jan 24, 2020 12:13 pm**

blueflood wrote: ↑Fri Jan 24, 2020 8:41 am ..and confirm; your pieces have been pre-wetted ? i.e. coat of epoxy on both pieces prior to spreading the glue ?

Marc

Laid on thick with a chip brush. The wood is very dry, but I did wait for a while before adding the glue. I didn't get to the stringers until I had glued the transom.

Posted: **Fri Jan 24, 2020 12:22 pm**

piperdown wrote: ↑Fri Jan 24, 2020 10:21 am Also, to keep them from sliding apart you can use wooden dowels to keep them lined up.
After cutting and shaping, clamp them together and drill some holes for dowels. Precoat the wood ( I also don't think you used enough nor thick enough) let gel, mix up some more epoxy and thicken it appropriately, spread, then insert the dowels in the first piece and then put the second on top lining up the dowels.

I used screws to clamp some items together along with weights spread out.

Have you gone around to any commercial woodshops and requested their sawdust? From there if you have a sieve you can use it to get the fine particles. Can't recall who it was on here but that's what they did. From a 5 gallon bucket of sawdust they got about 2 lbs of woodflour.

WEST recommends ketchup for bonding large flat surfaces and mayo or pb for general bonding or uneven surfaces. I was working within those guidelines, or so I thought.

Posted: **Fri Jan 24, 2020 12:30 pm**

7. I worked with a guy years ago who told me to do it right or don't bother. Sometimes, it is better to fail twice and teach yourself to be careful than mush on with errors. At the beginning of my build we struggled for a couple months learning to vac bag. I build a couple of large 33 foot long panels that cost about $1500 each that I rejected. I recommend you suck it up, accept the error, and make new stringers. They are the backbone of the boat and you will always be glad you did them right.

Thanks Fallguy this is exactly what I needed to hear. I've had a whole 5 hours sleep, and for now I'm going to do nothing but drill a few plugs in my transom. If the bond is good I'll accept it, if there are issues I'll rebuild that as well.

Posted: **Fri Jan 24, 2020 12:31 pm**

OneWayTraffic wrote: ↑Fri Jan 24, 2020 12:05 pm
fallguy1000 wrote: ↑Fri Jan 24, 2020 9:41 am Also, consider this failure a win if we identified a filler error now. If I am wrong; I would be surprised.
I am glad that at least that is not the problem. I'm using a 20L bag of WEST 406. I used it without issue on my dinghy.
It’s recommended for everything except fairing.

All good. Just too loose then.

Posted: **Fri Jan 24, 2020 12:33 pm**

OneWayTraffic wrote: ↑Fri Jan 24, 2020 12:22 pm
piperdown wrote: ↑Fri Jan 24, 2020 10:21 am Also, to keep them from sliding apart you can use wooden dowels to keep them lined up.
After cutting and shaping, clamp them together and drill some holes for dowels. Precoat the wood ( I also don't think you used enough nor thick enough) let gel, mix up some more epoxy and thicken it appropriately, spread, then insert the dowels in the first piece and then put the second on top lining up the dowels.

I used screws to clamp some items together along with weights spread out.

Have you gone around to any commercial woodshops and requested their sawdust? From there if you have a sieve you can use it to get the fine particles. Can't recall who it was on here but that's what they did. From a 5 gallon bucket of sawdust they got about 2 lbs of woodflour.
WEST recommends ketchup for bonding large flat surfaces and mayo or pb for general bonding or uneven surfaces. I was working within those guidelines, or so I thought.

Ketchup is a little thin. You really want peanut butter enough so a v notch trowel application doesn't collapse into a puddle.

Posted: **Fri Jan 24, 2020 1:12 pm**

I think that that was it. Especially the even pressure.

I have just gone back and reread my Gougeon book and also had another look at Tolman's book.

The Gougeons recommend just enough filler to thicken the epoxy enough to ensure good coverage and that there is complete contact.

Tolman actually writes regarding gluing a transom doubler to 1/2" ply: "When you glue the doublers, unthickened epoxy is probably sufficient. Just give them plenty of open time, and add more epoxy if necessary."
When gluing wood he uses cabosil to thicken the epoxy to a point where he can still roller it out. But he uses plenty of screws to fasten the surfaces.

So if I read that correctly, and the advice here from people on here building/built Mertens designs the only important thing is that the surfaces be in full, even, but not excessive contact for the whole setup time of the epoxy.

I can assure this by:
using more glue (even more than what Gougen bros reckon I'll need for bonding.)
using a thicker mix (more like a fillet thickness)
precoating and then waiting until gel instead of precoating and going straight to the glue. (Gougen say it's not needed, but it couldn't hurt. I can then precoat again if need be.)

I am feeling more optimistic about my transom. The panels were almost completly flat and I put more weight on. I'll still take some plugs out of it and check for peace of mind.

Posted: **Fri Jan 24, 2020 1:13 pm**

And I have a name for my boat:

With a little help from my friends!

Posted: **Fri Jan 24, 2020 7:56 pm**

You got a lot of good advice. Only thing I will add, lay a 2x4 down the length of the stringer, place weights on top of it. It will distribute the weight. This is what I did on my C19 stringers.

Screw method sounds hard to beat though.

Good luck!

Posted: **Fri Jan 24, 2020 8:36 pm**

I would really try to bring in someone locally who has some experience working with epoxy at this point to help with your next glue up. There are so many variables when you don't have experience with successful glue-ups(please correct me if I'm wrong about that).

Posted: **Fri Jan 24, 2020 9:12 pm**

joe2700 wrote: ↑Fri Jan 24, 2020 8:36 pm I would really try to bring in someone locally who has some experience working with epoxy at this point to help with your next glue up. There are so many variables when you don't have experience with successful glue-ups(please correct me if I'm wrong about that).

I built a D5. That taught me glassing, filleting, marking and cutting panels etc. I made my share of mistakes with that too.

The D5 did not really involve splicing panels or large laminations of plywood. I don't know of anyone nearby who has built a boat sadly.

I spent time today going over my transom lamination with a fine tooth hole drill. I was looking for obvious voids in the panels. The middle of the laminations looked ok actually. So I took a couple of plugs out. One of them was good, the other down by the bottom had the same lack of contact. Moreover the edges of the transom had gaps in a couple of places.

If that was all it was, I'd probably fill with epoxy and put it on the boat. But with the stringers and the promise I made myself at the start of this that I would do the best work that I was capable of I have decided to bite the bullet, buy a sheet or two of ply and start again. It will take me a week or so to get into Christchurch, buy the ply and get things in order, but at the end I will be happier. I will use screws this time and more glue.

Posted: **Sat Jan 25, 2020 12:29 am**

Again, glue squeeze must be minimal when done right.

That's exactly right. No need for massive pressure. Just enough glue and even pressure to make sure the two pieces are stuck together.

Nothing at all like woodworking with tight glue joints.

Totally agree with notched trowels to make sure you have enough. Don't obsess about the flavour of the glue (PB/mayo/ketchup). All will work pretty good but I would lean toward thicker than runny.

Posted: **Sat Jan 25, 2020 2:21 am**

Cheers. From a designers point of view, what could happen if I simply filled all the holes I drilled in my stringers and now my transom with goop, glassed over it a few times with some of that 100 metres of biaxial cloth I have sitting in my garage, did the same to the transom, put a five year warranty on it and sold it to some unsuspecting sod in a boat yard?

I know that it's anyones guess but I'm thinking that it would hold together, until water gets in somewhere, and then would spread throughout the transom/stringers in those little voids.

I've made the decision to have another go at it, using the screw technique as it seems most likely to be foolproof. I've also ordered WEST microfibres for the thickening agent. It seems to me that it should work better for large glueups.

Posted: **Sat Jan 25, 2020 5:49 am**

Most of the studies and reading I have done suggest 40 mil to be the perfect glue joint thickness. (1 millimeter) You cannot achieve the ideal thickness on epoxy alone. And most designers that recommend mechanical fastenings or require them, say like in a bolt on appendage, require glass to avoid squeezeout. 1708 wetted, for example is about 0.040" or pretty close to 1 millimeter. Your approach on the prior stringer to just butter the thixo is a big part of the issue, the glue joint thickness varied too much. It was thick in some places to the point of lifting the parts away from each other where thin...

You need to use a v or u trowel 1/8" for a one side, or 1/16th for both sides, or the joint will be uneven. It does take some time to trowel both sides, so if you try to do the work with fast epoxies, it is pretty hard to do..

I have never used screws for any lamination work. I have always laminated by being careful with even application of thixo and by making sure the weight applied or force applied (vaccum) is even. I realize screws are important for some laminating, but you need to avoid squeezing out the glues.

If you only use a trowel and thicken the epoxy to peanut butter and position the boards so they don't slide, your results will be much better. In the past, I used stainless brads to keep the laminate panels from sliding off each other. I simply predrilled with the nails and then dropped them in. I spotted like 4 nails in each board. They actually stayed in the part.

My panel weight was 10" of mercury under vac, but you can get that at 5 psi, so for a 60"x6" board, you'd need 1800 pounds. Of course, that is crazy too much, so I would try more for 1 psi or say 2-300 pounds or so..balanced on some 2x4s that run the length of the part...or screws.

The caution with screws is oversqueezing things, but they can get you closer to 2-5 psi than just weight. Just remember when you screw to avoid forcing the glues out much. And you don't need a ton of screws...maybe like 8 or 10 or so.

I also won't use anything but a 1/16th u or v trowel and I always do both sides. The 1/8" or 3mm can work in a pinch, but you end up a bit thicker than 1mm when done.

A boatyard would know to use a trowel. Do you know how when you put water between two shiny surface flat objects they tend to stick together? That is what will happen if you trowel out the mix. Only a force of a twist or a non-flat board will overcome that force; so it is also wise to keep boards to be laminated flat on a table vs leaning on a wall and bending out of flat...

Posted: **Sat Jan 25, 2020 5:59 am**

Your volumetric needs will be about 2 parts cabosil for one part epoxy.

A liquid measure of say 12 oz epoxy and a volume of about...25 oz of packed lightly fumed silica is about right. (Not weights! You might wish to start a bit lower at say 9 oz epoxy and 18-19 oz silica and see if you have enough. You can stretch it a wee bit by angling the trowel at the end over the entire part bs making more if you are short.

It is really hard for me to estimate it perfectly. But I can tell you I am always a little surprised at how much is needed...always seems a little epoxy thirsty.

You can calculate the neat coat needs at 2 oz per sq yard.

Posted: **Fri Jan 31, 2020 5:53 am**

Cut the transom again. I'm getting better at ripping stringers as well.

I used about 20 screws this time, and a few clamps around the edges. Tightened (inside screws first) until contact was made then another half turn. Squeeze out all around, but not a lot.

I'll have a look in the morning but it looks much much better. Used about 500ml (over a pound) of epoxy plus fillers and wetout coat.
Thickened to a bit past mayo, just enough to hold shape when spread with a notched spreader.
Used some excess to start plugging the outboard transom holes.

Posted: **Fri Jan 31, 2020 10:36 am**

OneWayTraffic wrote: ↑Fri Jan 31, 2020 5:53 am Cut the transom again. I'm getting better at ripping stringers as well.

I used about 20 screws this time, and a few clamps around the edges. Tightened (inside screws first) until contact was made then another half turn. Squeeze out all around, but not a lot.

I'll have a look in the morning but it looks much much better. Used about 500ml (over a pound) of epoxy plus fillers and wetout coat.
Thickened to a bit past mayo, just enough to hold shape when spread with a notched spreader.
Used some excess to start plugging the outboard transom holes.

I'd say you are in great shape. I figured 12 oz was sort of short even...but didn't want you to overmix.

Posted: **Fri Jan 31, 2020 5:30 pm**

I have predrilled some hole so could always fill with excess.

Have posted a photo so people reading this can see what worked for me. Hand turned screws in pilot holes the way to go I reckon. Easy to adjust pressure. Clamps for places around the edges where small gaps show.

Posted: **Fri Jan 31, 2020 9:36 pm**

You can't fill big holes or the epoxy will exotherm. fyi

Posted: **Sat Feb 01, 2020 4:09 am**

You can save the plugs from the cut holes and use them to plug the holes.

Posted: **Sat Feb 01, 2020 8:04 am**

I have a 3 inch hole in the bottom of my dory filled with epoxy and glass threads for a shoot through hull transducer which didn't "exotherm" beyond working. It probably got hot while curing but not a problem.

Posted: **Sat Feb 01, 2020 9:11 am**

cape man wrote: ↑Sat Feb 01, 2020 8:04 am I have a 3 inch hole in the bottom of my dory filled with epoxy and glass threads for a shoot through hull transducer which didn't "exotherm" beyond working. It probably got hot while curing but not a problem.

How thick is your glass/epoxy there and does it seem to effect the transducer's abilities?

I would like to do a small FF that way too.

Posted: **Sat Feb 01, 2020 9:25 am**

cape man wrote: ↑Sat Feb 01, 2020 8:04 am I have a 3 inch hole in the bottom of my dory filled with epoxy and glass threads for a shoot through hull transducer which didn't "exotherm" beyond working. It probably got hot while curing but not a problem.

All depends on thickness. 3/4"thick will exo and crack about half time on say a 2" wide hole, so if you are thicker, like 1 3/4; that shit will be smoking if you try to fill it. Mine was just a warning to the OP to avoid trouble. Epoxy can catch fire in a big ball; never saw it, but I have had a couple cups melt..

For a ducer fairing, there is no need to fill the whole hole.

Posted: **Sat Feb 01, 2020 10:52 am**

So fill it in a couple of smaller batches over the course of a couple days. It’s still going to form a chemical link and greatly reduce the risk. Not a hard problem to solve.

Posted: **Sat Feb 01, 2020 11:42 am**

Jaysen wrote: ↑Sat Feb 01, 2020 10:52 am So fill it in a couple of smaller batches over the course of a couple days. It’s still going to form a chemical link and greatly reduce the risk. Not a hard problem to solve.

You can even just wait an hour and a half or until the last one starts to cool off.

I just know he had trouble, so trying to watch out for the guy!

Posted: **Sat Feb 01, 2020 12:05 pm**

I am building the C17 in the Pacific NW. Sorry to hear your problem. I will tell you to figure it out now as you have a lot of gluing to do. I would say an average of 1/8” paste overall is about right. I use only wood flour for structural layups . You might try System Three off Amazon, or order direct from System Three. I usually step on my laminations to set the bond then back off with moderate weights for the cure. Good luck.

Posted: **Sat Feb 01, 2020 2:52 pm**

A few posts overnight. I haven’t had any issues with exotherm yet. Only filling the smaller holes for the outboard with putty. The two big ones will be sealed sanded and have fibreglass tubes in them.

I didn’t put the fourth layer on yet. I realised thT the three layers I have glued together have a slight bend in them. About 5mm Less than 1/4” inwards at the middle. It was only visible when I put it on its side and peered down it. A 20kg (50lb) weight lays it down flat. I was thinking about screwing in a batten or 2” by 4” to the inside before I install it to prevent locking this in.

Am I right in assuming that such a slight bend will only bug me, it won’t affect anything important?

Posted: **Sat Feb 01, 2020 5:07 pm**

Well bug me it did so I cut some kerfs screwed it flat to my old transom and filled with putty. Shouldn’t be able to tell when done.

Boat Builder Central - Builder Forums

Stringers AARGGHHH!

Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!

Re: Stringers AARGGHHH!