Building a Hardtop

[USA1791]

Hey everyone!

Wanted some opinion about building a hardtop dodger/Bimini.

From doing some research, I want to go with a carbon fiber/foam/carbon fiber sandwich panels.

Saw a video of them doing that on total boat and liked the look of it.

My main question is the supports. I’m not a fan of the pipe look, so would using the same sandwich method for making support beams be a good idea? Or using something else? I’m also thinking the best way is doing everything in sections. So building the dodger separately, hard bimini separate, and then the support beams separate and then bolt it all together?

Seems like a huge project and I’m just in the beginning research phase right now.
Plan on building a mold out of some plywood and then use that to build each part through the materials.

[Muaddib1116]

Check out project atticus' hard dodger build on youtube.

[Dsanduril]

There's a really beautiful solar arch support that Stevens 47 built in this thread. It's carbon and foam, lightweight. I'm envious.

[Clayfree]

Also look into Onboard Lifestyle on Youtube, they are in the middle of a hard top build now.

[coopec43]

Maybe you should have a look at this article before proceeding with your plan.


Heavy Weather Dynamics: Upwind Sailing, Windage and Resistance

[USA1791]

Originally Posted by Dsanduril

There's a really beautiful solar arch support that Stevens 47 built in this thread. It's carbon and foam, lightweight. I'm envious.

Oh wow that is gorgeous! Thanks for sharing that. Looks like a really nice idea of how he made the supports. I’m wondering how something similar would look as a support for a bimini?

[USA1791]

Originally Posted by Muaddib1116

Check out project atticus' hard dodger build on youtube.

Thanks for sharing that, was very informative and nice to see how their process went.

One of the things that got me thinking now is I’d have to move the traveler. Don’t think I’d want to move it forward since I’ve read on this forum that it could be bad structurally. So the best case would be moving it to the top of the dodger. Does anyone know if that should be beefed up with putting a wood block insert into it? Or would the cf/foam/cf panel be enough?

[Muaddib1116]

Originally Posted by USA1791

Thanks for sharing that, was very informative and nice to see how their process went.

One of the things that got me thinking now is I’d have to move the traveler. Don’t think I’d want to move it forward since I’ve read on this forum that it could be bad structurally. So the best case would be moving it to the top of the dodger. Does anyone know if that should be beefed up with putting a wood block insert into it? Or would the cf/foam/cf panel be enough?

Putting the traveler on top of the bimini is definitely possible, as long as you have the necessary clearance for the blocks and cars, but you need to be really sure about making the bimini strong enough. If you go that route, you may want to consult an engineer, or overbuild the thing like crazy.

[mvweebles]

I too thought of the Project Atticus dodger. He did a really nice job on the sides, and having watched them for years now, it's been a God send for them.

As a previous post said, fabricating and installing a hardtop capable of absorbing the point loads of a msinsheet is probably not practical. A welded metal frame would be your best option.

Good luck

Peter

[USA1791]

Originally Posted by mvweebles

I too thought of the Project Atticus dodger. He did a really nice job on the sides, and having watched them for years now, it's been a God send for them.

As a previous post said, fabricating and installing a hardtop capable of absorbing the point loads of a msinsheet is probably not practical. A welded metal frame would be your best option.

Good luck

Peter

I just hate the metal frame looks, which is the reason why I want to build a hard dodger and not have the metal/canvas option. A few extra layers and more thickness in the foam could be enough? I saw some people adding in handle bars they used a G10 insert which I’m thinking if I add in it and mount the traveler to it?

Another option would be to have a different setup with the traveler? Current boom vang is a “soft” one. Would replacing it with a rigid boom vang allow me to get rid of it? Read somewhere on this forum of someone saying that, but doing some research on that topic couldn’t find anyone else saying it. If anything, should decrease the load and make it better suited to place on the dodger?

[deltaten]

Consider encasing a metal frame in the finish frp. Incorporated into the design, it could be effective , yet pleasing to the eye....the ultimate goal of engineering.

[Joli]

We built ours from balsa and carbon fiber. We matched the deck camber but didn't add any for and aft contour, it's not a compound curve. For support we used aluminum tubing and the feet you find on Tuna towers. We can lift the whole thing of the boat and put it on a dock if we want to race, there are only 8 bolts. The dodger bimini both have soft sides, they work well unless there is heavy blue water coming across the deck. It's come down twice while beating into 45 knots and 20' waves. All in all its a great addition for cruising.

Oh, one last thing, paint the interior ceiling a darker flat color to reduce glare. Ours is sky blue, it helps air on sunny days.

[mvweebles]

Originally Posted by USA1791

I just hate the metal frame looks, which is the reason why I want to build a hard dodger and not have the metal/canvas option. A few extra layers and more thickness in the foam could be enough? I saw some people adding in handle bars they used a G10 insert which I’m thinking if I add in it and mount the traveler to it?

Another option would be to have a different setup with the traveler? Current boom vang is a “soft” one. Would replacing it with a rigid boom vang allow me to get rid of it? Read somewhere on this forum of someone saying that, but doing some research on that topic couldn’t find anyone else saying it. If anything, should decrease the load and make it better suited to place on the dodger?

I think doing it in fiberglass would be challenging - I would want to form the dodger in a single piece. Attaching it securely to the deckhouse would be important. I would use some sort of metal mechanical fastening.

Travelers are often mounted on a bridge over a companionway. Build a higher bridge that conforms to the underside of the dodger. Use something like 1/4" x 3" stainless steel bent to fit. You can either just run it beneath the dodger, or encapsulate it between layers.

If your existing traveler is already pretty long (Catalina's travelers are long due to width of companionway), you might be able to make "Z" shaped bracket on either side of the dodger (bottom of Z mounts to boat, top of Z mounts to traveler). You might need some small gussets in the crotch of the Z to provide strength.

Hope these are some helpful ideas

Peter

[USA1791]

Originally Posted by mvweebles

I think doing it in fiberglass would be challenging - I would want to form the dodger in a single piece. Attaching it securely to the deckhouse would be important. I would use some sort of metal mechanical fastening.

Travelers are often mounted on a bridge over a companionway. Build a higher bridge that conforms to the underside of the dodger. Use something like 1/4" x 3" stainless steel bent to fit. You can either just run it beneath the dodger, or encapsulate it between layers.

If your existing traveler is already pretty long (Catalina's travelers are long due to width of companionway), you might be able to make "Z" shaped bracket on either side of the dodger (bottom of Z mounts to boat, top of Z mounts to traveler). You might need some small gussets in the crotch of the Z to provide strength.

Hope these are some helpful ideas

Peter

Yeah I’d like to form it in a single piece, but I was thinking making the sides, and top and then attaching them would be easier to put together and adjust. Then just glass them together.

Z mount? What is that?

I’ve been trying to research some different options for the traveler but can’t find much and can’t find too many examples of other people putting it on the dodger. I saw harken has a dodger mounted traveler but looks like it’s for mid-boom, not sure if that makes a huge difference though.

[CassidyNZ]

When I bought my boat it had a soft top on SS tube frames (ubiquitous) with a soft screen wrapping to about a metre back on each side. Before our first voyage we had a sailmaker in San Diego attach clears all the way round. We lost that whole assembly when it got ripped off the boat in sustained 80kn.

Undeterred, I rebuilt it exactly the same when we got home (first image) and the new structure lasted right up until last year when I needed real estate to put another 600W of solar array so I went to a solid top (second image). Still on a tube frame it was quite heavy and unstable. As an interim measure I installed two diagonal SS wires across the front and that made a huge difference to the stability.

But since then I have decided to create a solid front with a three-panel glass window screen and two panels of glass in timber frames down the sides. From there the same clears will continue down the sides and around the back, all still on the SS tube frame.

Having done all the measurements and modelled the screen on Autocad, an FEA study shows very promising rigidity and the process of making the screen frames is made enormously easier by the existence of the roof structure.

I will try to remember to take pics as I go along and post them here but the process will only begin in February - a house move has left me temporarily without a workshop

Just a note on another point - seeing the instability of the back end of the structure in the FEA, there is no possible way I would exacerbate it by putting the mainsheet traveller on the roof. I reckon with the pressure of the sail combined with the boat falling off a wave, the roof would be at risk. And if the roof goes, all my instruments, solar array and other electrics would have to be cut free to jettison the roof (not to mention the loss of the solid dodger). Not on my boat.

I may still have some pics of how I built the roof if anyone is interested.