Jcubero's Merrimac

[jcubero]

Not much activity to report on today <sigh>. It's a wait, sand, wait some more sort of day. I sanded the butt joints then applied fiberglass tape to the front side this morning. Tonight I was able to flip the pieces over, sand and then fill some voids on the back sides of the butt joints. Now I have to wait until morning to sand that back down and fiberglass the back. That means another day before I can possibly begin stitiching.

[hairymick]

G'day Javier,

Recently, I have been applying the cloth wet on wet, over the wood flour. I wait till the epoxy in the wood flour just starts to go off then smoothe it down and lay the cloth right over the top and wet the whole lot out. No air pockets and it seems to be working fine. Saves a lot of time and sanding and I've had no problems with it so far.

I'm not sure if it affects the structural strength of the join or not. perhaps someone more experienced in this could advise.

[Kayak Jack]

Mick,

Actually, it does affect the joint strength. It helps to make it stronger. When you apply new epoxy over old, if it's done in less than about 72 hours, they bond chemically.

Otherwise, you have to sand the old to roughen it up so the new epoxy can stick to it mechanically. A chemical bond is stronger.

I like your idea of gooping peanut butter into a fillet, then applying tape & then wetting that out. GOD! I hate filleting!

[hairymick]

Hi Jack,

I like your idea of gooping peanut butter into a fillet, then applying tape & then wetting that out. GOD! I hate filleting!

Not my idea mate. When Dave (DA Wallace) visited the other day, he told me about it. I cleaned all the crap fillets I had done on my cocpit with a dremel (mate, ya gotta get one of these) re appied the fillets, waited an hour and then put the tape right over the lot. worked beautifully)

He also told me my wood flour is way to course It feels like talcum powder to me. That is why I have been having trouble smoothing it out. With this technique, it doesn't matter Just wet the glass out on top of it (before it goes hard) and all is sweetness and light. ya gotta be happy with that!!!

I used to hate filleting too, now I enjoy it.

[Kayak Jack]

I gather saw dust & dust from the catcher-basket on my orbital sander & run it through a sieve. As you say, when you lay tape over it, that covers a lot of sins. Plus, it adds strength to the joint.

[hairymick]

Mate, it doesn't so much hide the sins but fixes em. (without hours of sanding/re-filling etc.)

[Kayak Jack]

That alone will save about three knuckles per boat.

[jcubero]

A much better day today! I finished applying fiberglass to the backside of all the joints. Here it is:


It's funny, I can definitely tell the difference between my first joint and my last. The instructions say not too leave too much epoxy in the joint. However, I would definitely APPLY a lot of epoxy and squegee out the excess. It's better than having all your joints too dry. Several hours later I flipped the pieces over and sanded the back side down. I'll definitely use a single piece of fiberglass cloth next time. The overlap in the tape leaves lumps that are tough to sand out. It's still a bit wavy, but I figure I'll get a lot of that out in later coats - I didn't want to sand too much and compromise the joints. I then began working on the temp frames. A little later I sanded the other side of the fiberglass joints. Hey! I'm ready to start stitching!!
First the bottom. I put the flat sides together and drilled holes through both, like the instructions say. That worked well:


Then add the middles. I put the middle and bottom pieces together at the seam and drilled a couple holes through both. Then, with that as a reference I drilled holes in both pieces at 8" intervals, then assembled them. You can kinda see me using the spacing jig in the picture:


Also, I'm definitely seeing a lot of splintering. I was careful to use a backing board when drilling the holes - this reduces the splintering on the back side.

Finally, start putting in the frames:


It actually looks like a canoe!

Wow! I'm beat. I have to finish installing the frames tomorrow - I stopped right after that last picture. Then I can begin adding the top strip.
Since there are only three strips per side on a merrimac, it shouldn't take long to finish stitiching. that means soon I can start adjusting and fitting everything and then begin work on the seams.
That was a good day's work right there.

Question: Do you guys just drill all the stitching holes ahead of time, keeping them regular, or drill as you go? pros and cons?

[Kayak Jack]

I drill ahead. Lay the panels together, with mating edges matched. & drill. That way, you (1) are drilling two sets of holes at the same time, and (2) have a backing board.

[hairymick]

Looking real good mate.

I pre-drill all the holes along the centre/keel and then drill the side panels as I need to.

probably that is why it has taken me so long to get the hull stitched.