Suggestions for Hard Dodger Construction Please

[DennisDW]

Holy Moley Matt, There's almost no weight with the foam core construction. I can easily pick up the piece. I'd guess that it weighs 30 lbs as you see it in the photo. I've since cut out the window panels and it's probably 20 to 25lbs. It will, of course, be heavier with the windows and hatch installed but it shouldn't be and issue for virtually and sized vessel.

Go back and see an earlier reply for the material and layup schedule I used. Now then, glass over ply would be heavier but still not too bad I wouldn't think.

Yours,
Dennis
P.S. Yes, lots of little glass fibers do get through the paper suit but it would not be humanly possible to wear a tyvek suit in the heat.

[leftbrainstuff]

Originally Posted by OceanSeaSpray

Lots about the look of it, little about the way to build it! Dodgers rarely improve the look of a boat indeed... Draw it on top of a photo for a start for example.

In response to your actual question, I would use Divinycell foam core, 20mm thick in H60 grade (60kg/m^3). This is quite a standard spec for making hulls, wheelhouses etc. I have designed boats with this material and I have used a lot of it in the workshop as well. It is great stuff to work with and it lasts forever provided you do a proper job - more further down.

For a one-off hard dodger, you should be able to make a timber framework and "bend" the foam panels on it, rather than making moulds. Tie them through with plastic cable ties or similar, glue all your edges, sand them round once everything is set and glass the outside first.
After that, it will be dimensionally stable and you should be able to cut the cable ties flush, remove the mould and glass the inside.

I would do it in E-Glass/polyester as there is no benefit in using more expensive resins for something like this. Three layers of 450GSM woven roving and as little CSM as possible should give you a strong and light structure.
If you are going to fasten equipment to it and you already know where, you can replace the core with a small piece of marine ply for example, or glass one side, cut the core away from the other side and glass more heavily in the cavity etc. Standard stuff. With window cut-outs, you will have to remove/replace the core along the edges if you use through fasteners.

For curved panels especially, it is often better to glass the full panels and cut any windows afterwards. I use a simple jigsaw with a small metal blade (like a hacksaw blade). The glass in the laminate will dull it immediately, but it will keep working almost forever.

Now, most important piece of advice with foam cores: vacuum very carefully the core surface to remove all dust, wet it with resin, give it 10 minutes, make sure you get all the air out of the pores, wet it again and then lay your pre-cut glass cloth etc.
If you try to wet through or do anything else, you won't get a proper bond onto the core and this is how everything later delaminates.

Happy boatbuilding.

Good advice.

Sent from my GT-I9300 using Cruisers Sailing Forum mobile app

[DennisDW]

Phew! It's not done but it's painted and on the deck. I've spent two months of weekends sanding and fairing including one failed topcoat.

I'm pleased with the results. Especially the proportions. It looks to my eye to be an organic part of the boat. Perhaps a refined stolen phone booth even. I just hope a crewmember never asks for change to make a call.

I have yet to fabricate the window frames and install the windows but for now here a couple of shots.
Thanks again for all the help,
Dennis

[Terra Nova]

Very good looking. Nice job.

[Zach]

Great work!

[Matt Johnson]

Looks great! Wheres the photos from further away? We want the whole picture.

Matt

[Voyager269]

Very well done!!
i hope we will do the same job as good as you did.

Taco,

[ssanzone]

Originally Posted by DennisDW

Two questions please, Should I use epoxy paste to glue the foam bottom of the top to the foam edges of the side panels or just place it and start glassing? Next, how in the heck to I keep the polyester resin from curing too fast to work in the hot Florida sun? It's 92 degrees and in the direct sun, much higher.
Yours,
Dennis

If you are using Laminating Resin, add 75% of the kicker.

If you are using Epoxy, use 209 extra slow hardener.

Shade and refrigeration has also been mentioned. When I was doing a lot of glass work a few years back, I bought a 'college' fridge on craigslist for 30 dollars which enabled me to work longer without as many breaks to mix more resin.

-steve

[Paul Lefebvre]

Originally Posted by DennisDW

Go back and see an earlier reply for the material and layup schedule I used. Now then, glass over ply would be heavier but still not too bad I wouldn't think.

Yours,
Dennis
.

Dennis

I think it looks great. I went through your previous posts and can't find your layup schedule. I may be blind, but could you point me to the post or give it again. I see mention of 3/4" foam, but not the fiberglass layup schedule.

Thanks,
Paul

[ErikFinn]

That doghouse looks remarkably good.
Quite similar to the Hallberg Rassys and in my opinion they look the sweetest.
Please post more pics asap

[DennisDW]

Thanks Everyone for the kind words! I'll post photos when it's all done and try to get some from a distance if I ever quit working on it and go sailing.

It's only been a few months of weekend days but it feels like an eternity. I have reviewed my receipts and it looks like I'll have about $1300 in it for materials all told. It would be less if I had a wholesale account. I wonder how much it would have cost to have a yard build it?

Paul, Terra Nova gave me valuable advice in one of his posts. Also Zack's post has great information about design.

I used two layers of stitched coremat on the 3/4" divinyl core. I'll have to go back to those receipts for the weight. Quite honestly, it's plenty strong enough at that thickness but if I were doing it over I'd use three simply for the reason that the skin won't hold a load bearing screw. Any additional fittings I put on will have to be through bolted and backed unless they're cosmetic. I did have the prescience to bed in t-nuts for the window frames and hand holds on the top but I would like a handhold underneath at the companionway and I really couldn't decide where to put it until I start using the boat. I'm amazed at how complex such little job has turned out be. No wonder soft dodgers rule. Good luck on your project Paul.

Cheers,
Dennis

[Matt Johnson]

Was there glass over the Coremat? Isn't that just a filler and not a structural glass?

Matt

[DennisDW]

Oh, I may just be playing free and loose with terms I've heard whispered in dark corners of do it yourself yards. It was fiberglass cloth that was mat stitched to roving.

I'm sorry Matt. I'm an eye doctor and that's why I asked for advice from professionals.

Dennis

[robert sailor]

You have a good eye (no pun intended) the design is excellent. Well done!

[Matt Johnson]

Yeah, I'm always trying to understand the professional slang too. Every field has it, and it makes being a novice that much more difficult.

Matt