C17 (Classic 17) in London

[glcost]

Wobbly,

You're moving at an impressive rate even with the weather delays. I'll be following your method on fiberglassing when I get there. Sounds like a good systematic approach when working by yourself.

I have a question for you. How large of a gap did you leave between the hull panels at the bow stem? This weekend I placed the hull bottom panels and the lower side panels. I initial left a 6mm gap where the bottom panels meet at the bow. Placing the lower sides, however, pulled the bottom panel together, so there is very little gap now. I do have a 4-5mm gap between the lower side panels.

When the builder gallery is back online, I plan on starting a progress thread too.

George

[WobblyLegs]

Wobbly,

I have a question for you. How large of a gap did you leave between the hull panels at the bow stem? This weekend I placed the hull bottom panels and the lower side panels. I initial left a 6mm gap where the bottom panels meet at the bow. Placing the lower sides, however, pulled the bottom panel together, so there is very little gap now. I do have a 4-5mm gap between the lower side panels.

George

Hi George,

It may or may not be the right way to do it, but I have actually had very few gaps in the boat so far. The only place that I made sure that there was a gap between panels is along the centre-line of the boat and near the front between bottom and lower side panels.

I'm really comfortable with the joins as they are - bottom panels to transom has an angle, so there is a large wedge of epoxy glue in there.

At the front, it took quite an effort to bring the bottom panels together, and that basically forced me to have no gap along the curve (using little cylinders - cut up tent poles - inside, under the cable ties, to stop them overlapping), but the wood (at the edges) touched corner-to-corner, so I filled that groove with a fillet mixture.

With the lower side panels, the same along the chines up until the point near the front where the hard chine started to become flat with the bottom panels, where I put spacers in to force a gap of about 3mm. Where the lower side panels join at the bow, again it was corner-to-corner. I was looking over the plans after I'd filleted this joint and noticed that they say to leave a gap here, but obviously it was too late to change by then. I'm not worried - I can only imagine that my boat will be a couple of millimetres shorter as a result.

As for the bottom panels, again where the angle of join is very shallow, I put spacers in to create a 3mm-ish gap from stern up to the point where it starts curving up to the bow.

With all of these joins, I used a mixing stick to squeeze an epoxy glue (fairly thick) mixture into the gap until I could see it oozing out the other side, making sure there was enough sitting over the join to allow for absorbtion. Then removed cable ties (about a week later to be sure the glue was properly cured) and filled the spaces where they were (and all the holes left behind...).

When I get to laying the upper sides, there will probably be a substantial gap at the bow which suits me, as I'll need to create a flat area for mounting the bow-eye. The rest of the bow there, I will build up a radius of fillet mixture above and below where the eye will be, on top of the fibreglass layers.

Regards, and enjoy building (I am, still)

Wobb.

[glcost]

Yeah, my joints are all very tight. Along the keel and chine it's corner to corner between the panels for the most part. I used the bow mold and even there I have very little gap. Even though my hull is very fair, I didn't get the hump in the keel forward of frame C, I think I'll go back through and loosen the ties before gluing the joints.

Not much will happen over the next couple weeks since I'll be on holiday. First, I go up to Edmonton Canada for a rugby tournement then off to Orlando FL.

Take care,

George

[WobblyLegs]

So, it's been raining again!

But, unlike the other rain I've had to avoid so far on this project, which have been short showers followed by long, hot, dry spells (usually while I'm in the office!!), over the past two days it's been a light drizzle, fairly warm, and a relative humidity of 98%.

I think you could call it "sticky!"

So, what has this to do with the boat?

Well, the wood has started to absorb moisture and expanded. As I've recently covered the bottom with glass, this is mainly happening on the inside of the boat, and on the side panels. So, as the inside has expanded, the whole boat is changing shape. Not very good!

I don't think it's a real problem, but it is going to be a real delay as the weather is forecast to stay like this for another week or so, and then I will have to wait (hoping) for it to dry out again for me to continue building.

The pic below is of frame C, where - two days ago - the bottom panels and side panels were lying flush against the frame.





And this one is frame D, same again. The gap (again two days ago was flush) is 30mm!!!



I wonder how much moisture this wood can take before causing strain on the joints? I guess I'm about to find out...

Regards,

Wobbly.

[esparver]

... the wood has started to absorb moisture and expanded

Hi Wobbly,

As you're building outside, why don't you apply first coat of epoxy on the recently cut plywood and then sand the flat pieces before assemply? this is the way I am working with my CR11 right now and I'm sure it will avoid those problems.

I've been following your project very close as I like the C17 boat. You're doing a great job with it.

Regards,

[tech_support]

... the wood has started to absorb moisture and expanded

Hi Wobbly,

As you're building outside, why don't you apply first coat of epoxy on the recently cut plywood and then sand the flat pieces before assemply? this is the way I am working with my CR11 right now and I'm sure it will avoid those problems.

I've been following your project very close as I like the C17 boat. You're doing a great job with it.

Regards,

Not a bad idea. But wait for a few dry days first or you will seal in a high moister content.

[Welsh_diver]

I am watching this build very carefully as I plan to build a CX19 outside. Since it rains even more in Wales expansion due to moisture absorption is going to be a problem. Would it be possible to pre-coat all the plywood once it has been cut and then assemble the boat as normal?

[tech_support]

Yes, you can pre-coat it all. In a very small boat where the curves are more severe, pre-coating might make the wood more difficult to bend – but in your case it would probably be a good idea

[JASmine]

Wobbly....Looking at your recent photos I noticed that you are adding the sprayrails before you fair...IMHO it might be easier to fair if you add the spray rails after you fair the hull.
It looks great so far..good luck as you continue.

[Deadgobot]

Not a bad idea. But wait for a few dry days first or you will seal in a high moister content.

I thought about posting a question re: this topic on the Plywood board, but since you brought it up...

Do you have to take care to epoxy/fiberglass the plywood in relatively equal humidity conditions? Asked another way, is sealing in different moisture content in different panels a Bad Thing?

For a small boat like my first project, it will be easy to epoxy the whole thing at once, but as I move on to bigger boats the problem will present itself.