Perry's Bayou Skiff Build

[seedtick]

we do not overlay, cover or try to strengthen scarf joints. a good scarf joint is plenty strong enough

glass bubbles are not for structural use and are typically using for fairing

solid glass beads are for structural use (just like solid glass fibers)

 

[beekeeper]

Would the glass bubbles help in fairing over the scarf joint? A well made joint with good wood usually does not need to be faired over, but it is hard to make a perfect joint with cheap wood.
I use Titebond 3 for gluing joints but sometimes mix wood flour to make a paste for filling nail holes or to fair out a splice if needed. I think I will try adding some hollow glass bubbles to see if it will sand smoother.

Are the solid glass bubbles or silica used to fill large voids, like pouring an epoxy stem or doing filets for stitch and glue boats?

beekeeper

 

[oldsparkey]

Ya All are getting what I said about the glass bubbles confused. I guess we have a failure to communicate. :roll:

As far as a filler for the epoxy I used wood flour and sometimes the micro bubbles which are very fine glass bubbles.

The key word is .....FILLER ... as in what you add to the epoxy when doing the fillets.

Perry M said .........

I will be glueing up the side pieces. Should I add silica to the wood flour to make sanding easier? Can I just use silica?

From that I understood he meant the seams along the ....JUNCTION .... of the sides and the bottom of the boat , the area we do the fillet in to fill it in so the fiberglass has something to lay on and not a 90 degree angle.

The 2 light colored lines are the fillets using the glass bubbles ( with some wood flour ) when I made this Freedom from JEM Watercraft.

 

[seedtick]

I believe a fillet is structural as it adds strength, per the following definition:

"Applications
Stress concentration is a problem of load-bearing mechanical parts which is reduced by employing fillets on points and lines of expected high stress. The fillets distribute the stress over a broader area and effectively make the parts more durable and capable of bearing larger loads."

Of course the question always boils down to "How strong is strong enough?" Thousands and thousands of plywood boats were built before anyone ever thought of glass fiber.

 

[beekeeper]

I did misread Perry M's question. He asked about adding wood flour to a mix of silica and epoxy. I thought he meant adding silica to a wood flour/epoxy mix.
Either way silica will make the filler harder. Using wood flour, or glass bubbles mixed into the epoxy will make for an easier to sand paste.
This link explains the characteristics of some common fillers:
http://www.uscomposites.com/fillers.html

beekeeper

 

[Kayak Jack]

You fellas use the expensive stuff. I gather up sawdust and sanding dust, and run it through a kitchen sieve. Then store it in a Ziploc bag. The plastic bag is the high tech patt of my process. KISS principle.

I know the other stuff adds different characteristics. Didn't seem necessary to me, somehow. That's likely why Seedtick, Keith, and JD make prettier boats than I do.

 

[oldsparkey]

When I cut out those 1/4 by 3/4 inch 164 Red Wood strips to make the Stripper Pirogue , only used 144 of them. I keep the sawdust and even the dust from sanding all of them and used it as wood flour for fillets. It made a really nice deep purple fillet in a couple of the boats and even shared some of it with other builders that wanted to use it.

 

[PerryM]

Maybe I didn't "splain" me self correctly. LOL What I was asking is "Should I add Silica to the Epoxy, Wood Flour mixture that I'm using to glue up the scarfs on the side pieces?" I think I had planned on ordering glass bubbles, but somehow got the two confused when the order was placed. Now I have a bunch of silica and need to use it somewhere. :?

I decided to take the "better safe than sorry" road and added 6oz tape to the scarfs on both sides of the bottom panel. Being that its my first boat I wanna be sure the scarf holds. I considering only doing that to the outside surface of the side panels and then glassing the whole thing.

Discovered my first major boo boo... I bought 50" wide cloth instead of 60". Wanna cover the whole bottom and sides with one piece so think I'm gunna use the 4oz 50" cloth on the inside and order some 6oz 60" cloth for the outside. Used a piece of 4oz on the inside of the transom. It went down without a hitch and thats really got my confidence up.

If I want to double up on the cloth, do I need to fill the weave of the first piece or can the top piece be epoxied right on top of the first layer? Hope I made sense with that one. :lol:

 

[beekeeper]

Anything you add to the construction will add to the strength. Anything added also adds weight, more work, more money, and stiffness, etc. Only you can decide what is good enough. You may be safe and end up sorry too. It happened to me with my first build. I was so determined to build it "better safe than sorry" that I ended up with a tank of a boat but it was too heavy. If you are trailering your boat or never have to drag over logs or levies, etc. weight may not be an issue. Adding silica will not add much weight ,but glassing inside and out, double taping joints, or doubling the cloth, etc. will.
Food for thought. Consider these options:
1. Add the silica. You already have it, but lots of scarf joints are made with out it and it will be harder to sand.
2. Use the 50" cloth and not worry about the 5" of less coverage on each side unless your planning on scraping a lot of bridge pilings and the
like. My boats show little wear above the water line.
3. If the plywood is not exterior rated, glass and epoxy inside and out. If it is rated the ribs and strength of the ply should be strong enough
to prevent oil caning.
4. Since you refer this as your first build (implies you will be building more) fiberglass inside and out. It will be good practice for the next
ones.

beekeeper

 

[oldsparkey]

If I want to double up on the cloth, do I need to fill the weave of the first piece or can the top piece be epoxied right on top of the first layer? Hope I made sense with that one

Fill the weave for a better finish , contact and support between the two pieces of cloth. It will add some weight but also strength.

 

[tx river rat]

Yo8u need the heavier glass inside ,
Ron

 

[PerryM]

6oz on the inside and 4oz on the outside??? Why is that? Thought the heavier cloth would be best on the bottom. :?:

 

[tx river rat]

Somewhere there is a long discussion on this.
The outside compresses when you hit something , which isnt very strong the inside has tension the more pressure you put on it very strong.
The outside is for wear the inside is for strength.
Take a steel wire and try to bend it then tie both ends and see how hard it will bend ,same principle. You can take a 1/4 rod and pick up a car with it but you cant push 20 lbs with it.
Ron

 

[Kayak Jack]

Imthink that what Ron is trying to explain is that if you run a boat, especially a flat bottomed one, up on a rock, especially a pointy or sharp edged rock, it can severly bend the bottom panel inwards. He's right. The inside surface is trying to strecth to relieve the stress. This opens up splits, and tears the wood apart. Fiber glass on the knside can eliminate or minimize this. It's why bows are laminated on the backs.

Howsomever, in Louisiana, you have to look pretty hard to find a pointy rock. Or ANY rocks, for that matter. Still, logs are a hazard. You'd likely be fine with a lighter glass on the inside.

 

[PerryM]

Thanks guys. Think I'm going to use the 4oz on the inside and order some 60" cloth (either 4 or 6 oz) for the outside. I want to experience what its like to cover the outside with one whole piece of cloth. From what I've been reading here it sounds like piecing together the inside cloth can be somewhat of a chore but honestly I'm really looking forward to it.

 

[Kayak Jack]

It's easier to glass the inside in 2-3 pieces than one. Gravity works for you on the outside, but against you on the inside.

 

[oldsparkey]

Everyone has there own way of doing the inside of a boat............
I have done all my boats with one piece on the inside. I lay it out and let it form to the boat for a day or two.
Then when starting the epoxy I start in the center and work to each end. I use rollers made for epoxy and get the 9 inch ones then cut them in half so I have two 4 1/2 inch rollers.
You just have to be gentile and don't use a lot of pressure on the glass since it will slip and slide around.
I can do the boat with the two smaller rollers one for the front section and one for the rear section. When one starts to get sticky I switch it out.

 

[PerryM]

Might be able to get the sides, bow, and stern dry fitted together this weekend. Any thoughts on wether or not to glass the insides of the side pieces before final assembly? I plan on taping all the seems. Is it better to glass the sides after the fillets are done and taped? Sorry for asking so many questions but I want to consider all possibilities and want my posts here to be helpful to readers in the future that plan on building this skiff. I deeply appreciate all of your thoughts, opions, and advice!

 

[oldsparkey]

Is it better to glass the sides after the fillets are done and taped?

YES .........

Fillet the seams and then glass the boat................

If you run a fillet of epoxy and wood flour alone the seams it is not necessary to tape them and it will make it easier for you when you glass the inside of the boat.
The fillet fills in the seam letting the glass lay on the area better then having a 90 degree crease in the glass at the seams.

If you want extra protection on the outside wear areas then tape the outside seams before you glass them of just forget the tape and glass the outside.

Usually folks that only tape the seams do not completely glass the boat.

Any thoughts on weather or not to glass the insides of the side pieces before final assembly?

Some folks have epoxied and glassed the bottom and sides before assembling them , they say it is a lot harder to bend the pieces when they do that but it makes for a good glassing job.

When I fillet a seam I paint the seam with epoxy and about 1 1/2 inches on each side of the seam. The reason for this is that I let the epoxy dry and then when I place my tape it is normally a 1/4 to 1/2 of an inch on each side of the seam. That epoxy I painted on the sides is where the tape goes and when I pull the tape it does not pull any wood with it since it is applied to the epoxied area and not bare wood.
Keep checking the fillet to make sure it is cured enough to pull the tape and not set up all the way or you will have the tape as part of the fillet , usually 45 minutes to an hour is when I pull mine , the time varies with the temperature outside , hotter weather the epoxy sets up quicker.
After pulling the tape you might have a sharp edge on the fillet sticking up , a rag bunched up with some acetone on it can be brushed very lightly over it to smooth it out

 

[PerryM]

I'm taking your advice Sparkey. Dry fiited the bow, transom, sides and ribs together. Don't know how I would have gotten the sides attached to the bow stem without the help of my son-in-law! I can only imagine how difficult that would be if the sides were already glassed. i'm really happy with the look of the boat so far. It has a lot of rocker on both ends. Hope thats the way it is supposed to be. I'm glad I raised the side height to 13 1/2 inches. I know it will be heavy but thats ok with me. Really want to take the wife out in it so she can do some bird watching and she was kinda leary of the original's size. If momma ain't happy... nobody is happy. :lol:

Next I plan on fashioning a very small deck area for the bow and milling some rub rails. Then I'm gunna break her down, cut the bow stem to length, epoxy saturate some parts and finish glassing the transom. I have attached some pics below. Thanks again for the advice and support.

Perry