Hard Top Dodger

[gdavids]

I'm a total newbie here, so I hope I'm in the right place with my questions. I want to change the dodger on my boat, a Hylas 47, from the typical sunbrella fabric to a hard top. I would like to keep the same basic shape and use the existing stainless tube frame. The front and side windows would stay the same basic design.

I have never made anything like this, so I am looking for any and all advice. My thought is to remove all fabric and windows from the frame and then lay a core material over the top. Perhaps nida-core or something similar. I am assuming that this is flexible enough to match the curves of the frame. I would then coat the top with epoxy and lay down some glass cloth and matt. I am guessing that once this cures it would be stiff enough to hold the shape when I pull it off the frame. I would then do the same epoxy/cloth/mat on the bottom side. After doing final shaping with a saw, fairing and painting, I would bolt it to the frame.

Here are some questions:
1) Is this a reasonable approach?
2) If not, what would be a better way to go about this?
3) Is nidacore the best/easiest to work with for this sort of project?
4) I'm thinking either 1/2" or 3/4" core. Do you agree? I want this stiff, but I'm not going to get on top and jump up and down.
5) What is the best way to finish the edges?

I would greatly appreciate any and all advice you could offer. Thanks for your time.

Greg Davids

 

[Rurudyne]

I don't know if this would work, but reading the description of what you wanted to do made me wonder if you couldn't use the existing fabric already attached to the frame to staple your core material to from the underside in order to use the existing dodger on the frame like a mold. Once the top and some of sides are glassed and cured you could then pull the staples and detach the WIP from the old dodger. Then remove it and finish it up. It hopefully would be pretty much guaranteed to fit.

If the fabric isn't taunt I guess you could instead use straps of an inexpensive material that could be pulled taunt in its place.

You'll need to ask from someone who has experience with different epoxies it this approach (two separate curings) will really work.

 

[gdavids]

Good idea. The existing fabric is definitely taught.

 

[Rurudyne]

Another thought, as the fabric itself is a somewhat strong material, if it still looks good could you use it with a clear epoxy as the underside? First the core to it then use glass for the top and sides?

You'll really need advice from someone who knows before trying that. I've not even the slightest clue if how it would hold up in actual use.

 

[Blueknarr]

Welcome

Your approach is reasonable but needs slight tweeking.

Here are some questions:
1) Is this a reasonable approach?

There will be alot of resin drops on your deck if done in place.

2) If not, what would be a better way to go about this?

The core will want to "spring back" when it is released from form and flipped over. It will need to be slightly overbent so it can relax to proper shape.

3) Is nidacore the best/easiest to work with for this sort of project?

No. Nidacore is a honeycomb, so it won't be easily bent into your curves. It is also difficult for newbies to work. Foam or balsa would be a better choice for you.

4) I'm thinking either 1/2" or 3/4" core. Do you agree? I want this stiff, but I'm not going to get on top and jump up and down.

Depends on span. I think 3/4 or thicker.

5) What is the best way to finish the edges?

Wrap them in glass.

For best results, I would:
-replicate frame curves on to multiple 2x? to match depth of curve needed
-slightly exaggerate curvature
-sheet Formica to be mould of bottom of dodger.
-release agents, gelcoat, glass, core, let cure fully
-remove from mould and test fit
-rerun to mould with shims to correct fit
-replace core with non-compressibles at fasteners locations
-glass and gelcoat
-install and enjoy

Best luck

 

[JamesG123]

Have you scoured the Interwebs and boat rags to make sure no one makes one for your boat / dodger model? They will have (hopefully) built a few and tested them..