Dodger design

[Larks]

Looks good Rick. I’m wondering about the thinking behind using biaxial glass for the roof and double bias for the rest and why you wouldn’t just use one or the other for the lot? I used double bias for the hull and deck on mine, mostly because it was significantly cheaper to buy one roll sufficient for the whole job but also because that was what may boat builder mate recommended as suitable for both. Both weaves should contour as well as each other over the curves and edges (though I think the double bias does better wrapping around the bullnosed edges) but is there a structural reason behind using different glasses on your type of job over a foam core?

[Mike1902]

Hi Rick,
Looks like it's all coming together.
Have you given any thought to bringing the forward corner post slightly inboard, similar to the HR35 Rasmus in post #85.
The continuing line of the cabin breaks the height of the dodger, making it appear lower.

The roof overhang along each side with an eyebrow certainly helps combine the overall look. .. but that's just me.

Cheers,
Mike.

[RFNK]

Looks good Rick. I’m wondering about the thinking behind using biaxial glass for the roof and double bias for the rest and why you wouldn’t just use one or the other for the lot? I used double bias for the hull and deck on mine, mostly because it was significantly cheaper to buy one roll sufficient for the whole job but also because that was what may boat builder mate recommended as suitable for both. Both weaves should contour as well as each other over the curves and edges (though I think the double bias does better wrapping around the bullnosed edges) but is there a structural reason behind using different glasses on your type of job over a foam core?

Yes Greg, either would do, really. But the biaxial creates a stiffer roof and the double bias is easier to work around corners, joints etc. I'll be using unidirectional as well, for the posts and probably to line the inside surfaces of the rebates for the windows.

Most of this is new to me so please me if there's any sense that I know what I'm talking about! I have our friend David, a shipwright who's just finished a launch built entirely from foam and glass, another local shipwright who's built lots of composite boats, and I'm sharing the marina with Jeff Schionning, who's a pretty famous catamaran designer and those you know from the WBF. All are providing lots of valuable input although not always the same input so my 'role' is to be selective .

The dodger isn't very big so I don't really need whole rolls of material BUT, as we're still moving towards sheathing the folkboat, I will buy a roll of double bias - I think .... A few metres of biaxial doesn't add much to the cost.

I'll put the list of materials I'll actually use here for all to see, including weights of glass etc.

Today we took the boat off the marina to see the mock up from a distance. It was helpful to see how some details should be altered but, overall, I'm pretty happy with how it's shaping up:

As always, ideas are welcome!

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[Larks]

To be perfectly honest it looks just like it should size/proportion and angle wise - spot on! I can’t really imagine it being improved upon....appearance wise anyway

[RFNK]

Thanks Greg! The corners will be rounded off, the curves on the sides will be a bit smaller, the triangular windows won't be so pointy ..... stuff like that. The next step will be to mark the boat more accurately and take more accurate measurements, and then order the materials.

[willin woodworks]

Looks like it was born there.

[Stiletto]

Taking her out to look at it was a good idea. Looks good! Thanks for sharing the whole process with us.

[John B]

Neat!
Its personal preference thing I know but I like the lower window corners to be either tighly radiused or even 'squared' / mitred.

[RFNK]

Dodger details:
Roof and sides are 15mm Divynicell H80 plain foam. Roof is glassed with 600gsm biaxial, sides are 400gsm double-bias. Resin is Technirez laminating resin which is a 4:1 mix.

This is the foam fastened to the roof mould:

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This is foam cut as blanks for the sides. The foam will be glassed on both sides then cut for fitting. I hate cutting glass but it's hard getting good edges when glassing. I'll take some shots of the forming of edges later.

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[RFNK]

This is the roof mould

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[RFNK]

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These are the side 'blanks' glassed and peel ply squeegeed on. The other sides of these will be glassed tomorrow. I'll glass the roof this afternoon but I'll shape the edges of the roof beforehand.

[John B]

Interesting process...I've never worked with foam or glass apart from your basic boat cloth from time to time, maybe some patches on an old dinghy. Why the variation ? Won't one cloth do the whole job?
And how do you hold the roof section down for glassing the top.. is it relieved or some fastenings from under?

[RFNK]

Screws through battens into the foam.

Biaxial is stiffer and stronger than double-bias. Double-bias is easier to work around edges etc. So the roof will be biaxial top and bottom with double-bias around all edges and corners. With peel ply, overlaps are rendered fairly smooth so glass overlaps and edges get hidden in the fairing process.

[Besserwisser]

John convinced me to include rear posts and I'm very happy to be going that way.

What were the reasons that convinced you, if you don't mind my asking? Was it simply a matter of strength or something more complicated?

To me, the posts are a negative aesthetically but I can of course understand aesthetics being outbid by functional considerations.



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[Hugh MacD]

Looks to me like the rear posts will be great handholds when moving out from under the dodger and going forward. Maybe not the best aesthetically, but imminently practical, no? Looking good, Rick

[RFNK]

Yes, that's the reason. As you duck under the dodger, you need to steady yourself and the rear posts will serve that purpose. They also provide a solid frame to fasten clears to.

[RFNK]

Some progress
These are glassed sheets glued together with filleting mix. There's packing tape on the boat so this will be lifted off for shaping and finishing next, once I've marked out where to cut it to fit the roof.

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[RFNK]

This is the dodger body with the cavities for the windows cut out

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The edges of the cavities and the backs of the sides are routed out with a little bearing rebate bit

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This trench gets filled with a fillet mix and then the cavities get sanded back to their drawn lines. After that, I'll cut rebates all round, then glass those, for the windows. The side windows and the two front outside windows will be tempered glass but the centre window will be polycarbonate, as it will be hinged to open.

[RFNK]

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[Neil C]

Looks great, nice work

[RFNK]

Thanks Neil!

[John B]

Looks great Rick, I was wondering how it was going.

[RFNK]

Thanks JB! Tomorrow I hope to sand back to the window lines and then cut all the rebates, and make up the templates for the glass.

[willin woodworks]

Looks good from here. Nice work.

[Breakaway]

Looks great!
Thanks for having us along!

Kevin

[RFNK]

Thanks Kevin and WW!

[gypsie]

Looks perfect Rick, nice design, nice work.

[Priscilla]

Looks like I am going to be the odd one out but hey it wouldn't be for the first time ,however I would not have ever contemplated putting a hard dodger on that cracker of a sailboat boat.
Don't fix it down too aggressively as someone will want to remove it in the future.

[RFNK]

It'll be fastened down in a way that will allow later removal. Having sailed the boat from NZ and sailed it quite a lot around here over the last 8 years or so, there's never been a time when I've wanted to lower the soft dodger. I've worn out the soft dodger that came with the boat and the dodger I replaced it with over that time.

[RFNK]

Looks perfect Rick, nice design, nice work.

Thanks Trev!

[RFNK]

Some progress ....

Glass for the sides and forward wings has been ordered - 5 mm tempered. The centre, opening window will be 12 mm acrylic.

The window cavities have been rebated and then rounded off with filler. Then glassed. I glassed the vertical sides yesterday and have just glassed the horizontal sides this morning.

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Tomorrow or the next day I'll dry fit the body to the boat. This will involve putting plastic and tape on all mating surfaces on the boat and loading up the dodger body's mating surfaces with a goop of glue and fillet mix, epoxy. Then I'll start making flanges of glass that will be the fastening bases.

[RFNK]

To strengthen the internal corners of the dodger body, I'm making half-round tubes to glass into place. These can also carry wires if necessary. I've made a mould by just covering some conduit with packing tape and putting some bits of taped wood at the sides. I can make two tubes at once. The glass is pressed into shape with bits of taped wood. Two layers of 600 double bias. The finished tubes will be flexible enough to press into the corners and glued in place. They'll then be glassed to the body for strength. This is the mould with the first two tubes being pressed:

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[RFNK]

Here's the dodger body on the boat.

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Today I'll put tape on the boat to separate the dodger, then I'll run a line of bog to seat the dodger and form a better base for the sealant. Once that goes off, I'll check that the dodger hasn't stuck, put it back on and start laying glass for the flanges that'll fasten the dodger to the boat.

[Stiletto]

Looking good! Merry Christmas.

[RFNK]

Thanks, you too!